New phenotypic diversity associated with the mitochondrial tRNA(SerUCN) gene mutation

Neuromuscul Disord. 2005 May;15(5):364-71. doi: 10.1016/j.nmd.2005.01.006.


We performed detailed clinical, histopathological, biochemical, in vitro translation and molecular genetic analysis in patients from two unrelated families harbouring the tRNA(SerUCN) 7472C-insertion mutation. Proband 1 developed a progressive neurodegenerative phenotype characterised by myoclonus, epilepsy, cerebellar ataxia and progressive hearing loss. Proband 2 had a comparatively benign phenotype characterised by isolated myopathy with exercise intolerance. Both patients had the 7472C-insertion mutation in identical proportions and they exhibited a similar muscle biochemical and histopathological phenotype. However, proband 2 also had a previously unreported homoplasmic A to C transition at nucleotide position 7472 in the tRNA(SerUCN) gene. This change lengthens further the homopolymeric C run already expanded by the 7472C-insertion. These data extend the phenotypic range associated with the 7472C-insertion to include isolated skeletal myopathy, as well as a MERRF-like phenotype.

Publication types

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

MeSH terms

  • Adolescent
  • Adult
  • DNA Mutational Analysis / methods
  • DNA, Mitochondrial / genetics*
  • Electron Transport Complex IV / metabolism
  • Electrophoresis / methods
  • Female
  • Humans
  • Male
  • Microscopy, Electron, Transmission / methods
  • Mitochondria, Muscle / pathology
  • Mitochondrial Encephalomyopathies / enzymology
  • Mitochondrial Encephalomyopathies / genetics*
  • Mitochondrial Encephalomyopathies / pathology
  • Mitochondrial Encephalomyopathies / physiopathology
  • Mitochondrial Proteins / metabolism
  • Muscle, Skeletal / enzymology
  • Muscle, Skeletal / pathology
  • Muscle, Skeletal / ultrastructure
  • Mutation*
  • Nucleic Acid Conformation
  • Phenotype
  • RNA, Transfer, Ser / chemistry
  • RNA, Transfer, Ser / genetics*
  • Serine / metabolism


  • DNA, Mitochondrial
  • Mitochondrial Proteins
  • RNA, Transfer, Ser
  • Serine
  • Electron Transport Complex IV