Doctors Develop New Reflex DNA Test to Diagnose Syndromes
A more accurate test for Down’s Syndrome, Edwards and Patau syndromes has been developed by doctors.
According to the Guardian, adopted as part of a medical project, UK hospitals has found that it picked up nearly all affected pregnancies and slashed the number of women who wrongly tested positive, removing any anxiety over follow-up tests.
A report, published in Genetics in Medicine, states that the new procedure detected 101 of 106 pregnancies affected by the disorders, or 95%, compared with 81% for the conventional test used in hospitals. The rate of false positives, where babies were wrongly identified as having a condition, fell 100-fold with reflex DNA screening in two in 10,000. Compared with regular screening, the new procedure avoided 530 invasive tests to diagnose the disorders.
The technique, Reflex DNA screening draws on the traditional blood and ultrasound tests, but if the risk of an affected pregnancy is higher than one in 800, then some of the blood already taken from the mother is sent for DNA analysis. This searchers for fragments of DNA that have leaked from the placenta, which reveal whether the baby has the extra chromosomes. It is worth noting that the woman is only alerted to the risk if the DNA tests positive.
The NHS has revealed plans to introduce a similar screening procedure in 2018, which will be offered to about 10,000 women a year who are considered to have a higher risk of giving birth to a baby with one of the conditions.
Reflex DNA has a number of benefits for women who are screened. Nicholas Wald, from the Wolfson Institute of Preventative Medicine at Queen Mary, explained, “We don’t have to approach women to come back for a DNA test. This enormously reduced the false positive rate and the number of women needlessly made anxious as a result. This would potentially be offered to all pregnant women.”
Joseph Aquilina, a consultant obstetrician at Barts Health NHS Trust, one of the five units that trialed reflex DNA screening, believes its “transformational.”
She added, “Not only is the screening method better than current practice, but I have more time to devote to other clinical needs, as do the nursing and midwifery staff involved.”