How Is The Down Syndrome Inherited?!


Question: How Is The Down Syndrome Inherited.?
Answers:
its caused by an extra 21st chromosome, and as far as I know is a genetic mutation and not inherited. Women over about 35 who have children run a much greater risk of having a child with downs.Health Question & Answer

Down syndrome is a genetic disorder that causes mental retardation and other problems. The condition varies in severity, so developmental problems may range from mild to serious.

Most cases of DOWN SYNDROME ARE NOT INHERITED. They're caused by a mistake in cell division during the development of the egg, sperm or embryo.

Translocation Down syndrome is the only form of the disorder that can be passed from parent to child. However, only about 4 percent of children with Down syndrome have translocation. And only about half of these cases are inherited from one of the parents.

In these cases, the mother or father is a balanced carrier of the translocation, which means he or she has some rearranged genetic material, but no extra genetic material. A balanced carrier has no signs or symptoms of Down syndrome, but he or she can pass the translocation on to children.

The chance of passing on the translocation depends on the sex of the parent who carries the rearranged chromosome 21:The cause of Down syndrome is one of three types of abnormal cell division involving the 21st chromosome. All three abnormalities result in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of Down syndrome.

If the father is the carrier, the risk is about 3 percent.
If the mother is the carrier, the risk is about 12 percent. -
Health Question & Answer

Down syndrome is caused by extra genetic material from chromosome 21. Chromosomes are the structures in cells that contain the genes.
Each person normally has 23 pairs of chromosomes, or 46 in all. An individual inherits one chromosome per pair from the mother's egg and one from the father's sperm. When an egg and sperm cell join together, they normally form a fertilized egg with 46 chromosomes. Sometimes something goes wrong before fertilization. A developing egg or sperm cell may divide incorrectly, sometimes resulting in an egg or sperm cell with an extra chromosome number 21. When this cell joins with a normal egg or sperm cell, the resulting embryo has 47 chromosomes instead of 46. Down syndrome also is called trisomy 21 because affected individuals have three number 21 chromosomes, instead of two. This type of error in cell division causes about 95 percent of the cases of Down syndrome (3).

Occasionally, before fertilization, a part of chromosome 21 breaks off during cell division and becomes attached to another chromosome in the egg or sperm cell. The resulting embryo may have what is called translocation Down syndrome. Affected individuals have two normal copies of chromosome 21 plus extra chromosome 21 material attached to another chromosome. This type of error in cell division causes about 3 to 4 percent of the cases of Down syndrome (3). In some cases, the parent has a rearrangement of chromosome 21, called a balanced translocation, which does not affect his or her health.

If a couple, each with Down Syndrome marry, chances are that they will not have children. Most males with Down Syndrome are sterile, they do not produce sperm. In the event the Down Syndrome couple do concieve, the chances of a baby with Down Syndrome are about 50/50. However, most of the pregnanies end in miscarriage and not full term babies, because of the multiplication of genetic problems associated with a trisomy are compounded.

About 1 to 2 percent of individuals with Down syndrome have a form called mosaicism (3). In this form, the error in cell division occurs after fertilization. Affected individuals have some cells with an extra chromosome 21 and others with the normal number.

Health Question & Answer

It's a genetic disorder (passes through the genes). usually there is more information/genetic data in the 21st chromosome.Health Question & Answer



The consumer health information on youqa.cn is for informational purposes only and is not a substitute for medical advice or treatment for any medical conditions.
The answer content post by the user, if contains the copyright content please contact us, we will immediately remove it.
Copyright © 2007-2012 YouQA.cn -   Terms of Use -   Contact us

Health Q&A Resources