Referenced in: none

Automatically associated channels: Nav1.7

Title: Variable epilepsy phenotypes associated with a familial intragenic deletion of the SCN1A gene.

Authors: Renzo Guerrini, Elena Cellini, Davide Mei, Tiziana Metitieri, Cristina Petrelli, Daniela Pucatti, Carla Marini, Nelia Zamponi

Journal, date & volume: Epilepsia, 2010 Dec , 51, 2474-7

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/21204810

Abstract
Deletions and duplications/amplifications of the α1-sodium channel subunit (SCN1A) gene occur in about 12% of patients with Dravet syndrome (DS) who are otherwise mutation-negative. Such genomic abnormalities cause loss of function, with severe phenotypes, reproductive disadvantage and, therefore, sporadic occurrence. Inherited mutations, occurring in ∼5% of patients with DS, are usually missense; transmission occurs from a mildly affected parent exhibiting febrile seizures (FS) or the generalized epilepsy with febrile seizures plus (GEFS+) spectrum. We identified an intragenic SCN1A deletion in a three-generation, clinically heterogeneous family. Sequence analysis of SCN9A, a putative modifier, ruled out pathogenic mutations, variants, or putative disease-associated haplotype segregating with phenotype severity. Intrafamilial variability in phenotype severity indicates that SCN1A loss of function causes a phenotypic spectrum in which seizures precipitated by fever are prominent and schematic syndrome subdivisions would be inappropriate. SCN1A deletions should be ruled out even in individuals with mild phenotypes.