SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: Heterozygous SCN1A SNVs and CNVs have been previously reported in patients with intellectual disability, developmental delay, and a spectrum of epileptic encephalopathies of varied severity [74,75,76], ranging from the milder form of generalized epilepsy with febrile seizures plus type 2 (OMIM # 604403)-to-severe myoclonic epilepsy of infancy (or Dravet Syndrome) (OMIM # 607208) [77,78].