Embryo Selection

Diana Fleischman, Ives Parr, Jonathan Anomaly, and Laurent Tellier:

This is where a new technology comes in: preimplantation genetic testing for polygenic disorders (PGT-P) or polygenic screening, which may inform which embryo parents choose and who is born. Because embryo choice is so consequential, polygenic screening—like other, new reproductive technologies before it—attracts more than its share of controversy and critics, many of whom use the label of eugenics as a smear, to suggest that parents electing to screen their own embryos are somehow akin to Nazis endorsing sterilization and murder. Progressives who criticize polygenic screening tend to use accusations of eugenics inconsistently, applying it to reproductive technology like polygenic screening but not abortion.

Other similar reproductive technologies are less controversial today than when first introduced. For example, most couples using IVF choose to genetically test their embryos for an abnormal number of chromosomes, known as “aneuploidy.” One reason for this genetic screening is that aneuploid embryos almost always result in a miscarriage. Another reason is that the few cases that do not miscarry result in life-long, incurable syndromes, such as Down Syndrome—associated with health problems, disability, and shorter lifespan. While aneuploidy screening is not entirely uncontroversial, this screen is far more widely accepted than when it was first introduced decades ago, and criticism of screening out Down Syndrome as “eugenics” is increasingly a fringe position. 

Another commonly accepted embryo screen is for monogenic disorders, that is for diseases caused by single genes. For example, couples can screen out embryos with Tay-Sachs, a devastating neurological disorder that kills young children. Carriers of Huntington’s disease—a degenerative neurological disease that, on average, kills its victims in their early sixties – also often choose to use IVF to screen out embryos likely to be afflicted. For most people, it is clear today why future parents would not want their children to have chromosomal abnormalities or monogenic disorders. But the acceptance of these tests has taken time and was far from universal when these tests were introduced in the 1990s.