Your Life, Your Health: New test for Down syndrome
Updated: Saturday, May 3 2014, 06:04 PM EDT
Every year 6,000 babies are born in the United States with Down syndrome, according to the Centers for Disease Control. It is the most common chromosomal abnormality in the country. Pregnant women in a high-risk category, either due to maternal age or a medical condition, sometimes choose to have a diagnostic test to get an answer. However, the test is invasive (amniocentesis) and runs the risk of miscarriage.
For women looking for a specific diagnosis, there is a new option that is completely safe. It is a blood test which takes a sample of the mother's blood that contains bits of the baby's DNA. The test results come quickly and a red flag is raised if there is an abnormality.
Genetic counselor at Albany Medical Center, Jacquelyn Magner says unlike something like an amniocentesis, the blood test only screens for certain things.
"It specifically screens for Down syndrome, Trisomy 13, Trisomy 18, and some of the labs offer testing for sex chromosome abnormalities like Turner syndrome and Klinefelter syndrome."
Dr. Camille Kanaan, Director of Maternal Fetal Medicine at Albany Med says however about 17-20 percent of abnormalities are not detected by the blood test, so it should only be used when appropriate.
"Women who are at high risk, are a little bit older, and maybe have gone through treatment for infertility - they may not be willing to take a risk on the pregnancy. These are appropriately tested with the blood test." Dr. Kanaan says.
If a blood test comes back positive, the woman will likely follow-up with an amniocentesis to get more information on what the chromosomal abnormality may be. Since becoming available in 2010, and marketed by several companies, the blood test has been directly linked to a decrease in invasive procedures at Albany Medical Center.
While not 100% accurate, according to the New England Journal of Medicine it was 10 times greater in its ability to predict whether the fetus has Down syndrome then standard testing.