Dravet syndrome true OMIM:607208 GARD:10430 Dravet syndrome (previously known as severe myoclonic epilepsy of infancy, SMEI), typically presents in the first year of life in a normal child with prolonged, febrile and afebrile, focal (usually hemiclonic) and generalized tonic-clonic seizures. Other seizure types including myoclonic and atypical absence seizures appear between the age of 1 and 4 years. Seizures are usually intractable and from the second year of life children demonstrate cognitive and behaviour impairments. The clinical diagnosis is supported by the presence of abnormalities in the sodium channel gene SCN1A (found in 75% of cases). disease_ontology An early infantile epileptic encephalopathy that has_material_basis_in heterozygous mutation in the SCN1A gene on chromosome 2q24. DOID:0060171 ORDO:33069 DOID:0080422 early infantile epileptic encephalopathy 6 neonatal/infantile epilepsy syndrome