Searching for Human Epilepsy Genes: A Progress Report

Application of new genetic techniques has brought remarkable discoveries in the study of genetic diseases. The potential benefits from applying such technology to idiopathic epilepsies include improved understanding of cellular mechanisms and potential new methods of prevention and treatment. The complex problems involved in studying the hereditary epilepsies include: defining of specific phenotypes; detecting genetic and non-genetic heterogeneity; and specifying the appropriate mode of inheritance and penetrance. The gene loci for three primary epilepsies have been localized to specific chromosomal regions, and serve to demonstrate the process used in generalized linkage studies of hereditary epilepsy syndromes. Benign familial neonatal convulsions (BFNC) and Unverricht-Lundborg progressive myoclonus epilepsy are rare single-gene disorders that are sufficiently localized to chromosomal regions that positional cloning studies are likely to succeed. Juvenile myoclonic epilepsy (JME), a common hereditary syndrome with an uncertain mode of inheritance, has been reported to be linked to chromosome 6p. JME presents a challenge for generalized linkage methodology that may be overcome by attending to potential problems reviewed here. The candidate-gene method, combined with studies using animal models, holds promise for understanding these as well as other hereditary epilepsies.