Utility of polygenic embryo screening for disease depends on the selection strategy

Screening embryos for polygenic disease risk: a review of epidemiological, clinical, and ethical considerations

BACKGROUND

The genetic composition of embryos generated by in vitro fertilization (IVF) can be examined with preimplantation genetic testing (PGT). Until recently, PGT was limited to detecting single-gene, high-risk pathogenic variants, large structural variants, and aneuploidy. Recent advances have made genome-wide genotyping of IVF embryos feasible and affordable, raising the possibility of screening embryos for their risk of polygenic diseases such as breast cancer, hypertension, diabetes, or schizophrenia. Despite a heated debate around this new technology, called polygenic embryo screening (PES; also PGT-P), it is already available to IVF patients in some countries. Several articles have studied epidemiological, clinical, and ethical perspectives on PES; however, a comprehensive, principled review of this emerging field is missing.

OBJECTIVE AND RATIONALE

This review has four main goals. First, given the interdisciplinary nature of PES studies, we aim to provide a self-contained educational background about PES to reproductive specialists interested in the subject. Second, we provide a comprehensive and critical review of arguments for and against the introduction of PES, crystallizing and prioritizing the key issues. We also cover the attitudes of IVF patients, clinicians, and the public towards PES. Third, we distinguish between possible future groups of PES patients, highlighting the benefits and harms pertaining to each group. Finally, our review, which is supported by ESHRE, is intended to aid healthcare professionals and policymakers in decision-making regarding whether to introduce PES in the clinic, and if so, how, and to whom.

SEARCH METHODS

We searched for PubMed-indexed articles published between 1/1/2003 and 1/3/2024 using the terms 'polygenic embryo screening', 'polygenic preimplantation', and 'PGT-P'. We limited the review to primary research papers in English whose main focus was PES for medical conditions. We also included papers that did not appear in the search but were deemed relevant.

OUTCOMES

The main theoretical benefit of PES is a reduction in lifetime polygenic disease risk for children born after screening. The magnitude of the risk reduction has been predicted based on statistical modelling, simulations, and sibling pair analyses. Results based on all methods suggest that under the best-case scenario, large relative risk reductions are possible for one or more diseases. However, as these models abstract several practical limitations, the realized benefits may be smaller, particularly due to a limited number of embryos and unclear future accuracy of the risk estimates. PES may negatively impact patients and their future children, as well as society. The main personal harms are an unindicated IVF treatment, a possible reduction in IVF success rates, and patient confusion, incomplete counselling, and choice overload. The main possible societal harms include discarded embryos, an increasing demand for 'designer babies', overemphasis of the genetic determinants of disease, unequal access, and lower utility in people of non-European ancestries. Benefits and harms will vary across the main potential patient groups, comprising patients already requiring IVF, fertile people with a history of a severe polygenic disease, and fertile healthy people. In the United States, the attitudes of IVF patients and the public towards PES seem positive, while healthcare professionals are cautious, sceptical about clinical utility, and concerned about patient counselling.

WIDER IMPLICATIONS

The theoretical potential of PES to reduce risk across multiple polygenic diseases requires further research into its benefits and harms. Given the large number of practical limitations and possible harms, particularly unnecessary IVF treatments and discarded viable embryos, PES should be offered only within a research context before further clarity is achieved regarding its balance of benefits and harms. The gap in attitudes between healthcare professionals and the public needs to be narrowed by expanding public and patient education and providing resources for informative and unbiased genetic counselling.

Perspectives of preimplantation genetic testing patients in Belgium on the ethics of polygenic embryo screening

RESEARCH QUESTION

What are the perspectives of preimplantation genetic testing (PGT) patients in Belgium on the ethics of PGT for polygenic risk scoring (PGT-P)?

DESIGN

In-depth interviews (18 in total, 10 couples, 8 women, n = 28) were performed with patients who had undergone treatment with PGT for monogenic/single-gene defects (PGT-M) or chromosomal structural rearrangements (PGT-SR) between 2017 and 2019 in Belgium. Participants were asked about their own experiences with PGT-M/SR and about their viewpoints on PGT-P, including their own interest and their ideas on its desirability, scope and consequences. Inductive content analysis was used to analyse the interviews.

RESULTS

Participants stated that their experiences with PGT-M/SR had been physically, psychologically and practically difficult. Most participants stated that, partly because of these difficulties, they did not see the added value of knowing the risk scores of embryos via PGT-P. Many participants worried that PGT-P could lead to additional anxieties, responsibilities and complex choices in reproduction and parenthood. They argued that not everything should be controlled and felt that PGT-P, especially non-medical and broad screening, was going too far. With regards to the clinical implementation of PGT-P, participants in general preferred PGT-P to be limited to people with a serious polygenic family history and wanted embryo selection decisions to be made by healthcare professionals.

