Mitochondrial myopathy associated with a novel 5522G>A mutation in the mitochondrial tRNA(Trp) gene

Eur J Hum Genet. 2013 Aug;21(8):871-5. doi: 10.1038/ejhg.2012.272. Epub 2012 Dec 12.


We report a novel pathogenic mutation of the mitochondrial transfer RNA (tRNA) gene for tryptophan in a patient with isolated myopathy and persistently elevated creatine kinase. Muscle studies revealed ragged red fibres and decreased activity of respiratory chain complex I and cytochrome c oxidase (COX). Sequencing of the 22 mitochondrial tRNA genes revealed a mutation m.5522G>A, which alters a conserved base pairing in the D-stem of the tRNA for tryptophan. The mutation was heteroplasmic with a mutational load between 88 and 99% in COX-negative fibres. This case contributes to the genetic heterogeneity of mitochondrial diseases caused by mutations in mitochondrial tRNA genes.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Base Sequence
  • DNA Mutational Analysis
  • DNA, Mitochondrial / chemistry
  • DNA, Mitochondrial / genetics
  • Electron Transport Complex I / metabolism
  • Electron Transport Complex IV / metabolism
  • Humans
  • Immunohistochemistry
  • Male
  • Microscopy, Electron
  • Mitochondrial Myopathies / genetics*
  • Mitochondrial Myopathies / metabolism
  • Molecular Sequence Data
  • Muscle Fibers, Slow-Twitch / metabolism
  • Muscle Fibers, Slow-Twitch / pathology
  • Muscle Fibers, Slow-Twitch / ultrastructure
  • Point Mutation*
  • RNA, Transfer, Trp / genetics*
  • Sequence Homology, Nucleic Acid


  • DNA, Mitochondrial
  • RNA, Transfer, Trp
  • Electron Transport Complex IV
  • Electron Transport Complex I