Mitochondrial myopathies

Abstract

The mitochondrial myopathies are a diverse group of disorders characterized by defects in mitochondrial function. In addition to the recent identification of mutations in mitochondrial DNA (mtDNA) associated with both maternally inherited and sporadic mitochondrial encephalomyopathies, new classes of mitochondrial diseases have now been described. These result from apparent defects in nuclear genes or even from environmental effects on mitochondrial function. In this latter group, we have made progress in three areas: 1) we have developed a diagnostic test that can distinguish, in the critical first few weeks of life, the fatal and reversible forms of infantile myopathy with cytochrome c oxidase deficiency; 2) we have identified a new class of mitochondrial disease caused by tissue-specific, but variable, depletion of mtDNA; and 3) we have found that azidothimidine-induced myopathy in AIDS patients is also characterized by depletion of mtDNA in muscle.