Background: Little is known about offspring of parents who both have idiopathic generalized epilepsy (IGE). This is of importance for understanding the complex genetic architecture of IGE.
Methods: Families in whom both parents had proven IGE were ascertained through a multiplex families database. Clinical information including EEG recordings and detailed pedigrees was obtained.
Results: In family I, the mother had juvenile myoclonic epilepsy (JME), and the father had IGE. One daughter had Lennox-Gastaut syndrome, and the other had unclassified epilepsy. In family II, the mother had JME, and the father had IGE. Two of three sons had an identical clinical picture of clinical picture of childhood absence epilepsy (CAE), but with fast polyspike-wave discharges on EEG.
Conclusions: The clinical phenotype of affected offspring suggested that their epilepsy could be due to the combination of a putative "double dose" of genes from both sides of the family. In such families, as epilepsy genes could be inherited from both parents, a high risk of epilepsy in the offspring could be expected.