Novel mutations in the thymidine kinase 2 gene (TK2) associated with fatal mitochondrial myopathy and mitochondrial DNA depletion

Neuromuscul Disord. 2005 Jun;15(6):412-5. doi: 10.1016/j.nmd.2005.03.010.


We describe the clinical, morphological and genetic findings in two siblings with the myopathic form of mitochondrial DNA depletion syndrome (MIM 251880). Sequencing of the thymidine kinase-2 gene revealed two heterozygous missense mutations, a C-->T mutation at nucleotide 191 resulting in a change of threonine to methionine at residue 64 in exon 3, and a C-->T mutation at nucleotide 547 resulting in an arginine to tryptophan amino acid change at residue 183 in exon 8. Both mutations changed highly conserved residues in the gene and neither one has been described previously. This report extends the phenotypic expression of mutations in the thymidine kinase-2 gene.

Publication types

  • Case Reports

MeSH terms

  • Amino Acid Sequence
  • Biopsy
  • DNA, Mitochondrial / genetics*
  • Fatal Outcome
  • Female
  • Heterozygote
  • Humans
  • Infant
  • Mitochondrial Myopathies / genetics*
  • Mitochondrial Myopathies / pathology
  • Molecular Sequence Data
  • Phenotype
  • Siblings
  • Thymidine Kinase / genetics*


  • DNA, Mitochondrial
  • thymidine kinase 2
  • Thymidine Kinase