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.

• 1Genetic testing
• 2Clinical evaluation
• 3Family history assessment
• 4Specialized laboratory tests
• 5Imaging studies
• 6Biopsy (if applicable)

Progressive course with stepwise deterioration. Stroke-like episodes cause cumulative brain injury. Common causes of death are status epilepticus, cardiomyopathy, or progressive dementia in 30s-40s. Some patients survive into 50s-60s. Coenzyme Q10, L-arginine, and L-citrulline may provide modest benefit. Avoidance of mitochondrial stressors (valproate, certain antibiotics) important. Genetic counseling for maternal inheritance. Preimplantation genetic diagnosis available.

• Genetic counseling
• Carrier screening
• Prenatal diagnosis
• Preimplantation genetic diagnosis
• Family planning