Disease Database

Abetalipoproteinemia

A rare autosomal recessive disorder causing inability to synthesize apolipoprotein B, resulting in fat malabsorption, fat-soluble vitamin deficiency, and neurological complications. Presents with acanthocytosis and severe deficiency of fat-soluble vitamins.

650,000,000 affected111 countries

Severe Acne Vulgaris

A chronic inflammatory skin condition of the pilosebaceous unit characterized by comedones, papules, pustules, nodules, and cysts. Affects 85% of adolescents but can persist into adulthood. Severe forms include nodulocystic acne and acne conglobata with risk of permanent scarring.

600,000 affected15 countries

Acromegaly

A hormonal disorder caused by excessive growth hormone production from a pituitary adenoma, usually after puberty. Causes gradual enlargement of bones and tissues, particularly hands, feet, and face.

80,000 affected17 countries

Acute Lymphoblastic Leukemia (ALL)

The most common childhood cancer, characterized by uncontrolled proliferation of immature lymphoid cells (lymphoblasts) in bone marrow and blood. Peak incidence at 2-5 years. Multiple subtypes with varying prognosis.

140,000 affected15 countries

Addison's Disease (Primary Adrenal Insufficiency)

A rare endocrine disorder where the adrenal glands do not produce sufficient cortisol and aldosterone. Often caused by autoimmune destruction of the adrenal cortex. Can be life-threatening during adrenal crisis.

366,000,000 affected111 countries

Attention-Deficit/Hyperactivity Disorder (ADHD)

A neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity. Begins in childhood and often persists into adulthood. Affects approximately 5-7% of children and 2.5-4% of adults globally. Three subtypes: predominantly inattentive, predominantly hyperactive-impulsive, and combined.

196,000,000 affected111 countries

Age-Related Macular Degeneration

Progressive degenerative disease of the macula causing central vision loss. Leading cause of irreversible blindness in adults over 50 in developed countries. Dry (atrophic) and wet (neovascular) forms.

100,000 affected19 countries

Alpha-1 Antitrypsin Deficiency

An inherited disorder causing low levels of alpha-1 antitrypsin (AAT), a protein protecting lungs from neutrophil elastase. Leads to early-onset emphysema (especially in smokers) and liver disease. Most common in European populations.

60,000 affected15 countries

Alport Syndrome

A genetic disorder affecting the collagen network of the glomerular basement membrane, causing progressive kidney disease, hearing loss, and eye abnormalities. Caused by mutations in COL4A3, COL4A4, or COL4A5 genes. X-linked form most common and severe in males.

55,000,000 affected15 countries

Alzheimer's Disease

A progressive neurodegenerative brain disorder and the most common cause of dementia. Characterized by amyloid plaques and neurofibrillary tangles. Risk increases significantly with age, though not a normal part of aging.

Amyloidosis

A group of diseases characterized by abnormal protein (amyloid) deposition in tissues and organs, disrupting normal function. Can affect heart, kidneys, liver, spleen, nervous system, and digestive tract. Multiple types including AL (light chain), ATTR (transthyretin), and AA (secondary) amyloidosis.

Amyotrophic Lateral Sclerosis (ALS)

A progressive neurodegenerative disease affecting upper and lower motor neurons, leading to muscle weakness, atrophy, spasticity, and ultimately respiratory failure. Average survival 3-5 years from symptom onset. No cure.

Angelman Syndrome

A neurogenetic disorder caused by deletion or mutation of UBE3A gene on maternal chromosome 15. Characterized by severe developmental delay, speech impairment, ataxia, seizures, and happy demeanor with frequent laughing/smiling.

15,000,000 affected111 countries

Ankylosing Spondylitis

A chronic inflammatory arthritis primarily affecting the axial skeleton (spine and sacroiliac joints), causing pain, stiffness, and potential fusion. A form of spondyloarthritis. Strong association with HLA-B27. Onset typically in young adulthood.

301,000,000 affected111 countries

Anxiety Disorders (Generalized)

A group of mental health conditions characterized by excessive fear, worry, and related behavioral disturbances. Generalized Anxiety Disorder (GAD) involves persistent, uncontrollable worry about everyday things. Most common mental health disorder.

Aplastic Anemia

A rare serious condition where the bone marrow fails to produce sufficient blood cells (pancytopenia). Can be idiopathic, autoimmune, or caused by toxins, radiation, or certain medications. Median age of onset 25 years.

262,000,000 affected111 countries

Asthma

Chronic inflammatory airway disease causing reversible bronchospasm, wheezing, dyspnea. Affects 262 million globally. Can be life-threatening during severe attacks.

Ataxia-Telangiectasia

A rare neurodegenerative disorder caused by ATM gene mutations affecting DNA repair. Characterized by progressive cerebellar ataxia, ocular telangiectasia, immunodeficiency, and increased cancer risk (particularly lymphoma and leukemia).

60,000,000 affected111 countries

Atrial Fibrillation

The most common sustained cardiac arrhythmia, characterized by chaotic electrical activity in the atria leading to irregular ventricular response. Increases risk of stroke five-fold and heart failure. Prevalence increases with age, affecting ~10% of people over 80.

78,000,000 affected111 countries

Autism Spectrum Disorder (ASD)

A complex neurodevelopmental condition characterized by challenges with social communication and interaction, and restricted, repetitive patterns of behavior, interests, or activities. Spectrum disorder ranging from mild to severe. Affects approximately 1-2% of population, more common in males.

500,000 affected19 countries

Autoimmune Hepatitis

A chronic liver disease in which the immune system attacks the liver, causing inflammation and potentially leading to cirrhosis and liver failure. Can occur at any age, more common in women. Often associated with other autoimmune conditions.

50,000 affected22 countries

Autoimmune Polyglandular Syndrome

A group of disorders characterized by autoimmune destruction of multiple endocrine glands. Type 1 (AIRE gene): mucocutaneous candidiasis, hypoparathyroidism, adrenal insufficiency. Type 2: adrenal insufficiency, autoimmune thyroid disease, type 1 diabetes.

Bartter Syndrome

A group of renal tubular disorders affecting salt reabsorption in thick ascending limb of Henle. Characterized by salt wasting, hypokalemia, metabolic alkalosis, and hypercalciuria. Several genetic types with different severity.

150,000,000 affected30 countries

Beta-Thalassemia Minor (Trait)

Carrier state of beta-thalassemia with one normal and one mutated beta-globin gene. Mild microcytic anemia, usually asymptomatic. Important for genetic counseling as carriers can have children with thalassemia major if partner also carrier.

45,000,000 affected111 countries

Bipolar Disorder

A mental health condition causing extreme mood swings including emotional highs (mania/hypomania) and lows (depression). Formerly called manic depression. Types I and II. Affects approximately 2.8% of adults globally.

1,200,000 affected15 countries

BRCA1/BRCA2 Hereditary Breast-Ovarian Cancer Syndrome

Hereditary cancer syndrome caused by mutations in BRCA1 or BRCA2 tumor suppressor genes. Significantly increased lifetime risk of breast cancer (up to 70%), ovarian cancer (up to 44%), prostate cancer, and pancreatic cancer.

17,000,000 affected111 countries

Bronchiectasis

A chronic lung condition characterized by permanent abnormal dilation and destruction of bronchial walls, leading to impaired mucus clearance, recurrent infections, and progressive lung damage. Often underdiagnosed. Can be post-infectious or associated with underlying conditions.

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Cataracts

A clouding of the normally clear lens of the eye, leading to decreased vision. Most commonly age-related but can be congenital or secondary to other conditions. Leading cause of blindness globally but highly treatable.

95,000,000 affected111 countries

70,000,000 affected15 countries

Celiac Disease

An immune-mediated enteropathy triggered by gluten ingestion in genetically susceptible individuals (HLA-DQ2 or DQ8). Autoantibodies (tTG-IgA) cause villous atrophy in small intestine. Associated with dermatitis herpetiformis and increased lymphoma risk.

14,000 affected15 countries

Neuronal Ceroid Lipofuscinosis (NCL)

A group of progressive neurodegenerative disorders (Batten disease) causing accumulation of lipopigments in neurons. Multiple types with different ages of onset. Cause blindness, seizures, dementia, and premature death.

2,800,000 affected15 countries

Charcot-Marie-Tooth Disease

The most common inherited neurological disorder (hereditary motor and sensory neuropathy), affecting peripheral nerves. Progressive muscle weakness and sensory loss, particularly in feet and hands. Multiple genetic subtypes.

2,000,000 affected92 countries

Chikungunya

A mosquito-borne viral disease transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Causes sudden onset fever and severe joint pain. First identified in Tanzania in 1952. Name means 'that which bends up' describing the stooped posture from joint pain.

Chronic Granulomatous Disease (CGD)

A group of inherited immunodeficiencies affecting phagocytic cells' ability to kill intracellular pathogens due to NADPH oxidase defects. X-linked (CYBB) most common; autosomal recessive forms (CYBA, NCF1, NCF2, NCF4) also occur.

850,000,000 affected15 countries

Chronic Kidney Disease (Stages 4-5)

The gradual, irreversible loss of kidney function over months to years. Stage 4 (eGFR 15-29 mL/min) and Stage 5/end-stage renal disease (eGFR <15 mL/min or dialysis) require renal replacement therapy. Leading causes: diabetes and hypertension.

850,000,000 affected111 countries

Chronic Kidney Disease (Stage 4-5)

Progressive, irreversible loss of kidney function over months to years. Stage 4 (eGFR 15-29 mL/min) and Stage 5/end-stage renal disease (eGFR <15 mL/min or dialysis). Requires renal replacement therapy. Leading causes: diabetes and hypertension.

400,000 affected16 countries

Chronic Lymphocytic Leukemia (CLL)

The most common adult leukemia in Western countries, characterized by clonal proliferation of mature B lymphocytes. Often indolent with watchful waiting for early stage. Median age at diagnosis 70 years. Can transform to aggressive Richter syndrome.

1,200,000 affected111 countries

Chronic Pancreatitis

A progressive inflammatory disease of the pancreas causing permanent structural damage and loss of function. Characterized by chronic abdominal pain, exocrine insufficiency (malabsorption), and endocrine insufficiency (diabetes). Most commonly caused by alcohol.

40,000,000 affected15 countries

Chronic Venous Insufficiency

A condition where vein walls and/or valves in the leg veins don't work effectively, making it difficult for blood to return to the heart. Can lead to skin changes, ulcers, and quality of life impairment.

Chronic Inflammatory Demyelinating Polyneuropathy

A rare autoimmune disorder causing progressive weakness and sensory loss due to immune-mediated demyelination of peripheral nerves. Chronic counterpart to Guillain-Barré syndrome. Requires ongoing treatment to prevent progression.

120,000,000 affected111 countries

Cirrhosis

End-stage liver disease characterized by replacement of normal hepatic architecture with fibrosis and regenerative nodules. Results from chronic liver injury. Irreversible but progression can be halted.

12,000,000 affected18 countries

Cleft Lip and Palate

Congenital facial malformations occurring when tissues don't fuse properly during fetal development. Can affect lip alone, palate alone, or both. Most common craniofacial birth defect. Multifactorial etiology with genetic and environmental components.

1,000,000 affected111 countries

Cluster Headache

An extremely painful primary headache disorder characterized by severe unilateral orbital, supraorbital, or temporal pain lasting 15-180 minutes, occurring in clusters (periods of frequent attacks). Known as 'suicide headache' due to intensity. More common in men.

900,000 affected15 countries

Metastatic Colorectal Cancer

Colon or rectal cancer that has spread to distant organs (liver, lung, peritoneum). Stage IV disease is generally considered incurable, though some patients with limited metastases may achieve long-term survival or cure with aggressive multimodal therapy.

Common Variable Immunodeficiency (CVID)

The most common symptomatic primary immunodeficiency in adults, characterized by hypogammaglobulinemia with impaired antibody responses. Diverse genetic causes in subset; often sporadic. Increased risk of autoimmune disease and lymphoma.

200,000 affected17 countries

Congenital Adrenal Hyperplasia (CAH)

A group of autosomal recessive disorders affecting adrenal steroidogenesis. Most common is 21-hydroxylase deficiency causing cortisol and aldosterone deficiency with androgen excess. Can cause life-threatening salt-wasting crisis in newborns.

Congenital Cataracts

Opacification of the lens present at birth or developing in early childhood. Can be isolated or associated with genetic syndromes, metabolic disorders, or intrauterine infections. Leading treatable cause of childhood blindness.

35,000 affected15 countries

Congenital Diaphragmatic Hernia (CDH)

A birth defect where the diaphragm fails to form completely, allowing abdominal organs to move into the chest and compress lungs. Causes pulmonary hypoplasia and pulmonary hypertension. Life-threatening condition requiring immediate intervention.

Critical Congenital Heart Defects

A group of structural heart defects present at birth that require intervention in infancy. Includes hypoplastic left heart syndrome, transposition of the great arteries, tetralogy of Fallot, coarctation of aorta, and single ventricle defects.

Congenital Muscular Dystrophy

A group of muscular dystrophies presenting at birth or early infancy with hypotonia, muscle weakness, and contractures. Multiple subtypes including merosin-deficient, Ullrich, and LMNA-related. Variable severity and progression.

65,000,000 affected38 countries

Congestive Heart Failure (CHF)

Chronic progressive condition where heart muscle cannot pump enough blood to meet body needs. End-stage of many cardiac diseases with poor prognosis.

328,000,000 affected15 countries

Chronic Obstructive Pulmonary Disease

A chronic inflammatory lung disease causing obstructed airflow, including emphysema and chronic bronchitis. Third leading cause of death worldwide. Primarily caused by smoking, but also air pollution and occupational exposures. Characterized by irreversible airflow limitation.

100,000,000 affected111 countries

Severe COPD

Advanced chronic obstructive pulmonary disease (GOLD grades 3-4, FEV1 <50% predicted). Characterized by persistent respiratory symptoms and airflow limitation. Third leading cause of death globally. Severe disease significantly impairs quality of life and increases mortality.

200,000,000 affected39 countries

Coronary Artery Disease (CAD)

Atherosclerotic narrowing of coronary arteries reducing blood flow to heart muscle. Leading cause of death globally.

775,000,000 affected111 countries

COVID-19

Respiratory illness caused by SARS-CoV-2 virus. Global pandemic 2020-2023. Range from asymptomatic to severe pneumonia, ARDS, death. Long COVID affects millions.

65,000,000 affected111 countries

Long COVID (Post-Acute Sequelae of SARS-CoV-2)

Persistent symptoms following acute COVID-19 infection, lasting weeks to months after initial recovery. Affects multiple organ systems. Estimated 10-30% of COVID-19 survivors develop long COVID. Symptoms can be debilitating and fluctuating.

Craniosynostosis

Premature fusion of one or more cranial sutures leading to abnormal skull shape. Can be isolated or part of syndromes (Apert, Crouzon, Pfeiffer). Increased intracranial pressure risk with multiple suture involvement.

2,000 affected15 countries

Creutzfeldt-Jakob Disease (CJD)

A rare, fatal prion disease causing rapidly progressive dementia. Sporadic CJD (85% of cases), genetic (10-15%), and acquired/variant (<1%). Caused by misfolded prion protein (PrP^Sc) leading to spongiform changes in brain. Always fatal within months.

3,200,000 affected15 countries

Crohn's Disease

A type of inflammatory bowel disease (IBD) causing chronic inflammation of the gastrointestinal tract from mouth to anus, most commonly affecting the ileum and colon. Transmural inflammation can cause strictures, fistulas, and abscesses.

40,000 affected15 countries

Cushing's Syndrome

A disorder caused by prolonged exposure to high cortisol levels, either from exogenous steroids or endogenous overproduction (pituitary adenoma, adrenal tumor, or ectopic ACTH). Affects metabolism and multiple organ systems.

70,000 affected15 countries

Cystic Fibrosis

An autosomal recessive disorder caused by mutations in the CFTR gene on chromosome 7, affecting chloride ion transport. Results in thick, sticky mucus buildup in lungs, pancreas, and other organs, leading to severe respiratory and digestive problems.

150,000 affected33 countries

Cystinuria

An inherited disorder of renal amino acid transport causing excessive urinary excretion of cystine and other dibasic amino acids. Cystine precipitates forming recurrent kidney stones (cystine calculi), potentially leading to renal damage.

10,000,000 affected15 countries

Deep Vein Thrombosis (DVT)

Formation of a blood clot in a deep vein, usually in the legs. Can lead to pulmonary embolism, a life-threatening complication. Part of venous thromboembolism (VTE). Requires immediate anticoagulation.

Vascular Dementia

Cognitive decline caused by impaired blood flow to the brain, typically from strokes or small vessel disease. Second most common dementia after Alzheimer's. Often coexists with Alzheimer's (mixed dementia). Stepwise progression correlating with vascular events.

390,000,000 affected143 countries

Dengue Fever

Mosquito-borne viral infection caused by dengue virus (4 serotypes). Transmitted by Aedes aegypti and Aedes albopictus. 100-400 million infections annually. Can progress to severe dengue (dengue hemorrhagic fever/shock syndrome).

Dent Disease

An X-linked recessive renal tubular disorder caused by CLCN5 or OCRL1 mutations. Characterized by low-molecular-weight proteinuria, hypercalciuria, nephrocalcinosis, kidney stones, and progressive renal failure. Often presents in childhood.

Diabetes Insipidus

A disorder of water balance causing excessive urination and thirst due to insufficient ADH (central DI) or kidney resistance to ADH (nephrogenic DI). Distinct from diabetes mellitus despite similar name.

10,000,000 affected92 countries

Type 1 Diabetes (Juvenile Diabetes)

An autoimmune condition where the pancreas produces little or no insulin. Previously known as juvenile diabetes, it typically appears during childhood or adolescence but can develop in adults. Requires lifelong insulin therapy.

462,000,000 affected138 countries

Type 2 Diabetes (Adult-Onset Diabetes)

A chronic metabolic disorder characterized by high blood sugar, insulin resistance, and relative lack of insulin. The most common form of diabetes, accounting for 90-95% of cases. Often preventable and sometimes reversible with lifestyle changes.

