Down syndrome is a genetic condition where a person has three copies of chromosome 21 instead of the usual two. This extra genetic material causes developmental delays and other issues. Down syndrome can range from mild to severe depending on the individual. Over 90% of Down syndrome cases are caused by trisomy 21, where there are three copies of chromosome 21. Physical signs include a flattened nose, small ears and mouth, upward slanting eyes, and short hands and fingers. The risk of having a child with Down syndrome increases with the mother's age. Complications can include heart defects, leukemia, and early-onset Alzheimer's disease.

1. Down SyndromeBy: Natalie Brennan

2. What is Down syndrome?Down syndrome is a genetic condition in which a person has 47 chromosomes instead of the usual 46. This disorder causes mental retardation and other problems. Down syndrome ranges in severity, so developmental problems may range from mild to serious.

3. Causes of Down syndromeThere are 3 possible abnormalities which all result in extra genetic material from chromosome 21,which causes Down syndrome.12Trisomy 21Mosaic Down syndrome3 More than 90 percent of cases with Down syndrome are caused by Trisomy 21.

4. With Trisomy 21 there are 3 copies of chromosome 21, instead of the usual 2 copies.Translocation Down syndrome rare form of Down syndrome

5. With Mosaic Down syndrome some cells have an extra copy of chromosome 21, but not all.

6. Mosaic Down syndrome is caused by abnormal cell division after fertilization.

7. occurs when part of a chromosome 21becomes attached onto another chromosome, before or at conception.

8. Children with Translocation have the usual 2 copies of chromosome 21, but have additional material from chromosome 21 stuck to the translocated chromosome. MOST cases of Down syndrome are NOT inherited.

9. Common physical signs of Down syndromeIndividuals with Down syndrome have a widely recognized appearance.Common physical signs include: flattened nose

10. small ears

11. small mouth

12. upward slanting eyes