7 - Preconception and prenatal care

Personalized medicine for the embryo and the fetus - Options in modern genetics influence preconception and prenatal choices.

Combined Preimplantation Genetic Testing for Aneuploidy and Monogenic Disease in a Mexican Family Affected by X-linked Hypohidrotic Ectodermal Dysplasia

Introduction Pre- implantation Genetic Testing (PGT), including Pre- Implantation Genetic Screening (PGS) and Pre-Implantation Genetic Diagnosis (PGD) is defined as a group of genetic analysis applied to embryos produced through IVF programs. In Bahrain, these investigations were introduced since 2007, by referring embryo biopsy samples to PGD labs outside the country. Most of the tests were initially implemented using the techniques of FISH and PCR, while a-CGH and NGS emerged later. Genetic testing of embryos is laborious, costly, stressful and psychologically harsh on families. It should be organized and protected to ensure safety of testing and authenticity of outcome. Currently, the PGT practices in Bahrain and some of GCC countries lack many elements of quality management and require strategies for transformation of commercially oriented business to a patient-welfare oriented service. This study will present PGT data collected in the last 10 years from three major IVF centres in Bahrain. It will basically emphasize on the problems and the weaknesses encountered in our system through analysis of the data and treatment outcome in terms of pregnancy success rates. Also, in an endeavour to improve the quality of PGT services and to overcome some of the implementation-related issues observed, bioethical standards helping in improvement of the system and regulation of PGT practices will be proposed and discussed. Materials and Methods This study will present the findings of 500 infertility/ PGT cases treated in three major IVF centres in Bahrain from 2007 until present. All the centres refer their samples to satellite PGD laboratories. The tests were initially focussed on aneuploidy screening for 5 chromosomes by the technique of FISH, which was gradually shifted to 24-chromosome screening by A-CGH in 2013 through 2015 and later substituted with NGS when the technique was made available. The number of cases, the types of PGT tests performed, justifications of testing and the pregnancy outcome are all reviewed, analysed and evaluated. Results At least 70% of cases exhibited an unjustified FISH test, while 30% requested gender selection in favour of male embryos. As for screening and diagnosis of monogenic disorders, about 70% of cases displayed a trait status for hemoglobinopathies which are common in Bahrain (5%) and the eastern province of KSA (4.5%). Lower pregnancy success rates were observed mainly in FISH cases (0-15%), but they showed higher values (17- 48%) in A- CGH (p Conclusions and Recommendations Our health care system in the GCC needs urgent implementation of quality standards to improve the practices of pre- implantation genetic testing. In view of the current bioethical situation of genetic testing in GCC, measures for regulating practises of PGT under a strict controlling system will be suggested for future implementation. Ethical problems in genetic testing of embryoscan be avoided in GCC by considering the following:

Decision-making regarding prenatal screening and diagnostic testing has become more complex as the number of options has increased, with pregnant patients having access to more information about their pregnancies than ever before. Genetic counselors have extensive training in prenatal genetic screening and testing options, but personal decision-making in this well-informed population remains largely unstudied. This study describes the prenatal testing decisions genetic counselors made during their own pregnancies, and the factors identified as important when making those decisions. A web-based, mixed-methods survey was distributed to members of multiple professional societies for genetic counselors. A total of 318 genetic counselors across numerous specialties in the United States and Canada participated in this study. The satisfaction with decision scale was modified and applied to measure participants' decisional satisfaction. In their most recent pregnancies, most genetic counselors pursued carrier screening (77%) and aneuploidy and/or open neural tube defect screening (88%). A minority of genetic counselors (15%) utilized diagnostic testing. Common factors considered when making testing decisions included wanting information that could impact future decisions, test specifics (e.g., accuracy, methodology, and content), and knowledge gained from participants' genetic counseling background. The uptake of diagnostic testing among prenatal genetic counselors was significantly greater (p < 0.05) than the uptake among genetic counselors in other specialties. This informed study population largely self-directed their own prenatal care, leading to high satisfaction with their decisions. Data in this study provide evidence for promoting participation in prenatal screening and testing decision-making to maximize decisional satisfaction.

