Hearing loss in a patient with the myopathic form of mitochondrial DNA depletion syndrome and a novel mutation in the TK2 gene

Pediatr Res. 2010 Aug;68(2):151-4. doi: 10.1203/PDR.0b013e3181e33bbe.


Mitochondrial DNA (mtDNA) depletion syndrome (MDS) is a devastating disorder of infancy caused by a significant reduction of the number of copies of mitochondrial DNA in one or more tissues. We report a Spanish patient with the myopathic form of MDS, harboring two mutations in the thymidine kinase 2 gene (TK2): a previously reported deletion (p.K244del) and a novel nucleotide duplication in the exon 2, generating a frameshift and premature stop codon. Sensorineural hearing loss was a predominant symptom in the patient and a novel feature of MDS due to TK2 mutations. The patient survived up to the age of 8.5 y, which confirms that survival above the age of 5 y is not infrequent in patients with MDS due to TK2 deficiency.

Publication types

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

MeSH terms

  • Base Sequence
  • Child
  • DNA Mutational Analysis
  • DNA, Mitochondrial / genetics
  • DNA, Mitochondrial / metabolism*
  • Hearing Loss / etiology*
  • Hearing Loss / genetics*
  • Humans
  • Male
  • Mitochondrial Myopathies / complications*
  • Mitochondrial Myopathies / genetics*
  • Molecular Sequence Data
  • Muscle, Skeletal / metabolism
  • Muscle, Skeletal / pathology
  • Spain
  • Syndrome
  • Thymidine Kinase / genetics*


  • DNA, Mitochondrial
  • thymidine kinase 2
  • Thymidine Kinase