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Genetic and Rare Diseases Information Center (GARD)

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Down syndrome


* Not a rare disease
Información en español
Other Names for this Disease
  • Down's syndrome
  • Trisomy 21
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Down syndrome is a chromosome condition that is associated with intellectual disability, a characteristic facial appearance, and low muscle tone in infancy. The degree of intellectual disability varies from mild to moderate. People with Down syndrome may be born with a variety of health concerns, including heart defects or digestive abnormalities. In addition, they have an increased risk of developing gastroesophageal reflux, celiac disease, hypothyroidism, hearing and vision problems, leukemia, and Alzheimer disease. Down syndrome is caused by having three copies of chromosome 21, instead of the usual two copies.[1] This condition occurs in about 1 in 800 newborns. Researchers have identified genes that cause some of the features of Down syndrome and are working to learn more in order to improve treatment options.[2]

Last updated: 6/8/2012


  1. Down syndrome. Genetics Home Reference (GHR). 2008; Accessed 3/9/2012.
  2. Down syndrome. March of Dimes. 2009; Accessed 3/9/2012.
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Basic Information

In Depth Information

  • The Online Mendelian Inheritance in Man (OMIM) is an catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Down syndrome. Click on the link to view a sample search on this topic.

Resources for Kids

  • The Family Village Web site has a state by state list of summer camps for kids and teens with a variety of medical conditions, including cancer, skin conditions, bleeding disorders, diabetes, physical or intellectual disability and others.