146,000,000 affected111 countries

Diabetic Retinopathy

A diabetes complication affecting the eyes, caused by damage to blood vessels in the retina. Leading cause of blindness in working-age adults. Can progress from mild non-proliferative to proliferative retinopathy with neovascularization.

2,000,000 affected16 countries

Dilated Cardiomyopathy (DCM)

A condition in which the heart's main pumping chamber (left ventricle) becomes enlarged and weakened, reducing the heart's ability to pump blood effectively. Can lead to heart failure and sudden cardiac death.

15,000,000 affected15 countries

Diverticulitis

Inflammation or infection of diverticula (small pouches that form in the colon wall). Common in older adults in Western countries. Can range from mild to severe with complications like abscess, perforation, or fistula formation.

250,000 affected15 countries

Duchenne Muscular Dystrophy (DMD)

An X-linked recessive disorder caused by mutations in the DMD gene encoding dystrophin, essential for muscle fiber integrity. Primarily affects males (1 in 3,500-5,000 male births), causing progressive muscle degeneration and weakness.

35,000 affected35 countries

Ebola Virus Disease

A rare but severe, often fatal hemorrhagic fever caused by Ebola virus. Zoonotic disease transmitted from wild animals to humans, then human-to-human. Case fatality rate 25-90% depending on outbreak. West Africa 2014-2016 outbreak: 28,000+ cases.

230,000,000 affected111 countries

Atopic Dermatitis (Eczema)

A chronic, relapsing inflammatory skin condition characterized by intense itching, dry skin, and eczematous lesions. Part of the 'atopic triad' with asthma and allergic rhinitis. Affects up to 20% of children and 10% of adults. Often begins in infancy.

Ehlers-Danlos Syndromes (EDS)

A group of heritable connective tissue disorders affecting collagen structure or processing. Thirteen subtypes with varying severity. Most common: hypermobile EDS (hEDS) and classical EDS. Vascular EDS (vEDS) most dangerous due to arterial/organ rupture risk.

Emery-Dreifuss Muscular Dystrophy

A muscular dystrophy characterized by joint contractures (elbows, ankles, spine), slowly progressive muscle wasting and weakness, and cardiac conduction defects. X-linked (EDMD1/EMD), autosomal dominant (EDMD2/LMNA, EDMD3), and recessive forms.

190,000,000 affected15 countries

Endometriosis

A chronic inflammatory condition where tissue similar to the uterine lining grows outside the uterus, causing pain, inflammation, and infertility. Affects approximately 10% of reproductive-age women. Often underdiagnosed for years.

Epilepsy

Chronic neurological disorder characterized by recurrent, unprovoked seizures due to excessive neuronal activity in brain. Affects 50 million people worldwide. Many types: focal, generalized, unknown onset. Often begins in childhood or after age 65.

8,000,000 affected15 countries

Refractory (Drug-Resistant) Epilepsy

Epilepsy that does not respond adequately to two or more appropriately chosen and tolerated anti-seizure medications. Affects approximately one-third of the 50 million people worldwide with epilepsy. Can result from various structural, genetic, or metabolic causes.

600,000 affected15 countries

Esophageal Cancer

Cancer of the esophagus, with two main types: adenocarcinoma (associated with Barrett's esophagus, Western countries) and squamous cell carcinoma (associated with smoking, alcohol, hot beverages, Eastern countries). Often diagnosed at advanced stage with poor prognosis.

Essential Thrombocythemia

A chronic myeloproliferative neoplasm characterized by overproduction of platelets (thrombocytosis), increasing risk of blood clots and bleeding. Usually driven by JAK2, CALR, or MPL mutations. Can progress to myelofibrosis or acute leukemia.

Ewing Sarcoma

The second most common bone tumor in children and adolescents, characterized by EWSR1-ETS gene fusions. Can occur in bone or soft tissue (extraosseous Ewing). Peak incidence in adolescence. Highly aggressive but chemotherapy-responsive.

8,000 affected15 countries

Fabry Disease

An X-linked lysosomal storage disorder caused by GLA gene mutation, resulting in alpha-galactosidase A deficiency. Globotriaosylceramide (Gb3) accumulates in cells. Affects males more severely; females can be symptomatic. Leads to renal failure, cardiac disease, stroke.

Facioscapulohumeral Dystrophy (FSHD)

The third most common muscular dystrophy, characterized by progressive weakness of facial, scapular, and humeral muscles. Caused by abnormal expression of DUX4 gene due to contraction of D4Z4 repeats. Variable severity even within families.

34,000,000 affected19 countries

Familial Hypercholesterolemia

An inherited disorder of cholesterol metabolism causing severely elevated LDL cholesterol from birth. Autosomal dominant. Heterozygous: 1 in 250; Homozygous: 1 in 300,000. Causes premature cardiovascular disease if untreated.

Fanconi Anemia

A rare inherited bone marrow failure syndrome caused by mutations in DNA repair genes. Characterized by pancytopenia, congenital abnormalities, and increased risk of leukemia and solid tumors. 22 different complementation groups identified.

Fatal Familial Insomnia (FFI)

An extremely rare autosomal dominant prion disease caused by D178N mutation in PRNP gene with methionine at codon 129. Characterized by progressive inability to sleep, autonomic dysfunction, and eventual death. Onset typically age 40-60.

50 affected15 countries

2,000,000,000 affected138 countries

Nonalcoholic Fatty Liver Disease (NAFLD)

A condition in which excess fat builds up in the liver, not due to alcohol use. The most common chronic liver disease worldwide, affecting 25% of the global population. Ranges from simple steatosis to nonalcoholic steatohepatitis (NASH) which can progress to cirrhosis.

40,000,000 affected111 countries

Fibromyalgia

A chronic disorder characterized by widespread musculoskeletal pain, fatigue, sleep disturbances, and cognitive difficulties. Central sensitization syndrome where pain signals are amplified. Affects 2-4% of population, predominantly women.

Fish Eye Disease

A rare disorder of HDL metabolism caused by LCAT deficiency. Named for corneal opacities that resemble fish eyes. Very low HDL cholesterol but milder than complete LCAT deficiency. Cardiovascular risk unclear.

500 affected15 countries

540,000 affected15 countries

Focal Segmental Glomerulosclerosis (FSGS)

A rare kidney disorder characterized by scarring (sclerosis) in scattered regions (focal) of the kidney's glomeruli (segmental). It is a leading cause of nephrotic syndrome and end-stage renal disease. Can be primary (idiopathic) or secondary to various conditions including genetic mutations, infections, or drug toxicity.

Fibrodysplasia Ossificans Progressiva (FOP)

An extremely rare genetic disorder where muscle and connective tissue progressively turns into bone (heterotopic ossification). Caused by ACVR1/ALK2 gene mutation. Flare-ups often triggered by trauma, injections, or viral illness. Second skeleton eventually restricts movement.

800 affected15 countries

Friedreich Ataxia

The most common inherited ataxia, caused by GAA triplet repeat expansion in FXN gene. Progressive gait ataxia, sensory neuropathy, cardiomyopathy, and diabetes. Autosomal recessive. Onset typically adolescence.

Galactosemia

An inherited disorder affecting galactose metabolism due to deficiency of GALT, GALK, or GALE enzymes. Classic galactosemia (GALT deficiency) is most severe. Galactose-1-phosphate accumulates, causing multi-organ damage if untreated.

250,000,000 affected15 countries

Gallstone Disease (Cholelithiasis)

Formation of stones in the gallbladder, commonly cholesterol or pigment stones. Very common in adults, especially women. Can be asymptomatic or cause biliary colic, cholecystitis, or other complications.

200,000,000 affected138 countries

Gastritis

Inflammation of the stomach lining. Can be acute (sudden onset) or chronic (long-term). Common causes include H. pylori infection, NSAID use, and excessive alcohol consumption. Can lead to ulcers and increased stomach cancer risk if untreated.

1,500,000,000 affected138 countries

Gastroesophageal Reflux Disease (GERD)

A chronic digestive disease where stomach acid or bile irritates the food pipe lining. Occurs when the lower esophageal sphincter relaxes abnormally or weakens. Affects approximately 20% of adults in Western countries. Can lead to serious complications if untreated.

Gastroschisis

A congenital abdominal wall defect where intestines protrude through a defect usually to the right of the umbilicus. Not covered by protective membrane (unlike omphalocele). Increasing incidence worldwide, especially in young mothers.

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Gaucher Disease

The most common lysosomal storage disorder, caused by deficiency of glucocerebrosidase (GBA gene). Glucocerebroside accumulates in macrophages (Gaucher cells) in spleen, liver, bone marrow. Three types: Type 1 (non-neuronopathic, most common), Types 2 & 3 (neuronopathic).

21,000,000 affected138 countries

Gestational Diabetes Mellitus

Diabetes diagnosed for the first time during pregnancy. Affects approximately 2-10% of pregnancies worldwide. Increases risk of complications for both mother and baby but usually resolves after delivery. Women with GDM have 50% lifetime risk of developing type 2 diabetes.

200,000,000 affected111 countries

Giardiasis

An intestinal infection caused by the parasite Giardia lamblia (also called Giardia intestinalis or duodenalis). Common waterborne disease causing diarrhea, gas, and stomach cramps. Most common intestinal parasitic disease in US.

300,000,000 affected15 countries

Gilbert Syndrome

A benign genetic condition causing mild unconjugated hyperbilirubinemia due to reduced UDP-glucuronosyltransferase activity. Affected individuals have intermittent mild jaundice, often triggered by fasting, illness, or stress. No treatment needed.

Gitelman Syndrome

A renal tubular disorder caused by SLC12A3 mutations affecting thiazide-sensitive NaCl cotransporter. Characterized by hypokalemia, hypomagnesemia, metabolic alkalosis, and hypocalciuria. Milder than Bartter syndrome, often diagnosed in adolescence/adulthood.

80,000,000 affected111 countries

Glaucoma

A group of eye conditions damaging the optic nerve, often due to abnormally high pressure in the eye (intraocular pressure). Leading cause of irreversible blindness worldwide. Primary open-angle glaucoma most common; angle-closure glaucoma is emergency.

250,000 affected15 countries

Glioblastoma Multiforme (GBM)

The most common and aggressive malignant primary brain tumor in adults. Characterized by necrosis, microvascular proliferation, and cellular atypia. Median survival 15-18 months with standard treatment despite aggressive therapy. IDH-wildtype is most common.

400,000,000 affected63 countries

Glucose-6-Phosphate Dehydrogenase Deficiency

The most common enzyme deficiency worldwide, causing hemolytic anemia with oxidative stress. X-linked. Affects 400 million people, most commonly in malaria-endemic regions (protective against malaria). Triggers include fava beans, certain drugs, infections.

Glycogen Storage Disease Type I (Von Gierke)

An inherited disorder affecting glycogen metabolism due to glucose-6-phosphatase deficiency. Glycogen accumulates in liver and kidneys causing hepatomegaly, hypoglycemia, and lactic acidosis. Several subtypes with varying severity.

Goodpasture Syndrome (Anti-GBM Disease)

A rare autoimmune disease where antibodies attack the basement membrane in lungs and kidneys, causing rapidly progressive glomerulonephritis and pulmonary hemorrhage. Medical emergency with high mortality if untreated.

55,000,000 affected111 countries

Chronic Gout

A chronic inflammatory arthritis caused by hyperuricemia and deposition of monosodium urate crystals in joints and tissues. Characterized by recurrent acute flares and progressive joint damage. Associated with metabolic syndrome, cardiovascular disease, and chronic kidney disease.

3,000,000 affected17 countries

Graves' Disease

An autoimmune disorder causing hyperthyroidism due to thyroid-stimulating immunoglobulins (TSI) activating the TSH receptor. Associated with Graves' ophthalmopathy (thyroid eye disease) and dermopathy.

Guillain-Barré Syndrome

An acute inflammatory demyelinating polyradiculoneuropathy causing rapid-onset muscle weakness and paralysis. Autoimmune attack on peripheral nerves, often triggered by infections. Medical emergency requiring immediate treatment.

14,000,000 affected15 countries

Hashimoto's Thyroiditis

The most common cause of hypothyroidism in iodine-sufficient regions. An autoimmune disorder where antibodies (anti-TPO, anti-thyroglobulin) attack the thyroid gland. Strongly associated with other autoimmune diseases. More common in women (5-10:1).

100,000,000 affected111 countries

Heart Valve Disease

Structural abnormalities of one or more heart valves (aortic, mitral, tricuspid, pulmonic) causing stenosis (narrowing) or regurgitation (leakage). Can be congenital or acquired. Aortic stenosis most common in elderly; rheumatic heart disease prevalent in developing countries.

Hereditary Hemochromatosis

An inherited disorder causing excessive iron absorption and deposition in organs, leading to organ damage. Most common form caused by HFE gene mutations (C282Y). Called 'bronze diabetes' historically due to skin pigmentation and diabetes.

Hemolytic Uremic Syndrome (HUS)

A serious condition affecting blood and kidneys, characterized by hemolytic anemia, thrombocytopenia, and acute kidney injury. Most commonly caused by Shiga toxin-producing E. coli (STEC) infection. Atypical HUS is complement-mediated.

400,000 affected111 countries

Hemophilia A and B

Rare inherited bleeding disorders caused by deficiency in clotting factor VIII (Hemophilia A) or IX (Hemophilia B/Christmas disease). X-linked recessive inheritance affecting primarily males. Characterized by prolonged bleeding after injury, surgery, or spontaneous bleeding into joints and muscles.

296,000,000 affected15 countries

Chronic Hepatitis B

A viral infection of the liver caused by the hepatitis B virus (HBV). While vaccines prevent infection, there is no cure for chronic cases. HBV persists as covalently closed circular DNA (cccDNA) in hepatocytes. Can lead to cirrhosis and hepatocellular carcinoma.

58,000,000 affected156 countries

Hepatitis C

Viral infection causing liver inflammation, transmitted via blood. Often chronic, leading to cirrhosis and liver cancer. Curable with direct-acting antivirals (DAAs). 58 million chronically infected.

58,000,000 affected111 countries

Chronic Hepatitis C

A viral infection caused by hepatitis C virus (HCV) that causes liver inflammation, potentially leading to cirrhosis, hepatocellular carcinoma, and liver failure. Chronic infection develops in 75-85% of acute cases. Curable with direct-acting antivirals.

12,000 affected15 countries

Hepatoblastoma

The most common malignant liver tumor in children, usually occurring before age 3. Associated with prematurity, low birth weight, and Beckwith-Wiedemann syndrome. Rising incidence correlates with improved survival of premature infants.

Hereditary Angioedema (HAE)

An autosomal dominant disorder causing recurrent episodes of severe swelling (angioedema) affecting skin, gastrointestinal tract, and airway. Caused by C1 inhibitor deficiency (HAE types I/II) or factor XII mutation (HAE type III).

20,000,000 affected15 countries

Hernia (Inguinal and Ventral)

Protrusion of an organ or tissue through an abnormal opening, commonly occurring in the abdominal wall. Inguinal hernias most common in men, umbilical and incisional hernias also frequent. Can lead to serious complications if strangulated.

3,700,000,000 affected15 countries

Herpes Simplex Virus (HSV)

A lifelong viral infection with two types: HSV-1 (primarily oral, increasingly genital) and HSV-2 (primarily genital). Virus establishes latency in sensory ganglia. Reactivates periodically causing recurrent outbreaks. Highly prevalent worldwide.

39,000,000 affected15 countries

HIV/AIDS

Human Immunodeficiency Virus attacks CD4+ T cells, progressively weakening the immune system. Without treatment, progresses to Acquired Immunodeficiency Syndrome (AIDS). Transmitted through blood, sexual contact, and mother-to-child. First described in 1981.

Hodgkin Lymphoma

A lymphoid malignancy characterized by Reed-Sternberg cells in lymph nodes. Bimodal age distribution (young adults and elderly). Two main types: classical Hodgkin lymphoma (nodular sclerosis, mixed cellularity, lymphocyte-rich, lymphocyte-depleted) and nodular lymphocyte-predominant.

600,000,000 affected15 countries

Human Papillomavirus (HPV)

The most common sexually transmitted infection. Over 200 types exist; low-risk types cause warts, high-risk types (16, 18, 31, 33, 45, etc.) cause cancers. Virus persists in epithelial cells. Most infections clear spontaneously but some become persistent.

850,000 affected15 countries

Huntington's Disease

A hereditary neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the HTT gene on chromosome 4. It causes progressive breakdown of nerve cells in the brain, affecting movement, cognition, and psychiatric health. Inheritance is autosomal dominant with complete penetrance.

Primary Hyperparathyroidism

Overproduction of parathyroid hormone (PTH) usually due to a parathyroid adenoma, causing hypercalcemia. Most common cause of hypercalcemia in outpatients. Often asymptomatic but can cause kidney stones, osteoporosis, and neuropsychiatric symptoms.

15,000,000 affected138 countries

Hyperthyroidism (Overactive Thyroid)

A condition where the thyroid gland produces too much thyroid hormone (T3 and T4). Accelerates the body's metabolism, causing unintentional weight loss, rapid heartbeat, sweating, and nervousness. Graves' disease is the most common cause.

2,000,000 affected16 countries

Hypertrophic Cardiomyopathy (HCM)

A genetic condition characterized by abnormal thickening (hypertrophy) of the heart muscle, most commonly the interventricular septum. Can obstruct blood flow and cause arrhythmias. Leading cause of sudden cardiac death in young athletes.

Hypoparathyroidism

Deficiency of parathyroid hormone causing hypocalcemia and hyperphosphatemia. Most commonly due to thyroid/parathyroid surgery; can be autoimmune, genetic (DiGeorge, activating CaSR mutations), or idiopathic.

Hypopituitarism

Deficiency of one or more pituitary hormones affecting growth, metabolism, reproduction, and stress response. Can be congenital, due to tumors, trauma, radiation, or autoimmune. Requires lifelong hormone replacement.

