Down syndrome occurs in approximately 1 in 700 births and is the most common chromosome abnormality. Down syndrome is caused by an extra chromosome #21 (trisomy 21). Most cases do not run in a family. Most are caused by a misdivision of chromosomes in the egg or sperm that formed the pregnancy. Children with Down syndrome have similar facial features to each other, moderate to mild intellectual disabilities, and may have other birth defects, such as a heart defect.
Who is at risk to have a baby with Down syndrome?
A woman at any age can have a baby with Down syndrome; however as a woman’s age increases, the chance of having a baby with Down syndrome also increases.
Should I have this test if there has never been anyone in our families with Down syndrome?
In over 95 percent of the families in which a child is born with Down syndrome, there has never been anyone else in the family with the condition. A very small percentage of Down syndrome is inherited in families. If you or your partner has a relative with Down syndrome, please inform your doctor prior to having screening.
Should I consider having a screening test first to identify my risk of having a child with Down syndrome before deciding about an amniocentesis or CVS?
Many patients find that the screening result helps them to make a decision regarding whether CVS or amniocentesis is the right choice for them. Diagnostic testing is available for any patient who desires more definitive information. These
options require more extensive counseling by our genetic counselors before you make this important decision.