MELAS point mutation with unusual clinical presentation.

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is a multisystemic mitochondrial disorder (Pavlakis et al. Advances in Contemporary Neurology. Philadelphia: Davis, 1988: 95-133) and most patients with the typical MELAS phenotype have a point mutation in mitochondrial DNA, an A to G transition at nucleotide 3243 (Goto et al. Nature 1990; 348; 651-653; Koboyashi et al. Biochem Biophys Res Commun 1990; 173: 816-822; Ciafaloni et al. Ann Neurol 1992; 31: 391-398). A 9-yr-old boy presenting with chronic asthma and depression was found to have abnormal mitochondria, partial defects of respiratory chain enzymes, and the MELAS point mutation.