Distribution of wild-type and common deletion forms of mtDNA in normal and respiration-deficient muscle fibers from patients with mitochondrial myopathy

Monica Sciacco, Eduardo Bonilla, Eric A. Schon, Salvatore DiMauro, Carlos T. Moraes

Research output: Contribution to journalArticle


We studied the cellular distribution of both deleted (Δ) and wild-type (wt) mitochondrial DNAs (mtDNAs) in 'normal' and respiration-deficient muscle fibers from four patients with mitochondrial myopathy. PCR-based methods were used to quantitate both relative and absolute amounts of Δ- and wt-mtDNAs in microdissected fiber segments. Although Δ-mtDNAs were present in normal fibers (31% ± 26), their percentages were much higher in affected fibers (95% ± 2). Absolute levels of Δ-mtDNA were also increased in affected fibers, whereas levels of wt-mtDNA were significantly reduced in these fibers. These results indicate that a threshold ratio of Δ-/wt-mtDNA must be achieved before an impairment of respiration is observed in muscle. Moreover, the marked reduction in wt-mtDNA observed in affected fibers suggests that absolute amounts of mtDNA may play a role in the pathogenesis of mitochondrial myopathies.

Original languageEnglish
Pages (from-to)13-19
Number of pages7
JournalHuman Molecular Genetics
Issue number1
Publication statusPublished - Jan 1994


ASJC Scopus subject areas

  • Genetics
  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Public Health, Environmental and Occupational Health
  • Molecular Biology
  • Genetics(clinical)

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