The electroclinical features of a large Italian family with 13 living members having simple febrile seizures and SCN1A missense mutation (M145T), some complicated by temporal lobe epilepsy, are reported from University Magna Graecia, Catanzaro, and other centers in Italy. All 13 affected members (7 male, mean age 36.6 +/- 20.4 years) had febrile seizures up to the age of 6 years. Age at onset of febrile seizures ranged from 5 to 45 months, mean age of 12.8 +/- 12.9 months. EEGs were normal in 9 with simple febrile seizures only. Three developed temporal lobe epilepsy, 2 having MRI evidence of mesial sclerosis. 
COMMENT. SCN1A mutations may cause simple febrile seizures later associated with temporal lobe epilepsy, and separate from the characteristic association with generalized epilepsy with febrile seizures plus (GEFS+).
A frequency of 71% SCN1A abnormalities are associated with severe myoclonic epilepsy of infancy (SMEI) including borderline SMEI (SMEB), and 11.5% with GEFS+ probands.