Sodium voltage-gated channel alpha subunit 9 mutation in epilepsy

In humans, gene mutations in voltage-gated sodium channels can cause a range of epileptic symptoms, including genetic (generalized) epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS). The SCN9A is a member of the SCN9 gene family that encodes sodium transporter proteins. In the current case report, we delineate a 12-year-old patient who was referred to a pediatric neurology clinic for infantile-onset generalized epileptic seizures and progressive neurodevelopmental delay. Novel heterozygous mutations c.4702A>C (p.Asn1568His) in the SCN9A gene, and c.65G>A (p.Arg22Gln) in the MLC1 gene were detected using targeted next-generation gene sequencing. The replacement of Histidine (His) with Asparagine (Asn) at position 1568 in the topological domain of SCN9A channel protein provides new insights into the impaired excitation and inactivation patterns of sodium channels. The case report adds this new patient with genetic link of SCN9A variants with progressive myoclonic epilepsy and cognitive difficulties.