Abstracts

Rationale: KCNQ2 mutations are associated with benign familial neonatal seizures or early onset epileptic encephalopathy. In this study, we aimed to delineate the phenotype of KCNQ2 epileptic encephalopathy. Methods: Eleven patients of early onset epileptic encephalopathy with KCNQ2 mutations were included in the study. Characteristics of KCNQ2 mutations, electroclinical features, clinical course, and response to the treatment were analyzed. Results: Eleven patients were aged between 1.9 and 20.3 years. The onset of seizures were early neonatal period in ten patients and infantile period (4 months of age) in one patient. Most common initial epilepsy syndrome was Ohtahara syndrome in five patients. Burst-suppression pattern on EEG was found in most. Four patients evolved to West syndrome of Lennox-Gastaut syndrome. Nine patients became seizure free when treated with carbamazepine, oxcarbazepine, zonisamide, topiramate, phenytoin or valproic acid. All patients presented moderate to severe developmental delay or intellectual disability. Eleven kinds of de novo KCNQ2 mutations were identified; nine with missense mutations and two with deletions. Conclusions: De novo KCNQ2 mutations are involved in early onset epileptic encephalopathy. Ohtahara syndrome with burst-suppression patterns on EEGs are characteristic. Seizures are well controlled with sodium channel blockers, regardless of type of mutations.  Funding: This work was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare, Republic of Korea (grant number: HI18C0586)