While our findings provide highly suggestive evidence of the role of SCN9A in FS and Dravet syndrome, replication in multiple cohorts, combined with functional studies, is needed to confirm a hyperexcitable role of SCN9A in unrelated epilepsy patients. The gene discussed is SCN9A; the disease is encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.