Down’s syndrome could be detected in mother’s blood test

By Dr. Ananya Mandal, MDMar 7 2011

European researchers have devised a blood test that could help pregnant women avoid the invasive procedures now used to diagnose Down syndrome prenatally and make the diagnosis with 100% accuracy. The study report was published this Sunday in Nature Medicine.

At present doctors use one of two invasive procedures to diagnose the condition: either amniocentesis or chorionic villus sampling, which both involve inserting needles into the abdomen to extract fetal cells. These tests are about 80 percent accurate and carry a small risk of miscarriage; only 1 in 10 mothers choose to undergo either. Down’s syndrome is a serious from of mental retardation that occurs in some babies. It is usually accompanied by other problems like heart diseases, susceptibility to infections, cancer etc. Babies with Down’s syndrome are born with an extra copy of the chromosome number 21. Till date, a genetic analysis of the fetal tissues from amniocentesis and chorionic villus sampling was the only way of detecting this disorder before birth.

According to researchers this new blood test detects Down syndrome through fetal DNA that has spilled into the mother’s bloodstream. Forty pregnant women participated in the study, and researchers used the test to correctly identify 14 cases of Down syndrome and 26 normal fetuses, but warn that a larger study is necessary to validate the results. Study author Philippos Patsalis, chief executive medical director of the Cyprus Institute of Neurology and Genetics said, “We estimate we can introduce this to clinical practice in a couple of years.”