Down Syndrom

Topics: Down syndrome, Chromosomal translocation, Cytogenetics Pages: 6 (1625 words) Published: February 9, 2011
Sharjah American International School


Done By:


a) Down syndrome
b) Interesting topic
c) Understanding why down syndrome occurs
a) Who discovered Down syndrome
b) What is Down syndrome
Body research
A. What Causes it and is it inherited?

1-Trisomy 21
2-Mosaic Down syndrome
3-Translocation Down syndrome

B. How Down syndrome affects Kids
1-Physical features

C. Risk factors
1-Advancing maternal age
2- Being carriers of the genetic translocation for Down syndrome 3-Having had one child with Down syndrome

D. Health Issues
1- Health complications
2-Average life expectancy

E. Can Down syndrome be cured?
F. Can Down syndrome be diagnosed before the child is born? 1- Screening tests
2- Diagnostic tests.


* Many people ask what causes Down’s syndrome and what are the Signs and Symptoms of it. * To understand why Down syndrome occurs, the structure and function of the human chromosome must be understood. * This topic sounds interesting because we can learn more and more about Down’s syndrome and this make a big difference in the lives of both children and adults with Down syndrome. * During the research we will know the reasons why some parents have a greater risk of having a baby with Down syndrome.

In 1866, British Doctor John Langdon Down first described Down syndrome as a disorder, but he misunderstood how Down syndrome arises. In 1959 French doctor, named Jerome Lejeune, discovered it was caused by the inheritance of an extra chromosome 21. Down syndrome (DS), also called Trisomy 21, is a condition in which extra genetic material causes delays in the way a child develops, both mentally and physically. It affects about 1 in every 800 babies. The physical features and medical problems associated with Down syndrome can vary widely from child to child. While some kids with DS need a lot of medical attention, others lead healthy lives.

Body research
What Causes it and is it inherited?
Normally, at the time of conception a baby inherits genetic information from its parents in the form of 46 chromosomes: 23 from the mother and 23 from the father. In most cases of Down syndrome, a child gets an extra chromosome 21 — for a total of 47 chromosomes instead of 46. The cause of Down syndrome is one of three types of abnormal cell division involving chromosome 21. All three abnormalities result in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of Down syndrome. The three genetic variations that can cause Down syndrome include: Trisomy 21. More than 90 percent of cases of Down syndrome are caused by trisomy 21. A child with trisomy 21 has three copies of chromosome 21 instead of the usual two copies in all of his or her cells. This form of Down syndrome is caused by abnormal cell division during the development of the sperm cell or the egg cell.

Trisomy 21–the presence of three copies of chromosome 21–causes Down syndrome. This karyotype shows the classic appearance of trisomy 21. * Mosaic Down syndrome. In this rare form of Down syndrome, children have some cells with an extra copy of chromosome 21. This mosaic of normal and abnormal cells is caused by abnormal cell division after fertilization. * Translocation Down syndrome. Down syndrome can also occur when part of chromosome 21 becomes attached onto another chromosome, before or at conception. Children with translocation Down syndrome have the usual two copies of chromosome 21, but they also have additional material from chromosome 21 stuck to the translocated chromosome. This form of Down syndrome is uncommon. Most cases of Down syndrome aren't inherited....

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