Hong Kong researchers have found a way of scanning a fetus’s genome with cell-free fetal DNA in the mother’s blood. The breakthrough technology only requires the mother’s blood and the father’s DNA. This could prove significant as it allows for a non-invasive type of test for multiple fetal genetic disorders.
Prenatal tests currently available are commonly invasive, pose dangers on the unborn baby. Amniocentesis, one of these tests involves extracting a sample of fluid from the womb, along with chorionic villus sampling, requiring the embryo’s blood taken from a small piece of tissue from the placenta.
While the new technology was confirmed to be quite expensive, the costs are expected to diminish rapidly, said the researchers.
The experts showed how the fetal genome is actually in the fetal DNA molecules in the maternal blood plasma, but were faced with difficulties as the DNA were “highly fragmented.” DNA molecules are hard to detect given a plethora of surrounding maternal DNA molecules.
The team had to sequence almost 4 billion DNA fragments from the maternal blood sample to sequence the human genome 65 times, distinguishing the sequences of the mother’s from the father’s.
The next challenge lay in identifying the fetal genome map from the mother but without it being “contaminated” by DNA sequences which also came from the mother. This was a rather difficult task as only 10% of maternal plasma is fetal DNA, and the other 90% is entirely the mother’s.