14 January 2013
ByAppeared in BioNews 688
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.