Contribution to the genetics of symptomatic generalized tonic-clonic seizures: waking and sleep EEGs in siblings.

The presence of epileptiform activity (EA) in the EEG of patients' relatives points to the significance of genetics in the etiology of epilepsies. Waking and sleep EEGs were recorded in 83 siblings of 54 patients suffering from symptomatic generalized tonic-clonic seizures. EA was recorded in at least one sibling of 27 (50%) of the 54 patients. When the 83 siblings are taken as a basis, EA was found in 34 (41%) of them. Generalized spike-wave discharges were seen in 32 cases; 2 siblings showed benign sharp wave foci in the right parietal area. EA was seen only in sleep in 44.1%. The highest rates of EA were seen in the age range up to 15 years. EA was found in 15 of 50 male siblings (30%), but in 18 of 33 female siblings (54.5%). Therefore genetics also play an import role in the etiology of symptomatic generalized tonic-clonic seizures.