At least one private company has begun offering services to allow parents undergoing in vitro fertilization (IVF) to screen embryos for complex genetic risks with a procedure called polygenic embryo screening (PES). Although genetic testing of embryos for the risk of certain serious diseases with known strong genetic links (cystic fibrosis or Tay-Sachs, for example) has been around for decades, PES is a new form of screening that these companies say , can identify the risk of complex diseases. medical conditions, including psychiatric disorders, that do not have specific known risk genes.
However, this approach lacks scientific validity and raises a host of ethical issues, according to a new paper in a leading psychiatric journal. Lancet Psychiatry.
“We are concerned that these tests will be marketed with limited empirical data and virtually no scientific or ethical discussion. Without more research, it is unlikely that medical providers and the general public will have sufficient understanding to assess the pros and cons of this technology,” the researchers write.
The authors were led by Todd Lencz, a prolific expert in the genetics of psychiatric diagnoses. Lencz directs the Neurogenomic Biomarkers Laboratory at the Center for Psychiatric Neuroscience at the Feinstein Institutes for Medical Research. He is also the founder and leader of numerous groups of genetic researchers, called consortia. The article was co-authored by 18 members of the International Society for Psychiatric Genetics (ISPG).
The researchers explain that the PES uses polygenic risk scores (PRS) – combining the minute risk of thousands of genetic variants to arrive at a single number. The higher the number, the higher the risk. But a PRS does a poor job of estimating risk for individuals, and is currently only considered useful for population-level research. When it comes to an individual patient, it is clinically useless.
In a May 2021 statement, the ISPG writes:
“Although in general higher scores mean you are more likely to have a disease, many healthy people will have high scores; others might develop the condition even with a low score. The accuracy with which a polygenic score can predict psychiatric illnesses, such as schizophrenia, bipolar disorder, and major depression, is currently not good enough for clinical use.
The accuracy of a PRS, according to the researchers, depends on how well the condition is defined. It is therefore possible that for certain medical conditions, the PRS can provide useful information. However, psychiatric diagnoses are infamous for being arbitrary labels created by committees that “do not correspond to reality”, according to eminent researcher Kenneth Kendler. And of course, they change every few years (usually expanding; about half the population will meet the criteria for a psychiatric diagnosis at some point).
Indeed, the reliability and validity of psychiatric diagnoses are widely recognized as profoundly poor. According to philosophers of science, the profession consistently fails to use the scientific method and may even be completely “incompatible with theoretical science based on assumptions”.
According to the ISPG statement, PRS scores “measure only one of many possible risk factors,” and in the case of psychiatric diagnoses, the contribution of genetic factors is minimal. Previous research suggests that genetic testing may explain less than 1% of mental health issues. Indeed, a huge body of research suggests that psychiatric disorders are highly dependent on social and environmental factors, such as poverty, race, gender identity, and sexual orientation.
In the Lancet Psychiatry article, the authors note that “SRPs for behavioral and neurocognitive traits are…particularly susceptible to the confounding effects of ‘genetic culture’ – the fact that parental genes also shape the environment in which offspring grow up.
In other words, even when traits are strongly correlated with a specific genetic makeup, the correlation may be explained not by genetics but by environmental factors.
As historians of psychiatry and other researchers have noted, psychological science itself is rooted in racism. Thus, the very taxonomy and symptomatology of psychiatric disorders reflect white supremacist ideas of “sanity.”
Thus, researchers fear that the practice of screening embryos for “bad genes” to eradicate mental difference is a continuation of the United States’ long and storied history with eugenics. And because, as the authors note, “there are no regulations on the conditions or traits that can be sought in the United States,” there is no limit to the ideals of genetic purity that can be packaged and sold as “health” to private consumers. .
Lencz, T., Sabatello, M., Docherty, A., Peterson, RE, Soda, T., Austin, J., . . . & Davis, LK (2022). Concerns about the use of polygenic embryo screening for psychiatric and cognitive traits. Lancet Psychiatry. Published online August 2, 2022. doi: 10.1016/S2215-0366(22)00157-2 (abstract)