About SCN8A Encephalopathy
SCN8A carries the instructions for Nav1.6, one of the sodium channels that let electrical signals start and travel in nerve cells. Most of the changes that cause SCN8A encephalopathy make the channel stay open longer than it should, so sodium keeps flowing in and the cell keeps firing. The brain becomes prone to seizures from infancy, and the repeated seizures, together with the faulty channel itself, interfere with development. A smaller group of changes do the opposite and weaken the channel; those children more often have developmental delay and autism features, and only 50% to 70% of them have epilepsy.
In the severe form, called SCN8A developmental and epileptic encephalopathy, about half of children have severe intellectual disability and most speak few or no words. Movement disorders are common: low tone at first, then dystonia, chorea, ataxia or spasticity. Swallowing problems can lead to aspiration pneumonia, and breathing failure can occur. In one study of 190 people, 5.3% had died, with sudden unexpected death in epilepsy confirmed in 1.6%.
Because the overactive channel is the problem, the sodium channel blockers used in ordinary epilepsy, including phenytoin, carbamazepine, oxcarbazepine, lacosamide and lamotrigine, are often helpful, and some children respond to higher doses of phenytoin than are usual. Those same drugs can worsen seizures in the minority whose channel is underactive, and some families report that levetiracetam makes seizures worse. The ketogenic diet, vagus nerve stimulation and steroids are used when medicines fail.
Common Symptoms of SCN8A Encephalopathy
Recognizing the signs of SCN8A Encephalopathy early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- Seizures starting between birth and about 2 years of age, at a median age of 3 months
- Several seizure types in the same child, including spasms, staring spells, jerks and convulsions
- Seizures that resist medicines, sometimes hundreds a day
- Developmental delay or regression, with few or no words in the severe form
- Low muscle tone early, then stiffness or involuntary movements over time
- Feeding and swallowing difficulty, and in the severe form, aspiration pneumonia or breathing problems
Who SCN8A Encephalopathy Affects
Nearly all cases are new (de novo) changes in the child, so parents are unaffected and there is no family history. The disease is almost entirely one of children; most people diagnosed are under 20, and the oldest known patient was 47. The most common pattern, SCN8A-DEE, begins with seizures at a median age of 3 months. Milder patterns exist: some children have seizures that start later, and some have developmental delay or autism without epilepsy, usually when the gene change reduces channel activity rather than increasing it.
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Trusted SCN8A Encephalopathy Resources
Reputable organizations and medical references for learning more about SCN8A Encephalopathy, including disease registries, foundation resources, and clinical guidelines.
- MedlinePlus Genetics (NIH) - SCN8A-related epilepsy with encephalopathy
- GeneReviews - SCN8A-Related Epilepsy and/or Neurodevelopmental Disorders
- Praxis Precision Medicines - FDA Extends Review Period for Relutrigine NDA (June 29, 2026)
- Praxis Precision Medicines - EMBOLD data at the American Epilepsy Society meeting (December 8, 2025)
- Praxis Precision Medicines - Second Quarter 2026 Corporate Update (August 6, 2026)