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SCN1A gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SCN1A gene

The SCN1A gene provides instructions for making sodium channels that are critical for the generation and transmission of electrical signals in the brain.

Normal Function

The SCN1A gene belongs to a family of genes that provide instructions for making sodium channels, which transport positively charged sodium ions into cells. These channels are essential for a cell's ability to generate and transmit electrical signals.

The SCN1A gene specifically encodes the alpha subunit of a sodium channel called NaV1.1. These channels are primarily found in the brain, where they control the flow of sodium ions into neurons. This flow helps determine when neurotransmitters—chemicals used for communication between neurons—are released.

Health Conditions Related to Genetic Changes

Familial hemiplegic migraine

Mutations in the SCN1A gene have been identified in people with familial hemiplegic migraine type 3 (FHM3). These mutations alter the structure of the NaV1.1 channel, causing it to stay open longer than usual. This increases the flow of sodium ions into neurons, triggering the release of more neurotransmitters and increasing susceptibility to severe headaches.

Genetic epilepsy with febrile seizures plus

Hundreds of mutations in the SCN1A gene are linked to genetic epilepsy with febrile seizures plus (GEFS+), a spectrum of seizure disorders. This spectrum ranges from simple fever-associated seizures in infancy to more severe, difficult-to-control conditions like Dravet syndrome. These mutations affect the function of the NaV1.1 channel in various ways, such as reducing channel activity or altering the number of channels produced, though the exact mechanism linking these changes to seizure severity remains under study.

Other disorders

A common polymorphism in the SCN1A gene (ICS5N+5G>A) has been associated with the effectiveness and safety of anti-seizure medications like phenytoin and carbamazepine. Testing for this variant may help doctors determine the safest and most effective dose for individual patients.

Other Names for This Gene

  • GEFSP2
  • HBSCI
  • NAC1
  • Nav1.1
  • SCN1
  • SCN1A_HUMAN
  • sodium channel protein, brain I alpha subunit
  • sodium channel, voltage gated, type I alpha subunit
  • sodium channel, voltage-gated, type I, alpha
  • sodium channel, voltage-gated, type I, alpha polypeptide
  • sodium channel, voltage-gated, type I, alpha subunit

Frequently Asked Questions

Prompt fever control is key. Use acetaminophen or ibuprofen at the first sign of temperature ≥38 °C (100.4 °F). Keep the child well‑hydrated, dress them in light clothing, and avoid overheating. In some cases, a rescue medication such as a benzodiazepine (e.g., rectal diazepam or intranasal midazolam) is prescribed for emergency use at the onset of a seizure. Review the rescue plan with your neurologist and ensure caregivers know how to administer it.
blood sample (or sometimes saliva) is collected and sent for sequencing of the SCN1A gene. No special preparation is needed, but it helps to have a detailed seizure history, any family history of epilepsy or migraine, and a list of current medications. Results usually return in 2–4 weeks and will indicate whether a pathogenic variant, a variant of uncertain significance, or no mutation was found.
Drugs that block sodium channels (e.g., carbamazepine, phenytoin, lamotrigine) can worsen seizures in SCN1A‑related epilepsy and are generally avoided. First‑line options include stiripentol, clobazam, valproate, and the newer drug fenfluramine, often used in combination. Always discuss dosing and side‑effects with a neurologist experienced in Dravet syndrome or related SCN1A disorders.
If the SCN1A variant is a heterozygous autosomal‑dominant mutation (the most common scenario), each pregnancy carries a 50 % chance of inheriting the altered gene. The severity can vary even within the same family. Prenatal options include chorionic villus sampling or amniocentesis for targeted genetic testing, and pre‑implantation genetic diagnosis (PGD) if using in‑vitro fertilization. Genetic counseling is strongly recommended before conception.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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