The morphological and genetic characteristics of isolated muscle fibers from patients harboring an A->G mutation at nt-3243 in the mitochondrial tRNA(Leu(UUR)) gene have been analysed. This mutation is associated with two distinct disorders, namely, mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS3243) and progressive external ophthalmoplegia (PEO3243). Morphologically, the main distinctive feature in PEO3243 muscle sections is the presence of a subset of ragged-red fibers (RRF) with no cytochrome c oxidase activity, a feature which is present only rarely in MELAS3243 muscle. By single fiber PCR analysis, we have found that the two disorders exhibit a distinctive pattern in muscle of the distribution of the nt-3243 mutation. Furthermore, we have provided evidence that the focal concentration of the nt-3243 mutation in single muscle fibers induces impairment of respiratory chain function.
|Original language||English (US)|
|Number of pages||7|
|Journal||Bulletin of Molecular Biology and Medicine|
|State||Published - Dec 1 1995|
ASJC Scopus subject areas
- Clinical Biochemistry