Genetic and Rare Diseases Information Center (GARD)


Other names people use for this condition
  • Trisomy 21
  • Down's syndrome

* This condition is not a rare disease. It is a condition about which the GARD Information Center has received a question.

Down syndrome *
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Down syndrome was named after John Langdon Down, the first physician to identify the syndrome.  It is the most frequent genetic cause of mild to moderate mental retardation.[1]  Down syndrome is a chromosomal disorder that is caused by the presence of an additional chromosome 21, and is also known as trisomy 21. Individuals with Down syndrome have three copies of chromosome 21, instead of the usual two copies.

References
  1. Down syndrome. Genetics Home Reference Web site. 2005 Available at: http://ghr.nlm.nih.gov/condition=downsyndrome . Accessed October 9, 2007.

Questions & Answers (Found 1 Question)
A list of questions from the public on rare and/or genetic diseases that have been answered by the Genetic and Rare Disease Information Center. Click on each question to find the answer.


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