Adult onset limb-girdle type mitochondrial myopathy with a mitochondrial DNA np8291 A-to-G substitution.
We analyzed mitochondrial DNA (mtDNA) from 7 patients in four families with adult onset limb-girdle type mitochondrial myopathy to clarify their genetic background. The patients, 2 men and 5 women, showed common clinical features, characterized by isolated skeletal myopathy, high serum creatine kinase level, ragged-red fibers and cytochrome c oxidase-defective fibers. Analysis of muscle biopsy specimens indicated that cytochrome c oxidase activity was decreased relative to that of citrate synthase in 5 of the 7 patients. Southern blotting and direct sequence analyses showed an A-to-G homoplasmic transition at np8291 and intergenic COII/tRNA (Lys) 9bp deletion in all patients. This substitution was detected in only 2 of 600 control individuals including healthy subjects and patients with other neuromuscular disorders; these 2 individuals had diabetes mellitus and myotonic dystrophy, respectively. Consequently, the mtDNA transition at np8291 was a rare polymorphism. However, the 7 patients we studied had identical clinical, pathological, biochemical, and genetic features. Therefore, limb-girdle type mitochondrial myopathy with this rare polymorphism may form a subgroup of adult onset mitochondrial myopathy.
D000328:Adult; D017668:Age of Onset; D000368:Aged; D001483:Base Sequence; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics*; D042963:Electron Transport Complex II; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017240:Mitochondrial Myopathies / Q000175:diagnosis / Q000235:genetics*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D010085:Oxidative Phosphorylation; D010088:Oxidoreductases / Q000378:metabolism; D010375:Pedigree; D017354:Point Mutation; D011110:Polymorphism, Genetic; D013385:Succinate Dehydrogenase / Q000378:metabolism