MSH: Abnormalities in the development of the CEREBRAL CORTEX. These include malformations arising from abnormal neuronal CELL PROLIFERATION or APOPTOSIS; abnormal neuronal migration; and abnormal establishment of cortical organization via neurite extension, synaptogenesis, or neuronal maturation. As well as mutations effecting these developmental processes directly, there are a variety of inborn metabolic errors, such as PEROXISOMAL DISORDERS and mitochondrial and pyruvate metabolic disorders which effect them secondarily and also exhibit these malformations. They are common causes of EPILEPSY and developmental delay and are often a component of multiple congenital anomalies.,NCI: A group of neural cortical developmental malformations of diverse genetic causes. Clinical manifestations include epilepsy and developmental delays.