Hazar Haidar discusses the need for a societal debate to explore challenges related to polygenic embryo screening.
The possibility of genetically designing babies to select those with the “best” genes has been discussed since at least the publication of Brave New World in 1932. This topic has moved from science fiction to becoming a reality with the use of polygenic risk scores to select embryos.
What are polygenic risk scores? Complex diseases (e.g. cancer) and physical human traits (e.g. height), are shaped by both our inherited genes and environmental factors. To identify some of the genetic factors at play when it comes to a certain trait or medical condition, scientists have started looking at genetic differences correlated with differences in traits. This is done by scanning and analyzing the genomes from many different people – what is currently called genome-wide association studies. Polygenic risk scores are then calculated by adding up all the small genetic differences. Therefore, when a particular trait exhibits a large genetic component, polygenic risk scores can be used to predict an individual’s trait or increased risk for a particular disease. For instance, polygenic risk scores have been used to predict a range of diverse common conditions, from diabetes and cancer, to attention deficit issues and well-being in general. The key idea of polygenic risk scores is to use the genetic susceptibility to certain diseases to stratify individuals into low- and high-risk groups for these diseases in order to offer these individuals personalized medical treatments.
More recently, polygenic risk scores have been introduced into the reproductive context to select embryos (also known as “polygenic embryo screening”). This technique assesses an embryo’s statistical risks—even later in life—of developing diseases (e.g. cardiovascular diseases) and traits (e.g. intelligence) that result from the cumulative effect of countless and complex genetic variants. Polygenic embryo screening is offered to patients considering in vitro fertilization (IVF) to screen embryos for medical and non-medical conditions. Several companies, such as Genomic Prediction, MyOme, and Orchid Health, are currently selling polygenic embryo screening as part of their services and it was recently announced that the first baby, Aurea, was born after using this screening in 2020.
With polygenic embryo screening comes a host of ethical, social, policy, and legal issues that are also raised in another context: the use of non-invasive prenatal testing for fetal whole genome sequencing . Noninvasive fetal whole genome sequencing is not yet clinically available but has been developed in research settings. This technology would offer parents a wide range of complex information related to the fetus, such as the likelihood of late-onset genetic conditions (e.g. Alzheimer’s disease) and non-medical traits (e.g. athletic ability) through the analysis of cell-free DNA from maternal blood. These technologies—polygenic embryo screening and noninvasive fetal whole genome sequencing—differ in many of their clinical aspects. For instance, polygenic embryo screening is performed in an IVF setting, whereas noninvasive prenatal testing happens during pregnancy. Nonetheless, they raise similar ethical concerns and challenges. These include concerns about a eugenic society and discrimination against people with disabilities, altered societal perceptions of what is “healthy” and “normal”, concerns about the future child’s autonomy and right to know, societal pressure to use these technologies, psychological burdens for the future child and prospective parents, and the anxiety and stress that the complexity of information generated through these technologies will pose for prospective parents, among other concerns.
The rapid introduction of polygenic embryo screening into the market seems to be driven by a commercial push from companies to offer more IVF services, and an effort to bypass the rigorous scientific process to prove its clinical utility. For instance, there are concerns related to the prediction accuracy of polygenic risk scores given that these scores are affected by many factors such as family history and cultural differences. This highly competitive commercial environment combined with the absence of regulatory oversight, highlight the need for a broad ethical debate engaging diverse stakeholders, such as genomics experts, policymakers, clinicians, patients, disability advocates, and the public, to explore and address the use of polygenic embryo screening. In the meantime, the first and most urgent action to be taken is public education and awareness.
The information that would be offered by polygenic embryo screening is far from being predictive of a child’s future non-medical characteristics and health. Physical and medical traits are not determined solely by genes, though they are often portrayed as such on company websites, or in the media. Rather, these traits result from complex interactions between a myriad of biological, social, environmental, and economic factors, such as lifestyle choices, healthcare, and education. In other words, polygenic embryo screening is not a guarantee of a healthy or genetically “fit” baby.
Finally, professional societies must issue policy statements to provide guidance for practitioners who are willing to use polygenic embryo screening in order to communicate information about this technology to prospective parents in a responsible manner.