Problems of embryo selection

The possibility for future parents to choose genetically perfect children may seem like science fiction, but bioethicists warn that some companies have already begun to offer couples performing in vitro fertilization (IVF) the choice of the best embryos using polygenic evaluation.

A polygenic score is a weighted average of the influence of all genes whose functions are currently known. It is used to determine how likely a person is to manifest a specific disease or phenotypic trait.

Many couples will probably want to use this service to select embryos that are predicted to have certain traits, and produce children who are taller, smarter or less likely to develop cancer or other serious diseases.

However, polygenic estimates are not as predictable as genetic companies may claim, and there are many potential pitfalls in embryo selection, experts say.

The fact is that geneticists have not yet accumulated enough information about polygenic assessment to obtain the desired result. In fact, today this tool gives vague predictions that are infinitely worse than the forecasts of meteorologists.

However, the technology, which is currently undeveloped, will improve as the genetic risks are studied. And someday the embryo selection service will become part of the real world, in which there will be a division into the genetically haves and have-nots.

Given the differences that already exist in medicine, it would not be an exaggeration to say that in the future, with the embryo selection service, a thin stratum of society will form, which is more likely to benefit from polygenic evaluation than the rest, therefore there is some danger of further inequality.

At the moment, experts are mainly concerned that future parents are given false promises related to the polygenic analysis of embryos.

Poorly studied area

Genetic companies promise a polygenic assessment of embryos, which will determine the risk of developing cancer, cardiovascular diseases, including hypertension, high cholesterol, inflammatory bowel diseases, Alzheimer's disease, mental retardation, dwarfism and many other diseases and conditions.

But scientists do not yet have sufficient knowledge of human genetics to make bold promises that these assessments will significantly affect the individual traits of such "chosen" children.

There are many risks and uncertainties, but companies have no incentive to provide consumers with information about the shortcomings of the service they offer. It is much more likely that they will emphasize and possibly exaggerate the advantages and underestimate the limitations of polygenic evaluation.

For example, parents may want to use such an assessment to reduce the risk of having a small child. But a child chosen in this way, at best, will be only a couple of centimeters above average – a result that is hardly practically significant, but which will be perceived by parents as a success.

There is also a serious risk of unintended consequences, given that individual genes often perform multiple functions. Choosing an embryo with a reduced risk of one disease, for example, cancer or diabetes, it is possible to produce a child who is at high risk of some other disease that scientists do not yet know about.

So, a child who is predicted to have the highest level of intelligence, theoretically has an increased risk of bipolar disorder. This is a genetic link that is already known. For example, an embryo selected based on a polygenic intelligence assessment has a 16% higher risk of developing bipolar disorder, and the absolute genetic risk of developing bipolar disorder in a child will increase from 1% to 1.16%.

Larger social consequences can be assumed if we consider who can afford IVF in the first place, and which social groups benefit from greater knowledge of human genetics.

Who can afford it?

IVF costs tens of thousands of dollars per cycle and is often not covered by insurance payments, which makes this procedure available only to wealthy couples.

There is a risk that over time and in the aggregate, this may increase health disparities and other types of social inequality, because not everyone will have equal access to this technology.

We must not forget about racial inequality. It's not that an African-American, Asian or Latino couple can't afford IVF. But they are unlikely to get an equal effect from the polygenic evaluation of embryos, because most of the genetic information was collected for representatives of the Caucasian race, which makes the assessment more accurate for these people.

The researchers insist that government regulators step in and protect married couples from the false promises of genetic analysis companies. They should monitor advertising materials and campaigns so that they are truthful and not misleading.

In addition, the field of polygenic assessment needs additional research to determine how best to convey the risks and forecasts of this technology to ordinary people.

Screening out certain traits

Now scientists are just beginning empirical research to find out how people understand or do not understand polygenic assessments and how it is possible to inform them about it in such a way as to reduce the communicative risks, that is, associated with the lack of competence of one or several communication participants.

Armed with this knowledge, professional medical societies should develop policies and guidelines regarding the use of polygenic assessment and how it is explained to couples.

There is also a need for publicly available information about whether a polygenic assessment is something necessary when planning a pregnancy.

Do we want to choose which children to give birth to? Should we look at parenthood as a gift and try not to interfere so much in the process of having a child?

The researchers noted that with IVF, such a possibility already exists. Preimplantation genetic diagnosis is a common procedure used during IVF for couples with a high risk of transmitting a known genetic disease to their offspring.

Bioethicists have been working on similar problems for several decades. The rubicon has already been overcome, and there are people who use preimplantation diagnostics to prevent the birth of a deliberately sick child.

The number of people born with Down syndrome has declined over time, partly due to reproductive technologies. With all the seemingly obvious advantages, this phenomenon is not without contradictions. How does it feel for parents of children with Down syndrome to know that other people can afford not to have children with this syndrome? How will it affect their lives?

These questions are relevant for many other signs. Theoretically, if we start selecting embryos with certain traits, it is unknown how this will affect people whose parents did not use this technology or used it, but since this is not an absolute guarantee, their child still received this trait. How will their parents treat them? How will society treat them?

Article by P.Turley et al. Problems with Using Polygenic Scores to Select Embryos is published in the New England Journal of Medicine.

Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru , based on University of Southern California: Embryo selection aimed at ensuring health, intelligence of children scrutinized.