Outside of the arrhythmogenic mutations in NaV1.5CTD, recent findings directly link mutations in NaV1.6CTD with early infantile epilepsy [NM_001330260.2(SCN8A):c.5710C>T; p.Arg1904Cys] (42), while early reports of NaV1.6 gain-of-function mutations have described effects on cardiac electrophysiology (22, 43). The gene discussed is SCN8A; the disease is epilepsy.