December 6, 2022

Nature sceptical of polygenic embryo tests

The world’s leading science journal, Nature, is taking a very dim view of genetic tests which promise consumers a reduced risk of certain diseases if they sample their IVF embryos. A long news report focuses on a New Jersey company, Genomic Prediction.

At the moment, testing for rare genetic disorders and chromosomal abnormalities is almost routine in US IVF clinics. But even more advanced tests promise to detect polygenic conditions (PGT-P), which is much more difficult.

In the United States, people undergoing IVF can request that their clinicians order PGT-P, which promises screening for various conditions, including some cancers, heart disorders, diabetes and schizophrenia. Only a few hundred people have done so … But if experience with other forms of PGT is any indication, the use of PGT-P could skyrocket: the proportion of IVF cycles that included more-established forms of PGT in the United States increased from 13% in 2014 to 27% in 2016.

The article says that many scientists do not trust polygenic screening. The models are too weak to detect diseases in an embryo; the results are difficult to interpret for both clinicians and patients; there could be health risks. Even a spokesperson for the American Society for Reproductive Medicine told Nature that “it’s a technology not quite ready for prime time”.

Reservations like these have not stopped Genomic Prediction from offering screening tests for schizophrenia, four heart conditions, five cancers and type 1 and type 2 diabetes. Its website sums up its pitch to consumers: “Successful pregnancy. Healthy baby. Advanced embryo genetic testing. Choose your healthiest embryo.”

Obviously, there are weighty ethical concerns. But the chief scientific officer, Nathan Treff, believes that even a very small risk reduction is worthwhile for parents and says that it would be unethical not to offer the test. A clinical geneticist in London, told Nature that it would be unethical to without clear, real-world evidence that it is beneficial.

Nature gives the last word to Laura Hercher, a genetic counsellor at Sarah Lawrence College, in New York.

Hercher implores those debating using PGT-P to thoughtfully consider their intentions for using the test. Pregnancy is already a very fraught time, she says. If access to PGT-P continues to expand, Hercher wonders whether its existence will change people’s perception of parenthood. She worries that people will effectively be able to ‘shop’ for desirable traits, “taking us away from a place of being unconditional in our regard for our children and instead toward a consumerist mentality”.