Home Page
References OMIM Gene GeneReviews HGMD HGNC
GENATLAS PHENOTYPE
last update : 10-07-2012
Symbol MDDS2
Location 16q22
Name mitochondrial DNA depletion syndrome, myopathic form
Other name(s)
  • mtDNA depletion myopathy
  • mitochondrial DNA depletion syndrome 2
    • Corresponding gene TK2
    Other symbol(s) MTDPS2
    Main clinical features
  • reduction of the amount of mitochondrial deoxyribonucleic acid, which impairs the synthesis of respiratory chain complexes
  • severe mitochondrial myopathy due to tissue-specific depletion of mtDNA, normal early developmental phase followed by psychomotor regression, encephalopathy often with epileptic seizures, and myopathy with features of a progressive dystrophic process, (PMID: 12873860)) with mutations in TK2, resulting in mtDNA depletion, isolated skeletal myopathy, and death of the individual at an early stage of life (PMID: 22571666))
  • adult forms causing progressive mitochondrial myopathy with significant muscle mitochondrial DNA (mtDNA) depletion, a slowly progressive myopathy compatible with a fairly normal life during decades (PMID: 22345218)), or an autosomal-inherited progressive external ophthalmoplegia (PMID: 21937588))
    • Genetic determination autosomal recessive
    Related entries MDDS1
    Function/system disorder neuromuscular
    Type disease
    Gene product
    Name thymidine kinase 2
    Remark(s) Thymidine kinase 2 (TK2) and deoxyguanosine kinase (dGK) are the two key enzymes in mitochondrial DNA (mtDNA) precursor synthesis. Deficiencies in TK2 or dGK activity, due to genetic alteration, have been shown to cause tissue-specific depletion of mtDNA.
    Genotype/Phenotype correlations residual activity of mitochondrial enzymes correlate with disease development