Association between SCN1A and SCN2A mutations and clinical/EEG features in Chinese patients from epilepsy or severe...

We investigated the association between SCN1A and SCN2A mutations and clinical phenotype and electroencephalography (EEG) features.

In this study, 48 patients suffered from epilepsy or severe seizures with SCN1A and SCN2A mutations were recruited. Medical data and molecular diagnosis were analyzed.

A total of 47 mutations were identified, including 33 novel mutations. The onset of most epilepsy caused by SCN1A mutations (1-6 m) was later than that of SCN2A mutations (neonatal). SCN1A mutations included truncating mutations and missense mutations occurred in the crucial region were associated with more severe phenotypes and developmental delay (85.7%, P = 0.020). De novo mutations or truncating mutations of SCN2A mutations are mainly associated with severe phenotypes. The proportion of initial abnormal EEG of SCN2A mutation was higher than that of SCN1A mutation (54.2%, 100%). Patients with SCN1A mutations showed more focal epileptiform discharges (69.2%), while patients with SCN2A mutations had more multifocal epileptiform discharges (53.8%). Sodium channel blockers were less effective for patients with SCN1A mutations and SCN2A mutations with early seizures onset.

Our study expanded the mutation spectrum of the SCN1A and SCN2A, and led to a better understanding of the similarities and difference in the genetic and clinical features between the two genes.