Polygenic embryo screening

Summary

• Polygenic embryo screening, known as PGT P, scores each embryo on many genetic variants at once to estimate its chance of a disease or trait.
• The Human Fertilisation and Embryology Act 1990 allows embryo testing only for listed purposes. A serious condition qualifies only where there is a particular risk, such as known carriers in the family.
• The HFEA Board confirmed in September 2025 that PGT P does not fit any permitted purpose, so it is unlawful. A UK clinician who acted on the results would be acting unlawfully too.
• Some UK couples are reported to have found a route round the ban. A UK clinic reported that patients obtained the genetic data from their embryo tests, sent it to US firms for analysis, then asked for specific embryos to be transferred.
• The Guardian reported that Herasight charges $50,000 to assess an unlimited number of embryos. The company says it works from data parents have legally obtained, and there is no suggestion it breaks any regulation.
• The regulator's answer is that the ban cannot be circumvented by sending the analysis to another country. It restated this on 4 February 2026, and in June 2026 reports said Britons still travel abroad for screening the UK bans.

Dig deeper

• Supporters argue that the scores separate siblings as well as strangers. A 2021 review in Genes says the predictors work almost as well in pairwise sibling comparisons as between unrelated people. Its authors work for or own shares in Genomic Prediction, which offers the test, and the review says so.
• Critics answer that the scores are weaker within families. In a 2021 New England Journal of Medicine article, Turley and colleagues wrote that predictive power will be lower when comparing embryos from the same parents.
• The regulator's advisers agreed in June 2024 that PGT P is likely to reduce the number of embryos available for transfer. A 2019 study, later published in Cell, estimated the gain from picking the top scoring embryo at about 2.5 IQ points, with wide uncertainty.
• The European Society of Human Genetics called the use of these scores in embryo testing an unproven, unethical practice in December 2021. The European Society of Human Reproduction and Embryology says it shares those concerns.
• Dr Cristina Hickman, founder of Avenues, argued in March 2026 that the current position does not serve patients well. She suggests a structured evidence review within the HFEA framework.
• The question of who decides for a child, and where a parent's wishes stop, also arises in Indi Gregory.

Ethical issues

Interview questions

• What do you know about polygenic embryo screening?
• What did the HFEA say in February 2026, and what reason did it give?
• A couple tells you they have sent their embryo data to a company abroad and want the healthiest embryo chosen. What do you do?
• What is the strongest argument for letting parents rank embryos by predicted risk? What is the strongest argument against?
• Should a clinic be allowed to offer a test the regulator says is unlawful, if the patient asks for it?
• What does the Act allow embryo testing for, and who decides whether a case meets that test?
• Is a ban fair if the same test can be bought from a company abroad?
• Why might a test that predicts risk well in a group still be of little use for choosing one embryo?