200,000,000 affected138 countries

Hypothyroidism (Underactive Thyroid)

A condition where the thyroid gland doesn't produce enough thyroid hormones. Slows down many of the body's functions. Hashimoto's thyroiditis is the most common cause in developed countries. Can occur at any age but is more common in older women.

3,000,000 affected17 countries

Idiopathic Pulmonary Fibrosis (IPF)

A chronic, progressive, and ultimately fatal lung disease characterized by scarring (fibrosis) of the lung tissue without known cause. The fibrosis is irreversible and leads to progressive decline in lung function, making breathing increasingly difficult.

2,500,000 affected15 countries

IgA Nephropathy (Berger's Disease)

The most common form of glomerulonephritis worldwide, caused by deposition of IgA antibodies in the glomeruli. Often presents with hematuria following upper respiratory infections. Can progress to chronic kidney disease.

1,000,000,000 affected111 countries

Influenza (Seasonal Flu)

Viral respiratory infection caused by influenza A and B viruses. Annual epidemics causing significant morbidity and mortality. Vaccine composition updated yearly.

5,000,000 affected16 countries

Interstitial Lung Disease (ILD)

A large group of disorders characterized by inflammation and scarring of the interstitium (tissue and space around air sacs). Includes over 200 different conditions, many of unknown cause. Progressive fibrosis leads to impaired gas exchange and respiratory failure.

780,000,000 affected111 countries

Irritable Bowel Syndrome (IBS)

A common functional gastrointestinal disorder affecting the large intestine, characterized by abdominal pain and altered bowel habits (diarrhea, constipation, or both). Brain-gut interaction disorder without structural abnormalities. Affects 10-15% of global population.

10,000,000 affected17 countries

Keratoconus

A progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape, causing distorted vision. Typically affects both eyes and begins during puberty or late teens.

500,000,000 affected111 countries

Recurrent Kidney Stones (Nephrolithiasis)

Recurrent formation of solid mineral deposits in the kidneys, causing severe pain and potential kidney damage. Affects 1 in 10 people; 50% recurrence rate within 5-10 years without preventive measures. Most common type: calcium oxalate.

Klinefelter Syndrome

A chromosomal disorder affecting males with an extra X chromosome (47,XXY). Characterized by hypogonadism, tall stature, infertility, and variable cognitive/behavioral features. Most common sex chromosome disorder in males.

Leber Congenital Amaurosis (LCA)

A group of inherited retinal dystrophies causing severe visual impairment at birth or early infancy. Most common genetic cause of childhood blindness. Multiple genetic subtypes; RPE65-related LCA treatable with gene therapy.

Leber Hereditary Optic Neuropathy (LHON)

A mitochondrial disorder causing sudden, painless vision loss in young adults, typically males. Caused by mutations in mitochondrial DNA (MT-ND1, MT-ND4, MT-ND6, MT-ND4L). Usually affects one eye first, then the other within weeks to months.

Leigh Syndrome

A severe neurological disorder characterized by progressive loss of mental and movement abilities, typically beginning in infancy or childhood. Caused by mitochondrial dysfunction affecting brainstem and basal ganglia. Many genetic causes.

150,000 affected111 countries

Chronic Myeloid Leukemia

A myeloproliferative neoplasm characterized by the Philadelphia chromosome (t(9;22)) creating the BCR-ABL fusion gene, leading to constitutively active tyrosine kinase. Chronic phase is indolent; without treatment progresses to accelerated phase and blast crisis.

Li-Fraumeni Syndrome

A rare hereditary cancer syndrome caused by TP53 gene mutations. Extremely high lifetime cancer risk (nearly 100% in females, ~70% males). Early-onset cancers including sarcomas, breast cancer, brain tumors, and adrenal cortical carcinoma.

Liddle Syndrome

An autosomal dominant disorder causing severe early-onset hypertension and hypokalemia due to constitutive activation of epithelial sodium channel (ENaC). Mimics hyperaldosteronism but aldosterone is suppressed. Responds to amiloride/triamterene.

Limb-Girdle Muscular Dystrophy

A group of inherited muscular dystrophies affecting shoulder and pelvic girdle muscles. Multiple genetic subtypes with autosomal dominant (LGMD1) and recessive (LGMD2) inheritance. Variable age of onset and progression.

905,000 affected15 countries

Hepatocellular Carcinoma

The most common type of primary liver cancer, usually developing in the setting of chronic liver disease (cirrhosis) or chronic hepatitis B. Third leading cause of cancer death globally. Rising incidence in US due to NAFLD epidemic.

115,000,000 affected111 countries

Non-Alcoholic Steatohepatitis

The progressive form of non-alcoholic fatty liver disease (NAFLD), characterized by hepatic steatosis with inflammation and hepatocyte injury, with or without fibrosis. Can progress to cirrhosis and hepatocellular carcinoma. Now called MASH (metabolic dysfunction-associated steatohepatitis).

200,000 affected19 countries

Long QT Syndrome

A heart rhythm disorder that can potentially cause fast, chaotic heartbeats (torsades de pointes), leading to fainting, seizures, or sudden death. The QT interval on ECG is prolonged, indicating delayed ventricular repolarization.

2,200,000 affected111 countries

Lung Cancer

Malignant tumor arising from lung tissue. Leading cause of cancer death worldwide (1.8 million deaths/year). Two main types: non-small cell (NSCLC, 85%) and small cell (SCLC, 15%). Strongly associated with smoking but affects non-smokers too.

1,800,000 affected15 countries

Advanced Non-Small Cell Lung Cancer

The most common type of lung cancer (85% of cases) diagnosed at stage III or IV when cure is generally not possible. Major subtypes: adenocarcinoma, squamous cell carcinoma, large cell carcinoma. Strongly associated with smoking but occurs in never-smokers.

Systemic Lupus Erythematosus (SLE)

A chronic autoimmune disease where the immune system attacks healthy tissues, potentially affecting any organ system. Characterized by autoantibodies including ANA and anti-dsDNA. Nine times more common in women, especially of childbearing age and certain ethnicities.

Lupus Nephritis

Kidney inflammation caused by systemic lupus erythematosus (SLE), affecting 40-60% of lupus patients. Can lead to proteinuria, hematuria, hypertension, and end-stage kidney disease. Six histological classes with varying prognosis.

300,000 affected22 countries

Lyme Disease

A tick-borne illness caused by Borrelia burgdorferi bacteria. Most common vector-borne disease in US. Transmitted by Ixodes scapularis and Ixodes pacificus ticks. Can affect joints, heart, and nervous system if untreated.

800,000 affected15 countries

Lynch Syndrome (HNPCC)

The most common hereditary colorectal cancer syndrome, caused by mutations in mismatch repair genes (MLH1, MSH2, MSH6, PMS2, EPCAM). Increased risk of colorectal, endometrial, ovarian, gastric, urinary tract, and other cancers.

280,000,000 affected111 countries

Major Depressive Disorder

A common but serious mood disorder causing persistent feelings of sadness and loss of interest. Affects approximately 280 million people worldwide, leading cause of disability globally. Can occur at any age.

247,000,000 affected109 countries

Malaria

Parasitic disease transmitted by infected Anopheles mosquitoes. Caused by Plasmodium species (falciparum, vivax, ovale, malariae, knowlesi). Major public health problem in tropical regions, causing ~600,000 deaths annually, mostly children under 5.

Maple Syrup Urine Disease (MSUD)

An inherited amino acid disorder affecting branched-chain amino acid (leucine, isoleucine, valine) metabolism due to BCKDH deficiency. Named for characteristic sweet odor of urine. Can cause severe brain damage if untreated.

60,000 affected15 countries

Marfan Syndrome

An autosomal dominant connective tissue disorder caused by FBN1 gene mutation affecting fibrillin-1 protein. Affects skeletal, ocular, and cardiovascular systems. Most serious complication is aortic root dilation/dissection. Equal prevalence across ethnicities.

Maturity-Onset Diabetes of the Young (MODY)

A group of monogenic diabetes disorders characterized by early onset (usually <25 years), autosomal dominant inheritance, and beta-cell dysfunction. Multiple genetic subtypes with different clinical features and treatment responses.

8,000 affected15 countries

Medulloblastoma

The most common malignant brain tumor in children, arising in the cerebellum (posterior fossa). Embryonal tumor with multiple molecular subgroups (WNT, SHH, Group 3, Group 4) with different prognoses. Can spread through CSF.

dermatologichigh

Melanoma

A malignant tumor of melanocytes, the pigment-producing cells of the skin. The most serious form of skin cancer with high metastatic potential. Incidence rising globally, particularly in fair-skinned populations. Early detection critical for survival.

325,000 affected111 countries

40,000 affected15 countries

MELAS Syndrome

Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes. A maternally inherited mitochondrial disorder characterized by stroke-like episodes before age 40, seizures, dementia, and myopathy. Most commonly caused by m.3243A>G mutation.

1,000,000 affected111 countries

Ménière's Disease

A disorder of the inner ear causing episodes of vertigo, fluctuating hearing loss, tinnitus, and aural fullness. Caused by abnormal fluid buildup in the inner ear (endolymphatic hydrops). Affects approximately 12-30 per 100,000 people.

1,200,000 affected111 countries

Bacterial Meningitis

A life-threatening infection of the meninges (membranes surrounding the brain and spinal cord) caused by bacteria. Medical emergency requiring immediate antibiotic treatment. Can cause brain damage, hearing loss, and death. Vaccines available for some types.

Menkes Disease

A rare X-linked disorder of copper metabolism caused by ATP7A mutations. Copper deficiency leads to progressive neurodegeneration, connective tissue abnormalities, and distinctive kinky hair. Fatal in early childhood without treatment.

Malignant Mesothelioma

A rare, aggressive cancer of the mesothelial cells lining the pleura (most common), peritoneum, or pericardium. Strongly associated with asbestos exposure with 20-50 year latency period. Median survival 12-21 months depending on type and stage.

Metastatic Melanoma

Advanced skin cancer that has spread to lymph nodes or distant organs (stage III/IV). While treatments have dramatically improved survival, metastatic melanoma remains incurable for most patients. Often involves BRAF V600 mutations (~50%).

1,000,000,000 affected111 countries

Migraine

A primary headache disorder characterized by recurrent attacks of moderate to severe throbbing pain, usually on one side of the head, often accompanied by nausea, vomiting, and sensitivity to light and sound. Can last 4-72 hours. Second most disabling condition worldwide.

200,000 affected16 countries

Minimal Change Disease (MCD)

A kidney disorder that causes nephrotic syndrome, most commonly in children. Characterized by normal-appearing glomeruli on light microscopy with podocyte foot process effacement visible only on electron microscopy. Also called nil disease or lipoid nephrosis.

Mitochondrial Disease

A group of disorders caused by dysfunction of mitochondria, the cell's energy-producing organelles. Can affect any organ system. Extremely heterogeneous presentation. Can be caused by mitochondrial DNA or nuclear DNA mutations.

Infectious Mononucleosis

A contagious disease most commonly caused by Epstein-Barr virus (EBV). Characterized by fever, sore throat, swollen lymph nodes, and fatigue. Often called 'mono' or 'kissing disease' due to transmission via saliva. Most common in adolescents and young adults.

Mucolipidosis Type II (I-Cell Disease)

A severe lysosomal storage disorder caused by deficiency of N-acetylglucosamine-1-phosphotransferase. Affects the targeting of enzymes to lysosomes. Rapidly progressive with severe skeletal abnormalities and organ involvement.

Mucopolysaccharidoses (MPS)

A group of inherited lysosomal storage disorders caused by deficiency of enzymes needed to break down glycosaminoglycans (GAGs). Seven types (MPS I-VII) with varying severity. Accumulation of GAGs affects multiple organ systems.

Multiple Endocrine Neoplasia (MEN)

A group of inherited syndromes causing tumors in multiple endocrine glands. MEN1 (menin gene): parathyroid, pituitary, pancreas. MEN2 (RET gene): medullary thyroid carcinoma, pheochromocytoma, parathyroid hyperplasia.

500,000 affected16 countries

Multiple Myeloma

A malignancy of plasma cells characterized by clonal proliferation in bone marrow, monoclonal protein production, and end-organ damage (CRAB: hyperCalcemia, Renal insufficiency, Anemia, Bone lesions). Median age at diagnosis 69 years.

2,800,000 affected15 countries

Multiple Sclerosis (MS)

A chronic autoimmune disease of the central nervous system where the immune system attacks the myelin sheath covering nerve fibers. Characterized by relapsing-remitting or progressive course. More common in women (3:1 ratio) and at higher latitudes.

700,000 affected15 countries

Myasthenia Gravis

A chronic autoimmune disorder causing weakness in skeletal muscles due to antibodies against acetylcholine receptors (AChR), MuSK, or LRP4. Characterized by fluctuating muscle weakness worsening with activity and improving with rest. Can affect any voluntary muscle.

Myelodysplastic Syndromes (MDS)

A group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, cytopenias, and risk of progression to acute myeloid leukemia. More common in elderly. Primary or therapy-related (after chemotherapy/radiation).

180,000 affected15 countries

Myelofibrosis

A rare myeloproliferative neoplasm where scar tissue forms in the bone marrow, disrupting normal blood cell production. Can be primary or secondary to polycythemia vera or essential thrombocythemia. Risk of progression to acute leukemia.

Myotonic Dystrophy

The most common adult muscular dystrophy, caused by CTG repeat expansion in DMPK (DM1) or CCTG in CNBP (DM2). Multisystem disorder with myotonia, progressive muscle weakness, cardiac conduction abnormalities, cataracts, and endocrine dysfunction.

3,000,000 affected15 countries

neurologicallow

Narcolepsy

A chronic neurological sleep disorder characterized by dysregulation of sleep-wake cycles. Type 1 (with cataplexy, hypocretin deficiency) and Type 2. Often triggered by environmental factors in genetically susceptible individuals (HLA-DQB1*06:02).

5,000,000 affected17 countries

Nephrotic Syndrome

A clinical syndrome characterized by massive proteinuria (>3.5g/day), hypoalbuminemia, edema, and hyperlipidemia. Not a single disease but a manifestation of various glomerular disorders including minimal change disease, FSGS, membranous nephropathy, and diabetic nephropathy.

300,000 affected18 countries

Neural Tube Defects (Spina Bifida)

Congenital defects of the brain, spine, or spinal cord due to failure of neural tube closure in early pregnancy. Includes anencephaly, encephalocele, and spina bifida (myelomeningocele, meningocele). Folic acid deficiency major risk factor.

Neuroblastoma

The most common extracranial solid tumor in childhood, arising from neural crest cells of the adrenal medulla or sympathetic nervous system. Highly variable clinical behavior ranging from spontaneous regression to aggressive metastatic disease.

2,500,000 affected15 countries

Neurofibromatosis Type 1

An autosomal dominant disorder caused by NF1 gene mutations, characterized by multiple neurofibromas, café-au-lait spots, and learning disabilities. Increased risk of malignancies including malignant peripheral nerve sheath tumors.

Neurofibromatosis Type 2

An autosomal dominant disorder caused by NF2 gene mutations, characterized by bilateral vestibular schwannomas (acoustic neuromas), other nervous system tumors, and cataracts. Less common but more severe than NF1.

3,000 affected15 countries

Niemann-Pick Disease

A group of lysosomal storage disorders affecting lipid metabolism. Types A and B caused by SMPD1 deficiency (acid sphingomyelinase). Type C caused by NPC1 or NPC2 gene mutations affecting cholesterol transport. Types A and C have severe neurological involvement.

650,000,000 affected111 countries

Obesity (Class II-III)

Complex chronic disease characterized by excessive adipose tissue accumulation (BMI >=35). Associated with metabolic dysfunction, inflammation, and increased morbidity/mortality. Now recognized as relapsing-remitting disease requiring long-term management.

Obsessive-Compulsive Disorder (OCD)

A chronic mental health disorder characterized by uncontrollable, recurring thoughts (obsessions) and behaviors (compulsions) that the person feels compelled to repeat. Often time-consuming and interferes with daily life.

Oculopharyngeal Muscular Dystrophy (OPMD)

A late-onset muscular dystrophy characterized by ptosis (drooping eyelids) and dysphagia (difficulty swallowing). Caused by GCG repeat expansion in PABPN1 gene. Onset typically 40-60 years. More common in certain populations (French-Canadian, Bukhara Jews).

500,000 affected17 countries

Optic Neuritis

Inflammation of the optic nerve causing vision loss, usually in one eye. Often associated with multiple sclerosis but can occur in isolation or with other demyelinating diseases. Typically affects young adults.

Ornithine Transcarbamylase Deficiency (OTC)

The most common urea cycle disorder, an X-linked condition causing inability to eliminate ammonia. Ammonia accumulates causing neurotoxicity. Can present in neonates (severe) or later (variable). Hemizygous males more severely affected.

200,000,000 affected111 countries

Osteoporosis

A systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to increased bone fragility and fracture risk. Often called the 'silent disease' because bone loss occurs without symptoms until fracture occurs.

Osteosarcoma

The most common primary malignant bone tumor in children and adolescents, typically occurring at metaphysis of long bones. Associated with rapid growth and TP53 mutations. Peak incidence during adolescent growth spurt.

310,000 affected15 countries

Ovarian Cancer

Cancer arising from the ovaries or fallopian tubes. Most common subtype is high-grade serous carcinoma (70%). Often diagnosed at stage III/IV due to vague early symptoms and lack of effective screening. BRCA1/2 mutations increase risk significantly.

495,000 affected15 countries

Pancreatic Cancer

A highly aggressive cancer with poor prognosis, often diagnosed at advanced stages. Majority are pancreatic ductal adenocarcinoma (PDAC). 5-year survival rate approximately 12%. Risk factors include smoking, chronic pancreatitis, diabetes, and family history.

10,000,000 affected15 countries

Parkinson's Disease

A progressive neurodegenerative disorder affecting dopamine-producing neurons in the substantia nigra. Characterized by loss of dopaminergic neurons and presence of Lewy bodies. Second most common neurodegenerative disease after Alzheimer's.

Paroxysmal Nocturnal Hemoglobinuria (PNH)

A rare acquired hematopoietic stem cell disorder causing hemolytic anemia, thrombosis, and bone marrow failure due to PIGA gene mutation. Red blood cells lack CD55 and CD59, making them susceptible to complement-mediated lysis.

