SCN1A is a gene that codes for the voltage-dependent sodium channel α1 subunit and has been implicated in generalized epilepsy with febrile seizures plus and severe myoclonic epilepsy in infancy.
SCN1A mutations were found in 12 of the 71 patients (16.9%; ten with DS, and two with seizures in a Generalized Epilepsy with Febrile Seizures+(GEFS+) context).
STXBP1 gene variants have been identified in patients with many different types of epilepsy, including Dravet syndrome and epileptic encephalopathies, suggesting STX1B plays a similar role.
SCN2A mutations have been described in a very broad spectrum of clinical phenotypes including benign (familial) neonatal/infantile seizures and early infantile epileptic encephalopathies (EIEE) as Ohtahara syndrome (OS), Dravet syndrome (DS), epilepsy of infancy with migrating focal seizures and West syndrome (WS).
SCN1A mutations are associated with a spectrum of seizure-related disorders, ranging from a relatively mild form of febrile seizures to a more severe epileptic encephalopathy known as Dravet syndrome.
A case in point would be severe myoclonic epilepsy of infancy (classically known as Dravet syndrome) and severe myoclonic epilepsy of infancy-borderland/ borderline, which are associated with specific mutations in the sodium ion channel gene SCN1A.
A different substitution (G1674R) at the same amino acid position, as well as two other SCN1A mutations found in this study, had previously been reported in Dravet syndrome.