CONCLUSIONS

This study shows that individuals with experience of PGT-M/SR saw PGT-P as different from PGT-M/SR. They had various ethical concerns with regards to PGT-P, especially regarding broadly offering PGT-P. These stakeholder viewpoints need to be considered regarding potential PGT-P implementation and guidelines.

Preconception carrier screening and preimplantation genetic testing in the infertility management

BACKGROUND

Genetic testing serves as a valuable element of reproductive care, applicable at various stages of the reproductive journey: (i) before pregnancy, when a couple's genetic reproductive risk can be evaluated; (ii) before embryo implantation, as part of in vitro fertilization (IVF) treatment, to ascertain several inherited or de novo genetic/chromosomal diseases of the embryo before transfer; (iii) during the prenatal period, to assess the genetic costitution of the fetus. Preconception carrier screening (CS) is a genetic test typically performed on couples planning a pregnancy. The primary purpose of CS is to identify couples at-risk of conceiving a child affected by a severe genetic disorder with autosomal recessive or X-linked inheritance. Detection of high reproductive risk through CS allows prospective parents to be informed of their predisposition and improve reproductive decision-making. These include undergoing IVF with preimplantation genetic testing (PGT) or donor gametes, prenatal diagnosis, adoption, remaining childless, taking no actions. Both the presence of the affected gene (PGT-M) and chromosomal status (PGT-A) of the embryo can be comprehensively assessed through modern approaches.

OBJECTIVES

We provide a review of CS and PGT applications to equip healthcare providers with up-to-date information regarding their opportunities and complexities.

RESULTS AND DISCUSSION

The use of CS and PGT is currently considered the most effective intervention for avoiding both an affected pregnancy whilst using autologous gametes in couples with known increased risk, and chromosomal abnormalities. As our understanding in the genetic component in pathological conditions increases, the number of tested disorders will expand, offering a more thorough assessment of one's genetic inheritance. Nevertheless, implementation and development in this field must be accompanied by scientific and ethical considerations to ensure this approach serves the best long-term interests of individuals and society, promoting justice and autonomy and preserving parenthood and the healthcare system.

CONCLUSION

The combination of CS and PGT aligns with principles of personalized medicine by offering reproductive care tailored to the individual's genetic makeup.

Polygenic embryo screening: quo vadis?

Recently, the use of polygenic risk scores in embryo screening (PGT-P) has been introduced on the premise of reducing polygenic disease risk through embryo selection. However, it has been met with extensive critique: considered "technology-driven" rather than "evidence-based", concerns exist about its validity, utility, ethics, and societal effects. Its scientific foundations and criticisms thus need to be carefully considered. However, seeing as PGT-P is already offered in some settings, further questions need to be addressed, in order to give due diligence to various aspects of PGT-P. By examining the complexities of clinical introduction of PGT-P, we discuss whether PGT-P could be responsibly implemented in the first place, what elements need to be addressed if PGT-P is clinically implemented, and subsequently how counselling and decision-making of its users could be envisaged. By dissecting these elements, we provide an overview of important practical questions of PGT-P and emphasize elements of PGT-P that we think have yet to be given sufficient attention. These questions and elements are for example related to the potential target group, scope, and decision-making possibilities of PGT-P. The aspects we raise are crucial to consider by the scientific community and policy makers for the development of guidelines and/or an ethical framework for PGT-P.

Predicting the direction of phenotypic difference

Predicting phenotypes from genomic data is a key goal in genetics, but for most complex phenotypes, predictions are hampered by incomplete genotype-to-phenotype mapping. Here, we describe a more attainable approach than quantitative predictions, which is aimed at qualitatively predicting phenotypic differences. Despite incomplete genotype-to-phenotype mapping, we show that it is relatively easy to determine which of two individuals has a greater phenotypic value. This question is central in many scenarios, e.g., comparing disease risk between individuals, the yield of crop strains, or the anatomy of extinct vs extant species. To evaluate prediction accuracy, i.e., the probability that the individual with the greater predicted phenotype indeed has a greater phenotypic value, we developed an estimator of the ratio between known and unknown effects on the phenotype. We evaluated prediction accuracy using human data from tens of thousands of individuals from either the same family or the same population, as well as data from different species. We found that, in many cases, even when only a small fraction of the loci affecting a phenotype is known, the individual with the greater phenotypic value can be identified with over 90% accuracy. Our approach also circumvents some of the limitations in transferring genetic association results across populations. Overall, we introduce an approach that enables accurate predictions of key information on phenotypes - the direction of phenotypic difference - and suggest that more phenotypic information can be extracted from genomic data than previously appreciated.

