SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: For example, mutations in SCN1A (Nav1.1) are associated with Dravet syndrome, a severe myoclonic epilepsy of infancy, as well as West syndrome, genetic epilepsy with febrile seizures plus (GEFS+) and others (Steinlein, 2014).