This may take away the risk of testing for Down Syndrome in a fetus, which is great, but it also adds the ability to know if a baby has this condition early enough to abort the baby with a 2.1% false positive result. I don’t know the false positive ratio of the other testing types, but if women plan to use this test in order to consider abortion, I’m not so sure I like the 2.1% chance that the baby could be perfectly healthy.
From ABC News:
New Down Syndrome Test Could Cut Healthy Baby Deaths
Non-Invasive Blood Test Could Eliminate Miscarriage Risk of Amniocentesis
Lynn Harris, pregnant for the first time and in her late 30s, faced a decision many older women at higher risk for Down syndrome babies are asked to make: choose a form of prenatal testing.
“Such a brutally tough call,” wrote Harris, a New York City journalist, in an article on the topic on Babble.
“I talked to friends, I spread-sheeted statistics, I lay awake.”
Instead of amniocentesis, which would require her to wait until 18 to 20 weeks, she chose chorionic villus sampling (CVS) — an invasive test which, like amniocentesis, carries a risk of miscarriage.
Right after the procedure, Harris lost most of her amniotic fluid and lost an otherwise healthy baby at 12 weeks. “I am still not over it,” she said.
Pre-natal screening for Down syndrome, which affects 1 pregnancy in 691, is fraught with unclear test results, risks to the unborn baby and profound anxiety for expectant mothers and their partners.
But now, a new maternal blood test has the potential to reduce the number of women referred for invasive testing for Down syndrome by 98 percent.
A study, led by researchers at Li Ka Shing Institute of Health Sciences at The Chinese University of Hong Kong (CHUHK) and published this week in the Journal of British Medicine (BMJ) looked at the new technology, which uses the latest tools in gene sequencing to detect abnormalities in the fetus.
This technology was developed in 2008, but this is the first large-scale study, including more than 750 blood samples from pregnant women in Hong Kong, Britain and the Netherlands — 86 from those who were carrying a child with Down syndrome.
The most robust version of the new blood test tested on 314 pregnancies detected Down syndrome in 100 percent of the cases, with only a 2.1 percent false positive rate.
“Over the years, several versions of the test have been developed, but this test is one of the most promising in terms of diagnostic performance,” said Dr. Rossa Chiu, first author of the study and a clinical chemist at CUHK.