A case report of a family with overlapping features of autosomal dominant febrile seizures and GEFS+

Summary Familial febrile seizures occur in both generalized epilepsy with febrile seizures plus (GEFS+) and autosomal dominant febrile seizures (ADFS). The literature largely separates families with GEFS+ from those with ADFS. However, there is clinical overlap, and families with ADFS also include individuals with afebrile seizures. The phenotypic spectrum of GEFS+ is broader now than when first described, resulting in unclear boundaries between these two familial syndromes. The purpose of this report is to highlight the phenotypic similarities of GEFS+ and ADFS. A multigenerational family with febrile and afebrile seizures is described and the clinical features are compared to those of previously reported GEFS+ and ADFS families. This family meets the requirements for both ADFS and the broader definition of GEFS+. Linkage analysis has shown no clear linkage to known febrile seizure or GEFS+ loci. Despite locus heterogeneity, identified mutations in reported GEFS+ have so far all been in sodium channel or γ‐aminobutyric acid (GABA)–receptor genes, with other modifier genes postulated to affect individual phenotypes. The two mutations identified in families with ADFS are in genes implicated in GEFS+, SCN1A , and GABRG2 . We conclude that it is inappropriate to separate GEFS+ and ADFS at present given the clinical and genotypic overlap.