Wednesday 7 December 2016

Blood test for Down's syndrome may cut the risk of miscarriage

Simple test could prevent hundreds of women losing their babies during invasive procedure

Published 06/06/2015 | 17:48

Blood samples
Blood samples

A simple blood test for Down’s Syndrome could prevent the deaths of hundreds of babies a year though miscarriage, a study as shown.

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Currently women at high risk of having children with the debilitating condition are offered an invasive test in which a needle is inserted into the womb to take a genetic sample.

However the procedure causes miscarriage in one in a hundred cases, meaning around 300 babies are lost each year, some of which would have been born healthy.

Now, a study by University College London and Great Ormond Street Hospital, has shown that non-invasive prenatal testing (NIPT) for Down's syndrome is effective and should be made available on the NHS.

The test involves taking a simple blood sample from the mother and looking for DNA belonging to the unborn child.

It was hailed ‘the most exciting development in pregnancy care for decades’ when the pilot project began last year and is 99 per cent accurate.

It also screens for the rare genetic conditions Edward’s syndrome and Patau syndrome.

Healthy babies have two copies of chromosome 21, but babies with Down’s have three.

Professor Lyn Chitty, from the UCL Institute of Child Health and Great Ormond Street Hospital, London, UK, tested more than 2,500 women with the new screening procedure.

"There was a very high uptake of testing and we saw invasive test numbers fall sharply. NIPT performed well in identifying problems, and women were very positive about it,” she said.

"There will be significant savings resulting from a decrease in invasive testing whilst increasing the detection of affected babies. The reduction in invasive testing also means there will be a reduction in miscarriages and loss of unaffected babies which is much better for parents."

Current screening for Down’s on the NHS consists of a ‘combined’ test, which uses ultrasound to measure the amount of fluid at the back of the baby’s neck at 11 weeks, as well as a blood test. If those test are positive women are then offered an invasive diagositic test.

In Britain, 35,000 women a year currently have invasive amniocentesis or chorionic villus sampling. Current methods usually miss around 15 per cent of cases of Down’s syndrome, experts said.

The new test would combine all three stages, and also has the advantage of getting results back within days rather than a fortnight.

The UK National Screening Committee will consider whether it should be offered to every women this year.

About 750 babies with Down’s syndrome are born in the UK each year.

A separate research group also found that the test can pick up the early signs of ovarian cancer, follicular lymphoma and Hodgkin’s Lymphoma.

Both studies were presented at the European Society of Human Genetics annual conference and published in the journal JAMA Oncology.

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