Clinical characteristics of KCNQ2 encephalopathy

Brain Dev. 2021 Feb;43(2):244-250. doi: 10.1016/j.braindev.2020.08.015. Epub 2020 Sep 8.


Purpose: KCNQ2 mutations are associated with benign familial neonatal epilepsy (BFNE) or developmental and epileptic encephalopathy (DEE). In this study, we aimed to delineate the phenotype of KCNQ2 encephalopathy and evaluate the treatment response.

Methods: Thirteen patients of KCNQ2 encephalopathy were included in the study. Characteristics of KCNQ2 mutations, electroclinical features, clinical course, and response to the treatment were analyzed.

Results: Age range of the thirteen patients was between 3 months and 20.9 years. The onset of seizures in 11 patients ranged from 1 to 3 days of age, while in the other two patients it was 7 and 40 days, respectively. Most common initial seizure types were tonic seizures. Initial EEGs were suppression burst pattern in seven patients and slow and disorganized background with multifocal epileptiform discharges in six patients. Initial epilepsy syndrome was Ohtahara syndrome in seven patients, neonatal focal seizure in five patients, and focal epilepsy beyond neonatal period in one patient. Sodium channel blockers including oxcarbazepine (OXC) (n = 3), lamotrigine (LTG) (n = 3), phenytoin (PHT) (n = 2), topiramate (TPM) (n = 2), and zonisamide (ZNS) (n = 1) were tried and found effective in eleven patients. Ultimately, 12 of 13 patients became seizure-free. However, developmental outcomes were poor.

Conclusions: Sodium channel blockers are effective in seizure control in these patients with KCNQ2 encephalopathy. Early recognition of KCNQ2 encephalopathy and early use of sodium channel blockers might be helpful in seizure control.

Keywords: KCNQ2 encephalopathy; Neonatal seizures; Ohtahara syndrome; Sodium channel blockers.

MeSH terms

  • Adolescent
  • Anticonvulsants / therapeutic use
  • Brain Diseases / genetics*
  • Brain Diseases / metabolism
  • Child
  • Child, Preschool
  • Electroencephalography
  • Epilepsy / drug therapy
  • Epilepsy, Benign Neonatal / drug therapy
  • Female
  • Humans
  • Infant
  • KCNQ2 Potassium Channel / genetics
  • KCNQ2 Potassium Channel / metabolism*
  • KCNQ2 Potassium Channel / physiology
  • Male
  • Seizures / drug therapy
  • Sodium Channel Blockers / therapeutic use
  • Young Adult


  • Anticonvulsants
  • KCNQ2 Potassium Channel
  • KCNQ2 protein, human
  • Sodium Channel Blockers