The association between SCN1A and epilepsy is best documented for Dravet syndrome, a severe developmental and epileptic encephalopathy (Dravet, 1978; Covanis, 2012; McTague et al., 2016), with up to 85% of patients with Dravet syndrome carrying a pathogenic variant in SCN1A (Rosander and Hallböök, 2015; Cooper et al., 2016). Here, SCN1A is linked to encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.