The most common microdeletion syndrome caused by deletion of 22q11.2. Characterized by congenital heart defects, thymic hypoplasia, immunodeficiency, hypocalcemia, and characteristic facial features. Variable expressivity.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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).

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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%).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.