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.

Assessment of pre-implantation genetic testing for embryo aneuploidies: A SWOT analysis.

The recently re-named pre-implantation genetic testing for determining embryo aneuploidies (PGT-A) is presently very popular although its acceptance by the scientific community is controversial. This approach still encounters drawbacks. This paper uses a SWOT (strengths, weaknesses, opportunities and threats) analysis to discuss salient points to be considered when examining the pre-implantation genetic testing (PGT-A) strategy to gather information from a range of perspectives. One of the strengths associated with the procedure is represented by an increase in implantation rate although data from the highest level of evidence do not support an increase in cumulative pregnancy rates. The current difficulty in the management of mosaicisms represents a weakness of PGT-A. The application of the strategy represents an opportunity to favor the single embryo transfer while other advantages, such as reduction of time to pregnancy and emotional distress are controversial. Potential important threats, at present still undefined, are represented by the biopsy-related damage to the blastocyst and the impact on neonatal and long-term outcomes.

Ethical problems with the preimplantation genetic diagnosis of human embryos / Problemas éticos con el diagnóstico genético preimplantacional de embriones humanos / Problemas éticos com diagnóstico pré-implantacional de embriões humanos

Abstract: 14. The purpose of preimplantation genetic diagnosis by embryonary biopsy is to identify genetic alterations prior to the implantation of embryos produced by in vitro fertilization. The most important aim is the selection of genetically healthy embryos due to their genetic indemnity, but it can also be used to select the sex or, eventually, other detectable traits accrding to the wishes of the parents. This procedure has been the subject of scientific debates, in relation to the harm that it can cause to healthy embryos that are going to be implanted, and in relation to the interpretation of the genetic tests made. Ethical debates have also focused on the production of and respect for the life and the integrity of developing human beings. In this work, it is argued that most of the uses of PGD are morally reprehensible, because they are done with disregard to the dignity that should be granted to embryos as human persons.

Resumen: 18. El diagnóstico genético preimplantacional (DGP) mediante biopsia embrionaria tiene como objeto la detección de alteraciones genéticas previamente a la implantación de embriones producidos por fertilización in vitro (FIV). Su finalidad más significativa es la selección de embriones por su indemnidad genética. También se puede emplear para seleccionar el sexo o eventualmente otras características detectadas según el deseo de los padres. Este procedimiento ha sido objeto de debates en el ámbito científico, por el eventual daño que puede ocasionar la técnica en embriones sanos que serán implantados y por las interpretaciones de los exámenes genéticos realizados. También ha sido objeto de debates en el ámbito ético-antropológico, en cuanto a la producción y al respeto a la vida e integridad de los seres humanos en desarrollo. En este trabajo se argumenta que los usos que se hacen del DGP son, en su gran mayoría, moralmente reprochables, por hacerse con desprecio de la dignidad que debe darse al embrión como persona humana.

Resumo: 22. O Diagnóstico genético pré-implantacional (PGD) por meio de biópsia embrionária visa a identificação de alterações genéticas prévias à implantação de embriões produzidos por fertilização in vitro (FIV). Seu propósito mais significativo é a seleção de embriões por sua característica genética. Ele também pode ser usado para selecionar o sexo ou, eventualmente, outras características identificadas de acordo com os desejos dos pais. Este procedimento tem sido tema de debate em âmbito científico, por eventual dano que pode ocaciosionar a técnica em embriões saudáveis que serão implantados e pela interpretações dos exames genéricos realizados. Ele também tem sido objeto de debate na área ético-antropológica, no que concerne a produção e o respeito à vida e integridade do ser humano em desenvolvimento. Este artigo argumenta que os usos que são feitos do PGD são, em sua grande maioria, moralmente condenáveis, por ser instrumentalizado com desrespeito pela dignidade que deve ser dada ao embrião como uma pessoa humana.

Preimplantation Genetic Screening and Preimplantation Genetic Diagnosis.

Preimplantation genetic testing encompasses preimplantation genetic screening (PGS) and preimplantation genetic diagnosis (PGD). PGS improves success rates of in vitro fertilization by ensuring the transfer of euploid embryos that have a higher chance of implantation and resulting in a live birth. PGD enables the identification of embryos with specific disease-causing mutations and transfer of unaffected embryos. The development of whole genome amplification and genomic tools, including single nucleotide polymorphism microarrays, comparative genomic hybridization microarrays, and next-generation sequencing, has led to faster, more accurate diagnoses that translate to improved pregnancy and live birth rates.

