A compound heterozygous missense mutation and a large deletion in the KCTD7 gene presenting as an opsoclonus-myoclonus ataxia-like syndrome

J Neurol. 2012 Dec;259(12):2590-8. doi: 10.1007/s00415-012-6545-z. Epub 2012 May 26.


Mutations in the potassium channel-related gene KCTD7 were described so far in a single family with progressive myoclonus epilepsy. We describe a unique phenotype: acute onset of myoclonus and ataxia, associated with abnormal opsoclonus-like eye movements; improvement of clinical symptoms under steroid treatment; and appearance of epileptic activity on EEG 2 years later without overt seizures. After excluding possible genetic causes, whole-genome exome sequencing was performed in order to identify the causative gene. One heterozygous missense mutation (R84W) was detected by exome sequencing and a large heterozygous deletion of exons 3 and 4 by MLPA analysis. The father is heterozygous for the R84W mutation and the mother is heterozygous for the exon 3+4 deletion. The mutation affects a highly conserved segment of the predicted protein, changing a basic amino acid into neutral. The large deletion probably results in a truncated protein. The different phenotype broadens the spectrum of KCTD7-related diseases. Therefore, patients diagnosed as having opsoclonus-myoclonus with an atypical course should be evaluated for KCTD7 mutations.

Publication types

  • Case Reports

MeSH terms

  • Amino Acid Sequence
  • Child, Preschool
  • Diagnosis, Differential
  • Female
  • Gene Deletion*
  • Humans
  • Male
  • Molecular Sequence Data
  • Mutation, Missense / genetics*
  • Opsoclonus-Myoclonus Syndrome / diagnosis*
  • Opsoclonus-Myoclonus Syndrome / genetics*
  • Pedigree
  • Potassium Channels / genetics*


  • KCTD7 protein, human
  • Potassium Channels