Ready for polygenic risk scores? An analysis of regulation of preimplantation genetic testing in European countries

STUDY QUESTION

Would the different regulatory approaches for preimplantation genetic testing (PGT) in Europe permit the implementation of preimplantation genetic testing using polygenic risk scores (PGT-P)?

SUMMARY ANSWER

While the regulatory approaches for PGT differ between countries, the space provided for potential implementation of PGT-P seems limited in all three regulatory models.

WHAT IS KNOWN ALREADY

PGT is a reproductive genetic technology that allows the testing for hereditary genetic disorders and chromosome abnormalities in embryos before implantation. Throughout its history, PGT has largely been regarded as an ethically sensitive technology. For example, ethical questions have been raised regarding the use of PGT for adult-onset conditions, non-medical sex selection, and human leukocyte antigen typing for the benefit of existing siblings. Countries in which PGT is offered each have their own approach of regulating the clinical application of PGT, and a clear overview of legal and practical regulation of PGT in Europe is lacking. An emerging development within the field of PGT, namely PGT-P, is currently bringing new ethical tensions to the forefront. It is unclear whether PGT-P may be applied within the current regulatory frameworks in Europe. Therefore, it is important to investigate current regulatory frameworks in Europe and determine whether PGT-P fits within these frameworks.

STUDY DESIGN, SIZE, DURATION

The aim of this study was to provide an overview of the legal and practical regulation of the use of PGT in seven selected European countries (Belgium, France, Germany, Italy, the Netherlands, Spain, and the UK) and critically analyse the different approaches with regards to regulatory possibilities for PGT-P. Between July and September 2023, we performed a thorough and extensive search of websites of governments and governmental agencies, websites of scientific and professional organizations, and academic articles in which laws and regulations are described.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We investigated the legal and regulatory aspects of PGT by analysing legal documents, regulatory frameworks, scientific articles, and guidelines from scientific organizations and regulatory bodies to gather relevant information about each included country. The main sources of information were national laws relating to PGT.

MAIN RESULTS AND THE ROLE OF CHANCE

We divided the PGT regulation approaches into three models. The regulation of PGT differs per country, with some countries requiring central approval of PGT for each new indication (the medical indication model: the UK, the Netherlands), other countries evaluating each individual PGT request at the local level (the individual requests model: France, Germany), and countries largely leaving decision-making about clinical application of PGT to healthcare professionals (the clinical assessment model: Belgium, Italy, Spain). In the countries surveyed that use the medical indication model and the individual requests model, current legal frameworks and PGT criteria seem to exclude PGT-P. In countries using the clinical assessment model, the fact that healthcare professionals and scientific organizations in Europe are generally negative about implementation of PGT-P due to scientific and socio-ethical concerns, implies that, even if it were legally possible, the chance that PGT-P would be offered in the near future might be low.

LIMITATIONS, REASONS FOR CAUTION

The results are based on our interpretation of publicly available written information and documents, therefore not all potential discrepancies between law and practice might have been identified. In addition, our analysis focuses on seven-and not all-European countries. However, since these countries are relevant players within PGT in Europe and since they have distinct PGT regulations, the insights gathered give relevant insights into diverse ways of PGT regulation.

WIDER IMPLICATIONS OF THE FINDINGS

To the best of our knowledge, this is the first paper that provides a thorough overview of the legal and practical regulation of PGT in Europe. Our analysis of how PGT-P fits within current regulation models provides guidance for healthcare professionals and policymakers in navigating the possible future implementation of PGT-P within Europe.

STUDY FUNDING/COMPETING INTEREST(S)

This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 813707. The authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Public Attitudes, Interests, and Concerns Regarding Polygenic Embryo Screening

Importance

Polygenic embryo screening (PES) is a novel technology that estimates the likelihood of developing future conditions (eg, diabetes or depression) and traits (eg, height or cognitive ability) in human embryos, with the goal of selecting which embryos to use. Given its commercial availability and concerns raised by researchers, clinicians, bioethicists, and professional organizations, it is essential to inform key stakeholders and relevant policymakers about the public's perspectives on this technology.

Objective

To survey US adults to examine general attitudes, interests, and concerns regarding PES use.

