Cortical dysplasia (CD) represents a common neuropathologic substrate of pediatric epilepsy, one frequently encountered in surgical resection specimens from infants and children with intractable seizure disorders, including infantile spasms. Severe CD shows similarities to structural features noted in tubers from individuals with tuberous sclerosis (TSC). The latter disorder, one with neurocutaneous and visceral manifestations, results from mutations in one of two recently cloned genes, TSC1 or TSC2, which encode (respectively) the proteins hamartin and tuberin. There is circumstantial evidence that both proteins may influence cell growth and differentiation, specifically that they may represent growth suppressors. Neither protein has a defined role in brain development. We discuss and illustrate neuropathologic features of both CD and TSC, and discuss the patterns and time course of hamartin/tuberin expression in normal brain, CD and TSC. Other recently cloned genes associated with cortical malformations encompassed by the term CD are briefly described
