Down syndrome is a genetic disorder with an excess genetic material on 21th chromosome, mild mental retardation and anomalies of multiple organ systems. Physical and neurophysicological findings such as mental retardation, linguistic and memory problems accompany this syndrome. Neuroanatomical origins of this cognitive dysfunctions are not clear yet. The risk of Down syndrome differs with respect to races, and ethnic groups, maternal age distribution, prenatal diagnosis and cytogenetic analysis