Design, Setting, and Participants

For this survey study, data were collected from 1 stratified sample and 1 nonprobability sample (samples 1 and 2, respectively) between March and July 2023. The surveys measured approval, interest, and concerns regarding various applications of PES. In the second sample, presentation of a list of potential concerns was randomized (presented at survey onset vs survey end). The survey was designed using Qualtrics and distributed to participants through Prolific, an online sampling firm. Sample 1 was nationally representative with respect to gender, age, and race and ethnicity; sample 2 was recruited without specific demographic criteria. Analyses were conducted between March 2023 and February 2024.

Main Outcomes and Measures

Participants reported their approval, interest, and concerns regarding various applications of PES and outcomes screened (eg, traits and conditions). Statistical analysis was conducted using independent samples t tests and repeated-measures analyses of variance.

Results

Of the 1435 respondents in sample 1, demographic data were available for 1427 (mean [SD] age, 45.8 [16.0] years; 724 women [50.7%]). Among these 1427 sample 1 respondents, 1027 (72.0%) expressed approval for PES and 1169 (81.9%) expressed some interest in using PES if already undergoing in vitro fertilization (IVF). Approval among these respondents for using PES for embryo selection was notably high for physical health conditions (1109 [77.7%]) and psychiatric health conditions (1028 [72.0%]). In contrast, there was minority approval for embryo selection based on PES for behavioral traits (514 [36.0%]) and physical traits (432 [30.3%]). Nevertheless, concerns about PES leading to false expectations and promoting eugenic practices were pronounced, with 787 of 1422 (55.3%) and 780 of 1423 (54.8%) respondents finding them very to extremely concerning, respectively. Sample 2 included 192 respondents (mean [SD] age 37.7 [12.2] years; 110 men [57.3%]). These respondents were presented concerns at survey onset (n = 95) vs survey end (n = 97), which was associated with less approval (28-percentage point decrease) and more uncertainty (24 percentage-point increase) but with only slightly higher disapproval (4 percentage-point increase).

Conclusions and Relevance

These findings suggest that it is critical for health care professionals and medical societies to consider and understand the perspectives of diverse stakeholders (eg, patients undergoing IVF, clinicians, and the general public), given the absence of regulation and the recent commercial availability of PES.

Patient interest in and clinician reservations on polygenic embryo screening: a qualitative study of stakeholder perspectives

PURPOSE

We explored and compared perspectives of reproductive endocrinology and infertility specialists (REIs) and in vitro fertilization (IVF) patients regarding polygenic embryo screening (PES), a new type of preimplantation screening that estimates the genetic chances of developing polygenic conditions and traits in the future.

METHODS

Qualitative thematic analysis of semi-structured interviews with US-based REIs and IVF patients.

RESULTS

Clinicians and patients often held favorable views of screening embryos for physical or psychiatric conditions, though clinicians tended to temper their positive attitudes with specific caveats. Clinicians also expressed negative views about screening embryos for traits more frequently than patients, who generally held more positive views. Most clinicians were either unwilling to discuss or offer PES to patients or were willing to do so only under certain circumstances, while many patients expressed interest in PES. Both stakeholder groups envisioned multiple potential benefits or uses of PES and raised multiple potential, interrelated concerns about PES.

CONCLUSION

A gap exists between clinician and patient attitudes toward PES; clinicians generally maintained reservations about such screening and patients indicated interest in it. Clinicians and patients sometimes imagined using PES to prepare for the birth of a predisposed or "affected" individual-a rationale that is often associated with prenatal testing. Many clinicians and patients held different attitudes depending on what is specifically screened, despite the sometimes blurry distinction between conditions and traits. Considerations raised by clinicians and patients may help guide professional societies in developing guidelines to navigate the uncertain terrain of PES.

Preimplantation Genetic Testing for Polygenetic Conditions: A Legal, Ethical, and Scientific Challenge

The recent commercialization of the Embryo Health Score (EHS), determined through preimplantation genetic testing for polygenic conditions, offers the potential to select embryos with lower disease risk, thus potentially enhancing offspring longevity and health. Lately, Orchid Health company increased testing from less than 20 diseases to more than 900+ conditions for birth defects. However, the "geneticization" of phenotype estimates to a health state erases the environmental part, including the in vitro fertilization potential risks, questioning its scientific usefulness. EHS is utilized in countries with minimal regulatory oversight and will likely expand, while it remains illegal in other countries due to ethical and legal dilemmas it raises about reproductive autonomy, discrimination, impacts on family dynamics, and genetic diversity. The shift toward commercialized polygenic embryo screening (PES) redefines healthcare relationships, turning prospective parents into consumers and altering the physician's role. Moreover, PES could increase social inequalities, stigmatize those not born following PES, and encourage "desirable" phenotypic or behavioral traits selection, leading to ethical drift. Addressing these issues is essential before further implementation and requires a collaborative approach involving political, governmental, and public health, alongside geneticists, ethicists, and fertility specialists, focusing on the societal implications and acceptability of testing for polygenic traits for embryo selection.

