The m.12316G>A mutation in the mitochondrial tRNALeu(CUN) gene is associated with mitochondrial myopathy and respiratory impairment

Dario Ronchi, Roberta Virgilio, Andreina Bordoni, Elisa Fassone, Monica Sciacco, Patrizia Ciscato, Maurizio Moggio, Alessandra Govoni, Stefania Corti, Nereo Bresolin, Giacomo P. Comi

Research output: Contribution to journalArticle


Mitochondrial disorders are often associated with mutations in mitochondrial tRNA. Independent observation of the same molecular defect in unrelated subjects is a generally required proof of pathogenicity. A sporadic case of chronic external ophthalmoplegia (cPEO) with ragged red fibres (RRFs) has been previously related to an m.12316G>A substitution in tRNALeu(CUN). Sequencing muscle-derived mtDNA, we found the m.12316G>A substitution in an adult woman with mitochondrial myopathy and respiratory impairment. Her muscle biopsy presented several cytochrome c oxidase-negative (COX-) fibres, and RRFs as signs of mitochondrial proliferation. Restriction-fragment length polymorphism (RFLP) analysis of the mutation in isolated muscle fibres showed a threshold of at least 60% of mutated mtDNA to determine a COX deficiency phenotype. This second report of the m.12316G>A mutation in a sporadic patient consolidates its pathogenic nature and provides further elements for genetic counselling.

Original languageEnglish
Pages (from-to)107-110
Number of pages4
JournalJournal of the Neurological Sciences
Issue number1-2
Publication statusPublished - May 15 2010



  • Late-onset myopathy
  • mtDNA
  • tRNA

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology

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