Down syndrome is a genetic disorder that involves a combination of disorders, including some degree of mental retardation, characteristic factions and often heart defects, increased number of infections, visual and hearing impairments and other health problems . The severity of these problems varies greatly among different individuals involved.
Down syndrome is one of the most common genetic birth defects, affecting roughly one in every 800 to 1,000 babies. Its most common cause is the presence of a chromosome in pair 21. A chromosome is the cell that contain genetic information (genes).