Partial epilepsy with febrile seiure plus: A subtype of GFS+ or SM?

Objective: Febrile seizures (FS) are the most common convulsive events in humans. It can be a benign disorder occurring only in infancy or childhood between 3 months and 6 years. It also may be part of epilepsy syndromes such as generalized epilepsy with febrile seizure plus (GEFS+) and severe myoclonic epilepsy of infancy (SME or SMEI). GEFS+ is a recently recognized form of inherited childhood-onset epilepsy with heterogeneous epilepsy phenotypes, including tonic-clonic, myoclonic, atonic, absence, and partial seizures. Individuals with partial seizure accounted for about 10% in GEFS+. Mutations in SCN1A, SCN2A, SCN1B and GABRG2 genes have been identified in families with GEFS+. SME is an intractable epileptic encephalopathy, which is often considered to be the most severe phenotype of the GEFS+. Partial seizures can be observed in 43%-78.6% of SME patients. Prolonged partial febrile seizures in the first year of life are usually followed by intractable epilepsy and mental handicap. SME borderland (SMEB) may miss some key features of SMEI phenotype such as myoclonus. More than 150 mutations in SCN1A gene have been identified in children with this disorder, which account for 30% to 90% SME (SMEI and SMEB) patients tested. Most of the cases are sporadic with de novo mutations. Clinically, patients of febrile seizure with later onset partial epilepsy, which we prefer to name as partial epilepsy with febrile seizure plus (PEFS+), are more common. It is usually difficult to differentiate the patients of PEFS+ from the patients with partial seizures in GEFS+ or SME (especially SMEB). It is suspected that some of the patients with PEFS+ may have the same genetic basis as GEFS+ or SME. The present study is to identify the genetic basis of sporadic cases with PEFS+.