DEVELOPMENT OF THE CEREBRAL CORTEX

Many cases of pediatric epilepsy have a genetic component. For exam-ple, several twin studies have shown consistently high concordance rates for epilepsy in monozygotic twins.1,2 In addition, increasing num-bers of genes responsible for pediatric epilepsy have been found in recent years. Some of these genes encode ion channels and are inherited in an autosomal dominant fashion.3,4 On the other hand, there are genes that are known to cause pediatric epilepsy in asso-ciation with specific brain malformations. Some of the recently identified genes responsible for cortical malformations include ARX for lissencephaly with abnormal genitalia,5 ARFGEF2 for periven-tricular heterotopia with microcephaly,6 and GPR56 for bilateral fron-toparietal polymicrogyria.7 These disorders of cortical malformations are individually rare but still account for a large number of cases of pediatric epilepsy when combined.8,9 Identifying the disease genes for such disorders not only allows us to develop DNA-based diag-nostic tests and provide better genetic counseling for the families with affected children, it also helps us understand the basic mech-anisms of brain development and epileptogenesis