One individual with uDEE displayed hypermethylation of the promoter region and TSS of STX1B (MIM: 601485, Fig. 4A), an established epilepsy gene known to cause generalized epilepsy with febrile seizures plus (GEFs + ). This evidence concerns the gene STX1B and Febrile seizure (within the age range of 3 months to 6 years).