Pre-implantation HLA matching: The production of a Saviour Child.

Pre-implantation genetic diagnosis (PGD) requires the use of assisted reproductive technology (ART) to create several pre-implantation-stage embryos, followed by biopsy of embryonic cells for genetic testing and transfer of selected embryos to the womb to establish a pregnancy. HLA typing of ART-created embryos was first reported in 2001. The aim is to establish a pregnancy that is HLA-compatible with an affected sibling who requires haematopoietic stem cell transplantation. HLA-typing can be performed with or without PGD for the exclusion of a single-gene disorder. Haematopoietic stem cells collected from the umbilical cord blood or the bone marrow of the HLA-matched donor sibling born, or a combination of both sources, are used for transplantation and cure of the affected sibling. The procedure is multistep and technically challenging. All specialists involved must aim to adequately support and counsel prospective parents. Results have so far been encouraging, with many documented positive outcomes of affected children being cured.

'The BRCA clock is ticking!': negotiating medical concerns and reproductive goals in preimplantation genetic diagnosis.

Despite research on BRCA1/2 mutation carriers attitudes towards preimplantation genetic diagnosis (PGD), considerably less is known about individuals' experience with its use. Through case reports of BRCA1/2 mutation carriers' thoughts on, and use of, PGD, this paper highlights how the option of PGD is experienced and negotiated in the context of reproductive and life-course goals. Drawing on qualitative interviews with 38 BRCA1/2 mutation carriers, this article focuses on a subsample of 10 interviewees who sought consultation for, and/or attempted, PGD, with in-depth reports of 3 cases and summary decisions of the remaining 7. Three couples decided against PGD, and one was deciding at the time of the interview. Interviewees discuss key aspects of their experience prior to, and going through, PGD for BRCA1/2, including potential challenges of becoming pregnant through PGD and of heightened pressure to achieve their reproductive goals more quickly. Despite considerable focus on ethical issues in screening embryos for mutations associated with adult-onset cancer risk, less attention has been paid to the technical, logistical, and related psychosocial issues. Narrative case reports may help individuals develop appropriate expectations of PGD for BRCA prepare for possibly challenging decisions and outcomes, and ultimately determine whether it is compatible with their reproductive goals.

In vitro screening of embryos by whole-genome sequencing: now, in the future or never?

STUDY QUESTION: What are the analytical and clinical validity and the clinical utility of in vitro screening of embryos by whole-genome sequencing? SUMMARY ANSWER: At present there are still many limitations in terms of analytical and clinical validity and utility and many ethical questions remain. WHAT IS KNOWN ALREADY: Whole-genome sequencing of IVF/ICSI embryos is technically possible. Many loss-of-function mutations exist in the general population without serious effects on the phenotype of the individual. Moreover, annotations of genes and the reference genome are still not 100% correct. STUDY DESIGN, SIZE, DURATION: We used publicly available samples from the 1000 Genomes project and Complete Genomics, together with 42 samples from in-house research samples of parents from trios to investigate the presence of loss-of-function mutations in healthy individuals. PARTICIPANTS/MATERIALS, SETTING, METHODS: In the samples, we looked for mutations in genes that are associated with a selection of severe Mendelian disorders with a known molecular basis. We looked for mutations predicted to be damaging by PolyPhen and SIFT and for mutations annotated as disease causing in Human Genome Mutation Database (HGMD). MAIN RESULTS AND THE ROLE OF CHANCE: More than 40% of individuals who can be considered healthy have mutations that are predicted to be damaging in genes associated with severe Mendelian disorders or are annotated as disease causing. LIMITATIONS, REASONS FOR CAUTION: The analysis relies on current knowledge and databases are continuously updated to reflect our increasing knowledge about the genome. In the process of our analysis several updates were already made. WIDER IMPLICATIONS OF THE FINDINGS: At this moment it is not advisable to use whole-genome sequencing as a tool to set up health profiles to select embryos for transfer. We also raise some ethical questions that have to be addressed before this technology can be used for embryo selection. TRIAL REGISTRATION NUMBER: N/A.

