A mitochondrial tRNA(Lys) gene mutation (T8316C) in a patient with mitochondrial myopathy, lactic acidosis, and stroke-like episodes

We studied a patient with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes who had morphologically and biochemically abnorma l muscle mitochondria. Molecular analysis revealed a T8316C transition in t he mitochondrial DNA tRNA(Lys) gene. The mutation was homoplasmic in muscle from the proposita, heteroplasmic in her blood, and still less abundant in blood from her asymptomatic maternal relatives. The T8316C mutation affect s a highly conserved base pair and was not found in controls, thus satisfyi ng the accepted criteria for pathogenicity. Our data document the genetic h eterogeneity in mitochondrial encephalomyopathy, lactic acidosis, and strok e-like episodes syndrome, underlining that the same syndrome may be associa ted with mutations of different genes. (C) 2000 Elsevier Science B.V. All r ights reserved.