The use of polygenic risk score analyses on embryos to prospective parents has been condemned as “unproven and unethical”.
Following the publication of a paper in the *European Journal of Human Genetics* in December 2021, representatives from the European Society of Human Genetics say there is no evidence that PRSs can predict the likelihood of an unborn child being at risk of a specific disease.
They said while it is normal for parents to consider genetic risks they may pass to their children, such as Down syndrome or cystic fibrosis, these have a single genetic cause, which means testing to predict risk is more accurate.
However, PRSs are a “completely different matter”, said Dr Francesca Forzano, chair of the ESHG Public and Professional Policy Committee.
“Many conditions are caused by a combination of genetics and environment, and PRSs are only able to capture parts of any of the relevant genetic component, which is itself likely to be highly complex and difficult to analyse,” she said.
“In addition, while PRS may identify individuals at risk of a given disease in the general population (where the genetic variability is very wide) there is no evidence that they can be useful for a couple in determining the choice of one embryo over another, as the genetic variability within an individual family is limited.”
So far, PRS research has been performed mostly on adults, with the aim of deciphering the pathological mechanisms underlying complex multifactorial diseases.
However, there is no information on the value of PRSs on embryos to predict disease development in postnatal life.
The authors say this means that a PRS test for embryo selection would be premature at best.
There is the additional consideration of providing prospective parents with adequate, unbiased information on the risks and limitations of PRS tests, while a wider debate must take place before there is any potential application of the technique in embryo selection.
Professor Maurizio Genuardi, ESHG president, said: “It is also vital to provide prospective parents with a clear understanding of the difference between counselling and marketing.
“And at a time when healthcare resources are under strain, it is important that the limited money available should be spent on tests that are known to be effective. Currently, research resources would be better spent on improving knowledge about how PRSs interact with the environment in which we live, rather than on the premature application to our future children of an inadequately assessed test with potentially misleading results.”
Forzano F, Antonova O, Clarke A et al. The use of polygenic risk scores in pre-implantation genetic testing: an unproven, unethical practice. *European Journal of Human Genetics* December 2021
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