Last Updated (Monday, 20 July 2009 12:44)

What is the cause of Down syndrome?

Although many theories have been developed, it is not known what actually causes Down syndrome. Some professionals believe that hormonal abnormalities, X-rays, viral infections, immunologic problems, or genetic predisposition may be the cause of the improper cell division resulting in Down syndrome.

It has been known for some time that the risk of having a child with Down syndrome increases with advancing age of the mother; i.e., the older the mother, the greater the possibility that she may have a child with Down syndrome.

However, most babies with Down syndrome (more than 85 percent) are born to mothers younger than 35 years. Some investigators reported that older fathers may also be at an increased risk of having a child with Down syndrome.

It is well known that the extra chromosome in trisomy 21 could either originate in the mother or the father. Most often, however, the extra chromosome is coming from the mother.