Clinical and genetic analysis of Chinese patients with KCNQ2 mutation-induced neonatal/infantile epileptic disorders

Objective To reveal the clinical and genetic features of neonatal/infantile epileptic disorders caused by KCNQ2 mutations and to provide a clue for the treatment and prognosis evaluation. Methods Twenty-two patients were collected in the Department of Pediatrics, Peking University First Hospital from April 2007 to July 2016.The phenotype-genotype analysis was conducted of the neonatal/infantile epileptic patients in whom a KCNQ2 mutation was identified by the targeted next generation sequencing. Results Twenty-two de novo KCNQ2 missense mutations from 22 patients with neonatal/infantile epileptic disorders were found.These patients had an onset of epilepsy in early infancy (median age: 2 days). The seizure type of the first onset was mainly focal seizure.Atypical absence epilepsy, a novel phenotype of KCNQ2 mutation-induced epilepsies was found.The mortality of these patients was high, as 5 patients of the 22 patients died in the follow-up period, 4 of which might result from sudden unexpected death in epilepsy.In the 22 patients, 8 patients with anti-epileptic monotherapy became seizure-free.Of the 8 patients with a monotherapy, 3 patients were treated with valproic acid and no clinical onset was observed. Conclusions This study expands the phenotype of KCNQ2-related epileptic disorders.These patients have high mortality.Valproate acid is the potentially effective monotherapy for these patients. Key words: KCNQ2; Neonatal/infantile epileptic disorders; Sudden unexpected death in epilepsy patients; Antiepileptic therapy