"Are we not going too far?": Socio-ethical considerations of preimplantation genetic testing using polygenic risk scores according to healthcare professionals

The recent introduction of polygenic risk scores within preimplantation genetic testing (PGT-P) has been met with many concerns. To get more insights into the perspectives of relevant stakeholders on the socio-ethical aspects of PGT-P, an interview study with 31 healthcare professionals involved in reproductive medicine and genetics in Europe and North-America was performed. Healthcare professionals in our study were concerned that PGT-P was going too far in terms of selection, with regards to both medical conditions and non-medical traits. Healthcare professionals were worried about the ethical 'slippery slope' of PGT-P, the increasing medicalization of reproductive health, the commercial context of PGT-P, and potential stigmatization and discrimination. There were also concerns that the availability and the 'technological imperative' of PGT-P could lead to pressure and a sense of responsibility for parents to use PGT-P. Additionally, it could cause new anxieties about the child's health before the child has even been born. Since PGT-P provides polygenic risk scores before birth, the autonomy of the child has to be considered. These socio-ethical concerns heighten existing debates regarding reproductive genetic technologies and show that the specifics of PGT-P make this screening option especially ethically controversial.

Polygenic embryo screening: are there potential maternal and fetal harms?

Polygenic embryo screening (PES) and its derivate the Embryo Health Score (EHS) have generated interest in both infertile and fertile populations due to their potential ability to select embryos with a reduced risk of disease and improved long-term health outcomes. Concerns have been raised regarding the potential harms of IVF itself, including possible epigenetic changes that may affect the health of the offspring in late adulthood, which are not fully captured in the EHS calculation. Knowledge of the potential impacts of the trophectoderm biopsy, which is a key component of the PES procedure, on the offsprings' health is limited by the heterogeneity of the population characteristics used in the published studies. Nonetheless, the literature suggests a possible increased risk of preterm delivery, birth defects and pre-eclampsia after trophectoderm biopsy. Overall, the risks of PES for prenatal and postnatal health remain uncertain, and further research is needed. Counselling patients regarding these risks before considering PES is important, to provide an understanding of the risks and benefits. This review aims to highlight some of these issues, the need for continued investigation in this area, and the importance of informed decision-making in the context of PES.

Research progress and challenges of preimplantation genetic testing for polygenic diseases

Preimplantation genetic testing is an important part in assisted reproductive technology, which can block the intergenerational inheritance of a single gene or chromosomal diseases. Preimplantation genetic testing for polygenic disease risk (PGT-P) is one of the latest developments in the field. With the development of artificial intelligence and genetic detection technology, PGT-P can be used to analyze genetic material, calculate polygenic risk scores and convert these into incidence probability. Embryos with relatively low incidence probability can be screened for transfer, in order to reduce the possibility that the offspring suffers from the disease in the future. This has significant clinical and social significance. At present, PGT-P has been applied clinically and made phased progress at home and abroad. But as a developing technology, PGT-P still has some technical limitations as unstable results, environmental influences and racial differences cannot be ruled out. From the ethical perspective, if the screening indications are not strictly regulated, it is likely to cause new social problems. In this paper, we review the technical details and recent progress in PGT-P, and discuss the prospects of its future development, especially how to establish a complete and suitable screening model for Chinese population.

Divergence Between Clinician and Patient Perspectives on Polygenic Embryo Screening: A Qualitative Study

Objective

To explore and compare the perspectives of clinicians and patients on polygenic embryo screening.

Design

Qualitative.

Subjects

Fifty-three participants: 27 reproductive endocrinology and infertility specialists and 26 patients currently undergoing in vitro fertilization or had done so within the last five years.

Main Outcome Measures

Qualitative thematic analysis of interview transcripts.

Results

Both clinicians and patients often held favorable views of screening embryos for physical or psychiatric conditions, though clinicians tended to temper their positive attitudes with specific caveats. Clinicians also expressed negative views about screening embryos for traits more often than patients, who generally held more positive views. Most clinicians were either unwilling to discuss or offer polygenic embryo screening to patients or were willing to do so only under certain circumstances, while many patients expressed interest in polygenic embryo screening. Both sets of stakeholders envisioned multiple potential benefits or uses of polygenic embryo screening; the most common included selection and/or prioritization of embryos, receipt of more information about embryos, and preparation for the birth of a predisposed or "affected" child. Both sets of stakeholders also raised multiple potential, interrelated concerns about polygenic embryo screening. The most common concerns among both sets of stakeholders included the potential for different types of "biases" - most often in relation to selection of embryos with preferred genetic chances of traits -, the probabilistic nature of polygenic embryo screening that can complicate patient counseling and/or lead to excessive cycles of in vitro fertilization, and a lack of data from long-term prospective studies supporting the clinical use of polygenic embryo screening.

