Down syndrome is a genetic disorder caused by the presence of an extra chromosome 21. It can be detected prenatally through echography, amniocentesis or fetal chromosome analysis. Common medical conditions associated with Down syndrome include heart defects, gastrointestinal abnormalities like esophageal atresia or duodenal atresia, respiratory problems, hearing problems and an increased risk of leukemia. Management involves treating specific medical conditions and may include surgery, medications like digitalis or diuretics, and physical, occupational and speech therapy.