300,000,000 affected138 countries

Peptic Ulcer Disease

Open sores that develop on the inside lining of the stomach (gastric ulcers) and the upper portion of the small intestine (duodenal ulcers). Most common cause is H. pylori infection or NSAID use. Affects approximately 4% of the global population.

50,000 affected22 countries

Phenylketonuria (PKU)

An inherited metabolic disorder caused by deficiency of phenylalanine hydroxylase, leading to accumulation of phenylalanine. If untreated, causes severe intellectual disability, seizures, and behavioral problems. Newborn screening allows early treatment.

Pheochromocytoma

A rare tumor of the adrenal medulla that produces excess catecholamines (epinephrine and norepinephrine), causing episodic or persistent hypertension and other symptoms. Usually benign but can be malignant.

450,000,000 affected157 countries

Pneumonia

Infection causing inflammation of lung air sacs (alveoli). Can be bacterial, viral, or fungal. Leading cause of death in children worldwide and serious illness in elderly.

12,500,000 affected15 countries

Polycystic Kidney Disease (PKD)

A genetic disorder characterized by growth of numerous cysts in the kidneys, leading to enlarged kidneys and progressive loss of kidney function. Autosomal dominant PKD (ADPKD) is most common. Cysts can also develop in liver and other organs.

116,000,000 affected111 countries

Polycystic Ovary Syndrome (PCOS)

A common hormonal disorder affecting women of reproductive age, characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. Leading cause of infertility. Associated with metabolic syndrome and increased cardiovascular risk.

250,000 affected16 countries

Polycythemia Vera

A chronic myeloproliferative neoplasm characterized by overproduction of red blood cells due to JAK2 V617F mutation in most cases. Increases blood viscosity and risk of thrombosis, leading to strokes, heart attacks, and clots.

Pompe Disease

An autosomal recessive lysosomal storage disorder caused by GAA gene mutation, resulting in acid alpha-glucosidase deficiency. Glycogen accumulates in lysosomes, primarily affecting cardiac and skeletal muscles. Infantile-onset (IOPD) rapidly fatal; late-onset (LOPD) progresses more slowly.

Prader-Willi Syndrome

A complex genetic disorder caused by loss of paternal gene expression on chromosome 15. Neonatal hypotonia and feeding difficulties progress to hyperphagia, obesity, intellectual disability, and behavioral problems. Hypothalamic dysfunction.

120,000 affected15 countries

Primary Biliary Cholangitis (PBC)

A chronic autoimmune liver disease characterized by progressive destruction of small intrahepatic bile ducts, leading to cholestasis and cirrhosis. Predominantly affects middle-aged women. Previously called primary biliary cirrhosis.

Primary Hyperoxaluria

A group of rare genetic disorders causing overproduction of oxalate, leading to calcium oxalate kidney stones, nephrocalcinosis, and end-stage renal disease. Three types with different enzyme deficiencies (AGXT, GRHPR, HOGA1).

70,000 affected15 countries

Primary Sclerosing Cholangitis (PSC)

A chronic cholestatic liver disease characterized by inflammation and fibrosis of bile ducts, eventually leading to cirrhosis. Strongly associated with inflammatory bowel disease (70% of patients). Increased risk of cholangiocarcinoma and colorectal cancer.

Prion Diseases (TSEs)

A group of fatal, transmissible neurodegenerative disorders caused by misfolded prion protein (PrP^Sc). Includes Creutzfeldt-Jakob disease, variant CJD, Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia, and kuru. All are uniformly fatal.

Hutchinson-Gilford Progeria Syndrome

An extremely rare, fatal genetic disorder causing premature aging in children. Caused by LMNA gene mutation producing progerin. Autosomal dominant, usually de novo mutations. Average lifespan 14.5 years. Death typically from cardiovascular complications.

400 affected15 countries

Progressive Supranuclear Palsy (PSP)

A rare, rapidly progressive neurodegenerative disorder affecting movement, balance, speech, swallowing, and vision. Characterized by tau protein accumulation. Often misdiagnosed as Parkinson's disease. Average survival 5-7 years from onset.

125,000,000 affected15 countries

Psoriasis

A chronic autoimmune skin condition causing rapid skin cell turnover, resulting in thick, scaly plaques. Associated with psoriatic arthritis in 30% of patients and increased cardiovascular risk. Strong genetic component with environmental triggers.

125,000,000 affected111 countries

Plaque Psoriasis

A chronic immune-mediated inflammatory skin disease characterized by well-demarcated, erythematous plaques with silvery scale. Affects 2-3% of global population. Associated with psoriatic arthritis, cardiovascular disease, and metabolic syndrome.

350,000,000 affected111 countries

Post-Traumatic Stress Disorder (PTSD)

A mental health condition triggered by experiencing or witnessing a terrifying event. Characterized by intrusive memories, avoidance, negative changes in thinking and mood, and hyperarousal. Can develop after combat, assault, accidents, or natural disasters.

3,000,000 affected15 countries

Idiopathic Pulmonary Fibrosis

A chronic, progressive, fibrosing interstitial pneumonia of unknown cause, occurring primarily in older adults. Characterized by progressive scarring of lung tissue. Median survival 3-5 years without treatment. Associated with telomerase gene mutations in some families.

Pulmonary Hypertension (PAH)

A rare but serious condition characterized by high blood pressure in the pulmonary arteries, leading to right heart failure. Group 1 PAH is a progressive disease affecting the small pulmonary arteries, causing vessel narrowing and increased resistance to blood flow.

59,000 affected15 countries

Rabies

A fatal viral disease affecting the central nervous system, transmitted through saliva of infected animals. Once clinical symptoms appear, rabies is virtually 100% fatal. Preventable through post-exposure prophylaxis (PEP) if administered before symptom onset.

Rapidly Progressive Glomerulonephritis (RPGN)

A clinical syndrome characterized by rapid loss of kidney function over days to weeks, with crescent formation visible on kidney biopsy. Crescentic glomerulonephritis represents severe kidney inflammation requiring urgent treatment.

Renal Tubular Acidosis (RTA)

A group of disorders affecting the kidney tubules' ability to maintain acid-base balance, leading to metabolic acidosis. Types include distal (Type 1), proximal (Type 2), and hypoaldosteronism-related (Type 4). Can cause growth retardation in children and kidney stones.

Retinitis Pigmentosa

A group of inherited retinal dystrophies causing progressive vision loss due to photoreceptor degeneration. Most common inherited retinal disease. Can be isolated or part of syndromes (Usher syndrome, Bardet-Biedl syndrome).

18,000 affected15 countries

Retinoblastoma

The most common intraocular malignancy in children, caused by RB1 tumor suppressor gene mutations. Can be unilateral (usually non-hereditary) or bilateral (hereditary). Early detection critical for vision preservation and survival.

Retinopathy of Prematurity (ROP)

A potentially blinding eye disorder affecting premature infants, caused by abnormal blood vessel development in the retina. Risk increases with lower gestational age and birth weight. Leading cause of childhood blindness in developed countries.

Rhabdomyosarcoma

The most common soft tissue sarcoma in children, arising from skeletal muscle progenitors. Two main types: embryonal (including botryoid and spindle cell variants) and alveolar. Can occur anywhere in body including head/neck, genitourinary, and extremities.

18,000,000 affected15 countries

Rheumatoid Arthritis

A chronic inflammatory autoimmune disease primarily affecting synovial joints, causing painful swelling and potential joint deformity and bone erosion. Systemic features can affect cardiovascular, pulmonary, and other organ systems. Affects women 2-3 times more than men.

3,000,000 affected111 countries

Juvenile Idiopathic Arthritis

The most common chronic rheumatic disease in children, characterized by persistent joint inflammation lasting >6 weeks in children <16 years. Multiple subtypes including oligoarticular, polyarticular, and systemic (Still's disease). Can cause permanent joint damage and growth abnormalities.

2,000,000 affected20 countries

Pulmonary Sarcoidosis

A multisystem inflammatory disease characterized by formation of non-caseating granulomas, most commonly affecting the lungs and lymph nodes. Of unknown cause, thought to involve abnormal immune response to environmental triggers in genetically susceptible individuals.

24,000,000 affected111 countries

Schizophrenia

Severe chronic mental disorder characterized by disruptions in thought processes, perceptions, emotional responsiveness, and social interactions. Involves positive symptoms (hallucinations, delusions), negative symptoms (apathy, withdrawal), and cognitive impairment.

Systemic Sclerosis (Scleroderma)

A chronic autoimmune disease causing fibrosis of skin and internal organs (diffuse cutaneous) or primarily skin (limited cutaneous/CREST). Characterized by vasculopathy and immune activation. Limited form associated with anti-centromere antibodies, diffuse with anti-Scl-70.

49,000,000 affected111 countries

Sepsis

A life-threatening organ dysfunction caused by a dysregulated host response to infection. Medical emergency with high mortality. Septic shock is a subset with circulatory and cellular/metabolic dysfunction. Leading cause of death in hospitals.

Severe Insulin Resistance Syndrome

A group of rare disorders causing extreme insulin resistance. Includes type A insulin resistance (INSR mutations), type B (autoantibodies), leprechaunism, and lipodystrophies. Causes severe metabolic abnormalities despite high insulin levels.

Severe Combined Immunodeficiency (SCID)

A group of genetic disorders causing profound defects in both cellular and humoral immunity. 'Bubble boy disease' - affected infants lack functional T cells and B cells, making them vulnerable to severe infections. Medical emergency requiring immediate intervention.

20,000,000 affected15 countries

Sickle Cell Disease

An autosomal recessive hemoglobinopathy caused by a point mutation in the HBB gene (Glu6Val). Red blood cells become rigid and sickle-shaped, causing vaso-occlusion, hemolysis, and multi-organ damage. Most common inherited blood disorder in the US.

300,000,000 affected21 countries

Sickle Cell Trait Complications

Carrier state of sickle cell disease (HbAS), usually asymptomatic but associated with rare complications including exercise-related sudden death, rhabdomyolysis, renal medullary carcinoma, and splenic infarction at high altitude.

4,000,000 affected15 countries

Sjögren's Syndrome

A systemic autoimmune disease primarily affecting exocrine glands, particularly lacrimal and salivary glands, causing dry eyes and mouth. Can affect any organ system (systemic Sjögren's). Strongly female predominance (9:1). Associated with increased lymphoma risk.

936,000,000 affected111 countries

Obstructive Sleep Apnea

A sleep-related breathing disorder characterized by recurrent episodes of complete or partial upper airway obstruction during sleep, causing apneas or hypopneas. Leads to fragmented sleep, daytime sleepiness, and cardiovascular complications. Often undiagnosed.

Smith-Magenis Syndrome

A microdeletion syndrome caused by 17p11.2 deletion including RAI1 gene. Characterized by intellectual disability, behavioral problems, sleep disturbances (inverted circadian rhythm), and self-injurious behavior.

Spinal Muscular Atrophy (SMA)

An autosomal recessive motor neuron disease caused by SMN1 gene mutations affecting survival motor neuron protein. Progressive muscle weakness and atrophy. SMA type 1 (infantile) is most severe; SMA type 4 (adult-onset) is mildest.

250,000 affected15 countries

Spinocerebellar Ataxia (SCA)

A group of autosomal dominant neurodegenerative disorders characterized by progressive cerebellar ataxia. Multiple subtypes (SCA1, SCA2, SCA3/Machado-Joseph, etc.) caused by CAG repeat expansions or other mutations. Variable features.

1,089,000 affected15 countries

Gastric (Stomach) Cancer

Adenocarcinoma of the stomach, often associated with H. pylori infection, smoking, diet (salted/preserved foods), and genetic factors. Incidence declining in West but remains high in East Asia. Lauren classification: intestinal and diffuse types.

616,000,000 affected111 countries

Streptococcal Pharyngitis (Strep Throat)

A bacterial infection of the throat and tonsils caused by group A Streptococcus (GAS). Common in children but can affect all ages. If untreated, can lead to serious complications including rheumatic fever and post-streptococcal glomerulonephritis.

13,000,000 affected111 countries

Ischemic Stroke

Acute cerebral infarction caused by interruption of blood supply to the brain, typically from thrombosis or embolism. The most common type of stroke (85% of all strokes). Time-critical emergency requiring rapid intervention. Leading cause of disability worldwide.

1,000 affected15 countries

Tangier Disease

A rare disorder of cholesterol transport caused by ABCA1 mutations, causing extremely low HDL cholesterol and accumulation of cholesterol in tissues. Large orange-yellow tonsils are characteristic. Increased cardiovascular risk.

Tay-Sachs Disease

A fatal autosomal recessive lysosomal storage disorder caused by HEXA gene mutation, resulting in deficiency of beta-hexosaminidase A. GM2 ganglioside accumulates in neurons. Most common in Ashkenazi Jewish, French Canadian, and Cajun populations. Infantile form most severe.

75,000 affected18 countries

Testicular Cancer

The most common solid tumor in young men (15-35 years). Two main types: germ cell tumors (seminoma and non-seminoma) and non-germ cell tumors. Highly curable even when metastatic. Associated with cryptorchidism and family history.

Thalassemia

An autosomal recessive hemoglobinopathy caused by mutations in HBA (alpha-thalassemia) or HBB (beta-thalassemia) genes, reducing hemoglobin production. Beta-thalassemia major requires lifelong transfusions. Carrier frequency up to 20% in some Mediterranean and Asian populations.

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Thin Basement Membrane Disease (TBMD)

A benign genetic condition characterized by uniformly thinned glomerular basement membranes on kidney biopsy, causing persistent microscopic hematuria. Also called benign familial hematuria. Usually non-progressive with excellent long-term prognosis.

2,000,000,000 affected111 countries

Toxoplasmosis

A parasitic disease caused by Toxoplasma gondii. Most people experience no symptoms, but can cause serious complications in pregnant women and immunocompromised individuals. Transmitted through undercooked meat, cat feces, and mother-to-child.

12,000 affected15 countries

Trisomy 13 (Patau Syndrome)

A chromosomal disorder caused by an extra copy of chromosome 13. Severe condition with holoprosencephaly, polydactyly, heart defects, and rocker-bottom feet. Most die before birth or within first weeks of life.

Trisomy 18 (Edwards Syndrome)

A chromosomal disorder caused by an extra copy of chromosome 18. Severe, life-limiting condition with multiple organ abnormalities including heart defects, clenched fists with overlapping fingers, and rocker-bottom feet. Most die before birth or in infancy.

10,000,000 affected194 countries

Tuberculosis

Bacterial infection caused by Mycobacterium tuberculosis, primarily affecting lungs but can involve any organ. Leading infectious cause of death worldwide. Latent infection common; active disease in 5-10% of infected.

2,000,000 affected15 countries

Tuberous Sclerosis Complex

An autosomal dominant disorder caused by TSC1 or TSC2 mutations affecting tumor suppressor genes. Characterized by benign tumors (hamartomas) in multiple organs including brain, skin, kidneys, heart, and lungs.

1,000,000 affected17 countries

Turner Syndrome

A chromosomal disorder affecting females with complete or partial absence of one X chromosome (45,X or mosaic). Short stature, ovarian dysgenesis, cardiovascular abnormalities (coarctation, bicuspid aortic valve), and specific learning disabilities.

9,000,000 affected111 countries

Type 1 Diabetes Mellitus

Autoimmune destruction of pancreatic beta cells causing absolute insulin deficiency. Requires lifelong exogenous insulin. Onset typically in childhood/adolescence but can occur at any age.

537,000,000 affected111 countries

Type 2 Diabetes Mellitus

Progressive metabolic disorder characterized by insulin resistance and relative insulin deficiency. Accounts for 90-95% of diabetes cases. Strongly associated with obesity and sedentary lifestyle.

8,400,000 affected16 countries

Type 1 Diabetes

An autoimmune condition where the immune system destroys insulin-producing beta cells in the pancreas. Requires lifelong insulin replacement. Onset often in childhood or adolescence but can occur at any age. Strong genetic and environmental component.

Ulcerative Colitis

A chronic inflammatory bowel disease causing inflammation and ulcers in the innermost lining of the colon and rectum. Limited to continuous mucosal inflammation of the colon. Risk of colorectal cancer increased after 8-10 years of disease.

Usher Syndrome

An inherited disorder causing both hearing loss and progressive vision loss (retinitis pigmentosa). Most common cause of combined deafness and blindness. Three clinical types with varying severity and progression.

170,000,000 affected15 countries

Uterine Fibroids (Leiomyomas)

Benign smooth muscle tumors of the uterus, extremely common in women of reproductive age. Can cause heavy bleeding, pain, and reproductive issues. Vary greatly in size from microscopic to massive tumors distorting the uterus.

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Varicose Veins

Enlarged, twisted superficial veins, most commonly in the legs, caused by venous insufficiency and valve dysfunction. Common condition affecting up to 30% of adults. Can cause symptoms and cosmetic concerns.

300,000,000 affected15 countries

Von Hippel-Lindau Disease

An autosomal dominant disorder caused by VHL gene mutations affecting tumor suppressor function. Predisposes to hemangioblastomas (brain, spinal cord, retina), clear cell renal cell carcinoma, pheochromocytoma, and pancreatic cysts.

70,000,000 affected111 countries

Vitiligo

An autoimmune disorder characterized by loss of melanocytes resulting in depigmented patches of skin and hair. Affects 0.5-2% of global population. Can be segmental (limited) or non-segmental (generalized). Associated with other autoimmune diseases.

150,000,000 affected18 countries

Von Willebrand Disease

The most common inherited bleeding disorder, caused by deficiency or dysfunction of von Willebrand factor (vWF), essential for platelet adhesion and as carrier for factor VIII. Three main types with varying severity.

50,000 affected91 countries

West Nile Virus

A mosquito-borne flavivirus most commonly transmitted by Culex species mosquitoes. Can cause neurological disease in humans. Birds are primary hosts. First identified in Uganda in 1937; emerged in North America in 1999.

