RANDOM MITOTIC SEGREGATION OF MITOCHONDRIAL-DNA IN MELAS SYNDROME

We describe the heterogeneity of clinical features and molecular genet ic characteristics of the probands and other members in two families w ith mitochondrial myopathy, encephalopathy, lactic acidosis and stroke -like episodes (MELAS) syndrome. A point mutation at the 3243rd nucleo tide position of mtDNA was found only in some of the maternal lineage members of the two families. Furthermore, the proportions of mutant mt DNA were varied and found only in some tissues of the individuals. Int riguingly, in some subjects, the mutant mtDNA was found in blood cells or hair follicles but was absent in muscles. The data do not support the notion of a selective advantage of wild-type mtDNA to rapidly repl icating cells. We suggest that a rapid replicative segregation may occ ur in early embryogenesis. (C) Munksgaard 1996.