Trisomy 21

1. Trisomy 21 By: Cindy Lam

2. What is it? • Also known as Down syndrome • Down syndrome is when a person has 47 chromosomes instead of 46. • In Trisomy 21, they have an extra chromosome 21.

3. History • An essay was published in 1866 by John Langdon Down. • Originally called “Mongoloids” • 1960s: The name was dropped from scientific use when Asian genetic researchers thought of it as an insult. • Waardenburg & Bleyer: first people to consider it to be caused by chromosomal abnormalities in the 1930s. • Jerome Lejeune & Patricia Jacobs: determined that it is caused by trisomy (triplication) of the 21st chromosome in 1959.

4. What causes Down syndrome? • Cells divide into two, so the chromosomes splits and goes to one cell while the rest goes to another cell. • In rare cases, both chromosomes in a pair goes to one cell. • Down syndrome are not cause by the parents. Most times, the error occurs from the formation of the sperm or the egg. • 90% of the case, came from the mother’s egg. • 4% came from the father’s sperm. • The rest occurs after fertilization, as the embryo grows. • Older women are more likely to give birth to an infant with Down syndrome. • But about 60% of babies with Down syndrome are born to women under 35.

5. Health Problems • 75% of people may be affected with hearing loss. • When a person temporarily stops breathing while asleep, it’s called obstructive sleep apnea. About 50-75% are affected • Ear infections (between 50 -70%) • Eye diseases which requires glasses (up to 60%) • Heart defects present at birth (50%)

6. Developmental Issues • Head is abnormally shaped • Flattened nose • Separated joints between the bones of the skull • A crease in the palm of the hand • Small ears • Small mouth • Upward slanting eyes • Wide, short hands with short fingers • White spots on the colored part of the eye • Hypotonia, when they have decreased muscle tone, at birth.

7. A Possible “Cure”? • A compound that reverse learning abilities in mice was discovered. • Only works on the day of their birth. • Grows the cerebellum (structure at the back of the brain) to grow to its normal size. • Not proven safe for humans but can make drugs like the compound.

8. Special Olympics • Established by Eunice Kennedy Shriver. • Started out as a summer day camp in a backyard. • People with disabilities were treated unfairly & unreasonably. Children did not have a place to play. • Goal: To learn what the children can do in sports and other activities. • First Special Olympics Summer Games was held on July 20, 1968. • By May 2013, on the latest census shows the Olympics reaching a new milestone in growth with more than 4.2 million athletes and 70 thousand competitions around the world.

9. Sources • http://www.onhealth.com/down_syndrome/article.htm • http://www.nlm.nih.gov/medlineplus/ency/article/000997.htm • http://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html • http://www.ds-health.com/trisomy.htm • http://www.dailymail.co.uk/health/article-2412118/A-cure-Downs-syndrome-Scientists-discover-compound-reverses-learning-difficulties-caused-condition.html • http://www.specialolympics.org/Sections/Who_We_Are/Down_Syndrome.aspx • http://www.specialolympics.org/history.aspx