Unlike most epilepsy syndromes, where the diagnosis is based on a patient's seizure syndrome in isolation, GEFS+ is diagnosed by the presence of appropriate phenotypes in 2 or more family members.3,4The GEFS+ phenotypes are childhood-onset seizure syndromes with a strong tendency toward fever-induced seizures, although persistence of occasional generalized or partial seizures into adulthood may occur. The most common GEFS+ phenotypes are febrile seizures (FS) and febrile seizures plus (FS+). The syndrome FS+ is defined by febrile seizures that occur outside the usual age range of 3 months to 6 years or that are intermixed with afebrile convulsions. Both FS and FS+ may be accompanied by myoclonic, absence, and astatic seizures. Other phenotypes, including partial seizures, are seen as part of the GEFS+ spectrum, as are, rarely, the severe childhood epilepsies Dravet syndrome, described in the following subsection, and myoclonic-astatic epilepsy. Although the initial description emphasized the generalized nature of the phenotypes that predominate in GEFS+, the more inclusive term genetic epilepsy with febrile seizures plusbetter expresses the core features of the syndrome.