New mutation c.374C>T and a putative disease-associated haplotype within SCN1B gene in Tunisian families with febrile seizures

Background: Febrile seizures (FSs) relatively represent the most common form of childhood seizures. FSs are not thought of as a true epileptic disease but rather as a special syndrome characterized by its provoking factor (fever) and a typical range of 3 months to 5 years. Although specific genes affecting the majority of FS cases have not been identified yet, several genetic loci for FSs have been reported recently. The aim of this report is to search for the gene responsible for FSs in six affected Tunisian families. Methods: A microsatellite marker analysis was performed on the known FS and generalized epilepsy with febrile seizures plus (GEFS+) loci. According to the results obtained by statistical analyses for the six studied families and in agreement with the involvement of SCN1B gene in the GEFS+ syndrome in previous studies, SCN1B on GEFS+1 locus was considered as one of the potential candidate genes and was tested for mutations by direct sequencing. Results: A sequencing analysis of the SCN1B gene revealed a novel mutation (c.374G>T) that changed an arginine residue with leucine at position 125 of the protein. We consider that the variation R125L may affect the protein structure and stability by the loss of hydrogen bonding. Two identified single nucleotide polymorphisms that are located in a neighboring hypothetical polyadenylation were assumed to compose a putative disease‐associated haplotype. Conclusion: Our results support that SCN1B is the gene responsible in one amongst the six FS Tunisian families studied and might contribute to the FS susceptibility for the five others.