Non-Invasive DNA Blood Test Detects Down's Syndrome

Until now, women who were in high risk pregnancies for Down’s syndrome, underwent invasive procedures like amniocentesis or chorionic villus sampling, to detect the disorder, but it looks like there is a way of cutting invasive testing for Down’s syndrome by 98%.

BMJ published today a new research called 'Non-invasive prenatal assessment of trisomy 21 by multiplexed maternal plasma DNA sequencing: large scale validity study', which says that a DNA blood test could detect Down's syndrome, thus avoiding 98% of invasive procedures.

This test uses the latest DNA technology and analyzes the genetic components in the mother’s blood that can tell whether the fetus has Down’s or not.

Professor Dennis Lo from The Chinese University of Hong Kong, is the leader of the research team and along with his colleagues, they used state of the art DNA technology to test the blood samples from 753 pregnant women, based in Hong Kong, the UK and the Netherlands, who were all at high risk of having a baby with Down’s.

The tests concluded that 86 of the women were carrying a fetus with Down’s syndrome.

The results of the study concluded that this DNA test is very accurate in detecting the disorder in unborn babies and that it does not give false negative results.

Down’s syndrome or trisomy 21 affects around 1 in 800 births and older women are at higher risk.

Women in high risk groups usually went through a series of scans and hormone levels tests, to see if they need to take an invasive test (amniocentesis or chorionic villus sampling).

The problem is that these invasive tests take samples of genetic material from the fetus, and this implies a 1% risk of miscarriage, so they are usually used in high risk pregnancies.

But even so, there are still 3 to 5% of pregnant women in the UK who undergo invasive testing.

The authors say that this new blood test could be used to accurately establish whether there is a real risk for Down's syndrome in high risk pregnancies, before any invasive tests are even considered.

This could be the best chance to reduce the number of women requiring invasive procedures.