Sodium channel protein type 1 subunit alpha (SCN1A), is a protein which in humans is encoded by the SCN1A gene.

The SCN1A gene is located on chromosome 2, and is made up of 26 exons spanning a total length of 6030 nucleotide base pairs (bp).

The sodium channel is a voltage-gated ion channel essential for the generation and propagation of action potentials, chiefly in nerve and muscle. 

Voltage-sensitive sodium channels are heteromeric complexes consisting of a large central pore-forming glycosylated alpha subunit and 2 smaller auxiliary beta subunits. 

The transmembrane alpha subunit of the brain sodium channels is sufficient for expression of functional sodium channels.

There are several distinct sodium channel alpha subunit isoforms in skeletal and cardiac muscle.

The SCN1A gene codes for the alpha subunit of the voltage-gated sodium ion channel making it a member of ten paralogous gene families which code for the voltage-gated sodium transmembrane proteins.

SCN1A mutations cause  epilepsy and febrile seizures.

Indeed, the SCN1A gene is one of the most commonly mutated genes in the human genome associated with epilepsy (super culprit gene).

There are 900 distinct mutations reported for the SCN1A gene, approximately half of the reported mutations are truncations which result in no protein.

The remaining half of mutations are missense mutations.

Alterations in voltage-gated sodium ion channels can have devastating physiological effects and underlie abnormal neurological functioning.

Mutations to the SCN1A gene most often result in different forms of seizure disorders: Dravet Syndrome, Intractable childhood epilepsy with generalized tonic-clonic seizures, and severe myoclonic epilepsy borderline.

Clinically, 70-80% of patients with Dravet Syndrome have identified mutations specific to the SCN1A gene.

Mutations in the SCN1A gene cause inherited febrile seizures and genetic epilepsy and febrile seizures type 2.

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