What is Down Syndrome

Down syndrome is a condition that is derived from a genetic abnormality that affects the mental capacity and physical features of an affected individual. Individuals with this disease will experience varying degrees of medical and physical problems. Some people with the disease are able to lead fairly normal lives while others need constant medical care. It affects 1 in 800 newborns and is said to be more prevalent with increased maternal age. The disease cannot be prevented; however, it can be detected in uterus, before the baby is born. There is still a lot of controversy surrounding the implications of genetic testing for Down syndrome. It is said that an estimated 90-93% of pregnancies with a Down’s baby were terminated once this was identified through various genetic testing methods.

The prognosis for children with Down’s syndrome has improved in recent years. The average life span for an individual with Down syndrome was 25 years in the 1980′s it has now risen to 49 years of age in present times. Individuals with the disease will often be infertile especially males who are only partially fertile in extremely rare circumstances. Most children with Down syndrome will also experience significantly reduced cognitive abilities. However, with proper medical intervention, family support and vocational training the child with down syndrome can learn to overcome some of his or her disabilities.

What Causes Down Syndrome

The disease as previously mentioned is caused by a genetic abnormality. A normal individual will have 46 chromosomes, 23 of which will be inherited from each parent. In an individual with Down syndrome he or she will have a total number of 47 chromosomes or in other words one more chromosome than is expected. This chromosomal abnormality occurs because of an extra copy of the 21st chromosome. The effect of the extra copy will vary among affected individuals.

The condition cannot be prevented and is said to be a randomly occurring phenomenon. However, women over the age of 35 are at an increased risk of having a child with Down syndrome. The risks for different groups are as follows:

• Women who are 25 years of age will have a 1in 1,250 chance of having a Down’s baby.
• Women who are 30 years of age will have a 1 in 1000 chance of having a Down’s baby.
• Women who are 35 years of age will have 1in 400 chance of having a Down’s baby.
• Women who are 40 years of age will have 1 in 100 chance of having a Down’s baby.
• Women who are 45 years of age will have a 1 in 30 chance of having a Down’s baby.

The probability of having a child with Down’s Syndrome may also be associated with a familial genetic abnormality. A person who has a balanced translocation will not display any signs of down syndrome but will have an increased risk of conceiving a child with translocation Down syndrome. The estimated risk is 1 in 5 for the female carrier and 1 in 50 for a male carrier. In some instances where there is no unattached copy of chromosome 21 the carrier’s offspring will all have Down’s Syndrome. The affected parent is therefore considered a translocation carrier. This type of Down’s syndrome is said to occur in 2-3% of Down’s syndrome cases.