DNA testing for Down's syndrome could save babies' lives
A new study says giving pregnant women a DNA test for Down’s syndrome on the NHS would reduce the need for invasive testing, meaning the lives of unborn babies could be saved.
A team led by Professor Kypros Nicolaides at King's College Hospital and King's College London carried out the research into DNA testing for Down's syndrome, which involved 11,692 women with single pregnancies being treated at King’s College Hospital, London, and the Medway Maritime Hospital, Kent. Of these women, 395 were determined to be at high-risk of carrying a baby with Down's syndrome.
Sixty percent of the women at high risk opted for the “cell-free” DNA test, while 38 percent chose invasive testing.
Currently a woman's risk of carrying a baby with Down's syndrome is calculated taking into account her age, the level of hormones in her blood and the results of a “nuchal scan,” which measures the collection of fluid at the back of the unborn baby’s neck.
If a woman is found to be high risk after this initial test she has the option of further testing. A chorionic villus sampling (CVS) takes a sample of the placenta by needle. The alternative is an amniocentesis, which takes a sample from the fluid surrounding the baby. Both tests can provide a definitive diagnosis of Down's syndrome but also carry a risk of miscarriage.
On the other hand, the cell-free DNA test involves taking a blood sample from the pregnant woman and is also highly reliable. However it is currently only available privately, at a cost of hundreds of pounds.
Crucially the study showed that although Down's syndrome could be detected in more babies this did not result in a higher number of pregnancy terminations.
"Our research puts the case for offering the cell-free DNA test on the NHS," said Professor Kypros Nicolaides, Director of the Harris Birthright Research Centre for Fetal Medicine at King's College Hospital and Professor of Fetal Medicine at King's College London. "This would improve the performance of screening, and reduce the number of unnecessary invasive tests and miscarriages."
The study is published in the Ultrasound in Obstetrics and Gynaecology journal.