What is Trisomy 21?
Trisomy 21 (Down syndrome) is a chromosomal disorder caused by an error in cell division that results in the presence of an additional third
chromosome 21. It is the most frequent genetic cause of mild to moderate mental retardation and associated medical problems including heart defects,
congenital hypothyroidism, intestinal problems, hearing loss and vision disorders.
For more information on Trisomy 21 please visit these sites:
What Is Down Syndrome? By the National Institute of Child Health
& Human Development (NICHD)
MOD - Down Syndrome March of Dimes Foundation
Medline Plus U.S. National Library of Medicine
What is Down Syndrome? YourGenesYourHealth.org
Down Syndrome: Health Issues By Len Leshin, M.D., F.A.A.P.
Health Care and Associated Conditions By the National Down Syndrome Society (NDSS)
Down Syndrome Information By Children's Hospital of the Kings Daughters, Norfolk, Va.
Down Syndrome Fact Page By Patient Plus, United Kingdom
Down Syndrome By Harold Chen, MD, MS, FAAP, FACMG published by Emedicine.com
Down Syndrome and Alzheimer's From Better Health Channel, Published by the
Resourses, Down Syndrome and Cardiac Surgery BMJ: British Medical Journal