During recent decades, prenatal screening strategies have evolved greatly. Prenatal screening, including the diagnosis of fetal aneuploidy, includes invasive and non-invasive methods. Various combinations of first and second trimester maternal serum analytes and fetal ultrasound measurements have been proposed to construct a screening method with high sensitivity and specificity. Non-invasive tests are performed either by maternal serum analyte screening alone (double marker test, triple test, quadruple test, or serum integrated test), serum screening combined with ultrasound (integrated test, sequential test, or contingent test), or most recently, the cell-free fetal DNA test. Recent advances in prenatal screening methods have resulted in tremendous advantages to patients and healthcare providers. Therefore new approaches to counseling are necessary to ensure that all patients and healthcare providers receive the most comprehensive access to prenatal screening and diagnostic testing options. This article summarizes the various prenatal maternal serum screening options for fetal aneuploidy.

Study question Does embryo biopsy for preimplantation genetic testing (PGT) followed by fresh or vitrified-warmed embryo transfer affect children’s health up to 2 years of age? Summary answer Cleavage- or blastocyst-stage embryo biopsy followed by fresh or vitrified-warmed-embryo transfer had neither impact on anthropometry at birth, infancy or childhood nor on health outcomes. What is known already Literature data regarding neonatal outcomes after embryo biopsy for PGT show mixed results due to small sample sizes and/or the heterogeneity in terms of embryo biopsy (cleavage- or blastocyst-stage) and type of embryo transfer (fresh or frozen-thawed). Even fewer data exist on the impact of embryo biopsy on children’s health beyond infancy, including growth. Study design, size, duration This single-center cohort-study compared outcomes in singletons conceived after cleavage- or blastocyst-stage embryo biopsy either in a fresh or vitrified-warmed transfer cycle with results after non-biopsied embryo transfer between 2014 and 2018. Pregnancies after IVM, oocyte vitrification or oocyte/embryo donation were excluded. Eligible singletons living in Belgium were invited for examination at 3-6 months and 2 years. Anthropometric measurements at birth, infancy and childhood and health outcomes including surgeries, medication use and hospitalisations are reported. Participants/materials, setting, methods Birth characteristics were available for 630 and 222 children after cleavage-stage and blastocyst-stage embryo biopsy and for 1532 children after transfer of a non-biopsied embryo. Follow-up data were available for 426, 131 and 662 children, respectively. The impact on children’s health following embryo biopsy in vitrification and fresh cycles was the primary outcome. Other outcomes were the impact of timing of biopsy and of vitrification. Subgroup analysis according to infertility background was additionally performed. Main results and the role of chance Regarding the impact of embryo biopsy, either at the cleavage or blastocyst stage, no differences in anthropometrics were found at birth, infancy or childhood in vitrified-warmed transfer cycles compared to outcomes in non-biopsied vitrified-warmed transfer cycles, even after adjustment for neonatal, treatment and maternal characteristics. Likewise, no impact of embryo biopsy (cleavage stage) was found in fresh transfer cycles. The timing (day 3 or day 5/6) of embryo biopsy did not affect anthropometrics at birth, infancy or childhood. However, children born after cleavage-stage embryo biopsy followed by a vitrified-warmed transfer cycle had larger birth sizes than children born after cleavage-stage biopsy followed by a fresh transfer. Weight and height gain from birth to infancy and from infancy to early childhood were comparable in all biopsied and non-biopsied groups. Reassuringly, comparable rates of major congenital malformations, (severe) developmental problems, hospital admissions, surgical interventions and of chronic medication use up to the age of 2 years were observed in biopsied and non-biopsied groups. Subgroup analysis in children born to parents with an infertility diagnosis showed that birth parameters were not different in children born after embryo biopsy. Limitations, reasons for caution As the majority of the PGT cycles in our center are performed for a genetic indication only, the number of children born after embryo biopsy in infertile parents is rather limited and the results should therefore be interpreted cautiously. Wider implications of the findings Our findings add reassurance that embryo biopsy does not adversely affect the health of offspring up to 2 years of age. This is of particular importance given the widespread shift to blastocyst-stage embryo biopsy in PGT. Trial registration number Not applicable

