Mutation p.Asp25Asn (D25N; c.73G > A) of the β1 subunit, coded by the gene SCN1B, has been reported in a patient with generalized epilepsy with febrile seizure plus type 1 (GEFS+).
The first decade of the 21st century was marked by progress in understanding the basic biology of generalized epilepsies including generalized/genetic epilepsies with febrile seizures plus (GEFS+) and GGE through studies of large families, discovering causative mutations in SCN1A, SCN1B, GABRG2, and GABRA1.
The objective was to investigate whether the described mutations of the SCN1A, SCN1B and GABRG2 genes are associated to generalised epilepsy with febrile seizure plus (GEFS+) in two Tunisian families.
The syndrome of generalized epilepsy with febrile seizure plus (GEFS+) is associated with a single point mutation on the gene SCN1B that results in a substitution of the cysteine 121 with a tryptophane in the sodium channel beta 1-subunit protein.
A missense mutation was identified in the voltage-gated sodium (Na(+))-channel beta 1 subunit gene, SCN1B at chromosome 19p13.1 in generalized epilepsy with the febrile seizures plus type 1 (GEFS+1) family.
The sodium channel beta1 subunit gene (SCN1B) maps to this candidate region and has been shown to be involved in one Australian pedigree with generalized epilepsy and febrile seizures "plus" (GEFS +).