Phenotypic diversity associated with the MT-TV gene m.1644G>A mutation, a matter of quantity

Mitochondrion. 2014 Mar;15:34-9. doi: 10.1016/j.mito.2014.03.010. Epub 2014 Mar 29.


We describe four patients from three independent families with the m.1644G>A in the MT-TV gene, previously reported without demonstration of its deleterious impact. Very high mutation proportion co-segregated with cytochrome oxidase defect in single muscle fibers and respiratory defect in cybrids as shown by spectrophotometric assays and polarography. The mutation appeared to have a very steep threshold effect with asymptomatic life up to 70% mutation proportion, progressive encephalopathy above 80% and severe Leigh-like syndrome above 95% mutation. One patient did not fit within that frame but presented with characteristics suggesting the presence of an additional disease.

Keywords: Clinical diagnosis; Heteroplasmy; Mitochondrial DNA; Mitochondrial diseases.

Publication types

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

MeSH terms

  • Genes, Mitochondrial*
  • Humans
  • Mitochondrial Diseases / genetics*
  • Mitochondrial Diseases / pathology*
  • Point Mutation*
  • Polarography
  • Quantitative Trait Loci
  • RNA, Transfer, Val / genetics*
  • Spectrum Analysis


  • RNA, Transfer, Val