Preimplantation genetic testing (PGT) involves testing embryos created through in vitro fertilization for the presence of hereditary genetic disorders and chromosome abnormalities. PGT for monogenic conditions (PGT-M) is generally performed for childhood-onset, lethal disorders, but is increasingly accepted for certain adult-onset conditions, conditions with available treatment options or conditions with lower penetrance. Furthermore, the development of PGT for polygenic conditions (PGT-P) makes ethical questions regarding PGT indications imperative. A systematic review was therefore performed to gather and analyse studies on the perspectives of healthcare professionals on the appropriate scope of PGT, with the aim of getting insights into the concerns about the scope of PGT now and in the near future. PRISMA guidelines were followed. Twelve qualitative articles were included. The main themes extracted were the scope of PGT and decision-making about PGT. Defining 'a serious genetic condition' was seen as complex, but severity, high penetrance and absence of treatability and patients' experience were seen as relevant indications to determine the appropriateness of PGT. In navigating the decision-making processes with patients, professionals experienced friction between setting limits and respecting patients' autonomy. Such friction and ethical dilemmas around seriousness, informed decision-making and preventative medicine show that while expanding the list of possible PGT indications and the development of PGT-P could augment patients' reproductive autonomy, it could also lead to an increased reproductive 'burden' for patients. These insights are crucial for establishing guidelines that help healthcare professionals navigate ethical tensions associated with PGT.

Study question How do genetic centres in Belgium apply international guidelines on preimplantation genetic testing (PGT)? Summary answer We present the national consensus on how to practice PGT, starting from initial patient uptake and embryo selection to follow-up of pregnancies. What is known already PGT includes PGT-M for monogenic disorders, PGT-SR for structural rearrangements and PGT-A for aneuploidy screening. The application of whole-genome technologies to trophectoderm biopsies for PGT-M and PGT-SR/A has evidenced the high prevalence of mosaicism due to chromosome segregation errors during the first mitotic divisions, making biopsy results interpretation and embryo transfer policy more challenging and complex. Guidelines from several international societies have been published in recent years to leverage the standardization of the whole PGT service. Although these are based on expertise and continuously acquiring evidence, it is widely recognized that variations in local and national regulations diversify PGT practices. Study design, size, duration Recommendations regarding PGT indications, patient counselling, embryo transfer policy, reporting, quality and pregnancy follow-up have been built to harmonize PGT services nationally. With a special focus on mosaicism, aiming to balance the highest chance for a pregnancy with the lowest risk for a chromosomally abnormal ongoing pregnancy or child. Participants/materials, setting, methods The Belgian PGT working group consists of laboratory geneticists, clinical geneticists and IVF specialists from eight nationally accredited centres. The group operates under the BeSHG umbrella and meets quarterly to formulate opinions and statements on PGT practice with the main goal of guaranteeing a high standard of care, exchange knowledge and implement a harmonized workflow. The Belgian social security system provides reimbursement of six genetic testing cycles for all PGT-M/SR patients but not for PGT-A. Main results and the role of chance PGT is offered for all monogenic and chromosomal disorders, if the causal genetic variants are known and documented. PGT for HLA-typing is allowed for the therapeutic benefit of an existing child after couple's psychological evaluation. Aneuploidy screening can be offered to specific patient groups to increase IVF success rate. However, social sexing and testing for non-medical or eugenic purposes is prohibited. At intake, the couple is counselled about the genetic aspect of the disease, psychological and financial aspects of PGT, applied methodology, including average success and misdiagnosis rate, and embryo transfer policies. Affected embryos, and embryos without diagnosis for PGT-M/SR are not transferred. For PGT-A (combined or not with PGT-M/SR), embryos are categorized as: (A) Euploid - suitable for transfer, if mosaicism is absent or below the detection threshold. (B) Mosaic transferable - suitable for transfer, but only following ranking and/or counselling and follow up, if mosaicism for any chromosome not described in (C) is detected; (C) Aneuploid or Mosaic - not suitable for transfer, if mosaicism of 8, 9, 13, 16, 18, 21 and X or full aneuploidy of any chromosome is detected. Non-invasive prenatal testing is strongly recommended to all women pregnant after PGT and is nationally reimbursed. Limitations, reasons for caution The practical recommendations, which are supplementary to the recently published ESHRE PGT recommendations, are based on expertise and data from the literature available at the time of preparation. As such, they will need regular reconsideration and an update or extension may follow when new solid scientific evidence arises. Wider implications of the findings As international recommendations represent a greatest common denominator over many local regulations, this work serves as example for drawing country-specific agreements for genetic centres. The process of consensus expert opinion formation on best practice may be applicable in other countries where PGT service is not overseen by a designated agency. Trial registration number Not applicable

