Cardiac Involvement in Adults With m.3243A>G MELAS Gene Mutation

Cardiac data in adults with mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS syndrome) or asymptomatic gene carriers with the mitochondrial deoxyribonucleic acid adenine-to-guanine point mutation at nucleotide pair 3243 are scarce. Twelve subjects (mean age 35 ± 13 years), 8 with MELAS syndrome (patients) and 4 asymptomatic gene carriers (carriers), were enrolled in the study. Each subject underwent electrocardiography, exercise testing, Holter monitoring, echocardiography, and genetic and biochemical analysis for respiratory chain enzyme activity (complex I rest activity) in skeletal muscle. On electrocardiography and Holter monitoring, none of the subjects had evidence of preexcitation, cardiac arrhythmias, or conduction abnormalities. Patients had significantly lower (42 ± 17% from normal vs 103 ± 14%, p