The Fertility Show, London, 3-4 November 2018
Page URL: https://www.bionews.org.uk/page_94151

Maternal blood test for Down's syndrome has 'major advantages'

10 June 2013
Appeared in BioNews 708

A test using only a blood sample taken from a pregnant woman is more reliable than current checks in indicating the likelihood of Down's syndrome, say researchers.

In a study of 1,005 pregnancies, the new test was applied at the ten-week stage. Results were compared with the outcome of the standard 'combined test' currently offered in the UK which involves an ultrasound scan and a different maternal blood test performed between 11 and 13 weeks' gestation.

Both the new test and current screening techniques gave an indication of all subsequent cases of Down's syndrome or two other similar chromosomal conditions. However, the new test was able to offer predictions with greater certainty.

A clearer improvement on the combined test appeared when comparing false-positive results. Here the new test incorrectly indicated an elevated risk of Down's just once, or 0.1 percent of the time. The combined test had a false-positive rate of 3.4 percent.

Kypros Nicolaides, professor of fetal medicine at King's College London, who led the research, said the test was 'nearly diagnostic. It tells you almost certainly your baby has Down's or almost certainly it does not'.

The result of the combined test is a risk assessment for Down's syndrome, presented in the form of 'one in 150' or 'one in 1,000'. To be certain of whether or not the fetus is actually affected an invasive test would be necessary. Both of the invasive tests currently offered carry a one in 100 risk of miscarriage.

The new maternal blood test presents results as very high (greater than 99 percent) or very low (less than one in 10,000) risks. The greater reliability comes from analysis of the fetus' own DNA, called cffDNA, circulating in the mother's blood.

cffDNA testing is already available commercially in several countries, including the USA. Whether and how it should be available in the UK is currently being evaluated. The BBC reports that Professor Nicolaides is leading a two-year study of 20,000 pregnant women to help with the ongoing assessment. A wider programme, called RAPID, encompassing fundamental, clinical and health economics research is also underway (see BioNews 703).

But for Carol Boys, chief executive of the Down's Syndrome Association (DSA), the study showed how incorporation of cffDNA testing into the national screening programme 'is still a long way off'.

She added that the DSA's training programme to help health professionals provide 'relevant, accurate and up-to-date information about Down's syndrome' would be ready at that time.

The study was published in the journal Ultrasound in Obstetrics and Gynaecology.

SOURCES & REFERENCES
Blood test for Down's syndrome detection hailed
The Independent |  7 June 2013
Early Down's test 'more sensitive'
BBC News |  7 June 2013
Implementation of maternal blood cell-free DNA testing in early screening for aneuploidies
Ultrasound in Obstetrics & Gynecology |  7 June 2013
New Down's syndrome test developed at King's
King's College Hospital (press release) |  7 June 2013
Non-invasive first trimester blood test reliably detects Down's syndrome
Medical Xpress (Press release) |  7 June 2013
RELATED ARTICLES FROM THE BIONEWS ARCHIVE
8 June 2015 - by Kirsty Oswald 
Researchers say that a non-invasive prenatal test for Down's syndrome is ready to be introduced into the NHS...
13 April 2015 - by Kirsty Oswald 
Research shows that a new prenatal blood test for Down's syndrome outperforms current methods of screening...
11 August 2014 - by Dr Victoria Burchell 
Expectant mothers should be offered earlier screening for rare chromosomal conditions, the UK National Screening Committee (UK NSC) recommends...
10 March 2014 - by Dr Victoria Burchell 
A test using a simple blood sample from the expectant mother should soon be the primary screening method for Down's syndrome, according to a report from the Royal College of Obstetricians and Gynaecologists (RCOG)...
4 November 2013 - by María Victoria Rivas Llanos 
A new method for prenatal testing for Down's syndrome will be tried out at Great Ormond Street Hospital for Children (GOSH), London....
7 May 2013 - by James Brooks 
I know what they say about yesterday's news and today's fish and chip paper but what I'm about to tell you is six months old and still a little way off as a headline...
14 January 2013 - by Dr Daniel Grimes 
US biotech company Verinata Health has reported sequencing fetal DNA taken from pregnant women's blood to test for genetic abnormalities...
10 December 2012 - by Dr Lux Fatimathas 
More sensitive prenatal testing of fetal DNA could improve the detection of genetic diseases, studies find...
24 October 2011 - by Julianna Photopoulos 
A new prenatal test that can detect Down's syndrome by using a sample of the mother's blood was launched in twenty US cities last Monday....
HAVE YOUR SAY
Log in to add a Comment.

By posting a comment you agree to abide by the BioNews terms and conditions


Syndicate this story - click here to enquire about using this story.