Genetic predisposition to severe myoclonic epilepsy in infancy.

PURPOSE: To address genetic predisposition to febrile convulsions (FCs) and epilepsy as an etiologic background of severe myoclonic epilepsy in infancy (SMEI).

METHODS

Familial antecedents of epilepsy and FCs were analyzed in four groups of patients with SMEI (65 cases), FCs (57 cases), childhood absences (67 cases), and a control group of patients with no neurologic problems (64 cases).

RESULTS

Patients with SMEI and those with FCs had significantly increased incidence of FCs in their relatives compared with those with absence epilepsy and with the control group. The incidence of epilepsy in relatives of patients with SMEI and absence epilepsy was increased compared with that in the control group and reached statistical significance. Epilepsy in relatives with SMEI had the characteristics of idiopathic generalized epilepsy.

CONCLUSIONS

A genetic predisposition could determine three types of epileptic syndromes: FCs, idiopathic generalized epilepsy, and SMEI.