Child Neuropsychiatry Division, Neurological Institute Casimiro Mondino Foundation IRCCS, V. Palestro 3, 27100 Pavia Italy.
"Generalized epilepsy with febrile seizures plus" (GEFS+) syndrome has been recently described. This term defines a heterogeneous group of generalized epilepsies observed in several members of large pedigree studies. The syndrome spectrum has been widened by including others forms of generalized epilepsy. We report two Italian families in which the fathers showed febrile seizure plus (FS+), and two sons had severe myoclonic epilepsy of infancy (SMEI). The clinical setting of each epileptic member of the family will be discussed, focusing on the relationship with the GEFS+ group, confirming its wide clinical spectrum. In fact, GEFS+ is different from most other epilepsy syndromes as it is defined not by a set of associated symptoms but by the genetic transmission of a predisposition to febrile convulsions and other seizures, with a variable expression in several members of the same pedigree, perhaps due to ionic channel dysfunction. SMEI could represent the most severe end of the spectrum.Scheffer et al.  in 1997 described a genetic epilepsy syndrome termed generalized epilepsy with febrile seizures plus (GEFS+).
This syndrome is characterized by a wide spectrum of clinical phenotypes including: febrile seizures (FS), febrile seizures plus (FS+), FS+ with other seizure types (absences, myoclonic or atonic seizures) and myoclonic-astatic epilepsy.
The most common phenotype, denoted as "febrile seizures plus" (FS+), comprises multiple febrile seizures that, unlike in the typical febrile convulsions syndrome, continue to beyond the age of 6 years and are often associated with the occurrence of afebrile tonic-clonic seizures .
In 1999 Singh et al.  studied 8 cases of severe myoclonic epilepsy of infancy (SMEI). In 6 out of 8 families, a history of seizures with phenotypes consistent with the GEFS+ spectrum were present. This finding suggests that SMEI could be the severe end of the GEFS + spectrum.
We report two Italian families in which two brothers have SMEI, and other family members show other paroxysmal features consistent with the FS+ phenotype.