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Non-invasive prenatal test as good as invasive methods, say scientists

14 January 2013
Appeared in BioNews 688

US biotech company Verinata Health has reported sequencing fetal DNA taken from pregnant women's blood to test for genetic abnormalities.

Researchers took blood samples from 11 pregnant women carrying fetuses with genetic abnormalities and by sequencing the cell-free fetal DNA in the woman's blood were able to identify the abnormalities present.

'Our study shows that medically relevant information currently available only through an invasive prenatal procedure is accessible non-invasively from a single maternal blood sample', said Dr Richard Rava, chief scientific officer of Verinata Health.

Normally, prenatal diagnostic testing requires invasive tests, such as amniocentesis and chorionic villus sampling, which carry a low risk of miscarriage. A mapping process called karyotyping is then performed which provides doctors with a picture of the broad shape of chromosomes, allowing major defects in structure to be discovered. Doctors can obtain information about the rest of the genome through microarray techniques, but this requires the extraction of placental tissue.

The new technique was able to pick up the vast majority of the defects found by the more traditional approaches. 'Accuracy is greater than 99 percent', Dr Rava told TIME. The researchers said the study showed that the karyotypes produced were equivalent to those produced through microarray techniques.

Moreover, by using the new approach the scientists could potentially detect many more genetic defects than would be found using chromosome karyotyping.

Not only does the new method represent a safer alternative, the researchers could also increase the resolution with which the DNA of a fetus can be scrutinised. Professor Cynthia Morton, a geneticist at Harvard University, told Bloomberg that this technology 'could largely replace invasive testing'.

Since March 2012, Verinata has sold a blood test called Verifi that can detect conditions, where there is an extra copy of a chromosome - called trisomy - including Down's syndrome. The company now plans to expand that test to include some of the additional genetic aberrations that can be identified by fetal DNA sequencing.

'It's not going to happen tomorrow', Dr Rava told TIME, but the 'paper demonstrates it's technically feasible'.

The study was published in the American Journal of Human Genetics.

Could a Blood-Based Test Replace Amniocentesis?
Time |  10 January 2013
DNA in Mother’s Blood Can Spot Genetic Mutations in Fetus
Bloomberg |  10 January 2013
Noninvasive Detection of Fetal Subchromosome Abnormalities via Deep Sequencing of Maternal Plasma
American Journal of Human Genetics |  10 January 2013
Verinata Health Publishes Proof-of-Concept Data Showing Non-Invasive Fetal Karyotype Equivalent to Invasive Procedures
PR Newswire (press release) |  10 January 2013
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9 March 2015 - by Kirsty Oswald 
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10 March 2014 - by Dr Victoria Burchell 
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10 June 2013 - by James Brooks 
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...
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10 December 2012 - by Dr Lux Fatimathas 
More sensitive prenatal testing of fetal DNA could improve the detection of genetic diseases, studies find...
26 November 2012 - by Dr Lux Fatimathas 
Non-invasive pre-natal screening for certain abnormalities in fetal chromosomes should be offered to at-risks mothers, recommends the American College of Obstetricians and Gynecologists...
13 December 2010 - by Julianna Photopoulos 
Scientists have scanned the entire DNA of an unborn child from the mother's blood sample for the first time to safely check for genetic disorders...
8 December 2008 - by Evelyn Harvey 
By Evelyn Harvey: A new method for early detection of genetic diseases in unborn babies using a simple blood test can detect the inherited condition beta-thalassemia, according to a study published in Proceedings of the National Academy of Sciences. Although the technique, which analyses cell free fetal DNA (cffDNA) present...
13 October 2008 - by Lorna Stewart 
Scientists at Stanford University in California, US have developed a new non-invasive prenatal test for Down's syndrome. Stephen Quake and colleagues successfully identified presence and absence of fetal chromosomal abnormality in 18 pregnant women from maternal blood samples. The work is published this month in the journal...
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