KMT2B rare missense variants in generalized dystonia

Mov Disord. 2017 Jul;32(7):1087-1091. doi: 10.1002/mds.27026. Epub 2017 May 18.


Background: Recently a novel syndrome of childhood-onset generalized dystonia originating from mutations in lysine-specific methyltransferase 2B (KMT2B) has been reported.

Methods: We sequenced the exomes of 4 generalized dystonia-affected probands recruited from a Prague movement disorders center (Czech Republic). Bioinformatics analyses were conducted to select candidate causal variants in described dystonia-mutated genes. After cosegregation testing, checklists from the American College of Medical Genetics and Genomics were adopted to judge variant pathogenicity.

Results: Three novel, predicted protein-damaging missense variants in KMT2B were identified (p.Glu1234Lys, p.Ala1541Val, p.Arg1779Gln). Meeting pathogenicity criteria, p.Glu1234Lys was absent from population-based controls, situated in a key protein domain, and had occurred de novo. The associated phenotype comprised adolescence-onset generalized isolated dystonia with prominent speech impairment. Although linked to a similar clinical expression, p.Ala1541Val and p.Arg1779Gln remained of uncertain significance.

Conclusions: Rare missense variation in KMT2B represents an additional cause of generalized dystonia. Application of sequence interpretation standards is required before assigning pathogenicity to a KMT2B missense variant. © 2017 International Parkinson and Movement Disorder Society.

Keywords: KMT2B; dystonia; exome; rare missense variants.

MeSH terms

  • Adult
  • Dystonic Disorders / genetics*
  • Female
  • Histone-Lysine N-Methyltransferase / genetics*
  • Humans
  • Male
  • Middle Aged
  • Mutation, Missense


  • Histone-Lysine N-Methyltransferase
  • KMT2B protein, human