Mitochondrial DNA deletions in muscle fibers in inclusion body XXXX .

@entity1 @entity5442 @entity39 @entity7319 @entity5589 @entity2383
@entity5589 ( @entity5589 ) is an autoimmune, @entity5442 where morphological changes of muscle, including ragged red fibers, have indicated @entity2383 in some muscle fibers. In this study enzyme histochemical analysis showed that cytochrome c oxidase (COX)-deficient muscle fibers were present at a frequency ranging from 0.5 to 5% of the muscle fibers in a series of 20 @entity5589 @entity1 . In age-matched controls, only occasional @entity7319 muscle fibers were present. Polymerase chain reaction (PCR) analysis of DNA extracted from muscle tissue of the @entity5589 @entity1 showed multiple mtDNA deletions. PCR analysis of isolated, single muscle fibers showed presence of mtDNA with only one type of deletion and deficiency of wild-type mtDNA in each @entity7319 muscle fiber. This finding was supported by results from in situ hybridization using different mtDNA probes on consecutive sections. A 5 kb deletion was identified in all 20 @entity5589 @entity1 . DNA sequencing of the breakpoint region showed that this deletion was the so-called "common deletion." Most but not all of the investigated deletion breakpoints were flanked by direct repeats. @entity7319 fibers were more frequent among fibers with positive immunostaining with antibodies directed toward a regeneration marker, the Leu-19 antigen, than in the entire fiber population. These results show that @entity7319 in muscle fiber segments in @entity5589 is associated with deletions of mtDNA. Clonal expansion of mtDNA with deletions may take place in regenerating muscle fibers following segmental @entity39 .
