Down syndrome is a genetic disorder that is caused by the presence of an extra chromosome, which results in varying degrees of physical and mental abnormality. Physical characteristics of the syndrome include a flattened face, widely spaced and slanted eyes, comparatively smaller head size and lax joints. Although not always the case, mental retardation is typical. Developmental, disabilities associated with Down syndrome include delayed motor skills (such as sitting, crawling and walking in infancy) and delayed cognitive skills (such as speech and language acquisition and short-term memory abilities).Those who are affected with the syndrome will have a high propensity to suffer from common health problems, include a low resistance to infection, pronounced hearing loss, gastrointestinal problems, and heart defects.
Down syndrome occurs at the rate of around 1 in 700 to 1 in 900 live births worldwide, depending on contraception and termination attitudes in different communities. There are currently more than 2,000,000 people with Down syndrome worldwide.