Seizure Semiology and Response to Treatment in a Pediatric Cohort with SCN2A Variants: A Parent Report

We examined seizure semiology and response to medications in 28 children (9 female, 19 male) with likely pathogenic and pathogenic SCN2A-related epilepsy. Parents reported seizure onset, seizure semiology, genetic variants, therapies used for seizures, and response to treatment. 27 children experienced defined seizures and 1 reported no seizure history. The most common initial seizures were focal or hemi-convulsions (n=8). Tonic seizures were the most common reported seizure type while febrile and atonic or drop seizures were the least common. Most patients experienced multiple seizures daily or were entirely seizure-free, with no difference based on age at seizure onset. The proportion of effective trials of the 8 most commonly reported medications ranged from 4 of 26 trials (levetiracetam) to 5 of 10 trials (valproic acid). Phenytoin was the most commonly reported effective treatment (N=4). Topiramate was reported to be the most effective treatment in combination with another treatment (N=6). We found a wide phenotypic spectrum of SCN2A-related disorders and a possible correlation between genotype and seizure onset, semiology, and treatment response. Gain-of-function mutations in early-onset SCN2A epilepsies responded well to sodium channel blockers. Further exploration of SCN2A pathogenic variants are needed to identify mediation mechanisms of action in SCN2A-related epilepsy.