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Down Syndrome

for CP Bio class

Natalie Schiele

on 12 May 2010

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Transcript of Down Syndrome

Down Syndrome 21 Chromosome?
Down syndrome occurs because of the presence of an extra copy of chromosome 21. Down syndrome is the most common chromosome disorder and genetic cause of mental retardation. No treatment is available to cure Down syndrome. Treatment is directed at addressing the individual concerns of a particular patient. For example, heart defects may require surgical repair.

Characteristics Down syndrome is a chromosome disorder that causes mental retardation. Common characteristic features of Down syndrome include a flattened mid-face, small head, and short broad hands. Other physical features include: a small mouth, which causes the tongue to stick out and to appear overly large; upward slanting eyes; and shorter-than-normal stature.
Approximately 30-50% of all children with Down syndrome are found to have heart defects. Development in a baby and child affected with Down syndrome occurs at a much slower than normal rate. Because of weak, floppy muscles (hypotonia), babies learn to sit up, crawl, and walk much later than their unaffected peers. Talking is also quite delayed. The level of mental retardation is considered to be mild-to-moderate in Down syndrome. The degree of mental retardation varies a great deal from one child to the next.
The prognosis for an individual with Down syndrome is quite variable, depending on the types of complications (heart defects, susceptibility to infections, development of leukemia, etc.). People with Down syndrome appear to go through the normal physical changes of aging more rapidly, however. The average age of death for an individual with Down syndrome is about 50 to 55 years.
Still, the prognosis for a baby born with Down syndrome is better than ever before. Because of modern medical treatments, including antibiotics to treat infections, and surgery to treat heart defects and duodenal atresia, life expectancy has greatly increased. Community and family support allows people with Down syndrome to have rich, meaningful relationships.
Prognosis History of the discovery of the disease:
Down syndrome, the most common genetic cause of intellectual disabilities, was first described in 1866, during an era of great change in our understanding of genetics and evolution. Because of its importance, the history of research on Down syndrome parallels the history of human genetics.
It took scientists years to figure out that humans have 46 chromosomes because they relied heavily on tests conducted in 1923 by a man named Theophilus S. Painter who presented evidence that the correct number was 48. Scientists finding only 46 often threw out results because they couldn’t find the other two. HISTORY Down syndrome occurs in about one in every 800 live births. How is it passed
When a baby is conceived, the sperm cell from the father and the egg cell from the mother undergo a reduction of the total number of chromosomes from 46 to 23.
Occasionally an error occurs in this reduction process and instead of passing on 23 chromosomes to the baby, a parent will pass on 24 chromosomes. This event is called nondisjunction and it occurs in 95% of Down syndrome cases. Who gets it
It affects an equal number of male and female babies. Down syndrome occurs with equal frequency across all ethnic groups and subpopulations.
As a woman's age (maternal age) increases, the risk of having a Down syndrome baby increases significantly. By the time the woman is age 35, the risk increases to one in 400; by age 40 the risk increases to one in 110; and, by age 45, the risk becomes one in 35.

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Works Cited Tests for pregnant person Screening tests are used to estimate the chance that an individual woman will have a baby with Down syndrome. A test called the maternal serum alpha-fetoprotein test (MSAFP) is offered to all pregnant women under the age of 35. If the mother decides to have this test, it is performed between 15 and 22 weeks of pregnancy. The MSAFP screen measures a protein and two hormones that are normally found in maternal blood during pregnancy. The MSAFP test can detect up to 60% of all babies who will be born with Down syndrome.
Ultrasound screening for Down syndrome is also available. This is generally performed in the mid-trimester of pregnancy. Abnormal growth patterns characteristic of Down syndrome such as growth retardation, heart defects, duodenal atresia, T-E fistula, shorter than normal long-bone lengths, and extra folds of skin along the back of the neck of the developing fetus may all be observed via ultrasonic imaging.
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