Experts have warned against the “unproven” and “unethical” use of genetic testing to predict the risk of complex diseases in embryos created through IVF.
Although not currently available in the UK, such tests are marketed in the US and their availability is expected to increase as the technology develops, representatives of the European Society of Human Genetics (ESHG) have said. .
Writing in the European Journal of Human Genetics, they pointed out that there is currently no evidence that the technique called polygenic risk score (PRS) analysis can predict the likelihood of unborn children being at risk for complex diseases such as schizophrenia, diabetes mellitus 2 or breast cancer later in life.
The geneticists also called for a societal debate on the future application of such tests, such as selecting for traits like height or intelligence.
“We believe this is a very promising area in genetics and disease prevention, but [present] stage, it cannot be used,” said ESHG president Maurizio Genuardi, a professor of medical genetics at the Catholic University of the Sacred Heart in Rome. “There is no evidence that this type of selection can lead to better or healthier babies.”
Unlike genetic testing for Down syndrome or diseases such as cystic fibrosis which are caused by mutations in a single gene, PRS aims to calculate an individual’s susceptibility to complex traits or disorders by combining the effects of dozens or potentially millions of single digit genetic variants. . This involves analyzing the cells of embryos created by IVF, before their implantation.
“Many conditions are caused by a combination of genetics and environment, and PRS can only capture parts of one of the relevant genetic components, which themselves are likely to be very complex and difficult to analyze” , said Dr. Francesca Forzano, the president. of the ESHG Public and Professional Policy Committee and Clinical Genetics Consultant at Guy’s and St Thomas’ NHS Foundation Trust in London.
Even so, private testing companies are increasingly marketing such tests to expectant parents in order to select embryos with a lower risk of disease later in life. At least one child was born after such a procedure, Forzano and his colleagues said.
Although US companies are leading the charge, “we don’t really have a very good idea of what’s going on in every private clinic in Europe and other countries,” Forzano said.
Sarah Norcross, director of the Progress Educational Trust (PET), a charity that improves choices for people affected by infertility and genetic diseases, called on the Human Fertilization and Embryology Authority to clarify the legal and regulatory status of these tests in the UK, and said the Advertising Standards Authority and the Competition and Markets Authority should closely monitor whether and how these tests are marketed to UK patients.
“PET supports this clear and unequivocal warning to fertility patients not to waste their money having embryos tested using polygenic risk scores,” she said. “Even if – for the sake of argument, and despite a complete lack of clinical evidence – a polygenic risk score could significantly predict certain things about certain embryos, the number of embryos that would be needed to use this test could not not be performed in a clinical setting.
“There are very few embryos to choose from in a fertility treatment setting, and therefore the reasons for preferring one embryo over another must be based on clear evidence.”
The ESHG also called for a societal debate on the future application of the PRS, in order to avoid discrimination and the stigmatization of certain conditions. “If, theoretically, we are going to propose a test to select common traits, for which traits would our society consider it ethical to propose? said Forzano. “We have to ask ourselves if we think this is acceptable, if it’s ethical and if our society really wants to have something like this.”