What are the causes of Downs Syndrome?

Answer 1

Normally, each parents provides one of each of the 23 chromosomes that defines the genetic endowment of the child. When a Down Syndrome (DS) child is conceived (more on this later), one parent accidentally gives the child *two* copies of chromosome #21. This is called a "trisomy" ("tri" meaning three).

There are exceptions. Some children are conceived with the right number of chromosomes, but in cell division, gain an extra chromosome #21. This is called a "mosaic trisomy" because different cells have different genes--just like a mosaic is made up of different shapes and colors of stones. Depending on what percentage of the cells are correct and how many have the extra chromosome, the child may be less seriously affected by DS.

Answer 2

Down syndrome is caused by the chromosomes not paring correctly....

Down syndrome is usually caused by an error in cell division called non-disjunction. However, two other types of chromosomal abnormalities, mosaicism and translocation, are also implicated in Down syndrome - although to a much lesser extent. Regardless of the type of Down syndrome which a person may have, all people with Down syndrome have an extra, critical portion of the number 21 chromosome present in all, or some, of their cells. This additional genetic material alters the course of development and causes the characteristics associated with the syndrome.

Answer 3

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, however, a child gets an extra chromosome - for a total of 47 chromosomes instead of 46. It's this extra genetic material that causes the physical and cognitive delays associated with DS.

Although no one knows for sure why DS occurs and there's no way to prevent the chromosomal error that causes it, scientists do know that women age 35 and older have a significantly higher risk of having a child with the condition. At age 30, for example, a woman has less than a 1 in 1,000 chance of conceiving a child with DS. Those odds increase to 1 in 400 by age 35. By 42, it jumps to about 1 in 60.

Answer 4

As yet we do not know what causes the presence of an extra chromosome 21. It can come from either the mother or the father. There is no way of predicting whether a person is more or less likely to make and egg or sperm with 24 chromosomes.



There is a definite link with advanced maternal age for reasons yet unknown. However most babies with Down’s syndrome are born to women under the age of 35, as younger women have higher fertility rates.

Answer 5

Down syndrome (also Down's syndrome) or trisomy 21 is a genetic condition resulting from the presence of all or part of an extra 21st chromosome. Down syndrome is characterized by a combination of major and minor abnormalities of body structure and function. Among features present in nearly all cases are impairment of learning and physical growth, and a recognizable facial appearance usually identified at birth. Many other organ systems may be affected as well.

Answer 6

Normally, 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 - for a total of 47 chromosomes instead of 46. It's this extra genetic material that causes the physical and cognitive delays associated with DS.

Answer 7

Down syndrome (also Down's syndrome) or trisomy 21 is a genetic condition resulting from the presence of all or part of an extra 21st chromosome. Down syndrome is characterized by a combination of major and minor abnormalities of body structure and function. Among features present in nearly all cases are impairment of learning and physical growth, and a recognizable facial appearance usually identified at birth. Many other organ systems may be affected as well. It is named after John Langdon Down, the British doctor who first described it in 1866.

Answer 8

the causes of downs syndrome is genetic. On the 21st pair of chromosomes there is an extra one instead of 2 there are 3 so people with downs syndrome have 47 chromosomes instead of 46.

Answer 9

the cause of downe syndrome is most certainly a chromosome mutation that happens when the mother produces the egg cell (meiosis) the number of chromosomes should be 23, but at cell division one egg gets 24 and one 22. when fertilized, the egg with 24 (one EXTRA chromosome - number 21) will develop into a baby with downe syndrome.

Answer 10

Down's Syndrome is a genetic condition caused by the presence of an EXTRA CHROMOSOME and resulting in differing degrees of learning disablities.