Chapter 15 - Future technologies for preimplantation genetic applications

Carrier screening identifies individuals at risk of transmitting autosomal recessive or X-linked recessive conditions, supporting informed reproductive decisions. Despite international recommendations for universal carrier screening, integration into public healthcare systems remains limited. This study evaluated the feasibility of implementing a carrier screening program in Spain's public health system. Non-pregnant women aged 18 to 38 with reproductive intent were recruited through text messages sent from a primary care center, along with their partners. A sequential screening approach was used: women underwent a 351-gene massively parallel sequencing panel and complementary tests, while male partners were tested only if their partner carried autosomal recessive variants. Specific genetic counselling was provided, and emotional responses were assessed through pre- and post-test questionnaires. Of 518 candidates contacted, 400 (77%) responded positively and 152 couples (50.8% of those eligible) enrolled. Among 218 individuals screened, 62% (135) carried at least one pathogenic variant. Six carrier couples (4%) were identified as being at reproductive risk of non-syndromic hearing loss (GJB2, 2 couples), cystic fibrosis (CFTR), Stargardt disease and retinitis pigmentosa (ABCA4), Smith-Lemli-Opitz syndrome (DHCR7), and Fabry disease (GLA). Of four couples followed post-disclosure, 75% opted for in vitro fertilization with preimplantation genetic testing or prenatal diagnosis. Prevention of severe genetic conditions was the most frequently reported motivation for participation. This study proves the feasibility and clinical utility of carrier screening within a public healthcare system. Our findings demonstrate high participation rates, clinical relevance through the identification of 4% of carrier couples, and strong motivation among participants to prevent the transmission of severe genetic conditions.

X-linked myopia 26 (Myopia 26, MIM #301010), which is caused by the variants of ARR3 (MIM *301770), is characterized by female-limited early-onset high myopia (eo-HM). Clinical characteristics include a tigroid appearance in the fundus and a temporal crescent of the optic nerve head. At present, the limited literature on eo-HM caused by ARR3 mutations shows that its inheritance mode is complex, which brings certain difficulties to pre-pregnancy genetic counseling, pre-implantation genetic diagnosis, and prenatal diagnosis. Here, we investigated the genetic underpinning of a Chinese family with eo-HM. Whole exome sequencing of the proband revealed a novel frameshift mutation in ARR3 (NM_004312, exon10, c.666delC, p. Asn222LysfsTer22). Although the mode of inheritance of the eo-HM family fits the X-linked pattern of ARR3, the phenotypes of three patients deviate from the typical early-onset high myopia. Through X-chromosome inactivation experiments, the patient's different phenotypes can be precisely explained. In addition, this study not only enhanced the correlation between ARR3 and early-onset high myopia but also provided explanations for different phenotypes, which may inspire follow-up studies. Our results enrich the knowledge of the variant spectrum in ARR3 and provide critical information for preimplantation and prenatal genetic testing, diagnosis, and counseling.

