Sequencing the unborn summery

Scientists have figured out how to determine the medical future of an unborn child by sequencing DNA from the mother’s blood and DNA from the father’s saliva. At the moment, prenatal diagnosis for a small number of genetic conditions is usually done from fetal cells that doctors capture from fluid in the womb or as nippet of placental tissue. In 1997, chemical pathologist Dennis Lo, discovered that roughly 10% of the cell-free DNA floating in a pregnant woman's blood stream stems from her fetus. In 2010 in a paper published in Science Translational Medicine, Lo's group showed that enough fragments of fetal DNA are there to reconstruct the fetus's whole genome, and it should be possible to use this DNA to test the unborn child for genetic diseases without exposing it to the risk of an invasive procedure. One strategy makes use of subtle genetic variations that exist between a mother's pairs of chromosomes.
In most cases, for a particular genetic sequence on a specific chromosome, the variants from each pair should be represented equally in the woman's blood. In an expectant woman, whose child has received only one variant as part of its genetic inheritance, her blood will contain a little more of that variant because of the free-floating fetal DNA. If the mother's patterns of genetic variants, or haplotypes, are known, statistics allow researchers to conclude what variants she passed on to her offspring. Lo showed that with both parents' haplotypes known, it would be possible to predict the child's genome from the DNA in an expectant mom's blood. In the new study, he and his team sequenced DNA from the plasma-blood minus the cells-of a woman who was 18.5 weeks pregnant. Comparing that DNA with genome sequences obtained from the father's saliva and the mother's blood allowed the researchers to identify fetal DNA sequences that they could piece together into the child's genome. The scientists also tried to find new mutations in the child that neither the father nor