SCN2A mutations and benign familial neonatal-infantile seizures: the phenotypic spectrum.
Mutations of the sodium channel subunit gene SCN2A have been described in families with benign familial neonatal-infantile seizure (BFNIS). We describe two large families with BFNIS and novel SCN2A mutations. The families had 12 and 9 affected individuals, respectively, with phenotypes consistent with BFNIS. Two mutations were discovered in SCN2A (E430Q; I1596S). Both families had individuals with neonatal onset but the typical age of onset was in the early infantile period (mean 3.0 months). One mutation positive individual, with an otherwise typical clinical pattern, had seizures beginning at 13 months. Two individuals with SCN2A mutations were identified with seizures in later life. In each family a single individual with infantile seizures was mutation negative and thus represented phenocopies. This study extends the age range of presentation of BFNIS, confirms that neonatal and early infantile onsets are characteristic, and emphasizes the role of molecular diagnosis to confirm the etiology.
Herlenius
Eric
E
Department of Woman and Child Health, Astrid Lindgren's Children's Hospital, Karolinska Institutet, Stockholm, Sweden.
Heron
Sarah E
SE
Grinton
Bronwyn E
BE
Keay
Deborah
D
Scheffer
Ingrid E
IE
Mulley
John C
JC
Berkovic
Samuel F
SF
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D002648:Child; D004252:DNA Mutational Analysis; D004569:Electroencephalography / Q000706:statistics & numerical data; D020936:Epilepsy, Benign Neonatal / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D005190:Family; D006580:Genetic Carrier Screening; D006801:Humans; D007223:Infant; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D062551:NAV1.2 Voltage-Gated Sodium Channel; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D015222:Sodium Channels / Q000235:genetics*; D013548:Sweden / Q000453:epidemiology
D062551:NAV1.2 Voltage-Gated Sodium Channel; D009419:Nerve Tissue Proteins; C568251:SCN2A protein, human; D015222:Sodium Channels