Mitochondrial myopathy, encephalopathy, lactic acidosis and strokelike episodes (MELAS): report of a sporadic case and review of the literature.

We studied a 5-year-old boy with mitochondrial myopathy, encephalopathy, lactic acidosis and strokelike episodes that are characteristic of the MELAS syndrome. Results of biochemical, histopathological, and molecular genetic studies from the patient's tissue meet the criteria for diagnosis of mitochondrial disease. An A to G transition at the 3243th nucleotide position of mitochondrial DNA (mtDNA) was found in the blood cells and hair follicles, instead of in muscle, from the propositus. To the best of our knowledge, this is the first reported MELAS case associated with mtDNA mutation in blood cells and hair follicles, instead of in the target muscle tissue, that has ever been documented in Taiwan. Brain lesions demonstrated by angiography, computed tomography (CT) and magnetic resonance imaging (MRI) are discussed.