Heterozygous missense SCN1A/NaV1.1 genetic variants can cause GEFS+, a familial epilepsy syndrome characterized by a distinctive pattern of pleiotropy in clinical phenomenology (Escayg et al., 2000; Scheffer & Berkovic, 1997; Zhang et al., 2017): the most frequent phenotype is febrile seizures plus (FS+: febrile/hyperthermic seizures that extend beyond 6 years of age) and afebrile generalized tonic–clonic seizures. This evidence concerns the gene SCN1A and Febrile seizure (within the age range of 3 months to 6 years).