[Preimplantatory genetic diagnosis and ″saviour sibling″: ethical criteria found in the biomedical and bioethics literature]. / Diagnóstico Genético Preimplantatorio y el ″Bebé Medicamento″: Criterios Éticos Encontrados en la Literatura Biomédica y Bioética.

UNLABELLED: A bibliographic review on <> was performed in order to find out the ethical criteria put forward by the authors on this issue. 23 biomedical and 10 bioethical journals were reviewed and authors for and against the procedure were found. In the Biomedical journals, the main arguments for this issue are that nobody should be hurt and that there is an ethical imperative that is to save a life and that this is preferable to abortion. Those against, believe that an inadequate discrimination against women is being exerted on one hand by subjecting them to a complex, inefficient and dangerous procedure, and on the other, against embryos when many healthy ones are rejected because they are not compatible, or because of the dangers to the embryo, and also the psychological problems for the sick child as well as the donor. In the bioethical journals, we found a higher proportion of papers that are in its favor than in biomedical journals. The arguments are similar to those of the bioethical ones, but there are some particular arguments such as that the autonomy of parents must be respected; that it is a success of the common sense; that it is not an invasive process as it is considered; that it only involves blood donation not a solid organ; that the child that donates will feel accompanied by the saved one and he/she will feel the satisfaction of since having helped someone to live because without this procedure, the baby child would probably not have been born. The arguments against are the discrimination women undergo when they are subjected to this procedure with potential risks for her, the embryos and children. IN CONCLUSION: a) the morality of <> medicine not has been debated in the bioethics and biomedical community before its implementation b) in both communities the majority of authors consider it to be ethically licit; c) paradoxically there is a greater relative percentage of authors who are critical of it within the biomedical field than in bioethics; d) from a personalist bioethics perspective a human embryo is endowed with the dignity of a person and as such must be respected, this technique being an positive eugenics practice, in which, after previous selection health embryos are deprived of their right to exist.

Preimplantation genetic diagnosis with HLA matching - a way to save a child.

Preimplantation genetic diagnosis can be used to establish a pregnancy with an embryo that is human leukocyte antigen (HLA)-matched to a sibling having a hematological or immunological disease and needing a life-saving bone marrow transplantation. The ethical aspects of this procedure have been discussed intensively. The procedure applies where no unrelated HLA-matching donor is available or when transplantation from an HLA-matching sibling is considered a better solution. It is only offered in a limited number of centers in Europe as this is a challenging procedure. Where both HLA matching and diagnosis of a dominant disease are necessary, only a small proportion of the embryos can be used, and the procedure is not always technically feasible. The clinical pregnancy rate per cycle started is much lower than following normal in vitro fertilization (IVF) due to a high cycle cancellation rate, but the success rate is only somewhat lower when measured per transfer.

An analysis of US fertility centre educational materials suggests that informed consent for preimplantation genetic diagnosis may be inadequate.

The use of preimplantation genetic diagnosis (PGD) has expanded both in number and scope over the past 2 decades. Initially carried out to avoid the birth of children with severe genetic disease, PGD is now used for a variety of medical and non-medical purposes. While some human studies have concluded that PGD is safe, animal studies and a recent human study suggest that the embryo biopsy procedure may result in neurological problems for the offspring. Given that the long-term safety of PGD has not been clearly established in humans, this study sought to determine how PGD safety is presented to prospective patients by means of a detailed website analysis. The websites of 262 US fertility centres performing PGD were analysed and comments about safety and risk were catalogued. Results of the analysis demonstrated that 78.2% of centre websites did not mention safety or risk of PGD at all. Of the 21.8% of centres that did contain safety or risk information about PGD, 28.1% included statements highlighting the potential risks, 38.6% presented information touting the procedure as safe and 33.3% included statements highlighting potential risks and the overall safety of the procedure. Thus, 86.6% of PGD-performing centres state that PGD is safe and/or fail to disclose any risks on their websites despite the fact that the impact of the procedure on the long-term health of offspring is unproven. This lack of disclosure suggests that informed consent is inadequate; this study examines numerous factors that are likely to inhibit comprehensive discussions of safety.

Saviour-sibling and the psychological, ethical and judicial issues that it creates: should English and French legislators close the Pandora's Box?

