Occurrence of epilepsies in family members of Indian probands with different epileptic syndromes.

PURPOSE: Large numbers of families with many members having seizures have been used to understand the role of hereditary factors in the pathogenesis of human epileptic syndromes. We aimed to establish a genetic database to form a hypothesis on the possible genetic contributions in different epileptic syndromes.
METHODS: The occurrence and patterns of different epilepsies and epileptic syndromes in 1,219 Indian probands and their relatives were studied. The concordance of epilepsies between probands and relatives was also analyzed.
RESULTS: Of probands, 231 (19% of 1219) had first- or second-degree relatives affected with seizures. Incidence of family history in probands with generalized epilepsies (GES) and syndrome of single, small, enhancing lesions (SSEL) was comparable and significantly higher than that in probands with localization-related epilepsies (LRES). The ratio of affected first- to second-degree relatives was close to 4:1. Generalized epilepsies were the commonest type of epileptic syndromes seen among all relatives. The proportion of sibs and second-degree relatives with epileptic syndromes similar to probands was significantly greater in the GES group as compared with the concordant relatives of probands with LRES and SSEL.
CONCLUSIONS: A significant percentage of first- and second-degree relatives of probands with all types of epileptic syndromes have seizures. The risk of relatives being affected varied as a function of the relation with the proband. Concordance of epileptic syndromes between probands and relatives was related to the epileptic syndromes in probands. The syndrome of SSEL is probably a benign epileptic syndrome seen in Indians genetically predisposed to seizures. Hereditary factors may play an almost equal role in the predisposition of relatives to epilepsy in families of probands with different epileptic syndromes.