The Syndrome of Mitochondrial Encephalomyopathy, Lactic Acidosis, and Strokelike Episodes Presenting Without Stroke

OBJECTIVE: To study and describe a large family with the tRNA Leu(UUR) point mutation at position 3243 in mitochondrial DNA, which is associated with the syndrome of mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes. DESIGN: Survey; case series. SETTING: University hospital inpatient and outpatient neurology department. PATIENTS: Twelve patients from three generations in a family carrying the tRNA Leu(UUR) point mutation at position 3243 were studied. INTERVENTIONS: Clinical evaluation, muscle biopsy, and mitochondrial DNA point mutation quantitation of the syndrome of mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes in muscle and blood. MAIN OUTCOME MEASURE: Correlation between clinical, pathologic, and genotypic features. RESULTS: Family members had various combinations of sensorineural hearing loss, retinal pigmentary degeneration, migraine, hypothalamic hypogonadism, and mild myopathy. Only one member had a strokelike episode at the age of 46 years. This patient had the highest point mutation percentage. CONCLUSION: This report suggests that this point mutation may not be associated with stroke in all families and that whether patients develop stroke may depend on the percentage of mutant mitochondrial DNA and its tissue distribution.