Recent Advances and Ethical Considerations in Embryo Screening
A review of a new paper coauthored by Steve Hsu entitled "Embryo Screening for Polygenic Disease Risk: Recent Advances and Ethical Considerations"
Steve Hsu of InfoProc has recently (July 21, 2021) published an article entitled "Embryo Screening for Polygenic Disease Risk: Recent Advances and Ethical Considerations."
Embryo screening and selection are interesting issues because they provide the ability for picking embryos that are physically and mentally healthy. This is clearly of great value to the individuals who live healthier and likely happier lives, as well as their family and society. The process already takes place to some extent because over a million babies are born via in vitro fertilization yearly. In IVF, multiple embryos are produced and selected from for their future health already. As more genetic information is gathered, better predictions can be made about future health and risk of disease. The level of risk is called a Polygenic Risk Score (PRS).
Polygenic risk predictors for dozens of important disease conditions have been published and validated by numerous research groups around the world [5–12]. We can roughly characterize the performance of these polygenic risk predictors as follows: Individuals with very high PRSs will typically have an incidence rate that is many times higher than the population average. For example, in [5], it was found that for atrial fibrillation, a 99th percentile PRS implies ∼ 10 times higher likelihood of case status. The rapid, nonlinear increase in absolute risk for the condition with the PRS percentile is shown in Figure 1 below. For outliers at very high PRS percentiles (e.g., within the top 1%), risk can exceed that associated with well-known monogenic risk factors, such as BRCA1 and BRCA2 [7]. Absolute risk can even approach 1 (near certainty) for some individuals.
There is the ability to significantly reduce the risk of disease by selecting embryos with low polygenic risk scores. Imagine knowing that your child is unlikely to develop cancer, have a heart attack or stroke prematurely. The predicted health of the embryo is aggregated into something called the Embryo Health Score (EHS). The EHS is “the sum of the predicted absolute risks for each disease condition weighted by the life-span impact of the condition.”
There are many ethical concerns around the creation of life. One primary concern for liberal minded people who do not care so much about abortion is that of inequality. This technological breakthrough will have significant effects for those who can afford it, which will be limited for financial reasons for some years to come.
PGT-P of preimplantation embryos is only available to couples who can afford to undertake IVF and genetic screening of their preimplantation embryos. Even in countries that provide a comprehensive national healthcare program, IVF began as a privately funded medical service, and this still predominates. For many couples, the right to choose exists, but only if they can afford many of the options open to them. In most societies, the opportunity to choose trumps the principle of justice, more through societal pragmatism than desire, thus raising concerns that we must strive to treat everyone alike, but genetic advantage is available only to the wealthy [40]. Not only does this issue arise in many aspects of human innovation, with, perhaps, the greatest reservations being directed at medically assisted procreation, but history also demonstrates that with the launching of such benefits on a small scale amidst a welter of debate (and sometimes outrage), over time, opportunity and acceptance widen across society.
Hopefully, we will see widespread acceptance. This technology is important and very interesting. This will not be my last article on the matter.
I'm very concerned about the inequality implications of this new technique. It seems that it would just drive another wedge between the upper and lower classes in the US.
I recently red a book called "Red Families Vs. Blue Families" which showed how there are two different cultures of family and childrearing in America. In the "blue" model of families, every child is considered a significant investment and is given maximum potential for success as an individual; the "red" model certainly considers children as important, but in more of an aggregate sense, and the idea of an extended-family support net is emphasized. The idea of embryo screening seems to fit in with the "blue" model. The book is fascinating; I would highly recommend it if you are interested in reading about how different cultural expectations shape family structure. https://www.amazon.com/Red-Families-v-Blue-Polarization/dp/0199836817/ref=sr_1_1?dchild=1&keywords=red+families+vs+blue+families&qid=1627387245&sr=8-1