SCN1A and Epileptic encephalopathy: SCN1A has a pleiotropic effect, since variants in this gene have been linked to several phenotypes, and heterozygous mutations in the SCN1A gene can cause a spectrum of early-onset epileptic encephalopathies (MIM #604403, #607208, #619317), FHM3 (MIM #609634) [29], and autism spectrum disorders (ASD) [30].