Patients with a mutation that renders one allele of SCN1A nonfunctional often present with the most severe form of GEFS+: Dravet syndrome [DS; also known as severe myoclonic epilepsy in infancy (SMEI); Claes et al., 2001; Marini et al., 2011]. Here, SCN1A is linked to encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.