Scientists are now able to sequence almost the entire genome of a fetus using a blood sample from the mother and saliva from the father. This new non-invasive approach — in contrast to amniocentesis, which involves sampling fluid from the uterus and carries a slight risk of miscarriage — means that virtually the entire DNA of an 18-week-old fetus can be determined. Prenatal testing for a number of genetic disorders could be a real possibility very soon. Expecting parents could soon find themselves faced with some wrenching ethical decisions, should the tests reveal that their fetus has a genetic disorder.
New Study: “Noninvasive Whole-Genome Sequencing of a Human Fetus”
Genome scientists at the University of Washington used new high-speed DNA sequencing techniques along with statistical and computational modeling to create the test, which can determine a fetus’ genome with up to 98 percent accuracy. They drew on research from the 1990s that found that a pregnant woman’s blood plasma contains cell-free DNA from her fetus and that these fragments can be genetically analyzed. Indeed, there are already commercially available tests that rely on analysis of fetal DNA fragments to determine a fetus’ gender, paternity and whether it might have Down Syndrome.
The new test would allow for the detection of Mendelian disorders, which result from the mutation of a single gene and include cystic fibrosis, Tay-Sachs disease and Marfan syndrome. Besides such inherited genetic disorders, the new test can potentially identify de novo or spontaneous mutations, which are responsible for the majority of genetic defects and which have been linked to disorders including schizophrenia and autism. De novo mutations are thought to account for about 10 percent of cases of mental retardation and learning disabilities.
The research, which was published in the Science Translational Medicine, could enable doctors to screen fetuses for some 3,500 genetic disorders.
Parents Could Face Wrenching Ethical Questions From Prenatal Testing Results
While analyzing one fetus’ DNA would currently cost about $20,000 to $50,000, researchers predict that, due to fast-moving developments in DNA sequencing, the test could be widely available in three to five years.
Some 85 percent of expecting parents who learn their fetus has Down Syndrome choose to abort. As the New York Times quotes Marcy Darnovsky, associate executive director of the Berkeley-based public interest group, the Center for Genetics and Society, the test could lead to scenarios in which people are able to decide “who deserves to be born” — the prospect of “designer babies,” of parents perhaps choosing to end a pregnancy because a fetus does not have certain desired traits. Could people even start requesting that potential partners undergo genetic testing at some point in the dating process?
What If There Were a Prenatal Genetic Test For Autism?
What parents decide to do with such information will be certainly highly personal.
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