Williams Syndrome

A microdeletion syndrome caused by deletion of 7q11.23 including ELN gene. Characterized by cardiovascular disease (supravalvular aortic stenosis), distinctive facial features, intellectual disability, and unique personality (overly friendly).

Wilms Tumor (Nephroblastoma)

The most common renal malignancy in children, typically affecting ages 3-4 years. Often associated with WT1 or WT2 gene mutations. Can be part of syndromes (WAGR, Denys-Drash, Beckwith-Wiedemann). Excellent prognosis with treatment.

Wilson Disease

A rare inherited disorder of copper metabolism caused by ATP7B gene mutations. Copper accumulates in liver, brain, cornea (Kayser-Fleischer rings), and kidneys. Fatal if untreated but excellent prognosis with early treatment.

Wiskott-Aldrich Syndrome

An X-linked immunodeficiency characterized by thrombocytopenia with small platelets, eczema, and immunodeficiency. Caused by WAS gene mutations affecting hematopoietic cell signaling. Risk of autoimmune disease and lymphoma.

X-linked Agammaglobulinemia (XLA)

The first described primary immunodeficiency, caused by BTK gene mutations leading to absent B cells and severe hypogammaglobulinemia. Affected males develop recurrent bacterial infections starting after 6 months when maternal antibodies wane.

Zellweger Syndrome

The most severe peroxisome biogenesis disorder (PBD), caused by mutations in PEX genes. Peroxisomes fail to form, affecting multiple metabolic pathways. Causes severe neurological abnormalities, liver dysfunction, and characteristic facial features.

500,000 affected33 countries

Zika Virus Disease

A mosquito-borne flavivirus infection causing mild illness in most, but associated with severe birth defects (microcephaly) when contracted during pregnancy and Guillain-Barré syndrome. Aedes aegypti and Aedes albopictus mosquitoes are vectors.

150,000 affected16 countries

Fabry Disease (Renal Manifestations)

X-linked lysosomal storage disorder causing accumulation of globotriaosylceramide due to alpha-galactosidase A deficiency. Affects multiple organs including kidneys (proteinuria, progressive renal failure), heart, and nervous system. Renal involvement is major cause of morbidity.

80,000 affected18 countries

Homocystinuria

A group of autosomal recessive disorders affecting methionine metabolism. Most common form is cystathionine beta-synthase deficiency. Characterized by lens dislocation, intellectual disability, thromboembolism, and skeletal abnormalities. Responds to pyridoxine (B6) in some patients.

60,000 affected20 countries

Tyrosinemia

A group of hereditary disorders affecting tyrosine metabolism. Type I most severe, caused by fumarylacetoacetate hydrolase deficiency. Causes liver failure, renal dysfunction, and neurologic crises. Types II and III less severe with mainly skin/eye or developmental symptoms.

120,000 affected16 countries

Urea Cycle Disorders

A group of inherited metabolic disorders affecting the urea cycle, leading to hyperammonemia. Can present as life-threatening neonatal encephalopathy or later with episodic hyperammonemia. OTC deficiency most common in females; CPS1, ASS, ASL deficiencies also occur.

150,000 affected17 countries

Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCAD)

The most common fatty acid oxidation disorder, caused by ACADM gene mutations. Presents with hypoketotic hypoglycemia during fasting or illness. Can lead to seizures, coma, and sudden death if untreated. Excellent prognosis with proper management.

100,000 affected16 countries

Gaucher Disease Type 1

The most common lysosomal storage disorder, caused by glucocerebrosidase deficiency. Characterized by hepatosplenomegaly, cytopenias, and bone disease. Non-neuronopathic form (Type 1) accounts for 90% of cases. Most common in Ashkenazi Jewish population.

Mucopolysaccharidosis Type I (Hurler Syndrome)

The severe form of MPS I caused by alpha-L-iduronidase deficiency. Characterized by multisystem involvement including coarse facies, skeletal abnormalities, intellectual disability, cardiac disease, and hepatosplenomegaly. Rapid progression without treatment.

80,000 affected16 countries

Glycogen Storage Disease Type I (von Gierke)

The most common glycogen storage disease, caused by glucose-6-phosphatase deficiency (Type Ia) or translocase deficiency (Type Ib). Characterized by severe fasting hypoglycemia, hepatomegaly, lactic acidosis, hyperuricemia, and hyperlipidemia.

1,000,000 affected17 countries

Alpha-1 Antitrypsin Deficiency (Pulmonary)

A genetic disorder causing low levels of alpha-1 antitrypsin, leading to panacinar emphysema, particularly in the lower lobes. Patients develop early-onset COPD, often before age 45. Can also cause liver disease.

500,000 affected16 countries

Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

A form of pulmonary hypertension caused by chronic obstruction of pulmonary arteries due to organized thrombi. Develops in 2-4% of patients after acute pulmonary embolism. Potentially curable with pulmonary endarterectomy.

Lymphangioleiomyomatosis (LAM)

A rare lung disease characterized by proliferation of abnormal smooth muscle-like cells (LAM cells) causing cystic destruction of lung tissue. Almost exclusively affects women. Associated with tuberous sclerosis complex or sporadic. Can cause pneumothorax and chylous effusions.

2,000,000 affected17 countries

Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia (ARVC/D)

A progressive cardiomyopathy characterized by fibrofatty replacement of the myocardium, predominantly affecting the right ventricle. Major cause of sudden cardiac death in young athletes, especially in Mediterranean populations.

1,000,000 affected21 countries

Brugada Syndrome

An inherited channelopathy characterized by specific ECG pattern (coved ST elevation) in V1-V3 and increased risk of ventricular fibrillation and sudden cardiac death. Most common in Southeast Asian males. Often presents during sleep or fever.

3,000,000 affected19 countries

Wolff-Parkinson-White Syndrome (WPW)

A congenital heart condition characterized by an accessory atrioventricular pathway (bundle of Kent) allowing pre-excitation. Associated with paroxysmal supraventricular tachycardia and risk of sudden cardiac death from atrial fibrillation with rapid ventricular response.

1,000,000 affected18 countries

Restrictive Cardiomyopathy (RCM)

The least common cardiomyopathy characterized by stiff ventricles with impaired diastolic filling but preserved systolic function. Can be idiopathic, genetic, or secondary to infiltrative diseases (amyloidosis, sarcoidosis, hemochromatosis).

200,000 affected18 countries

Budd-Chiari Syndrome

A rare condition caused by obstruction of hepatic venous outflow from thrombosis of hepatic veins or inferior vena cava. Acute form is life-threatening; chronic form causes cirrhosis. Associated with hypercoagulable states.

3,000,000 affected19 countries

Hereditary Hemochromatosis (Liver Manifestations)

The most common genetic disorder in populations of Northern European descent, causing iron overload due to increased intestinal absorption. Leads to cirrhosis, hepatocellular carcinoma, and liver failure if untreated. HFE C282Y homozygosity most common.

200,000 affected17 countries

Alpha-1 Antitrypsin Deficiency (Liver Disease)

Liver disease caused by accumulation of misfolded alpha-1 antitrypsin protein in hepatocytes. Can present as neonatal cholestasis, childhood cirrhosis, or adult chronic liver disease. Same genetic defect causing pulmonary disease.

50,000 affected18 countries

Glycogen Storage Disease Type IV (Andersen Disease)

A rare glycogen storage disease caused by glycogen branching enzyme deficiency. Accumulation of abnormal glycogen (polyglucosan) causes progressive liver failure, cirrhosis, and death in infancy or childhood. Also affects muscle and nervous system.

415,000,000 affected15 countries

Rosacea

A chronic inflammatory skin condition primarily affecting the face, characterized by facial redness, visible blood vessels, papules, and pustules. Often mistaken for acne or sunburn. Four subtypes: erythematotelangiectatic, papulopustular, phymatous, and ocular rosacea.

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Hidradenitis Suppurativa (Acne Inversa)

A chronic inflammatory skin condition affecting apocrine gland-bearing areas (armpits, groin, under breasts, buttocks). Characterized by painful nodules, abscesses, sinus tracts, and scarring. Significantly impacts quality of life. Three stages (Hurley) based on severity.

4,000,000 affected15 countries

Lichen Planus

An inflammatory condition affecting skin, hair, nails, and mucous membranes. Characterized by purplish, itchy, flat-topped bumps. Oral lichen planus affects mucous membranes. Can be triggered by hepatitis C, certain medications, or flu vaccine.

70,000,000 affected15 countries

Scoliosis

A sideways curvature of the spine that occurs most often during the growth spurt just before puberty. Most cases are idiopathic. Can cause disability if severe and untreated. Curves measured by Cobb angle. Classified by age of onset and cause.

10,000,000 affected15 countries

Carpal Tunnel Syndrome

A common condition causing pain, numbness, and tingling in the hand and arm due to compression of the median nerve as it travels through the wrist. Most common nerve entrapment syndrome. Often work-related.

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Osteomyelitis

An infection of the bone caused by bacteria or fungi. Can occur suddenly (acute) or over long periods (chronic). Requires prompt treatment to prevent permanent bone damage. Most commonly affects long bones and spine.

3,000,000 affected15 countries

Lateral Epicondylitis (Tennis Elbow)

A painful condition affecting the tendons on the outside of the elbow, caused by overuse and repetitive motions. Common in tennis players but affects many occupations. Microtears in extensor carpi radialis brevis tendon.

Retinal Detachment

A serious eye condition where the retina pulls away from its normal position. Medical emergency requiring prompt treatment to prevent permanent vision loss. Types include rhegmatogenous, tractional, and exudative.

13,000,000 affected15 countries

Strabismus (Crossed Eyes)

A condition in which the eyes do not properly align with each other when looking at an object. One eye may turn in, out, up, or down. Can cause amblyopia (lazy eye) in children. Affects depth perception.

70,000,000 affected19 countries

Eating Disorders (Anorexia, Bulimia, Binge Eating)

Serious mental health conditions characterized by severe disturbances in eating behaviors and related thoughts and emotions. Types include anorexia nervosa, bulimia nervosa, and binge-eating disorder. Can be life-threatening.

1,200,000,000 affected24 countries

Iron Deficiency Anemia

The most common type of anemia, caused by insufficient iron leading to decreased hemoglobin production. Can result from inadequate dietary intake, blood loss, or malabsorption. Affects all age groups globally.

6,000,000 affected19 countries

Immune Thrombocytopenia (ITP)

An autoimmune disorder characterized by isolated low platelet count due to immune-mediated platelet destruction and impaired production. Formerly called idiopathic thrombocytopenic purpura. Acute form common in children, chronic in adults.

Gastroparesis

A condition affecting stomach muscles and preventing proper stomach emptying. Caused by damage to the vagus nerve or stomach muscles. Associated with diabetes, surgery, and certain medications. No structural blockage.

537,000,000 affected28 countries

Diabetes Mellitus

A group of metabolic diseases characterized by high blood sugar levels over a prolonged period. Types include Type 1 (autoimmune), Type 2 (insulin resistance), and gestational diabetes. Leading cause of blindness, kidney failure, and amputations.

Hemochromatosis (Liver Focus)

Iron overload disorder causing liver damage. Covered in detail in hematologic section. Primary focus here on hepatic manifestations including fibrosis, cirrhosis, and hepatocellular carcinoma risk.

2,300,000 affected35 countries

Breast Cancer

Cancer that forms in the cells of the breasts. Most common cancer in women worldwide. Can occur in men rarely. Subtypes include ductal carcinoma in situ, invasive ductal carcinoma, and invasive lobular carcinoma. HER2, hormone receptor status important.

1,400,000 affected35 countries

Prostate Cancer

Cancer that occurs in the prostate, a small walnut-shaped gland in men that produces seminal fluid. Second most common cancer in men. Most grow slowly; some are aggressive. PSA screening controversial.

2,500,000 affected21 countries

Ehlers-Danlos Syndrome

A group of inherited disorders affecting connective tissues, primarily skin, joints, and blood vessel walls. Thirteen subtypes with varying severity. Hypermobile type most common; vascular type most dangerous.

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Basal Cell Carcinoma

The most common type of skin cancer, originating from basal cells in the epidermis. Slow-growing and rarely metastasizes but can cause local tissue destruction. Strongly associated with UV exposure.

4,000,000 affected22 countries

1,500,000 affected22 countries

Squamous Cell Carcinoma

The second most common type of skin cancer, arising from squamous cells in the epidermis. More aggressive than BCC with metastatic potential. UV exposure main risk factor.

400,000 affected29 countries

Endometrial Cancer (Uterine Cancer)

Cancer that begins in the lining of the uterus (endometrium). Most common gynecologic cancer in developed countries. Type I (endometrioid) associated with estrogen; Type II (serous) more aggressive.

570,000 affected29 countries

Bladder Cancer

Cancer that begins in the cells of the bladder, most commonly urothelial carcinoma. Smoking is the leading risk factor. Often presents with painless hematuria.

600,000 affected23 countries

Thyroid Cancer

Cancer that develops in the thyroid gland. Papillary carcinoma most common and most curable. Thyroid nodules common but usually benign. Rising incidence partly due to increased detection.

600,000 affected27 countries

Cervical Cancer

Cancer that begins in the cervix, almost always caused by persistent HPV infection. One of most preventable cancers through screening and vaccination. Declining in developed countries due to screening.

700,000,000 affected19 countries

Chronic Constipation

Infrequent bowel movements or difficulty passing stools that persists for several weeks or longer. Can significantly affect quality of life. Various types: normal transit, slow transit, and outlet dysfunction.

120,000 affected19 countries

Gallbladder Cancer

A relatively rare but aggressive cancer that begins in the gallbladder. Often diagnosed at advanced stage due to lack of early symptoms. Associated with gallstones and chronic inflammation.

1,500,000 affected19 countries

Achalasia

A rare esophageal motility disorder where the lower esophageal sphincter fails to relax and the esophagus lacks normal peristalsis. Causes difficulty swallowing and regurgitation. Degeneration of nerve cells in esophagus.

1,500,000 affected16 countries

Eosinophilic Esophagitis (EoE)

A chronic immune/antigen-mediated disease characterized by eosinophil-predominant inflammation of the esophagus. Associated with food allergies and atopic conditions. Increasing in incidence.

150,000 affected19 countries

Familial Adenomatous Polyposis (FAP)

An inherited disorder characterized by hundreds to thousands of adenomatous polyps in the colon and rectum. Without intervention, nearly 100% risk of colorectal cancer. Associated with APC gene mutation.

60,000,000 affected22 countries

Actinic Keratosis (Solar Keratosis)

Rough, scaly patches on the skin caused by damage from the sun's ultraviolet (UV) rays. Considered precancerous lesions that can develop into squamous cell carcinoma. Most common on sun-exposed areas.

350,000,000 affected19 countries

Seborrheic Dermatitis

A common inflammatory skin condition causing flaky, scaly patches, red skin, and dandruff. Affects areas with many oil glands including scalp, face, and trunk. Associated with Malassezia yeast overgrowth.

147,000,000 affected19 countries

Alopecia Areata

An autoimmune condition causing patchy hair loss, typically on the scalp, but can affect any hair-bearing area. Occurs when immune system attacks hair follicles. Can progress to total hair loss (alopecia totalis) or universalis.

200,000,000 affected19 countries

Contact Dermatitis

A skin reaction caused by contact with an irritant (irritant contact dermatitis) or allergen (allergic contact dermatitis). Causes red, itchy rash. Very common occupational skin condition.

162,000,000 affected27 countries

Impetigo

A highly contagious bacterial skin infection most common in young children. Characterized by red sores that quickly rupture, ooze, and form honey-colored crusts. Caused by Staphylococcus or Streptococcus bacteria.

1,000,000,000 affected27 countries

Tinea Pedis (Athlete's Foot)

A fungal infection of the feet, particularly between the toes. Common in people with sweaty feet who wear tight-fitting shoes. Highly contagious and can spread to other parts of body.

100,000,000 affected19 countries

Shingles (Herpes Zoster)

A viral infection causing a painful rash, caused by reactivation of the varicella-zoster virus (chickenpox). Characterized by a stripe of blisters on one side of the body. Risk increases with age.

95,000,000 affected22 countries

Age-Related Cataracts

A clouding of the normally clear lens of the eye, most commonly due to aging. Leading cause of vision loss worldwide. Develops gradually and affects both eyes, usually one more than the other.

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Conjunctivitis (Pink Eye)

Inflammation of the conjunctiva, the thin clear tissue that lies over the white part of the eye and lines the inside of the eyelid. Can be viral, bacterial, or allergic. Highly contagious in infectious forms.

600,000,000 affected27 countries

21,000,000 affected19 countries

Diabetic Macular Edema (DME)

A complication of diabetic retinopathy where fluid builds up in the macula, the part of the retina responsible for sharp central vision. Leading cause of vision loss in people with diabetes.

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Dry Eye Syndrome

A multifactorial disease of the tears and ocular surface resulting in discomfort, visual disturbance, and tear film instability. Can be due to decreased tear production or increased evaporation.

350,000,000 affected19 countries

2,800,000 affected19 countries

Uveitis

Inflammation of the uvea, the middle layer of the eye consisting of the iris, ciliary body, and choroid. Can be infectious or non-infectious. Serious condition that can lead to vision loss.

16,000,000 affected19 countries

Retinal Vein Occlusion (RVO)

A blockage of the small veins that carry blood away from the retina. Can be central (CRVO) or branch (BRVO). Second most common retinal vascular disease after diabetic retinopathy.

120,000,000 affected19 countries

Temporomandibular Joint Disorder (TMD/TMJ)

A group of conditions affecting the temporomandibular joint, jaw muscles, and facial nerves. Causes pain and dysfunction in the jaw joint and muscles controlling jaw movement.

100,000,000 affected19 countries

Bursitis

Inflammation of the bursae, small fluid-filled sacs that cushion bones, tendons, and muscles near joints. Common in shoulder, elbow, hip, and knee. Causes pain and limits movement.

150,000,000 affected19 countries

Tendinitis

Inflammation or irritation of a tendon, the thick fibrous cords that attach muscle to bone. Common in shoulders, elbows, wrists, knees, and heels. Often due to repetitive motion or overuse.

