By: Abby Foulk

Inheritance Pattern:•Trisomy 21 is a Nondisjunction.

-Nondisjunction: An event during meiosis in which homologous chromosomes or sister chromatids fail to separate.

•An extra chromosome is located on the 21st group

Location:

• Trisomy 21 (Down Syndrome) is located on chromosome 21.

Extra Chromosome 21

Superoxide Dismutase (SOD1)– over expression may cause premature aging and decreased function of the immune system; its role in Senile Dementia of the Alzheimer's type or decreased cognition is still speculative COL6A1 – over expression may be the cause of heart defects

ETS2 – over expression may be the cause of skeletal abnormalities

CAF1A – over expression may be detrimental to DNA synthesis Cystathione Beta Synthase (CBS)– over expression may disrupt metabolism and DNA repair DYRK – over expression may be the cause of mental retardation

CRYA1 – over expression may be the cause of cataracts

GART – over expression may disrupt DNA synthesis and repair IFNAR -- the gene for expression of Interferon, over expression may interfere with the immune system as well as other organ systems

Trisomy 21 is not located on a gene, but possible genes that could be affected by Trisomy 21 are:

• No gender is more likely to have Trisomy 21 than others.

•The older a woman is, the chance of her giving birth to a child with Trisomy 21 is greater.

Older women do have a more likely chance of having a child with down syndrome. But because younger women are giving birth to more babies, the majority of babies with down syndrome come from younger mothers.

•At age 25, the risk of having a baby with Down syndrome is 1 in 1,250. •At age 30, the risk is 1 in 1,000. •At age 35, the risk is 1 in 400. •At age 40, the risk is 1 in 100. •At age 45, the risk is 1 in 30.

There are many Symptoms of Trisomy 21 :

•Decreased muscle tone at birth•Excess skin at the nape of the neck•Flattened nose•Separated joints between the bones of the skull•Single crease in the palm of the hand•Small mouth•Upward slanting eyes•Wide, short hands with short fingers•White spots on the colored part of the eye•Smaller head than average•Abnormally shaped head•Never fully reach their average adult height

• Usually you can tell a person has down syndrome by looking at them.

•Also, people with Down syndrome may have:-impulsive behavior-poor judgment-short attention span-slow learning abilities

•People with Down Syndrome also have a great risk of having heart defects and some will even need to have major surgery after birth.

•Trisomy 21 effects one in every eight-hundred babies

(About 3,400 babies a year in the U.S.)

According to the National Down

Syndrome Society, there are

more than 400,000 individuals

with Down syndrome in the

United States

Trisomy 21 can be deadly.

Statistics show that:•15% will die before turning the age of one.

•35% will die at the age of fifty.

50% will die after turning the age of fifty.

People can be tested for Trisomy 21, usually while they are still in the womb or after the baby is born. Some of these tests include:

•Amniocentesis. A sample of the amniotic fluid surrounding the fetus is withdrawn through a needle inserted into the mother's uterus. This sample is then used to analyze the chromosomes of the fetus. Doctors usually perform this test after 15 weeks of gestation. The test carries a one in 200 risk of miscarriage

•Chorionic villus sampling (CVS). Cells taken from the mother's placenta can be used to analyze the fetal chromosomes. Typically performed between the ninth and 14th week of pregnancy, this test carries a one in 100 risk of miscarriage.

•Percutaneous umbilical blood sampling (PUBS). Blood is taken from a vein in the umbilical cord and examined for chromosomal defects. Doctors generally perform this test after 18 weeks of gestation. This test carries a greater risk of miscarriage than does amniocentesis or chorionic villus sampling. Generally, this test is only done when speed of diagnosis is essential.

After birth, the initial diagnosis of Down syndrome is often based on the baby's appearance. If your child displays some or all of the characteristics of Down syndrome, your doctor probably will order a test called a chromosomal karyotype. This test is an analysis of your child's chromosomes. If there's an extra chromosome 21 present in all or some of the cells, the diagnosis is Down syndrome.

Each of these three tests is 98 to 99 percent accurate in diagnosing Down syndrome before birth.

There is no treatment or cure for down syndrome. However, there are some cures for heart defects, which is a symptom of down syndrome. Surgery is that number one fix.

Even though there are no exact treatments, people with down syndrome can still live successful lives.

NATIONAL DOWN SYNDROME SOCIETY:

-National Down Syndrome Society 666 Broadway, 8th FloorNew York, New York 10012

- 800-221-4602 

-  info@ndss.org   

•92% of women who know that their fetus has Trisomy 21 (Down Syndrome) choose abortion.

- Brian Skotko

•Down syndrome is really the only trisomy compatible with life. Only two other trisomies have been observed in babies born alive (trisomies 13 and 18), but babies born with these trisomies have only a 5% chance of surviving longer than one year.

•In 90% of Trisomy 21 cases, the additional chromosome comes from the mother's egg rather than the father's sperm.

•Down syndrome was originally described in 1866 by John Langdon Down. It wasn't until 1959 that a French doctor, named Jerome Lejeune, discovered it was caused by the inheritance of an extra chromosome 21

Sarah Palin’s son, Trig, has down syndrome

Johnson, Summer. "Will The Down Syndrome Children Disappear? | Blog.bioethics.net." Blog.bioethics.net: a Nature Top 50 Science Blog from The American Journal of Bioethics. Center of Practical Bioethics, 16 Sept. 2009. Web. 25 Jan. 2011.

<http://blog.bioethics.net/2009/09/will-the-down-syndrome-children-disappear/>.Leshin, Len. "Trisomy 21: The Origin of Down Syndrome." Down Syndrome: Health Issues - Medical Essays and Information. 1997. Web. 25 Jan. 2011.

<http://www.ds-health.com/trisomy.htm>.March of Dimes. "Down Syndrome | Baby | March of Dimes." Pregnancy, Baby, Prematurity, Birth Defects | March of Dimes. July 2009. Web. 25 Jan. 2011. <http://www.marchofdimes.com/Baby/birthdefects_downsyndrome.html?gclid=CK_QxffV1qYCFULNKgodMwpTIA>.

Staff, Mayo Clinic. "Down Syndrome: Tests and Diagnosis - MayoClinic.com." Mayo Clinic. 5 Nov. 2010. Web. 26 Jan. 2011. <http://www.mayoclinic.com/health/down-syndrome/DS00182/DSECTION=tests-and-diagnosis>.

University of Utah. "Down Syndrome." Learn.Genetics™. 2011. Web. 26 Jan. 2011. <http://learn.genetics.utah.edu/content/disorders/whataregd/down/>.