Abstract

A significant number of genes that have a significant impact on epilepsy have been identified in recent genetic research; however, the genes that have been identified so far only affect risk in a very small number of patients,primarily those whose families follow Mendelian modes of inheritance. For the upcoming ten years, it will be a major challenge to identify genes in genetically complex epilepsies that affect the vast majority of patients. The types of genetic mechanisms that could be involved, the study designs used to identify them and the findings of recent family and genetic studies of complex epilepsies are all discussed in this chapter. Understanding the relationship between genotype and phenotype is an extremely important goal for gene identification research because of the epilepsy's clinical and etiologic heterogeneity. In order to clarify the "phenotype definition" in the epilepsies, we examine two research designs: studies of family concordance and familial aggregation. These analyses may shed light on the extent to which the various clinically defined epilepsy syndromes differ in terms of their genetic contributions, assisting in the
best way to identify epilepsy subgroups with susceptibility genes in common.