<unk> , or Down's syndrome (primarily in the United Kingdom), trisomy 21, or trisomy G, is a genetic disorder caused by the presence of all or part of an extra 21st chromosome. Often<unk>  is associated with some impairment of cognitive ability and physical growth, and a particular set of facial characteristics.<unk>  in a fetus can be identified with amniocentesis during pregnancy, or in a baby at birth. Individuals with<unk>  tend to have a lower than average cognitive ability, often ranging from mild to moderate developmental disabilities. A small number have severe to profound mental disability. The incidence of<unk>  is estimated at 1 per 800 to 1,000 births, although it is statistically much more common with older mothers. Other factors may also play a role.early childhood intervention, screening for common problems, medical treatment where indicated, a conducive family environment, and vocational training can improve the overall development of children with<unk> . Although some of the physical genetic limitations of<unk>  cannot be overcome, education and proper care will improve quality of life.
Down syndrome
Apert syndrome
Lawrence-Moon syndrome
Williams syndrome
XX male syndrome
Goldstein-Hutt syndrome
Young Simpson syndrome
Hurler syndrome