Conclusion

Despite patients' interest in polygenic embryo screening, clinicians feel such screening is premature for clinical application. Though now embryos can be screened for their genetic chances of developing polygenic conditions and traits, many clinicians and patients maintain different attitudes depending on what is specifically screened, despite the blurry distinction between conditions and traits. Considerations raised by these stakeholders may help guide professional societies as they consider developing guidelines to navigate the uncertain terrain of polygenic embryo screening, which is already commercially available.

Limitations, concerns and potential: attitudes of healthcare professionals toward preimplantation genetic testing using polygenic risk scores

Preimplantation genetic testing using polygenic risk scores (PGT-P) has recently been introduced. However, PGT-P has been met with many ethical concerns. It is therefore important to get insights into the perspectives of stakeholders regarding PGT-P. We performed a qualitative interview study on the views of healthcare professionals toward PGT-P. We conducted in-depth semi-structured interviews with 31 healthcare professionals working in the field of preimplantation genetic testing. The interviews explored the attitudes of healthcare professionals toward the technology of PGT-P, e.g., the validity, utility, limitations and potential benefits of PGT-P. We found that most healthcare professionals were concerned about the prematurity of introducing PGT-P into clinical practice. They had various ethical considerations, such as concerns related to validity and utility of PGT-P, limited embryos and options, and difficulties for prospective parents regarding comprehension and informed decision-making. Positive aspects were also identified, e.g., regarding reproductive autonomy and potential health benefits. Overall, most healthcare professionals considered that clinical implementation of PGT-P is premature. More comprehensive, longitudinal and inclusive studies are needed first, though these might not improve PGT-P enough to responsibly implement it. Healthcare professionals were also concerned that PGT-P could cause anxiety and create difficult choices for prospective parents. These perspectives and ethical considerations are crucial to consider for future guidelines and recommendations regarding PGT-P.

Public views on polygenic screening of embryos

Understanding moral acceptability and willingness to use is crucial for informing policy.

15 years of GWAS discovery: Realizing the promise

It has been 15 years since the advent of the genome-wide association study (GWAS) era. Here, we review how this experimental design has realized its promise by facilitating an impressive range of discoveries with remarkable impact on multiple fields, including population genetics, complex trait genetics, epidemiology, social science, and medicine. We predict that the emergence of large-scale biobanks will continue to expand to more diverse populations and capture more of the allele frequency spectrum through whole-genome sequencing, which will further improve our ability to investigate the causes and consequences of human genetic variation for complex traits and diseases.

Sibling variation in polygenic traits and DNA recombination mapping with UK Biobank and IVF family data

We use UK Biobank and a unique IVF family dataset (including genotyped embryos) to investigate sibling variation in both phenotype and genotype. We compare phenotype (disease status, height, blood biomarkers) and genotype (polygenic scores, polygenic health index) distributions among siblings to those in the general population. As expected, the between-siblings standard deviation in polygenic scores is [Formula: see text] times smaller than in the general population, but variation is still significant. As previously demonstrated, this allows for substantial benefit from polygenic screening in IVF. Differences in sibling genotypes result from distinct recombination patterns in sexual reproduction. We develop a novel sibling-pair method for detection of recombination breaks via statistical discontinuities. The new method is used to construct a dataset of 1.44 million recombination events which may be useful in further study of meiosis.

Gattaca as a lens on contemporary genetics: marking 25 years into the film's "not-too-distant" future

The 1997 film Gattaca has emerged as a canonical pop culture reference used to discuss modern controversies in genetics and bioethics. It appeared in theaters a few years prior to the announcement of the "completion" of the human genome (2000), as the science of human genetics was developing a renewed sense of its social implications. The story is set in a near-future world in which parents can, with technological assistance, influence the genetic composition of their offspring on the basis of predicted life outcomes. The current moment-25 years after the film's release-offers an opportunity to reflect on where society currently stands with respect to the ideas explored in Gattaca. Here, we review and discuss several active areas of genetic research-genetic prediction, embryo selection, forensic genetics, and others-that interface directly with scenes and concepts in the film. On its silver anniversary, we argue that Gattaca remains an important reflection of society's expectations and fears with respect to the ways that genetic science has manifested in the real world. In accompanying supplemental material, we offer some thought questions to guide group discussions inside and outside of the classroom.

