When doctors want to accurately test high-risk patients to determine whether their unborn babies will have Down syndrome, they currently perform karyotyping after an amniocentesis or chorionic villus sampling, procedures that have small chance of causing miscarriage. However, the Los Angeles Times reports that a team of researchers from China and the UK have proved that a much safer test can be effective in detecting trisomy 21. In a procedure similar to one we covered at Medgadget two years ago, the researchers analyzed fetal DNA which they recovered from maternal blood plasma to determine whether the baby would have Down syndrome.
From Los Angeles Times‘ coverage:
Using the new technology, researchers found they could rule out Down syndrome in 98% of cases, sparing the women from further testing. The blood test did not produce false negative results (showing the fetus did not have the disorder when, in fact, the condition was present).
Currently, women in the United States are offered a blood test combined with an ultrasound test — called the combined test — to assess the risk of Down syndrome in pregnancy. The combined test still leaves an estimated 3% to 5% of women in need of invasive testing. The new blood test, which is conducted in the first trimester, could be used after the combined test or even as a first-tier test, said the study authors, from the Institute of Health Sciences in Hong Kong.
Los Angeles Times Coverage: Prenatal blood test for Down syndrome shows high level of accuracy
Full text of the study in the British Medical Journal: Non-invasive prenatal assessment of trisomy 21 by multiplexed maternal plasma DNA sequencing: large scale validity study
Flashback: New Blood Test for Down Syndrome
