trisomy+21

In the 20th century people with down syndrome as well as those with other disabilities were still being institutionalized and often sterilized. in Germany 1940, Hitler implented the Akiton T-4 program, which refers to euthanize people with down syndrome and other disabilities.

1959 DR Jerome Lejune, a French physician made the discovery that down syndrome was the result of the chromosomal abnormality. His research helped him see that people with the disorder had 47 chromosomes, whereas people without the disorder had 46 chromosomes. After that, he discovers that chromosome number 21 contained an extra partial or complete chromosome in these mongoloids, because of that the term Trisomy 21 was born. []

Human cells divide in two ways. The first is ordinary cell division (**"mitosis"**), by which the body grows. In this method, one cell becomes two cells which have the exact same number and type of chromosomes as the parent cell. The second method of cell division occurs in the ovaries and testicles (**"meiosis"**) and consists of one cell splitting into two, with the resulting cells having half the number of chromosomes of the parent cell. So, normal eggs and sperm cells only have 23 chromosomes instead of 46.

Many errors can occur during cell division. In meiosis, the pairs of chromosomes are supposed to split up and go to different spots in the dividing cell; this event is called "disjunction." However, occasionally one pair doesn't divide, and the whole pair goes to one spot. This means that in the resulting cells, one will have 24 chromosomes and the other will have 22 chromosomes. This accident is called "**nondisjunction**." If a sperm or egg with an abnormal number of chromosomes merges with a normal mate, the resulting fertilized egg will have an abnormal number of chromosomes. In Down syndrome, 95% of all cases are caused by this event..Recent research has shown that in these cases, approximately 90% of the abnormal cells are the eggs. The cause of the nondisjunction error isn't known, but there is definitely connection with maternal age. Research is currently aimed at trying to determine the cause and timing of the nondisjunction event

People that receive the disorder are the ones that have 47 chromosomes. people with the disorder are living a full and happy life, but may need a little help with learning things

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Symptoms of down syndrom vary from person to person and can be severe or mild. People with down syndrome can have decreased muscle tone at birth,they could have excess skin at the nape of the neck,they can have a flattned nose,seperated joints single creses at the palm of the hands, small ears and a small mouth,upward slanting eyes,wide short hands with short fingers,or white spots on the colored part of the eye.

In children they mave have impulsive behavior or poor judgement, a short attention span or slow learning. They can also feel angry and frustrated once there aware of there limitations. They could also have many different birth defects such as [|atrial septal defect] or [|ventricular septal defect].

People with down syndrome could have eye problems like cataracts. Most children with down syndrome need to wear glasses. They could have hearing problems caused by constanly having ear infections. Teeth can appear latter then normal and the location of the teeth can cause problems with chewing. [].

there is no cure for down syndrome no one is sure how to prevent the chromosomal error that causes Down Syndrome.a recent study suggests that some women who have had a baby with Down syndrome had an abnormality in how their bodies metabolize the B vitamin folic acid. If confirmed, this finding may provide yet another reason why all women who might become pregnant should take a daily multivitamin containing 400 micrograms of folic acid (which has been shown to reduce the risk of certain birth defects of the brain and spinal cord).The March of Dimes is investigating why errors in chromosome division occur, in the hope of someday preventing Down syndrome and other birth defects caused by abnormalities in the number or structure of chromosomes. Other researchers are seeking to improve the outlook for children with Down syndrome. One example of this includes developing improved language intervention programs to help these children communicate more easily.