The problem of the conscientious objection of healthcare workers has recently become the subject of serious interest from both the scientific and socio-political perspective. In the context of genetic testing, the most important issue connected with the conscientious objection of health care workers are preimplantation and prenatal diagnosis. The most important reason for objections to preimplantation diagnosis is the association of this procedure with embryo destruction and its predictive value (the risk of false positive results). Preimplantation diagnosis may be a subject of conscientious objection sometimes independent of the acceptance of the IVF procedure itself. Prenatal diagnosis is one of the medical diagnostic methods and, as such, raises little controversy. However, the moral assessment of prenatal testing can be different and it depends on the aim of the diagnosis, the risk to the fetus and the validity of the testing. The conscientious objection to preimplantation and prenatal genetic testing may also be reinforced by religious rations. In conclusion, conscientious objection in the medical practice results mainly from situations which violate the principle of respect for human life and the principle of non-maleficence and is connected with the issue of the criteria of hominization. The conscientious objection of health care workers cannot therefore be reduced only to their individual beliefs or the moral teachings of the religious community to which they belong; it is based on principles which constitute the basis of professional ethics and are part of a universal morality.

BackgroundCousin marriages, in the Netherlands most frequently between Turkish or Moroccan couples, are at higher risk of having offspring with recessive disorders. Often, these couples not perceive or accept this risk, and it is hardly considered a reason to refrain from family marriages. Preconception carrier screening (PCS) is offered to Jewish groups, and more recently in the Netherlands, to genetically isolated communities. In this study, Dutch Moroccan and Turkish women’s perspectives on preconception carrier screening (PCS) and reproductive choices were explored.MethodsIndividual interviews were held with Dutch Turkish and Moroccan consanguineously married women (n = 10) and seven group discussions with Turkish and Moroccan women (n = 86). Transcripts and notes were analyzed thematically.ResultsAll women welcomed PCS particularly for premarital genetic screening; regardless of possible reproductive choices, they prefer information about their future child’s health. Their perspectives on reproductive choices on the basis of screening results are diverse: refraining from having children is not an option, in vitro fertilization (IVF) combined with pre-implantation genetic diagnosis (PGD) was welcomed, while prenatal genetic diagnosis (PND), termination of pregnancy (TOP), in vitro fertilization with a donor egg cell, artificial insemination with donor sperm (AID), and adoption, were generally found to be unacceptable. Besides, not taking any special measures and preparing for the possibility of having a disabled child are also becoming optional now rather than being the default option.ConclusionsThe women’s preference for PCS for premarital screening as well as their outspokenness about not marrying or even divorcing when both partners appear to be carriers is striking. Raising awareness (of consanguinity, PCS and the choice for reproductive options), and providing information, screening and counseling sensitive to this target group and their preferences are essential in the provision of effective health care.

Preconception or prenatal carrier screening is an effective approach for preventing devastating recessive diseases. Traditionally, DNA-based carrier testing used targeted genotyping panels to detect common mutations among specific ethnic groups. While the sensitivity of this approach is generally acceptable, private or ultra-rare mutations will be missed. Next generation sequencing (NGS) has been adopted in recent years for carrier screening in order to increase test sensitivity for pan-ethnic individuals. Important issues regarding NGS-based carrier screening panels’ workflow design, variant interpretation, reporting, and genetic counseling follow-ups are reviewed and discussed in this chapter.

Recently, new noninvasive prenatal genetic screening technologies for Down syndrome and other genetic conditions have become commercially available. Unique characteristics of these screening tests have reignited long-standing concerns about prenatal testing for intellectual and developmental disabilities. We conducted a web-based survey of a sample of the US public to examine how attitudes towards disability inform views of prenatal testing in the context of these rapidly advancing prenatal genetic screening technologies. Regardless of opinion toward disability, the majority of respondents supported both the availability of screening and the decision to continue a pregnancy positive for aneuploidy. Individuals rationalized their support with various conceptions of disability; complications of the expressivist argument and other concerns from the disability literature were manifested in many responses analyzed.