Objectives: To investigate the contribution of hereditary factors in the causation of different epilepsy syndromes.
Material and methods: Occurrence of seizures among first- and second-degree relatives of 5628 Indian probands with epilepsy, and 3357 probands with non-epilepsy neurological disorders (who acted as control population) was documented. Syndromic concordance between epilepsy probands and affected relatives was investigated.
Results: Twenty percent epilepsy probands (1129) had affected relatives. Relatives of epilepsy probands were more often affected compared with relatives of non-epilepsy probands (OR: 3.4). Probands with some epilepsy syndromes more often had a positive family history. Relatives of younger probands were at greater risk of having epilepsy. Sibs were more often affected compared with other first- and second-degree relatives (OR: 1.3 and 4.6). Sibs having generalized epilepsies and syndromes and febrile convulsions (FC) were at greater odds of syndromic concordance with probands compared with second-degree relatives. Sibs and second-degree relatives having idiopathic/cryptogenic epilepsy had greater odds for concordance compared with those with symptomatic epilepsies.
Conclusions: One-fifth of probands with all types of epileptic syndromes have family history of seizures. Familial risk of epilepsy correlated with the epilepsy syndrome among probands and their age at presentation. Risk of relatives being affected varied as a function of the relation with probands. Concordance of epilepsy syndromes varied both as a function of the epilepsy syndrome and relation with the probands.