Genetic embryo diagnosis tests called polygenic risk score (PRS) analysis, would serve to predict the risk of disease in embryos produced by in vitro fertilization

According to Nature “A polygenic score (PGS) or polygenic risk score (PRS) is an estimate of an individual’s genetic liability to a trait or disease, calculated according to their genotype profile and relevant genome-wide association study (GWAS) data”.

Representatives of the European Society for Human Genetics (ESHG) have written an article in the European Journal of Human Genetics to emphasize that there is currently no evidence that the polygenic risk score (PRS) analysis technique can predict the probability that unborn children are at risk of diseases such as type 2 diabetes or breast cancer in adulthood.

According to them, PRS tests are being marketed for parents using in vitro fertilization to select embryos that would have a lower risk of future diseases. But the utility of a PRS is very limited and its diagnostic effectiveness in embryos has not been evaluated.

Patients should be adequately informed about the limitations of its use. In addition, a social debate, focused on what would be considered acceptable with respect to the selection of individual traits, should be raised before any further implementation of the technique in this population.

Unlike genetic tests for Down’s syndrome or diseases like cystic fibrosis that are caused by mutations in a single gene, PRS aims to estimate an individual’s susceptibility to complex traits or disorders by combining the effects of dozens or potentially millions of genetic variants. It involves carrying out a preimplantation genetic diagnosis, aimed at selecting the embryos produced by assisted reproduction techniques that must be implanted.

According to Dr. Francesca Forzano, chair of ESHG’s professional and public policy committee, many conditions are caused by a combination of genetics and environment, and PRS can only capture parts of any of the relevant genetic components, which is likely to be highly complex and difficult to analyze.

However, private companies promote these tests in order to promote the selection of embryos with a supposed lower risk of future diseases. Although American companies are leading this initiative, it is unknown what is happening in private clinics in Europe and other countries.

In that regard, Sarah Norcross, director of the Progress Educational Trust (PET), a charity that assists people with infertility and genetic conditions, has asked the Human Fertilization and Embryology Authority to clarify the legal and regulatory status of this type of tests in the United Kingdom.

She warns that her organization advises patients with fertility problems not to waste their money doing PRS tests. And that, even if despite the lack of clinical evidence a polygenic risk score could significantly predict certain diseases, the number of embryos that would be needed to make use of this test could not be achieved in a clinical setting.

In a fertility treatment, few embryos can be chosen, so the reasons for preferring one embryo over another must be based on clear evidence.

Bioethical assessment

The therapeutic scope of preimplantation genetic diagnosis tests, such as the one referred to in this article, is practically invalid. Its application is aimed at embryonic selection, and, therefore, at the discarding of many embryos that may present certain genetic anomalies, often of uncertain significance, but which are condemned to destruction as a preventive measure.

This eugenic practice, which betrays the fundamentals of medicine, must be denounced once again, because far from diagnosing and trying to cure or alleviate those who need it, it chooses to select the supposedly healthy, eliminating the defective.

Many couples who resort to preimplantation genetic diagnosis as another option offered by assisted reproduction techniques are not properly informed of the collateral effects of these diagnostic techniques, which mean that many of their embryonic children are discarded as “imperfect”.

Their right to make autonomous decisions freely requires that they be duly informed of the scope of the collateral effects associated with embryo selection in assisted reproduction.

The life of just one of those embryos is worth more than all the wishes or fears of their parents and the presumed future health of their children, whose dignity is violated by denying them the right to life and the care they require. His life and his medical care is what should be sought in any case, if we are talking about true medicine.


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