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Disease Profile

SCN8A encephalopathy

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Early infantile epileptic encephalopathy-13; Epileptic Encephalopathy, early infantile, 13; EIEE13;


SCN8A encephalopathy is a very rare form of early-onset epilepsy that causes multiple types of seizures and developmental delay or regression (loss of skills).[1] Seizures begin during the first 18 months of life, at an average age of 4 months. Types of seizures may include generalized tonic-clonic seizures, infantile spasms, absence seizures, and focal seizures. Other signs and symptoms of SCN8A encephalopathy may include low muscle tone (hypotonia), a high pain tolerance, movement disorders (such as dystonia and ataxia), mild to severe intellectual disability, sleep problems, and autistic-like features.[1][2][3][4] In some people with SCN8A encephalopathy, various other medical problems have been reported including hearing or vision problems, scoliosis, and difficulty regulating body temperature. About 10% of people with SCN8A encephalopathy reported in the literature have died from sudden unexpected death in epilepsy (SUDEP).[2]

SCN8A encephalopathy is caused by mutations in the SCN8A gene. Inheritance is autosomal dominant, but most people with SCN8A encephalopathy have a new mutation in the gene that was not inherited from a parent.[2] Treatment aims to control seizures with medications, which is extremely challenging. Seizure control should be managed by a pediatric neurologist with expertise in epilepsy who is familiar with SCN8A encephalopathy.[2]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
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5%-29% of people have these symptoms
Cerebral atrophy
Degeneration of cerebrum
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
Developmental regression
Loss of developmental milestones
Mental deterioration in childhood

[ more ]

Epileptic encephalopathy
Epileptic spasm
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

Global developmental delay
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific

[ more ]

Progressive microcephaly
Progressively abnormally small cranium
Progressively abnormally small skull

[ more ]



Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.


    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Organizations Providing General Support

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        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        In-Depth Information

        • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 


          1. Helbig E. SCN8A encephalopathy – and how it differs from Dravet Syndrome. International League Against Epilepsy (ILAE). January 13, 2015; https://epilepsygenetics.net/2015/01/13/scn8a-encephalopathy-and-how-it-differs-from-dravet-syndrome.
          2. Hammer MF, Wagnon JL, Mefford HC, Meisler MH. SCN8A-Related Epilepsy with Encephalopathy. GeneReviews. August 25, 2016; https://www.ncbi.nlm.nih.gov/books/NBK379665/.
          3. Larsen J & cols. The phenotypic spectrum of SCN8A encephalopathy. Neurology. 2015; 84(5):480-489. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4336074.
          4. About SCN8A Epilepsy. The Cute Syndrome Foundation. https://www.thecutesyndrome.com/scn8a.html.