100,000,000 affected19 countries

Meniscus Tear

A tear in the meniscus, the C-shaped cartilage that acts as a cushion between the shinbone and thighbone. Common knee injury, especially in athletes. Can occur with twisting or degenerative changes.

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Sickle Cell Trait

A genetic condition where a person inherits one sickle cell gene and one normal hemoglobin gene. Usually asymptomatic but can cause complications under extreme conditions. Different from sickle cell disease.

300,000,000 affected20 countries

500,000 affected21 countries

Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)

A fatty acid oxidation disorder where the body cannot break down medium-chain fatty acids for energy. Can lead to hypoglycemia, seizures, and brain damage during fasting or illness. Most common fatty acid oxidation disorder.

10,000,000 affected25 countries

Hand, Foot, and Mouth Disease

A common viral illness that causes sores in the mouth and a rash on the hands and feet. Most commonly caused by coxsackievirus A16. Very contagious, especially among young children. Not related to foot-and-mouth disease in animals.

8,000,000 affected19 countries

Fifth Disease (Erythema Infectiosum)

A mild viral illness caused by parvovirus B19, characterized by a distinctive 'slapped-cheek' rash on the face and a lacy rash on the body. Called fifth disease because it was fifth in a historical list of common childhood rash illnesses.

15,000,000 affected19 countries

Roseola (Sixth Disease)

A common viral illness in young children caused by human herpesvirus 6 (HHV-6). Characterized by high fever followed by a rash as fever resolves. Also known as exanthem subitum or sixth disease.

50,000 affected21 countries

Kawasaki Disease

An acute febrile illness of childhood causing inflammation of blood vessels throughout the body. Leading cause of acquired heart disease in children in developed countries. Cause unknown but likely infectious trigger in genetically susceptible children.

200,000 affected20 countries

Takayasu Arteritis

A rare form of vasculitis affecting the large arteries, particularly the aorta and its main branches. Causes inflammation that damages arteries, leading to narrowing, blockage, or aneurysm formation. Affects mainly young women. Called 'pulseless disease'.

1,000,000 affected20 countries

Behçet's Disease

A rare chronic vasculitis causing recurrent mouth ulcers, genital ulcers, eye inflammation, and skin lesions. Can affect blood vessels of all sizes. Associated with HLA-B51 in some populations. Silk Road disease.

50,000,000 affected28 countries

Acute Bronchitis

Inflammation of the bronchial tubes in the lungs, typically caused by viral infections. Characterized by cough, mucus production, and chest discomfort. Usually self-limiting but can be bothersome. One of the most common respiratory conditions.

1,000,000,000 affected32 countries

Common Cold

A viral infection of the upper respiratory tract, primarily caused by rhinoviruses. The most frequent infectious disease in humans, with adults averaging 2-3 episodes per year. Self-limiting but highly contagious.

15,000,000 affected25 countries

Tonsillitis

Inflammation of the tonsils, lymph nodes at the back of the throat. Can be viral or bacterial (primarily streptococcal). Common in children but can affect adults. May be acute or recurrent.

31,000,000 affected20 countries

Acute Sinusitis

Inflammation of the sinuses causing facial pain, pressure, and nasal congestion. Usually follows a cold or allergies. Most cases viral; bacterial sinusitis less common. Can become chronic if lasting over 12 weeks.

70,000,000 affected20 countries

Acute Otitis Media

Middle ear infection, most common in children due to eustachian tube anatomy. Caused by bacteria or viruses. Characterized by ear pain, fever, and possible hearing loss. Major reason for pediatric antibiotic use.

2,000,000,000 affected26 countries

Viral Gastroenteritis

Inflammation of the stomach and intestines caused by viruses (norovirus, rotavirus, adenovirus). Commonly called 'stomach flu.' Highly contagious, causing diarrhea, vomiting, and abdominal cramps. Major cause of morbidity worldwide.

7,000,000 affected20 countries

Measles (Rubeola)

A highly contagious viral disease causing fever, cough, runny nose, conjunctivitis, and characteristic rash. One of the most contagious infectious diseases. Can cause serious complications including pneumonia, encephalitis, and death. Vaccine-preventable.

500,000 affected20 countries

Mumps

A viral infection affecting the salivary glands, particularly the parotid glands. Causes painful swelling of the cheeks and jaw. Can lead to serious complications including orchitis, meningitis, and deafness. Vaccine-preventable through MMR.

100,000 affected20 countries

Rubella (German Measles)

A mild viral infection causing rash and fever, but devastating to developing fetuses (congenital rubella syndrome). Usually mild in children and adults but can cause miscarriage, stillbirth, or severe birth defects if contracted during pregnancy. Vaccine-preventable.

24,000,000 affected20 countries

Pertussis (Whooping Cough)

A highly contagious respiratory infection causing severe coughing fits ending in a 'whoop' sound. Most dangerous for infants who may stop breathing. Caused by Bordetella pertussis bacteria. Vaccine-preventable but immunity wanes.

1,000,000 affected20 countries

Tetanus (Lockjaw)

A serious bacterial infection causing painful muscle spasms and lockjaw. Caused by Clostridium tetani spores found in soil. Not transmitted person-to-person. Fatal in 10-20% of cases even with treatment. Entirely vaccine-preventable.

50,000 affected17 countries

Diphtheria

A serious bacterial infection causing thick gray membrane in throat and nose, breathing difficulty, heart damage, and nerve paralysis. Caused by Corynebacterium diphtheriae. Once major childhood killer, now rare in vaccinated populations. Vaccine-preventable.

140,000,000 affected20 countries

Chickenpox (Varicella)

A highly contagious viral infection causing itchy blister-like rash, fever, and fatigue. Caused by varicella-zoster virus (VZV). Usually mild in children but more severe in adults. Can reactivate later as shingles. Vaccine-preventable.

42,000,000 affected30 countries

Benign Prostatic Hyperplasia (BPH)

Non-cancerous enlargement of the prostate gland common in aging men. Causes urinary symptoms including frequency, urgency, weak stream, and incomplete emptying. Very common, affecting about half of men over 50. Not related to prostate cancer.

3,500,000 affected20 countries

Prostatitis

Inflammation of the prostate gland, can be acute or chronic. Causes pelvic pain, urinary symptoms, and sexual dysfunction. Four types: acute bacterial, chronic bacterial, chronic pelvic pain syndrome (most common), and asymptomatic inflammatory.

200,000,000 affected27 countries

Scabies

A contagious skin infestation caused by the Sarcoptes scabiei mite. Causes intense itching and rash as the mites burrow into skin to lay eggs. Spreads through close skin-to-skin contact. Common in crowded conditions and healthcare settings.

12,000,000 affected20 countries

Head Lice (Pediculosis Capitis)

Infestation of the scalp hair by head lice. Very common in school-age children. Causes itching but does not spread disease. Not a sign of poor hygiene. Spread through head-to-head contact. Easily treated.

11,000,000 affected23 countries

Typhoid Fever

A life-threatening bacterial infection caused by Salmonella typhi. Spread through contaminated food and water. Causes sustained high fever, abdominal pain, and rose-colored spots. Endemic in areas with poor sanitation. Vaccine-preventable.

1,400,000 affected25 countries

Cholera

An acute diarrheal infection caused by Vibrio cholerae bacteria. Causes severe watery diarrhea and dehydration, can kill within hours if untreated. Spread through contaminated water. Major public health problem in areas with poor sanitation.

200,000 affected31 countries

Yellow Fever

A mosquito-borne viral hemorrhagic fever endemic to tropical Africa and South America. Causes fever, jaundice, bleeding, and organ failure. Named for yellowing of skin and eyes. Can be fatal. Vaccine-preventable and provides lifelong immunity.

50,000,000 affected22 countries

Kidney Stones (Nephrolithiasis)

Hard deposits of minerals and salts that form inside the kidneys. Can affect any part of the urinary tract. Cause severe pain when passing. Very common, affecting 1 in 11 people. Often recurrent. Types include calcium oxalate, uric acid, struvite, and cystine stones.

150,000,000 affected111 countries

Urinary Tract Infection (UTI)

A common bacterial infection affecting any part of the urinary system including kidneys, ureters, bladder, and urethra. Most commonly affects the lower urinary tract (bladder and urethra). Women are at greater risk than men. Recurrent UTIs affect 20-30% of women.

423,000,000 affected111 countries

Urinary Incontinence

The involuntary loss of bladder control, ranging from occasional leakage to complete inability to hold urine. Affects twice as many women as men, especially after pregnancy, childbirth, and menopause. Not a normal part of aging but becomes more common with age.

150,000,000 affected111 countries

Erectile Dysfunction (ED)

The consistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance. Affects approximately 50% of men aged 40-70. Often an early indicator of cardiovascular disease. Can significantly impact quality of life and relationships.

3,300,000 affected111 countries

Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS)

A chronic condition causing bladder pressure, bladder pain, and sometimes pelvic pain. Part of a spectrum of painful bladder syndromes. More common in women. Symptoms often mimic UTI but urine cultures are negative. Cause is unknown but may involve bladder lining defects.

10,000,000 affected111 countries

Peyronie's Disease

A connective tissue disorder characterized by the development of fibrous scar tissue (plaque) inside the penis, causing curved, painful erections. Affects 3-9% of men, most commonly between ages 45-60. Can significantly impact sexual function and psychological well-being.

2,500,000 affected111 countries

Hydrocele

A collection of fluid in the scrotum around the testicle, causing swelling. Common in newborns (usually resolves within first year) and older men. Typically painless but can cause discomfort due to swelling. Two types: communicating (patent processus vaginalis) and non-communicating.

120,000,000 affected111 countries

Varicocele

Enlargement of the veins within the loose bag of skin holding the testicles (scrotum), similar to varicose veins in legs. Occurs in 15% of men, most commonly on left side due to venous anatomy. Leading cause of correctable male infertility.

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Testicular Torsion

A surgical emergency caused by twisting of the spermatic cord, cutting off blood supply to the testicle. Most common in adolescent males (ages 12-18) but can occur at any age. Requires immediate treatment within 6 hours to save the testicle. Affects 1 in 4,000 males under 25 annually.

500,000 affected111 countries

600,000 affected111 countries

Epididymitis

Inflammation of the epididymis, the coiled tube at the back of the testicle that stores and carries sperm. Most common cause of acute scrotal pain in adults. Can be caused by bacterial infection (sexually transmitted or urinary pathogens) or non-infectious inflammation.

2,000,000 affected111 countries

Urethritis

Inflammation of the urethra, the tube that carries urine from the bladder out of the body. Most commonly caused by sexually transmitted infections (chlamydia, gonorrhea) but can also be non-infectious. Affects both men and women, though symptoms are more prominent in men.

60,000,000 affected111 countries

Panic Disorder

An anxiety disorder characterized by recurrent unexpected panic attacks—sudden periods of intense fear that reach a peak within minutes. Affects 2-3% of adults annually. Often associated with agoraphobia (fear of situations where escape might be difficult).

300,000,000 affected111 countries

Social Anxiety Disorder (Social Phobia)

A chronic mental health condition characterized by intense, persistent fear of being watched and judged by others. Goes beyond ordinary shyness. Affects approximately 7% of adults. Often begins in childhood or adolescence. Can severely impact social and occupational functioning.

1,500,000 affected111 countries

Hepatitis A

A highly contagious, vaccine-preventable liver infection caused by hepatitis A virus. Transmitted through fecal-oral route, typically via contaminated food/water or close contact. Usually self-limited with full recovery and no chronic infection. Common in areas with poor sanitation.

20,000,000 affected111 countries

Hepatitis E

A liver disease caused by hepatitis E virus, transmitted primarily through contaminated water. Similar to hepatitis A in transmission and course. Most common in South Asia and East Asia. Genotypes 1 and 2 cause large waterborne outbreaks; genotypes 3 and 4 are zoonotic. High mortality in pregnant women (15-25%).

15,000,000 affected89 countries

Aortic Aneurysm

A bulge or ballooning in the wall of the aorta, the body's main artery. Can occur in the chest (thoracic) or abdomen (abdominal). Life-threatening if it ruptures. Often asymptomatic until complications occur. Associated with atherosclerosis, hypertension, and genetic conditions.

12,000,000 affected89 countries

Aortic Stenosis

Narrowing of the aortic valve opening, restricting blood flow from the heart to the aorta. Most commonly caused by age-related calcification, congenital bicuspid valve, or rheumatic fever. Progressive disease; severe cases require valve replacement.

24,000,000 affected89 countries

Mitral Regurgitation

A condition where the mitral valve doesn't close tightly, causing blood to flow backward into the left atrium when the heart contracts. Can be primary (valve problem) or secondary (heart enlargement). Leads to heart enlargement and heart failure if severe.

600,000 affected89 countries

Pericarditis

Inflammation of the pericardium, the thin sac surrounding the heart. Causes chest pain and can lead to fluid accumulation (pericardial effusion) or heart compression (cardiac tamponade). Often idiopathic but can follow viral infections or autoimmune conditions.

1,500,000 affected89 countries

Myocarditis

Inflammation of the heart muscle (myocardium) that can weaken the heart and affect its electrical system. Often follows viral infections but can be autoimmune or drug-related. Can cause heart failure, arrhythmias, or sudden cardiac death.

20,000,000 affected89 countries

Hypertrophic Cardiomyopathy

A genetic condition causing abnormal thickening of the heart muscle, particularly the left ventricle. Most common cause of sudden cardiac death in young athletes. Can obstruct blood flow (obstructive HCM) or not (non-obstructive).

230,000,000 affected89 countries

Peripheral Artery Disease

Narrowing of peripheral arteries, usually in the legs, due to atherosclerosis. Reduces blood flow to limbs causing pain with walking (claudication). Strong marker for cardiovascular disease elsewhere. Increases risk of heart attack and stroke.

150,000 affected89 countries

Infective Endocarditis

Infection of the inner lining of the heart chambers and valves. Usually caused by bacteria entering the bloodstream. Life-threatening condition requiring prolonged antibiotic therapy and sometimes surgery. Risk increased in those with prosthetic valves or congenital heart disease.

500,000 affected89 countries

Cardiac Amyloidosis

Buildup of abnormal amyloid protein in the heart tissue causing stiffening and restrictive cardiomyopathy. Two main types: ATTR (transthyretin, age-related or hereditary) and AL (light chain, associated with multiple myeloma). Increasingly recognized cause of heart failure with preserved ejection fraction.

10,000,000 affected89 countries

Pulmonary Embolism

A blockage in one of the pulmonary arteries in the lungs, usually caused by blood clots that travel from deep veins in the legs (DVT). Life-threatening condition requiring immediate treatment. Can cause sudden death if massive.

1,500,000 affected89 countries

Pleural Effusion

Accumulation of excess fluid in the pleural space between the lungs and chest wall. Can be caused by heart failure, pneumonia, cancer, pulmonary embolism, or liver/kidney disease. Symptoms depend on amount and rate of fluid accumulation.

60,000 affected89 countries

Lung Abscess

A pus-filled cavity in the lung surrounded by inflamed tissue, usually caused by bacterial infection. Often follows aspiration pneumonia. Associated with poor dental hygiene, alcoholism, or swallowing disorders. Modern antibiotics have reduced incidence significantly.

750,000 affected89 countries

Pneumothorax

Collapsed lung due to air leaking into the space between the lung and chest wall. Can be spontaneous (no obvious cause), traumatic (injury), or tension (life-threatening). Primary spontaneous occurs in tall, thin young men. Requires prompt treatment.

1,500,000 affected89 countries

Obesity Hypoventilation Syndrome

A breathing disorder in obese people where poor breathing leads to too much carbon dioxide and too little oxygen in the blood. Often overlaps with obstructive sleep apnea. Can lead to pulmonary hypertension, heart failure, and early death if untreated.

180,000 affected89 countries

Laryngeal Cancer

Cancer of the voice box (larynx), most commonly squamous cell carcinoma. Strongly associated with tobacco and alcohol use. Hoarseness is the most common early symptom. Can affect voice, swallowing, and breathing depending on location.

130,000 affected77 countries

Nasopharyngeal Cancer

Cancer arising from the nasopharynx, the area behind the nose and above the back of the throat. Strongly associated with Epstein-Barr virus (EBV), genetic factors, and certain dietary habits (salted fish). Common in Southeast Asia and North Africa.

15,000,000 affected147 countries

Hepatitis D

Also known as delta hepatitis, caused by the hepatitis D virus (HDV) which requires hepatitis B virus to replicate. The most severe form of viral hepatitis with rapid progression to cirrhosis. Occurs as coinfection (with HBV) or superinfection (in chronic HBV).

120,000,000 affected89 countries

Non-Alcoholic Steatohepatitis (NASH)

Progressive form of non-alcoholic fatty liver disease (NAFLD) characterized by liver inflammation and damage in people who drink little or no alcohol. Can progress to cirrhosis, liver failure, and liver cancer. Associated with obesity, diabetes, and metabolic syndrome.

3,500,000 affected89 countries

Acute Pancreatitis

Sudden inflammation of the pancreas, usually mild and self-limiting but can be life-threatening. Most commonly caused by gallstones or alcohol. Presents with severe abdominal pain. Can lead to pancreatic necrosis, organ failure, or pseudocysts.

6,500,000,000 affected137 countries

Lactose Intolerance

Inability to fully digest lactose, the sugar in milk and dairy products, due to deficiency of lactase enzyme in the small intestine. Very common worldwide, especially in certain ethnic groups. Not dangerous but can cause uncomfortable symptoms.

500,000 affected89 countries

Esophageal Stricture

Narrowing of the esophagus causing difficulty swallowing (dysphagia). Most commonly caused by chronic acid reflux (GERD) leading to scar tissue formation. Other causes include radiation, eosinophilic esophagitis, cancer, and ingestion of caustic substances.

1,000,000,000 affected89 countries

Metabolic Syndrome

A cluster of conditions including increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol levels. Occurring together, they increase risk of heart disease, stroke, and type 2 diabetes. Very common in developed countries.

50,000 affected89 countries

Osteogenesis Imperfecta

A group of genetic disorders causing brittle bones that break easily. Caused by defects in type I collagen. Range from mild (few fractures) to severe (lethal in infancy). Also known as brittle bone disease. Can affect teeth, hearing, and connective tissue.

