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GENATLAS PHENOTYPE
last update : 08-01-2019
Symbol GEFSP2
Location 2q24.3
Name generalized epilepsy with febrile seizures plus, 2
Corresponding gene SCN1A , SCN9A
Other symbol(s) GEFS2,GEFS+, FHM3
Main clinical features
  • a familial epilepsy syndrome characterized by phenotypic and genetic heterogeneity
  • the GEFS+ spectrum comprises a range of mild to severe phenotypes varying from classical febrile seizures to Dravet syndrome (see SMEI2)
    • Genetic determination autosomal dominant
    Related entries . including familial simple febrile seizures, and familial hemiplegic migraine-3 (OMIM 609634)
    Function/system disorder neurology
    Type disease
    Gene product
    Name sodium voltage gated channel I alpha, sodium channel voltage-gated type 2 alpha 1 polypeptide
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    other   truncated protein  
    missense   abnormal protein/loss of function M145T is a loss-of-function mutant associated to febrile seizures
    Remark(s) more than 70% of patients with Dravet syndrome have mutations of SCN1A; these include both truncation and missense mutations. In contrast, only 10% of GEFS+ families have SCN1A mutations and these comprise missense mutations. GEFS+ has also been associated with mutations of genes encoding the sodium channel beta 1 subunit, SCN1B, and the GABA(A) receptor gamma 2 subunit, GABRG2. The phenotypic heterogeneity that is characteristic of GEFS+ families is likely to be due to modifier genes
  • SCN1A intronic and “poison exon” variants cause GEFS+ phenotypes (PMID: 30526861))