GTR Home > Conditions/Phenotypes > Severe myoclonic epilepsy in infancy


Excerpted from the GeneReview: SCN1A-Related Seizure Disorders
SCN1A-related seizure disorders encompass a spectrum that ranges from simple febrile seizures (FS) and generalized epilepsy with febrile seizures plus (GEFS+) at the mild end to Dravet syndrome and intractable childhood epilepsy with generalized tonic-clonic seizures (ICE-GTC) at the severe end. Phenotypes with intractable seizures including Dravet syndrome (also known as severe myoclonic epilepsy in infancy [SMEI] or polymorphic myoclonic epilepsy in infancy [PMEI]) are usually associated with progressive dementia. Less commonly observed phenotypes include myoclonic-astatic epilepsy (MAE or Doose syndrome), Lennox-Gastaut syndrome (LGS), infantile spasms, and vaccine-related encephalopathy and seizures. The phenotype of SCN1A-related seizure disorders can vary even within the same family.

Genes See tests for all associated and related genes

  • Also known as: EIEE6, FEB3, FEB3A, FHM3, GEFSP2, HBSCI, NAC1, Nav1.1, SCN1, SMEI, SCN1A
    Summary: sodium voltage-gated channel alpha subunit 1

  • Also known as: ETHA, FEB3B, GEFSP7, HSAN2D, NE-NA, NENA, Nav1.7, PN1, SFNP, SCN9A
    Summary: sodium voltage-gated channel alpha subunit 9

Clinical features


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Practice guidelines

  • EFNS, 2010
    EFNS guidelines on the molecular diagnosis of channelopathies, epilepsies, migraine, stroke, and dementias.
  • Orphanet, 2008
    Orphanet, Dravet syndrome, 2008

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