FAMILIAL MITOCHONDRIAL ENCEPHALOMYOPATHY WITH DEAF-MUTISM, OPHTHALMOPLEGIA AND LEUKODYSTROPHY

We report two sisters (32 and 36 years old) with familial deaf-mutism, progressive external ophthalmoplegia, leukodystrophy and mitochondria l myopathy. T2-weighted brain MRI demonstrated diffuse symmetrical hig h intensity areas in the white matter. Their muscle biopsies showed ra gged-red fibers and cytochrome c oxidase (CCO)-negative fibers. CCO ac tivity in biopsied muscle decreased to about 20% of normal control. Th ey had no deletions of the mitochondrial DNA and no point mutations in mitochondrial tRNA. Their brother was diagnosed as having Kugelberg-W elander disease, grand mal seizures and urinary dysfunction. Their par ents and grandparents had consanguinity. Three relatives were found to have deaf-mutism without accompanying ophthalmoplegia. This rare comb ination of mitochondrial encephalomyopathy and familial deaf-mutism mi ght be caused by a nuclear DNA mutation in these sisters.