SCN1A (2528delG) novel truncating mutation with benign outcome of severe myoclonic epilepsy of infancy

Abstract

The epileptic syndrome related to mutations in the SCN1A gene includes benign febrile seizures (FS), the more variable phenotype FS+, and severe myoclonic epilepsy in infancy (SMEI) or Dravet syndrome, one of the most severe types of infant epilepsy, which is resistant to drugs.1 The clinical spectrum related to mutations of the SCN1A gene (chromosome 2q) has been divided according to the type of seizure and CNS impairment into four categories from the lightest (benign FS) to the most severe (classic type SMEI).2 Evidence suggests that a severe disturbance of the function of the SCN1A gene is a major cause of SMEI, and that FS, FS+ (even with other types of seizures), and the milder and classic types of SMEI form a continuum of mutations in the α subunit of SCN1A . Severe de novo mutations, such as truncating mutations, have been reported in SMEI.2,3 We report a patient with SMEI with a benign outcome, in whom the clinical picture changed from SMEI in infancy to FS+ in adolescence and was associated with a novel, de novo truncating mutation of the SCN1A gene. The patient was a 13-year-old …