Psychiatric polygenic risk scores: Child and adolescent psychiatrists' knowledge, attitudes, and experiences

Psychiatric polygenic risk scores (PRS) have potential utility in psychiatric care and prevention, but there are concerns about their implementation. We surveyed 960 US-based practicing child and adolescent psychiatrists' (CAP) about their experiences, perspectives, and potential uses of psychiatric PRS. While 23% of CAP reported that they had never heard of PRS, 10 % of respondents have had a patient/family bring PRS to them and 4% have generated PRS for patients. Though 25% stated they would request PRS if a patient/caregiver asked, 35% indicated that nothing would prompt them to request PRS. Most respondents (54%) believed psychiatric PRS are currently at least slightly useful and 87% believed they will be so in 5 years. More than 70% indicated they would take action in response to a child with a top fifth percentile psychiatric PRS but no diagnosis: 48% would increase monitoring of symptoms, 42% would evaluate for current symptoms, and 4% would prescribe medications. Yet, most respondents were concerned that high-PRS results could lead to overtreatment and negatively impact patients' emotional well-being. Findings indicate emerging use of psychiatric PRS within child and adolescent psychiatry in the US. It is critical to examine the ethical and clinical challenges that PRS may generate and begin efforts to promote their informed and responsible use.

Concerns about the use of polygenic embryo screening for psychiatric and cognitive traits

Private companies have begun offering services to allow parents undergoing in-vitro fertilisation to screen embryos for genetic risk of complex diseases, including psychiatric disorders. This procedure, called polygenic embryo screening, raises several difficult scientific and ethical issues, as discussed in this Personal View. Polygenic embryo screening depends on the statistical properties of polygenic risk scores, which are complex and not well studied in the context of this proposed clinical application. The clinical, social, and ethical implications of polygenic embryo screening have barely been discussed among relevant stakeholders. To our knowledge, the International Society of Psychiatric Genetics is the first professional biomedical organisation to issue a statement regarding polygenic embryo screening. For the reasons discussed in this Personal View, the Society urges caution and calls for additional research and oversight on the use of polygenic embryo screening.

Polygenic risk score for embryo selection-not ready for prime time

Numerous chronic diseases have a substantial hereditary component. Recent advances in human genetics have allowed the extent of this to be quantified via genome-wide association studies, producing polygenic risk scores (PRS), which can then be applied to individuals to estimate their risk of developing a disease in question. This technology has recently been applied to embryo selection in the setting of IVF and preimplantation genetic testing, with limited data to support its utility. Furthermore, there are concerns that the inherent limitations of PRS makes it ill-suited for use as a screening test in this setting. There are also serious ethical and moral questions associated with this technology that are yet to be addressed. We conclude that further research and ethical reflection are required before embryo selection based on PRS is offered to patients outside of the research setting.

Genetic risk factors have a substantial impact on healthy life years

The impact of genetic variation on overall disease burden has not been comprehensively evaluated. We introduce an approach to estimate the effect of genetic risk factors on disability-adjusted life years (DALYs; 'lost healthy life years'). We use genetic information from 735,748 individuals and consider 80 diseases. Rare variants had the highest effect on DALYs at the individual level. Among common variants, rs3798220 (LPA) had the strongest individual-level effect, with 1.18 DALYs from carrying 1 versus 0 copies. Being in the top 10% versus the bottom 90% of a polygenic score for multisite chronic pain had an effect of 3.63 DALYs. Some common variants had a population-level effect comparable to modifiable risk factors such as high sodium intake and low physical activity. Attributable DALYs vary between males and females for some genetic exposures. Genetic risk factors can explain a sizable number of healthy life years lost both at the individual and population level.

Challenges and Opportunities for Developing More Generalizable Polygenic Risk Scores

Polygenic risk scores (PRS) estimate an individual's genetic likelihood of complex traits and diseases by aggregating information across multiple genetic variants identified from genome-wide association studies. PRS can predict a broad spectrum of diseases and have therefore been widely used in research settings. Some work has investigated their potential applications as biomarkers in preventative medicine, but significant work is still needed to definitively establish and communicate absolute risk to patients for genetic and modifiable risk factors across demographic groups. However, the biggest limitation of PRS currently is that they show poor generalizability across diverse ancestries and cohorts. Major efforts are underway through methodological development and data generation initiatives to improve their generalizability. This review aims to comprehensively discuss current progress on the development of PRS, the factors that affect their generalizability, and promising areas for improving their accuracy, portability, and implementation.

