Loss-of-Function and Gain-of-Function Mutations in KCNQ5 Cause Intellectual Disability or Epileptic Encephalopathy

Am J Hum Genet. 2017 Jul 6;101(1):65-74. doi: 10.1016/j.ajhg.2017.05.016. Epub 2017 Jun 29.


KCNQ5 is a highly conserved gene encoding an important channel for neuronal function; it is widely expressed in the brain and generates M-type current. Exome sequencing identified de novo heterozygous missense mutations in four probands with intellectual disability, abnormal neurological findings, and treatment-resistant epilepsy (in two of four). Comprehensive analysis of this potassium channel for the four variants expressed in frog oocytes revealed shifts in the voltage dependence of activation, including altered activation and deactivation kinetics. Specifically, both loss-of-function and gain-of-function KCNQ5 mutations, associated with increased excitability and decreased repolarization reserve, lead to pathophysiology.

Keywords: KCNQ5; Kv7.5; epilepsy; epileptic encephalopathy; intellectual disability; potassium channels.

MeSH terms

  • Electroencephalography
  • Epilepsy / genetics*
  • Genetic Predisposition to Disease*
  • Humans
  • Intellectual Disability / genetics*
  • Ion Channel Gating
  • KCNQ Potassium Channels / chemistry
  • KCNQ Potassium Channels / genetics*
  • Mutant Proteins / chemistry
  • Mutant Proteins / genetics
  • Mutation / genetics*
  • Phenotype
  • Sequence Alignment


  • KCNQ Potassium Channels
  • KCNQ5 protein, human
  • Mutant Proteins