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Hypokalemic Periodic Paralysis

A rare genetic disorder causing episodes of muscle weakness or paralysis triggered by low potassium levels. Episodes often occur during rest after exercise or high-carbohydrate meals. Muscles work normally between attacks. Can lead to permanent weakness over time.

50,000 affected89 countries

3,000,000 affected89 countries

Narcolepsy Type 1

A chronic neurological disorder affecting the brain's ability to control sleep-wake cycles. Characterized by excessive daytime sleepiness and cataplexy (sudden muscle weakness triggered by emotions). Often caused by loss of hypocretin-producing neurons. Onset typically in adolescence.

150,000,000 affected89 countries

Restless Legs Syndrome

A neurological disorder causing uncomfortable sensations in the legs and an irresistible urge to move them. Symptoms worse at rest and in the evening/night. Significantly disrupts sleep. Associated with iron deficiency, kidney disease, pregnancy, and certain medications.

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Benign Paroxysmal Positional Vertigo (BPPV)

One of the most common causes of vertigo, triggered by specific changes in head position. Caused by tiny calcium crystals (canaliths) becoming dislodged in the inner ear. Brief, intense episodes of spinning sensation lasting less than a minute.

64,000,000 affected89 countries

40,000,000 affected89 countries

Rotator Cuff Tear

A tear in one or more of the four rotator cuff tendons in the shoulder (supraspinatus, infraspinatus, teres minor, subscapularis). Can occur from acute injury or degenerative changes with aging. Causes shoulder pain and weakness, especially with overhead activities.

250,000,000 affected89 countries

Spinal Stenosis

Narrowing of the spaces within the spine, putting pressure on the spinal cord and nerves. Most commonly affects the lower back (lumbar) and neck (cervical). Causes pain, numbness, and muscle weakness. Usually age-related degenerative changes.

20,000,000 affected89 countries

Lumbar Herniated Disc

When the soft inner material of a spinal disc in the lower back pushes through the tough outer layer, irritating nearby nerves. Commonly called a slipped or ruptured disc. Most common in ages 30-50. Most improve with conservative treatment within 6 weeks.

23,000,000 affected89 countries

Achilles Tendinitis

Inflammation of the Achilles tendon, the large tendon connecting the calf muscles to the heel bone. Common in runners and athletes who have suddenly increased training intensity. Causes pain and stiffness along the back of the leg near the heel.

100,000,000 affected89 countries

Plantar Fasciitis

Inflammation of the plantar fascia, a thick band of tissue running across the bottom of the foot connecting the heel bone to the toes. Causes stabbing heel pain, especially with first steps in the morning. Most common cause of heel pain.

800,000 affected89 countries

Chronic Pyelonephritis

Persistent or recurrent infection of the kidneys causing progressive scarring and damage. Usually results from repeated acute pyelonephritis, often due to urinary tract obstruction or vesicoureteral reflux. Can lead to chronic kidney disease and end-stage renal disease.

7,000,000 affected89 countries

Renal Artery Stenosis

Narrowing of one or both renal arteries reducing blood flow to the kidneys. Causes hypertension that can be difficult to control and can lead to kidney damage. Usually caused by atherosclerosis (older patients) or fibromuscular dysplasia (younger women).

2,000,000 affected89 countries

Nephrogenic Diabetes Insipidus

A kidney disorder where the kidneys cannot concentrate urine due to resistance to antidiuretic hormone (ADH/vasopressin). Causes excessive thirst and excretion of large amounts of dilute urine. Can be inherited (genetic) or acquired (lithium, other medications).

546,000,000 affected89 countries

Overactive Bladder

A condition characterized by sudden, involuntary contraction of the bladder muscle causing urgency to urinate, often with frequency and nocturia. May or may not involve urge incontinence. Very common, especially with aging, but not a normal part of aging.

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Kidney Cancer

Cancer that starts in the kidneys, most commonly renal cell carcinoma (RCC). Often discovered incidentally on imaging. Associated with smoking, obesity, and hypertension. Can be cured if caught early but has poor prognosis if metastatic.

430,000 affected89 countries

1,200,000 affected89 countries

Hypospadias

A congenital condition in males where the opening of the urethra is located on the underside of the penis rather than at the tip. One of the most common birth defects of the male genitalia. Varies in severity based on location of urethral opening.

15,000,000 affected89 countries

Epididymal Cyst (Spermatocele)

A fluid-filled sac in the epididymis, the coiled tube behind each testicle that stores and carries sperm. Very common and benign. Usually painless and discovered during self-exam. Can vary in size. Different from testicular cancer.

80,000,000 affected89 countries

Primary Open-Angle Glaucoma

A chronic eye condition where fluid in the eye doesn't drain properly, causing increased pressure that damages the optic nerve. The most common type of glaucoma. Called the 'silent thief of sight' because it causes gradual vision loss without early symptoms.

95,000,000 affected89 countries

Senile Cataract

Clouding of the eye's natural lens that occurs with aging. The most common type of cataract and a leading cause of vision impairment worldwide. Develops gradually over years. Surgery is the only effective treatment and is highly successful.

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Blepharitis

Inflammation of the eyelids causing red, irritated, itchy eyelids and dandruff-like scales on eyelashes. Very common and chronic condition. Associated with dry eye, meibomian gland dysfunction, and sometimes skin conditions like rosacea or dandruff.

80,000,000 affected89 countries

200,000 affected89 countries

Hyphema

Blood pooling in the anterior chamber of the eye between the cornea and iris, usually due to trauma. Can cause increased eye pressure and vision loss. Medical emergency requiring prompt evaluation and management to prevent complications like glaucoma and corneal staining.

4,000,000 affected89 countries

Adult Strabismus

Misalignment of the eyes in adults, either persistent from childhood or newly acquired. Can cause double vision, eye strain, and difficulty with depth perception. New-onset in adults often indicates underlying neurological or medical condition requiring evaluation.

52,000,000 affected89 countries

Hyperthyroidism

Overproduction of thyroid hormones causing accelerated metabolism. Most commonly caused by Graves' disease, toxic nodular goiter, or thyroiditis. Affects multiple body systems and requires treatment to prevent serious complications like heart problems and osteoporosis.

18,000 affected15 countries

Adrenoleukodystrophy (ALD)

A rare X-linked genetic disorder caused by mutations in the ABCD1 gene, leading to accumulation of very long-chain fatty acids in the nervous system and adrenal glands. Childhood cerebral form causes progressive neurological deterioration.

42,000,000 affected15 countries

Gout

Form of inflammatory arthritis caused by monosodium urate crystal deposition. Sudden severe joint pain, often in big toe. Associated with metabolic syndrome.

Huntington Disease

Autosomal dominant neurodegenerative disorder. CAG repeat expansion in HTT gene. Choreiform movements, cognitive decline, psychiatric symptoms. Inevitably fatal.

32,000,000 affected84 countries

Myocardial Infarction (Heart Attack)

A medical emergency occurring when blood flow to the heart is severely reduced or blocked, causing heart muscle damage. Usually caused by a blood clot forming in a coronary artery already narrowed by atherosclerosis. Time-critical condition requiring immediate treatment to minimize heart damage.

14,000,000 affected83 countries

Cellulitis

A common bacterial skin infection affecting the deeper layers of skin and subcutaneous tissue. Usually caused by Streptococcus or Staphylococcus bacteria entering through breaks in the skin. Can spread rapidly and become life-threatening if not treated promptly.

65,000,000 affected83 countries

Diverticulosis

A condition where small pouches (diverticula) form and bulge outward through weak spots in the colon wall. Very common in adults over 60 in developed countries. Usually asymptomatic but can lead to diverticulitis (inflammation) or bleeding. Associated with low-fiber Western diet.

10,000,000 affected124 countries

Preeclampsia

A pregnancy complication characterized by high blood pressure and signs of damage to other organ systems, typically liver and kidneys. Usually begins after 20 weeks of pregnancy. Can lead to serious complications for both mother and baby including eclampsia (seizures). Leading cause of maternal and perinatal morbidity worldwide.

3,000,000 affected122 countries

Ectopic Pregnancy

A potentially life-threatening condition where a fertilized egg implants and grows outside the main cavity of the uterus, most commonly in a fallopian tube. The pregnancy cannot proceed normally and can cause the fallopian tube to rupture, leading to severe internal bleeding. Requires immediate medical intervention.

384,000,000 affected97 countries

Chronic Obstructive Pulmonary Disease (COPD)

A chronic inflammatory lung disease causing obstructed airflow from the lungs. Includes emphysema (destruction of lung air sacs) and chronic bronchitis (inflammation of bronchial tubes). Progressive disease that makes breathing increasingly difficult over time. Primarily caused by smoking.

200,000,000 affected83 countries

Osteopenia

A condition where bone mineral density is lower than normal but not low enough to be classified as osteoporosis. Considered a precursor to osteoporosis and increases fracture risk compared to normal bone density. Often asymptomatic until a fracture occurs.

800,000 affected27 countries

CHARGE Syndrome

A rare genetic disorder characterized by a specific set of birth defects: Coloboma, Heart defects, Atresia of the choanae, Growth retardation, Genital abnormalities, and Ear abnormalities. Caused by mutations in the CHD7 gene in most cases. Affects approximately 1 in 8,500-15,000 births.

240,000,000 affected71 countries

Schistosomiasis (Bilharzia)

A tropical parasitic disease caused by blood flukes (trematode worms) of the genus Schistosoma. Acquired through contact with contaminated freshwater. Affects over 240 million people worldwide, primarily in Africa. Second most devastating parasitic disease after malaria.

20,000,000 affected51 countries

Onchocerciasis (River Blindness)

A parasitic disease caused by the nematode worm Onchocerca volvulus, transmitted through the bites of infected blackflies. Leading cause of infectious blindness worldwide. Affects approximately 20-25 million people, primarily in sub-Saharan Africa. WHO goal is elimination by 2030.

120,000,000 affected99 countries

Lymphatic Filariasis (Elephantiasis)

A neglected tropical disease caused by filarial worms transmitted by mosquitoes. Damages lymphatic system causing abnormal enlargement of body parts. Affects over 120 million people in 72 countries. WHO goal is elimination by 2030.

1,000,000 affected33 countries

Human African Trypanosomiasis (Sleeping Sickness)

A parasitic disease transmitted by tsetse flies, caused by Trypanosoma brucei parasites. Affects rural populations in sub-Saharan Africa. Two forms exist: T.b. gambiense (West/Central Africa, chronic) and T.b. rhodesiense (East/Southern Africa, acute). Without treatment, fatal.

1,500,000 affected47 countries

Leishmaniasis

A parasitic disease caused by Leishmania protozoa, transmitted by sandfly bites. Three main forms: cutaneous (skin sores), mucocutaneous (destruction of mucous membranes), and visceral (affects organs, fatal if untreated). Affects 1-2 million people annually, with 350 million at risk in 98 countries.

6,000 affected20 countries

Buruli Ulcer

A necrotizing skin disease caused by Mycobacterium ulcerans. Destroys skin and soft tissue, causing large ulcers. Most common in West and Central Africa. Third most common mycobacterial disease after tuberculosis and leprosy. Affects approximately 5,000-6,000 people annually.

800,000 affected28 countries

Dermatomyositis

A rare inflammatory disease affecting skin and muscles, causing muscle weakness and distinctive skin rash. Belongs to a group of conditions called inflammatory myopathies. Can occur at any age but most common in adults 40-60 and children 5-15. Associated with increased cancer risk in adults.

600,000 affected28 countries

Polymyositis

A rare inflammatory muscle disease causing progressive muscle weakness, particularly in the proximal muscles (shoulders, hips, thighs). Belongs to idiopathic inflammatory myopathies. Affects adults primarily, rare in children. Associated with interstitial lung disease in some cases.

2,000,000 affected34 countries

Sarcoidosis

An inflammatory disease causing granulomas (clumps of inflammatory cells) to form in various organs, most commonly the lungs and lymph nodes. Can affect any organ system. Cause unknown. Affects approximately 1-40 per 100,000 people, more common in African Americans and Scandinavians. Often remits spontaneously.

5,000,000 affected30 countries

Antiphospholipid Syndrome

An autoimmune disorder characterized by recurrent blood clots (thrombosis), pregnancy complications, and the presence of antiphospholipid antibodies. Can occur alone (primary) or with other autoimmune diseases (secondary, usually lupus). Affects approximately 1-5 per 100,000 people.

3,000,000 affected32 countries

Giant Cell Arteritis (Temporal Arteritis)

An inflammatory disease of blood vessels, most commonly affecting the arteries in the head, particularly the temples. Most common form of vasculitis in adults over 50. Can cause sudden blindness if untreated. Associated with polymyalgia rheumatica in 50% of cases. Affects approximately 0.5-27 per 100,000 people.

200,000 affected44 countries

Takayasu Arteritis (Pulseless Disease)

A rare large vessel vasculitis affecting the aorta and its major branches, causing vessel wall inflammation, stenosis, occlusion, and aneurysm formation. Primarily affects young women of Asian descent. Called 'pulseless disease' because pulses may be absent. One of the most common vasculitides in Asia.

3,000,000 affected30 countries

Postural Orthostatic Tachycardia Syndrome (POTS)

A condition characterized by an abnormal increase in heart rate upon standing, without a drop in blood pressure. Part of a group of disorders called dysautonomia. Affects primarily women aged 15-50. Can be debilitating. Affects approximately 1-3 million people in the US alone.

1,300,000 affected30 countries

Tuberous Sclerosis Complex (TSC)

A genetic disorder causing noncancerous (benign) tumors to develop in many parts of the body, particularly the brain, skin, kidneys, heart, and lungs. Affects approximately 1 in 6,000 people. TSC1 or TSC2 gene mutations cause overactivation of mTOR pathway.

200,000 affected30 countries

Sturge-Weber Syndrome

A rare congenital neurological and skin disorder characterized by a facial port-wine birthmark, neurological abnormalities including seizures, and eye problems such as glaucoma. Caused by somatic mutation in GNAQ gene. Affects approximately 1 in 20,000-50,000 people.

30,000 affected30 countries

Alexander Disease

A rare, usually fatal neurological disorder causing destruction of white matter in the brain. Characterized by abnormal protein (GFAP) deposits called Rosenthal fibers. Most common form is infantile, but juvenile and adult forms exist. Affects approximately 1 in 2.7 million people. No cure available.

80,000 affected30 countries

Krabbe Disease (Globoid Cell Leukodystrophy)

A rare, inherited disorder destroying the protective coating (myelin) of nerve cells in the brain and throughout the nervous system. Caused by deficiency of galactocerebrosidase enzyme. Most common form is infantile with rapid progression. Affects approximately 1 in 100,000 people.

Lassa Fever

A viral hemorrhagic fever endemic in West Africa, caused by Lassa virus. Transmitted to humans through contact with food or household items contaminated with rodent urine or feces. Person-to-person transmission possible. Affects approximately 100,000-300,000 people annually with 5,000 deaths.

50,000 affected31 countries

Marburg Virus Disease

A severe, often fatal hemorrhagic fever caused by Marburg virus, related to Ebola virus. Transmitted through contact with infected animals (primarily fruit bats) or person-to-person through bodily fluids. First recognized in 1967 in Germany and Yugoslavia. Case fatality rate 23-90%.

2,600 affected140 countries

Middle East Respiratory Syndrome (MERS)

A viral respiratory illness caused by Middle East Respiratory Syndrome Coronavirus (MERS-CoV). First reported in Saudi Arabia in 2012. Transmitted from camels to humans and person-to-person in close contact. Case fatality rate approximately 35%. Most cases in Arabian Peninsula.

Nipah Virus Infection

A zoonotic virus transmitted from animals (fruit bats, pigs) to humans, with potential for person-to-person spread. Causes severe respiratory illness and encephalitis. First identified in Malaysia in 1998. Case fatality rate 40-75%. Outbreaks in Southeast Asia, primarily Bangladesh and India.

1,000 affected15 countries

Hendra Virus Infection

A rare zoonotic virus transmitted from horses to humans, causing severe respiratory and neurological disease. First identified in Hendra, Australia in 1994. Fruit bats (flying foxes) are natural reservoir. Case fatality rate 57%. Only reported in Australia.

13,000,000 affected15 countries

Acute Kidney Injury (AKI)

A sudden episode of kidney failure or kidney damage that happens within a few hours or days. Causes waste products to build up in the blood and makes it hard for kidneys to maintain the right balance of fluids. Can be prerenal, intrinsic, or postrenal.

430,000 affected15 countries

Renal Cell Carcinoma (Kidney Cancer)

The most common type of kidney cancer in adults, arising from the lining of the proximal convoluted tubule. Subtypes include clear cell (70-80%), papillary (10-15%), chromophobe (5%), and collecting duct. Often asymptomatic in early stages.

1,200,000 affected15 countries

Glomerulonephritis

Inflammation of the glomeruli, the tiny filters in the kidneys. Can be acute or chronic, primary or secondary to systemic diseases. Various types including IgA nephropathy, membranous, minimal change disease, and post-infectious GN.

Fanconi Syndrome

A disorder of the kidney tubules in which certain substances that are normally absorbed into the bloodstream are instead released into the urine. Can be inherited or acquired. Leads to loss of glucose, amino acids, phosphate, bicarbonate, and other substances.

Trigeminal Neuralgia

A chronic pain condition affecting the trigeminal nerve, which carries sensation from the face to the brain. Characterized by sudden, severe, shock-like facial pain lasting seconds to minutes. Often triggered by simple activities like eating, talking, or touching the face. One of the most painful conditions known.

300,000,000 affected17 countries

Chronic Sinusitis

A common condition in which the cavities around nasal passages (sinuses) become inflamed and swollen for at least 12 weeks, despite treatment attempts. Also known as chronic rhinosinusitis. Can affect both adults and children, causing difficulty breathing through the nose and facial pain.

Bell's Palsy

A condition that causes sudden, temporary weakness or paralysis of facial muscles, typically affecting one side of the face. Results from dysfunction of the facial nerve (cranial nerve VII), often related to inflammation. Usually develops rapidly, reaching peak severity within 48-72 hours.