Polygenic embryo screening: four clinical considerations warrant further attention

Recent advances in developing polygenic scores have made it possible to screen embryos for common, complex conditions and traits. Polygenic embryo screening (PES) is currently offered commercially, and though there has been much recent media and academic coverage, reproductive specialists' points of view have not yet been prominent in these discussions. We convened a roundtable of multidisciplinary experts, including reproductive specialists to discuss PES and its implications. In this Opinion, we describe four clinically relevant issues associated with the use of PES that have not yet been discussed in the literature and warrant consideration.

Capturing additional genetic risk from family history for improved polygenic risk prediction

Family history of complex traits may reflect transmitted rare pathogenic variants, intra-familial shared exposures to environmental and lifestyle factors, as well as a common genetic predisposition. We developed a latent factor model to quantify trait heritability in excess of that captured by a common variant-based polygenic risk score, but inferable from family history. For 941 children in the Avon Longitudinal Study of Parents and Children cohort, a joint predictor combining a polygenic risk score for height and mid-parental height was able to explain ^~55% of the total variance in sex-adjusted adult height z-scores, close to the estimated heritability. Marginal yet consistent risk prediction improvements were also achieved among ^~400,000 European ancestry participants for 11 complex diseases in the UK Biobank. Our work showcases a paradigm for risk calculation, and supports incorporation of family history into polygenic risk score-based genetic risk prediction models.

A review of normative documents on preimplantation genetic testing: Recommendations for PGT-P

PURPOSE

Recently, preimplantation genetic testing (PGT) for polygenic conditions (PGT-P) has been introduced commercially. In view of the lack of specific guidance on this development, we analyzed normative documents on PGT for monogenic conditions (PGT-M) to understand what we can learn from these documents for recommendations for PGT-P.

METHODS

We conducted a systematic review of normative guidelines and recommendations on PGT-M. The aim was to understand what the current consensus and disagreements are on ethical acceptability of PGT-M and how this compares with PGT-P.

RESULTS

We analyzed 38 documents by advisory committees at the national, European, and global level. In total, 2 themes were identified, which included the following: (1) what PGT is considered appropriate for and (2) who can make decisions regarding the use of PGT. Many aspects of PGT-M documents apply to PGT-P as well. Additional factors such as the fact that PGT-P screens for risk indications of multiple polygenic conditions increase ethical difficulties regarding severity, risk, autonomy, and informed decision-making.

CONCLUSION

On the basis of PGT-M normative documents, we conclude that ethical acceptability for PGT-P is limited. Our findings present various factors that have to be considered for the development of guidelines and the appropriateness of PGT.

Whole-genome risk prediction of common diseases in human preimplantation embryos

Preimplantation genetic testing (PGT) of in-vitro-fertilized embryos has been proposed as a method to reduce transmission of common disease; however, more comprehensive embryo genetic assessment, combining the effects of common variants and rare variants, remains unavailable. Here, we used a combination of molecular and statistical techniques to reliably infer inherited genome sequence in 110 embryos and model susceptibility across 12 common conditions. We observed a genotype accuracy of 99.0–99.4% at sites relevant to polygenic risk scoring in cases from day-5 embryo biopsies and 97.2–99.1% in cases from day-3 embryo biopsies. Combining rare variants with polygenic risk score (PRS) magnifies predicted differences across sibling embryos. For example, in a couple with a pathogenic BRCA1 variant, we predicted a 15-fold difference in odds ratio (OR) across siblings when combining versus a 4.5-fold or 3-fold difference with BRCA1 or PRS alone. Our findings may inform the discussion of utility and implementation of genome-based PGT in clinical practice.

A computational approach combining whole-genome sequencing of parental genomes and genotyping of preimplantation embryos allows accurate prediction of the inherited genomes of embryos and calculation of polygenic risk scores.

Ethical, anticipatory genomics research on human behavior means celebrating disagreement

Despite the many social and ethical considerations in human genetics, researchers and communities remain largely siloed as for-profit, direct-to-consumer genetic testing and the application of polygenic scores to in vitro fertilization services become increasingly prevalent. The multifaceted challenges facing genomics, both empirical and ethical, require collaborations that foster critical dialogue and honest debate between communities inside and outside the research enterprise. This piece argues that in order to respond to the premature or inappropriate use of genomic data in industry, the scientific community needs to first embrace, understand, and be in dialogue about its disagreements. We introduce the research framework of adversarial collaboration as a way to celebrate disagreement and productively work toward policy-informed, ethical, and anticipatory genomics research.

What's the use?

A theoretical framework predicts that using polygenic screening to select embryos against traits that depend on many genes has few benefits.