SCN1A and familial hemiplegic migraine: Different pathogenic variants of SCN1A can have different effects on sodium channel function, which may lead to a wide range of phenotypes with different disease severities, including Dravet syndrome (DS, OMIM #607208), developmental and epileptic encephalopathy 6B (DEE, OMIM #619317), generalized epilepsy with febrile seizures plus type 2 (GEFS+, OMIM #604403), and familial hemiplegic migraine (FHM, OMIM #609634) [11].