Abstract: Objective To analyze the clinical and genetic characteristics of children with epilepsy associated with SCN8A mutations. Methods High-throughput whole-exome genetic testing was performed in children with suspected gene mutation-related epilepsy and 15 children with seizures caused by SCN8A mutations were identified. Retrospective analysis was used to collect medical records and genetic results of children with the disease. Results Totally 12 cases were identified with de novo mutations and three cases were identified with genetic heterozygous mutations. The earliest age of onset was only 10 minutes after birth, and the maximum age of onset was 2 years old. Three patients were treated with a single drug, 5 patients were treated with two anti-seizure medicines (ASMs), 7 patients were treated with three or more ASMs and 2 patients were treated with a ketogenic diet, but the efficacy was not satisfactory. Ten patients responded to sodium-blocking agents, with doses ranging from higher than the standard pediatric dosage. Except for one case with normal electro-encephalogram, all others were abnormal, mainly with multifocal and widespread discharge mainly characterized by multifocal and widespread dischargess. Conclusions SCN8A mutation causes early-onset childhood epilepsy with early onset, mostly within 1 year of age or even in the neonatal period, with common manifestation of focal or focal secondary generalized seizures, and seizure types such as convulsions and myoclonus are uncommon.

Key words: SCN8A, genetic mutation, epilepsy, clinical phenotype, sodium ion blocker