In a new study in Science Translational Medicine, the University of Washington's Jay Shendure and his colleagues report that they can decipher a fetus's genome by testing the DNA of its parents, reports The New York Times' Andrew Pollack. This could allow doctors to test for thousands of genetic defects and anomalies in a fetus before it is born, he adds. The team took blood samples from pregnant women 18.5 weeks into pregnancy and tested for fragments of fetal DNA in the women's blood. "[The researchers] were able to detect 39 of 44 spontaneous mutations, though with a huge number of false positives," Pollack says. "The researchers sequenced the genomes of the mother and father. They then sequenced nearly three billion DNA fragments from the mother's blood." They determined which genes were passed from the father, as they were unique in the mother's blood sample, and then determined which variants from the mother were passed to the fetus.
"After it was determined what the fetus inherited from the mother and father, what was left in the fetus's DNA was considered a possible spontaneous mutation," Pollack says. The test is nowhere near ready for primetime, he adds. It needs to be refined to reduce the false positives, and is also currently unaffordable for most people. But it could lead to a new era for prenatal testing, Pollack adds.