Journal of Bioenergetics and Biomembranes

, Volume 26, Issue 3, pp 301–310

Mitochondrial DNA diseases: Histological and cellular studies

  • Eric A. Shoubridge


Large-scale deletions and tRNA point mutations in mitochondrial DNA (mtDNA) are associated with a variety of different mitochondrial encephalomyopathies. Skeletal muscle in these patients shows a typical pathology, characterized by the focal accumulation of large numbers of morphologically and biochemically abnormal mitochondria (ragged-red fibers). Both mtDNA deletions and tRNA point mutations impair mitochondrial translation and produce deficiencies in oxidative phosphorylation. However, mutant and wild-type mtDNAs co-exist (mtDNA heteroplasmy) and the translation defect is not expressed until the ratio of mutant: wild-type mtDNAs exceeds a specific threshold. Below the threshold the phenotype can be rescued by intramitochondrial genetic complementation. The mosaic expression of the skeletal muscle pathology is thus determined by both the cellular and organellar distribution of mtDNA mutants.

Key words

Mitochondrial encephalomyopathy mitochondrial DNA gene expression protein translation 


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Copyright information

© Plenum Publishing Corporation 1994

Authors and Affiliations

  • Eric A. Shoubridge
    • 1
  1. 1.Department of Neurology and Neurosurgery and Department of Human GeneticsMcGill UniversityMontrealCanada

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