2,000,000 affected17 countries

Vasculitis

An inflammation of blood vessels that causes changes in vessel walls including thickening, weakening, narrowing, and scarring. Can affect arteries, veins, and capillaries. These changes restrict blood flow, resulting in organ and tissue damage. There are many forms affecting different vessel sizes and organs.

900,000 affected17 countries

Polymyalgia Rheumatica

An inflammatory disorder causing muscle pain and stiffness, especially in the shoulders, neck, and hips. Symptoms are typically worse in the morning. Usually develops quickly, often overnight. Closely related to giant cell arteritis and can occur together. Almost exclusively affects adults over 50.

2,000,000,000 affected16 countries

Acute Gastroenteritis

Inflammation of the stomach and intestines causing diarrhea, vomiting, and abdominal cramps. Usually caused by viral, bacterial, or parasitic infections. Common worldwide and especially dangerous in young children and elderly.

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Allergic Rhinitis (Hay Fever)

An allergic response causing sneezing, runny nose, and itchy eyes when exposed to allergens like pollen, dust mites, or pet dander. One of the most common allergic conditions worldwide affecting quality of life.

400,000,000 affected16 countries

200,000 affected16 countries

Atrial Flutter

An abnormal heart rhythm characterized by rapid, regular atrial contractions at around 250-350 beats per minute. Similar to atrial fibrillation but with organized electrical activity. Increases stroke risk.

35,000,000 affected16 countries

Diverticular Disease

A condition where small bulging pouches (diverticula) develop in the digestive tract, typically the colon. Includes diverticulosis (presence of pouches) and diverticulitis (inflammation/infection). Very common in Western populations.

100,000 affected16 countries

Epidural Hematoma

A serious brain injury where blood accumulates between the skull and the dura mater, usually due to traumatic head injury. Often involves arterial bleeding and is a medical emergency requiring immediate surgery.

10,000,000 affected16 countries

Hemorrhoids

Swollen veins in the lower rectum and anus, similar to varicose veins. Very common condition affecting about half of adults over age 50. Can cause pain, itching, and bleeding.

15,000,000 affected16 countries

Hypoglycemia

A condition characterized by abnormally low blood glucose levels (below 70 mg/dL). Can occur in diabetics due to medication or in non-diabetics due to various medical conditions. Requires immediate treatment.

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Laryngitis

Inflammation of the voice box (larynx) causing hoarseness or voice loss. Usually temporary and caused by viral infection, overuse, or irritation. Can be acute or chronic.

5,000,000 affected16 countries

3,000,000 affected16 countries

Lichen Sclerosus

A chronic inflammatory skin condition causing patchy, discolored, thin skin, typically in genital and perianal areas. More common in postmenopausal women but affects all ages and genders. Associated with increased skin cancer risk.

170,000 affected16 countries

Meningioma

A tumor that arises from the meninges, the membranes that surround the brain and spinal cord. Usually benign and slow-growing, but can become atypical or malignant. Most common type of primary brain tumor.

35,000,000 affected16 countries

Onychomycosis (Fungal Nail Infection)

A fungal infection of the toenails or fingernails causing discoloration, thickening, and crumbling of the nail. Very common condition, especially in older adults. Can be difficult to treat.

1,500,000 affected16 countries

Patellar Tendinitis (Jumper's Knee)

Inflammation of the patellar tendon connecting the kneecap to the shinbone. Common in athletes who jump frequently. Causes pain below the kneecap and can lead to tendon degeneration if untreated.

20,000,000 affected16 countries

Peripheral Neuropathy

Damage to the peripheral nerves causing weakness, numbness, and pain, typically in hands and feet. Can result from diabetes, infections, injuries, or toxins. Affects millions worldwide.

83,000,000 affected16 countries

Seborrheic Keratosis

Common benign skin growths that appear as waxy brown, black, or tan spots. Often called 'barnacles of aging.' Very common in older adults. Not contagious or premalignant but can be cosmetically concerning.

500,000 affected16 countries

Subarachnoid Hemorrhage

Bleeding into the subarachnoid space between the brain and surrounding membrane. Usually caused by ruptured cerebral aneurysm. Medical emergency with high mortality. Classic 'thunderclap' headache.

3,000,000 affected16 countries

Temporal Lobe Epilepsy

The most common form of focal epilepsy originating in the temporal lobe. Often associated with hippocampal sclerosis. Causes seizures with distinctive features like déjà vu, strange smells, or autonomic symptoms.

1,800,000 affected16 countries

Urinary Retention

Inability to empty the bladder completely. Can be acute (sudden, painful) or chronic (gradual, painless). Caused by obstruction, nerve problems, or medications. Requires prompt treatment to prevent kidney damage.

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Vocal Cord Nodules

Benign growths on both vocal cords, usually at the midpoint, caused by vocal abuse or overuse. Also called singer's or screamer's nodules. Most common in children and professional voice users.

1,400,000 affected16 countries

25,000,000 affected111 countries

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

A complex, chronic disorder characterized by extreme fatigue that cannot be explained by any underlying medical condition and does not improve with rest. Associated with post-exertional malaise, cognitive impairment, and orthostatic intolerance.

88,000,000 affected111 countries

Pelvic Inflammatory Disease (PID)

An infection of the female reproductive organs, usually caused by sexually transmitted bacteria spreading from the vagina to uterus, fallopian tubes, or ovaries. Affects approximately 4.4% of women of reproductive age. Leading preventable cause of infertility and ectopic pregnancy.

21,000,000 affected111 countries

Vaginitis

Inflammation of the vagina that can result in discharge, itching and pain. The most common types are bacterial vaginosis, yeast infections, and trichomoniasis. Affects millions of women annually and is one of the most common reasons for gynecologic visits.

56,000,000 affected111 countries

Vulvodynia

A chronic pain condition affecting the vulva, characterized by burning, stinging, irritation, or rawness. Affects up to 16% of women. The cause is unknown and diagnosis is often delayed. Significantly impacts quality of life and sexual function.

500,000,000 affected111 countries

Menorrhagia (Heavy Menstrual Bleeding)

Abnormally heavy or prolonged menstrual bleeding affecting up to 25% of women. Can cause anemia and significantly impact quality of life. Often caused by hormonal imbalances, uterine fibroids, or bleeding disorders.

1,500,000,000 affected111 countries

Premenstrual Syndrome (PMS)

A combination of physical and emotional symptoms that occur 1-2 weeks before menstruation. Affects up to 90% of women of reproductive age. Severe form (PMDD) affects 3-8% and causes significant functional impairment.

300,000,000 affected111 countries

Dyspareunia (Painful Intercourse)

Persistent or recurrent genital pain that occurs just before, during, or after intercourse. Affects up to 20% of women. Can have physical or psychological causes. Significantly impacts sexual health and relationships.

366,000,000 affected111 countries

Attention Deficit Hyperactivity Disorder (ADHD)

A neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity. Affects approximately 5-7% of children and 2.5-5% of adults globally. Often persists into adulthood and can significantly impact academic, occupational, and social functioning.

400,000,000 affected111 countries

Vitamin B12 Deficiency Anemia

A condition characterized by low levels of vitamin B12, leading to megaloblastic anemia and potential neurological complications. Affects approximately 6% of people under 60 and up to 20% of those over 60. Can cause irreversible nerve damage if untreated.

200,000,000 affected111 countries

Alcoholic Liver Disease

Liver damage caused by excessive alcohol consumption, ranging from fatty liver to alcoholic hepatitis and cirrhosis. A leading cause of liver disease worldwide. Risk increases with amount and duration of alcohol use. Can be reversible in early stages.

21,000,000 affected22 countries

Bacterial Vaginosis

The most common vaginal infection in women of reproductive age, caused by disruption of normal vaginal flora with overgrowth of anaerobic bacteria. Not sexually transmitted but associated with sexual activity. Increases risk of STI acquisition, pelvic inflammatory disease, and pregnancy complications.

5,000,000 affected20 countries

Cervical Dysplasia (CIN)

Precancerous changes in cervical cells caused primarily by persistent infection with high-risk human papillomavirus (HPV). Classified as CIN 1 (mild), CIN 2 (moderate), or CIN 3 (severe/carcinoma in situ). Most cases of CIN 1 resolve spontaneously; CIN 2-3 require treatment to prevent progression to invasive cervical cancer.

25,000,000 affected19 countries

Ovarian Cysts

Fluid-filled sacs that develop on the ovaries, extremely common in women of reproductive age. Most are functional cysts (follicular or corpus luteum) that resolve spontaneously within 1-3 menstrual cycles. Pathological cysts include dermoid cysts, endometriomas, and cystadenomas. Rarely, cysts may be malignant, especially in postmenopausal women.

135,000,000 affected20 countries

Vaginal Yeast Infection (Vulvovaginal Candidiasis)

A common fungal infection affecting up to 75% of women at least once in their lifetime. Caused by Candida overgrowth, most commonly Candida albicans. Characterized by intense itching and thick, white discharge. Recurrent infections (≥4 per year) affect 5-8% of women and significantly impact quality of life.

273,000,000 affected20 countries

Generalized Anxiety Disorder (GAD)

A chronic mental health condition characterized by persistent, excessive, and uncontrollable worry about everyday situations and events. Affects 3-6% of adults worldwide, with women affected twice as often as men. Causes significant impairment in social, occupational, and other important areas of functioning.

46,000,000 affected20 countries

Bipolar I Disorder

A severe mood disorder characterized by at least one manic episode, often alternating with major depressive episodes. Affects approximately 1% of the population equally across genders. Manic episodes cause significant impairment and may include psychotic features. Associated with high suicide risk and functional disability.

24,000,000 affected20 countries

Bipolar II Disorder

A mood disorder characterized by at least one hypomanic episode and at least one major depressive episode. Hypomania is less severe than mania and does not cause marked impairment or psychosis. Depressive episodes are typically more frequent and longer-lasting than in Bipolar I, with significant suicide risk.

78,000,000 affected20 countries

Borderline Personality Disorder (BPD)

A complex personality disorder characterized by pervasive instability in mood, interpersonal relationships, self-image, and behavior. Affects 1-2% of the general population and up to 20% of psychiatric inpatients. Associated with high rates of self-harm, suicide attempts, and significant functional impairment.

354,000,000 affected21 countries

Post-Traumatic Stress Disorder (PTSD)

A psychiatric disorder that may occur in people who have experienced or witnessed a traumatic event. Affects 6-8% of the population at some point in life. Characterized by intrusive memories, avoidance, negative alterations in cognition and mood, and marked alterations in arousal and reactivity.

32,000,000 affected18 countries

Anorexia Nervosa

A serious eating disorder characterized by restriction of energy intake leading to significantly low body weight, intense fear of gaining weight, and disturbed body image. Has the highest mortality rate of any psychiatric disorder. Affects approximately 0.5-1% of women and 0.1-0.3% of men, typically beginning in adolescence.

64,000,000 affected19 countries

Bulimia Nervosa

An eating disorder characterized by recurrent episodes of binge eating followed by inappropriate compensatory behaviors to prevent weight gain, such as self-induced vomiting, laxative misuse, fasting, or excessive exercise. Affects 1-2% of women and 0.1-0.5% of men. Associated with significant medical complications.

400,000 affected20 countries

Hemophilia A (Factor VIII Deficiency)

An X-linked recessive bleeding disorder caused by deficiency of clotting factor VIII. The most common severe inherited bleeding disorder, affecting approximately 1 in 5,000-10,000 male births. Characterized by spontaneous and trauma-induced bleeding, particularly into joints (hemarthrosis) and muscles.

100,000 affected20 countries

Hemophilia B (Factor IX Deficiency)

An X-linked recessive bleeding disorder caused by deficiency of clotting factor IX, also known as Christmas disease. Affects approximately 1 in 30,000 male births. Clinically indistinguishable from Hemophilia A but requires different treatment. Less common than Hemophilia A, representing 15-20% of hemophilia cases.

50,000 affected19 countries

Hunter Syndrome (Mucopolysaccharidosis Type II)

An X-linked lysosomal storage disorder caused by deficiency of iduronate-2-sulfatase, leading to accumulation of glycosaminoglycans (GAGs). Affects multiple organ systems including skeleton, heart, and brain. Only MPS disorder that is X-linked. Ranges from severe (with cognitive decline) to attenuated (without cognitive involvement).

80,000 affected19 countries

Tyrosinemia Type I

A severe autosomal recessive disorder of amino acid metabolism caused by deficiency of fumarylacetoacetate hydrolase (FAH). Leads to accumulation of toxic metabolites causing liver failure, kidney dysfunction, and neurologic crises. Untreated, fatal in childhood. Newborn screening allows early treatment.

13,000,000 affected15 countries

Adenomyosis

A condition where the inner lining of the uterus (endometrium) breaks through the muscle wall of the uterus (myometrium). Can cause menstrual cramps, lower abdominal pressure, and bloating before menstrual periods. Often coexists with endometriosis.

2,000,000 affected15 countries

Endometrial Hyperplasia

Thickening of the uterine lining (endometrium) due to excessive proliferation of endometrial glands. Can be simple or complex, with or without atypia. Atypical hyperplasia is considered a precancerous condition.

3,500,000 affected15 countries

Complex Ovarian Cysts

Ovarian cysts that contain solid components, septations, or are irregular in nature. Different from simple functional cysts. May be benign (mature cystic teratoma, endometrioma) or malignant. Requires careful evaluation.

Ureteropelvic Junction (UPJ) Obstruction

Blockage at the point where the renal pelvis meets the ureter, preventing urine from draining properly from the kidney. Can be congenital or acquired. May cause hydronephrosis and kidney damage if untreated.

Pyruvate Kinase Deficiency

Inherited hemolytic anemia caused by deficiency of the enzyme pyruvate kinase, which is essential for red blood cell energy metabolism. Most common enzyme deficiency in the glycolytic pathway causing hemolytic anemia.

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Hereditary Elliptocytosis

Inherited blood disorder characterized by oval or elliptical red blood cells. Usually autosomal dominant inheritance. Most common in people of African or Mediterranean descent. Spectrum from asymptomatic carriers to severe hemolytic anemia.

Congenital Dyserythropoietic Anemia (CDA)

Rare inherited blood disorder characterized by ineffective erythropoiesis, leading to anemia, iron overload, and characteristic bone marrow abnormalities. Three main types with type I and II being most common.

Thrombotic Thrombocytopenic Purpura (TTP)

Rare, life-threatening blood disorder causing blood clots in small blood vessels throughout the body. Characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ ischemia. Caused by ADAMTS13 deficiency or inhibitors.

Mucopolysaccharidosis Type I (MPS I)

Lysosomal storage disorder caused by deficiency of alpha-L-iduronidase enzyme. Accumulation of glycosaminoglycans affects multiple organ systems. Spectrum from severe Hurler syndrome to attenuated Scheie syndrome.

Primary Hyperoxaluria Type 1

Rare autosomal recessive disorder caused by deficiency of alanine-glyoxylate aminotransferase (AGT). Leads to overproduction of oxalate, causing recurrent kidney stones, nephrocalcinosis, and end-stage renal disease.

Acute Chest Syndrome

Life-threatening complication of sickle cell disease characterized by fever, chest pain, hypoxia, and pulmonary infiltrates. Leading cause of death and hospitalization in sickle cell patients. Can be triggered by infection, fat embolism, or asthma.

40,000 affected15 countries

Chronic Graft-Versus-Host Disease (cGVHD)

Major complication of allogeneic stem cell transplantation where donor immune cells attack recipient tissues. Affects multiple organs including skin, eyes, mouth, liver, and lungs. Leading cause of non-relapse mortality post-transplant.

3,000 affected15 countries

Barth Syndrome

Rare X-linked disorder caused by tafazzin gene mutations affecting cardiolipin metabolism. Characterized by cardiomyopathy, neutropenia, skeletal myopathy, and growth delay. Primarily affects males.

Miller-Dieker Syndrome

Rare genetic disorder caused by deletion of chromosome 17p13.3 including LIS1 gene. Characterized by lissencephaly (smooth brain), severe developmental delay, seizures, and characteristic facial features. Life-limiting condition.

180,000 affected15 countries

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Vulvar Intraepithelial Neoplasia (VIN)

Abnormal cell growth on the vulva, considered a precancerous condition. Associated with HPV infection and can progress to vulvar cancer if untreated.

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Primary Ovarian Insufficiency (POI)

Loss of normal ovarian function before age 40, characterized by irregular or absent periods and elevated FSH levels. Formerly called premature ovarian failure.

45,000,000 affected15 countries

Vaginal Atrophy (Genitourinary Syndrome of Menopause)

Thinning, drying, and inflammation of the vaginal walls due to decreased estrogen levels, typically occurring after menopause. Affects urinary and sexual function.

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Cervical Incompetence

Painless cervical dilation and effacement leading to second-trimester pregnancy loss or preterm birth. The cervix is unable to retain the pregnancy until term.

120,000 affected15 countries

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Pelvic Congestion Syndrome

Chronic pelvic pain caused by varicose veins in the pelvis. Often underdiagnosed and associated with incompetent valves in ovarian and pelvic veins.

800,000 affected15 countries

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Gestational Trophoblastic Disease (GTD)

A group of rare tumors that involve abnormal growth of cells inside a woman's uterus that would normally develop into the placenta during pregnancy. Includes complete and partial moles.

45,000 affected15 countries

Warm Autoimmune Hemolytic Anemia (wAIHA)

A condition where the body's immune system mistakenly attacks and destroys its own red blood cells, causing anemia. IgG antibodies react at body temperature.

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Factor V Leiden Thrombophilia

The most common inherited blood clotting disorder, caused by a mutation in the F5 gene that makes factor V resistant to inactivation by protein C. Increases risk of venous thrombosis.

Glycogen Storage Disease Type I (von Gierke Disease)

A rare inherited disorder caused by deficiency of glucose-6-phosphatase enzyme, leading to abnormal accumulation of glycogen in liver and kidneys, severe hypoglycemia, and lactic acidosis.