SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: Nonsense and missense mutations in SCN1A are associated with a catastrophic epilepsy of childhood known as Dravet syndrome (DS; Escayg et al., 2000; Claes et al., 2001; Sugawara et al., 2002; Harkin et al., 2007; Depienne et al., 2009; Dravet, 2011; Catterall, 2014).