Clinical and cellular consequences of the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene

Mitochondrion. 2012 Mar;12(2):288-93. doi: 10.1016/j.mito.2011.10.004. Epub 2011 Nov 7.


We report, for the first time, a patient with an overlap MERRF-NARP syndrome who carries the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene. The mutation was heteroplamic and more abundant in her muscle and fibroblast than in blood from her oligosymptomatic mother. Single muscle fiber analysis revealed that the proportion of mutant mtDNA in ragged red fibers was higher than that in normal fibers. Combined defects of mitochondrial respiratory chain complexes were detected in muscle, fibroblasts and transmitochondrial hybrid cells. Significant reduction of total ATP and mitochondrial membrane potential and an increased production of reactive oxygen species were observed.

Publication types

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

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Child
  • Child, Preschool
  • Female
  • Fibroblasts / physiology
  • Humans
  • Leukocytes / physiology
  • Membrane Potentials
  • Mitochondrial Diseases
  • Mitochondrial Membranes / physiology
  • Muscle Cells / physiology
  • Muscle Fibers, Skeletal / pathology
  • Point Mutation*
  • RNA / genetics*
  • RNA, Mitochondrial
  • RNA, Transfer, Leu / genetics*
  • Reactive Oxygen Species / metabolism


  • RNA, Mitochondrial
  • RNA, Transfer, Leu
  • Reactive Oxygen Species
  • RNA
  • Adenosine Triphosphate