Event Review: Polygenic Embryo Screening – The promise and perils of selecting our children's traits

Hosted as a part of the Museum of Science in Boston, Massachusetts' Research Ethics Consortia Webinar Series, 'Polygenic Embryo Screening: The promise and perils of selecting our children's traits' led listeners through a timely conversation focused on the bioethical concerns wrapped up in the clinical use of polygenic embryo screening.

As genetic screening continues to improve, various preimplantation genetic testing (PGT) methods have been developed. These include PGT-A and PGT-M, which screen embryos for aneuploidy or monogenic conditions, respectively. Unlike PGT-M, which screens embryos for a genetic condition indicated by a family's medical history, polygenic embryo screening or PGT-P assesses the probability that an embryo will develop common conditions or exhibit complex traits linked to multiple genes. The ability to not only screen out embryos likely to be at risk for harmful genetic conditions, but also select for positively regarded traits such as intelligence, makes clinical implementation of this technology ethically contentious.

The Research Ethics Consortia is a monthly seminar series aimed at exploring ethical issues in biotechnology and society. Hosted by the director of the Centre for Life Sciences at the Museum of Science, Dr Insoo Hyun, and moderated by health care attorney Lauren Walsh, this seminar featured a lively discussion with bioethicist and researcher Dr Vardit Ravitsky from Harvard Medical School in Cambridge, Massachusetts.

The session kicked off with a clarification between polygenic embryo screening and other types of PGT. Dr Ravitsky explained that all types of PGT are meant to help prospective parents make informed medical decisions during embryo selection. However, by additionally enabling prospective parents to select for future children likely to possess specific physical or cognitive traits, polygenic embryo screening extends beyond medical concerns and bleeds into ethical and societal issues.

In the UK, PGT is highly regulated by the Human Fertilisation and Embryology Authority (HFEA), with embryo screening limited to avoidance of serious inherited illnesses (see BioNews 1134). Despite being illegal in the UK and various other European countries, Dr Ravitsky pointed out that polygenic embryo screening remains unregulated in the USA. Without legal oversight, American companies have largely commercialised this service, making information and test results accessible online.

Dr Ravitsky also emphasised that IVF is a necessary part of polygenic embryo screening. Given the costly and physically taxing nature of IVF treatment, couples already undergoing IVF may be more inclined to request polygenic embryo screening than couples without an active medical concern that would have to undergo IVF purely to access this service.

The discussion then shifted to focus on what the results of polygenic embryo screening look like to prospective parents. To set the scene, Dr Ravitsky opted to show a short snippet of the film Gattaca, which depicts a dystopian future in which effectively all children are born following a screening process comparable to polygenic embryo screening. In the clip, a pair of prospective parents are presented with a batch of embryos to choose from that have been pre-screened for various harmful diseases and undesirable traits. While the 1997 film impressively captures the concept of polygenic embryo screening, Dr Ravitsky aptly pointed out one important discrepancy between the film's version of the future and reality. Although polygenic embryo screening enables prospective parents to select for or against traits in future children, interpretation of results is far from clear-cut.

With a limited number of embryos, prospective parents are more likely to be presented with embryos that have variable configurations of risks for developing various conditions. The question then becomes how can prospective parents possibly weigh these risks? And how does a physical condition such as heart disease compare to a mental condition such as schizophrenia? Even if prospective parents select against a certain disease, there is no guarantee that that child will not develop that condition.

Beyond the inevitability of moral quandaries, Dr Ravitsky was additionally concerned with the overall performance of these tests. As a researcher studying the genetics of human disease, I am well-versed in genome-wide association studies (GWAS) which generate the base data for polygenic embryo screening. While I would argue that polygenic risk scores from GWAS broadly hold great promise for assessing individual disease risk, I agree with Dr Ravitsky's claims that this screening method is still in its infancy and person-to-person performance is likely to be variable.

Dr Ravitsky also warned of the potential societal dangers of selecting for the quote-on-quote 'best' embryos. 'If we put so much on genetics,' stated Dr Ravitsky, 'we take those responsibilities off of ourselves and off of society and off of policy makers, so to me that's very worrisome'.

At the heart of Dr Ravitsky's argument against polygenic embryo screening seemed to be fear. Fear that women will be pressured to undergo IVF, fear that polygenic embryo screening will be viewed as a more responsible approach to conception, and fear that selection of children's traits will drive a pro-eugenic dialogue. While I perhaps remain slightly more optimistic of the future trajectory of this method, I agree that polygenic embryo screening is a double-edged sword which necessitates careful consideration of the ethical and societal implications.

The session wrapped up with a Q&A that touched on various curiosities from online listeners. The result was a 20-minute-long discussion touching on the potential for devaluation of traits, the perceived violation of the Hippocratic Oath, and a bioethical parallel with the clinical use of CRISPR genome editing.

Overall, I found this event to be a well-rounded and pertinent discussion addressing the bioethical implications of a relatively new technique in the world of reproductive genetics. Although this session could have benefited from having more than one speaker to contribute to the discussion, I highly recommend those interested to give this seminar a listen.