severe myoclonic epilepsy of infancyA rare disorder (OMIM:607208) characterised by generalised tonic, clonic and tonic-clonic seizures triggered at first by fever and arising shortly after birth. Later, patients also manifest other seizure types, including absence, myoclonic, and simple and complex partial seizures. Psychomotor developmental delay appears by the second year of life. SMEI is the most severe phenotype in the spectrum of generalised epilepsies with febrile seizures-plus.
Defects of GABRG2, which encodes a subunit of a ligand-gated ionic channel that plays a key role in inhibiting neurotransmission, cause severe myoclonic epilepsy of infancy.
[Charlotte Dravet, Fr. psychiatrist and epileptologist, b. 1936]
A severe form of childhood epilepsy, often beginning in the first year of life as a febrile seizure. As the affected children grow up, they develop myoclonic jerking, and their seizures may become refractory to treatment. Synonym: severe myoclonic epilepsy of infancy