Abstracts

This study deals with the establishment of a sample of twins ascertained from population-based twin registries in three countries in order to study the importance of genetic factors for seizure liability.
A sample of twins with seizures was established from twin registries in the U.S., Norway and Denmark. Twins were screened by questionnaire/telephone interview for a history of seizures (epilepsy, febrile seizures, other seizures and staring spells). Seizure frequencies were calculated both within and across twin samples. Classical twin analyses were performed, using probandwise concordance rates, to compare the similarity between monozygotic (MZ) and dizygotic (DZ) twins within and across twin samples for each of the seizure categories.
Among the 47,614 twin pairs who provided health history information included in the three twin samples, members of 6,234 pairs responded positively to at least one of the questions concerning seizures. Among those with a positive history of seizures 1.6% reported epilepsy, 2.1% reported febrile seizures, 3.4% reported other seizures (without epilepsy and febrile seizures) and 1.2% reported a history of staring spells (without reporting epilepsy, febrile seizures or other seizures). Table 1 provides number of affected pairs and concordance rates for MZ and DZ twins by seizure category for the combined twin sample.
By merging data collected from three twin populations, we have created the largest unselected, population-based sample of twins with seizures to be developed to date. Our finding of MZ-DZ concordance rates that are consistent with the presence of genetic effects on the expression of epilepsy, febrile seizures, other seizures and staring spells confirms the importance of genes in the occurrence of seizures. All twins, who reported a history of seizures, are currently being clinically evaluated by neurologists. Seizures and epileptic syndromes are being classified according to the ILAE. This sample is an important resource for studying the genetics of epilepsy subtypes and febrile seizures.[table1]
[Supported by: In part by the following grants: NIH NINDS grant (NS-31564); The Clinical Research Institute, University of Southern Denmark; The grant committee of Consultancy Counsel, Odense University Hospital; The Danish Epilepsy Society Research Foundation; The Hede Nielsen Foundation; The K.A. Rohdes Foundation; The Novo Nordic Foundation and the Norwegian Research Council.]