Since the advent of test-tube babies, advances in the biomedical field have risen steadily. In parallel, the scientific body has never since ceased to debate the ethical issues that they arise. This is particularly the case regarding saviour-sibling. Saviour-sibling refers to a child who is conceived to cure an older brother or sister suffering from a serious family genetic disease. Therefore, it is meant to give birth to a child who will provide stem-cells taken from the umbilical cord or bone marrow afterwards, to treat an elder sick sibling. In England, this practice has been explicitly allowed by the new Human Fertilisation and Embryology Act 2008 under some strict conditions. In France, this practice, authorized by the Bioethics Law of August 2004 and confirmed by its decree of implementation published in the Official Journal on 23 December 2006, is also strictly regulated. This technique opens up new perspectives and enormous hope. Its legalisation is certainly justified by the suffering of the parents and to avoid that they travel to other States where it is permitted. However, it raises serious psychological ethical and judicial issues. Following an analysis of the English and French laws on saviour siblings, its controversial side will be highlighted, before concluding whether or not this new Pandora's box which is saviour-sibling, should be closed and other alternative methods encouraged.

Barriers to conceiving sibling donors for sickle cell disease: perspectives from patients and parents.

OBJECTIVES: The lack of matched sibling donors poses a significant barrier to utilizing hematopoietic cell transplantation (HCT), the only proven cure for children with sickle cell disease (SCD). Little is known about current patient and parent perspectives towards HCT for SCD. This study examines the perceived barriers of transplant, and the use of in vitro fertilization (IVF) and preimplantation genetic diagnosis (PGD), when there is no pre-existing sibling donor. DESIGN: Semi-structured interviews were conducted with adult patients with SCD and parents of children with SCD in an urban medical center in the US. Transcribed data was analyzed using qualitative methods. RESULTS: Of 23 participants, 17 reported having heard of HCT for SCD. Fewer knew of IVF or PGD as a means for conceiving an unaffected child (n =7) or to select a potential umbilical cord blood donor (n =1). The financial cost of IVF and PGD was perceived as a significant initial barrier to accessing these technologies, with the clinical risks of HCT and the ethical appropriateness of using PGD also identified as barriers. The value of informing families of these options was a recurring theme, even among respondents who personally disagreed with their application. CONCLUSION: The low utilization of curative strategies for SCD appears to be partly attributable to a lack of information about the technologies available to facilitate transplantation. Ethical reservations, while present, were not static and did not preclude patients' and parents' desire to be informed. We discuss the implications of these perceived barriers to the dissemination of advanced medical technologies for SCD.

[Extending preimplantation genetic diagnosis to HLA typing: the French exception]. / Le diagnostic pré-implantatoire couplé au typage HLA: l'expérience française.

Umut-Talha, a "sibling savior", was born on 26 January 2011 at Beclère Hospital after embryo selection at the Paris preimplantation genetic diagnosis (PGD) center. His birth revived the controversy over "double PGD". This procedure, authorized in France since 2006, allows couples who already have a child with a serious, incurable genetic disease, to opt for PGD in order to select a healthy embryo that is HLA-matched to the affected sibling and who may thus serve as an ombilical cord blood donor. The procedure is particularly complex and the baby take-home rate is still very low. Double PGD is strictly regulated in France, and candidate couples must first receive individual authorization from the Biomedicine Agency. In our experience, these couples have a strong desire to have children, as reflected by the large number of prior spontaneous pregnancies (25% of couples). Likewise, most of these couples request embryo transfer even when there is no HLA-matched embryo, which accounts for more than half of embryo transfers. The controversy surrounding this practice has flared up again in recent weeks, over the concepts of "designer babies" and "double savior siblings" (the baby is selected to be free of the hereditary disease, and may also serve as a stem cell donor for the affected sibling).

Preimplantation genetic diagnosis.

Preimplantation genetic diagnosis (PGD) is the screening of embryos at the cleavage stage in order to select and transfer only the desired embryo. The main indications of PGD are monogenic disorders and aneuploidy. This article reviews the recent advances in PGD methodology and presents their advantages, disadvantages and challenges. Ethical considerations arising with more widespread use of PGD for physical traits is also discussed. PGD for monogenic disorders remains the most successful indication, but is technically more challenging. PGS for aneuploidy has passed through a period of reconsideration and is now re-emerging with complete genome screening.