Generalized epilepsy is the most common epilepsy with a prominent genetic etiology. Currently, a substantial number of genes related to generalized epilepsy have not been identified. In this study, we report two de novo heterozygous and three biallelic IFIH1 variants in five unrelated patients with generalized epilepsy with antecedent febrile seizures. Patients showed an early onset age and got seizure-free with favorable outcome. Further literature review showed a sub-regional effect and genotype-phenotype correlation of IFIH1. Identification of IFIH1 as a novel cause of generalized epilepsy, the sub-molecular implication, and genotype-phenotype are helpful for management of patients with IFIH1 variants. (By Dr Na He, https://jmg.bmj.com/content/early/2024/07/04/jmg-2024-109950 )