Natural History Study of Infants and Children With Developmental and Epileptic Encephalopathies

Exclusion Criteria

• •Copy number variant of SCN1A, including SCN1A microdeletion, if affecting other genes.
• •SCN1A mutation present on both alleles.
• •Known pathogenic or clinically suspected mutation in a seizure-associated gene besides SCN1A.
• •Confirmed mutation in a gene besides SCN1A that is known to increase the severity of the seizure phenotype.
• •Known gain-of-function genetic mutation, as defined by functional studies, including p.Thr226Met.
• •History of notable developmental deficit that was evident prior to seizure onset.
• •Known central nervous system structural abnormality as found on magnetic resonance imaging or computed tomography scan of brain.
• •Currently taking or has taken for 6 or more consecutive weeks anti-seizure medications (ASMs) at a therapeutic dose that are contraindicated in SCN1A-positive Dravet Syndrome, including sodium channel blockers.
• •Known concomitant genetic mutation or clinical comorbidity that potentially confounds typical Dravet phenotype.