SCN1A and atypical Rett syndrome: The SCN1A gene is not only associated with DS and GEFS+, but can also cause other disorders, including epilepsy diseases such as Doose syndrome, epilepsy of infancy with migrating focal seizures (EIMFS), West syndrome, Lennox–Gastaut syndrome (LGS), Rett syndrome, and nonsyndromic epileptic encephalopathy (NEE), as well as nonepileptic diseases such as hemiplegia migraine, autism spectrum disorder (ASD), sudden death (sudden unexpected death in epilepsy [SUDEP] and nonepileptic SCN1A-related sudden deaths), and arthrogryposis multiplex congenita (AMC).