Chromosomal instability and aneuploidy are similar concepts but not synonymous. CIN is the process that leads to chromosome copy number alterations, and aneuploidy is the result. While CIN and resulting aneuploidy often cause growth defects, they are also selected for in cancer cells. Although such contradicting fates may seem paradoxical at first, they can be better understood when CIN and aneuploidy are assessed separately, taking into account the in vitro or in vivo context, the rate of (...) CIN, and severity of the aneuploid karyotype. As CIN can only be measured in living cells, which proves to be technically challenging in vivo, aneuploidy is more frequently quantified. However, CIN rates might be more predictive for tumor outcome than assessing aneuploidy rates alone. In reviewing the literature, we therefore conclude that there is an urgent need for new models in which we can monitor chromosome mis-segregation and its consequences in vivo. Also see the video abstract here: https://youtu.be/fL3LxZduchg Chromosomal Instability leads to chromosome mis-segregations, creating different forms of aneuploidy over time. Some forms of aneuploid are detrimental, while others are favorable to cell growth. CIN is often studied in vitro, it is rarely studied in vivo, despite its role in both cancer and aging. (shrink)

Despite its widespread existence, the adaptive role of aneuploidy (the abnormal state of having an unequal number of different chromosomes) has been a subject of debate. Cellular aneuploidy has been associated with enhanced resistance to stress, whereas on the organismal level it is detrimental to multicellular species. Certain aneuploid karyotypes are deleterious for specific environments, but karyotype diversity in a population potentiates adaptive evolution. To reconcile these paradoxical observations, this review distinguishes the role of aneuploidy in cellular (...) versus organismal evolution. Further, it proposes a population genetics perspective to examine the behavior of aneuploidy on a populational versus individual level. By altering the copy number of a significant portion of the genome, aneuploidy introduces large phenotypic leaps that enable small cell populations to explore a wide phenotypic landscape, from which adaptive traits can be selected. The production of chromosome number variation can be further increased by stress‐ or mutation‐induced chromosomal instability, fueling rapid cellular adaptation. (shrink)

ZusammenfassungZumindest bei bestimmten Gruppen kann die Aneuploidietestung im Rahmen der PID für die Schwangerschaft medizinisch sinnvoll sein. Die gegenwärtige Rechtslage in Deutschland scheint die PID auf eine Chromosomenfehlverteilung im Embryo nicht auszuschließen; diese Testung muss aber im Einzelfall begründet und von der Frau bei einer PID-Ethikkommission beantragt werden. Der Artikel untersucht die Frage aus ethischer und rechtlicher Sicht, ob prinzipielle Gründe dagegen stehen, dass die zuständigen Ethikkommissionen Anträgen auf die Durchführung von Aneuploidietests zustimmen. Es können drei verschiedene Fallkonstellationen unterschieden werden, (...) in denen Aneuploidietests Teil von unterschiedlichen Handlungen werden und entsprechend unterschiedliche ethische Implikationen aufweisen: Das Ziel der IVF kann (i) der Aneuploidietest selbst sein, oder (ii) die IVF kann eine indizierte Unfruchtbarkeitsbehandlung sein, bei der man auch PID und Aneuploidietests durchführen kann, oder (iii) die PID ist indiziert zur Vermeidung einer Erbkrankheit oder Chromosomenschädigung und Aneuploidie kann in dieser Situation ein Zufalls- oder ein Zusatzbefund werden. Ethische Argumente, die grundsätzlich gegen eine Zulässigkeit von Aneuploidietests sprechen könnten, sind die Vermeidung einer Diskriminierung von Menschen mit Aneuploidien und der Embryonenschutz. Sie könnten gegen das Fallszenario (i) erhoben werden, aber nicht gegen (ii) und (iii). Es gibt aber mindestens drei ethische Argumente, die für die Zulässigkeit sprechen: die „gute Praxis“ der IVF, die Pflicht gegenüber dem entstehenden Kind und die Mitsprache des Paares. Ergebnis: Es ist aus rechtlichen und ethischen Gründen nicht ausgeschlossen und deshalb in Deutschland durch die zuständigen PID-Kommissionen offen zu diskutieren, ob Aneuploidietests in der PID möglich werden. (shrink)

Selected aneuploidies can be rapidly diagnosed by the analysis of fluorescent polymerase chain reaction (PCR) products of chromosome‐specific and highly polymorphic small tandem repeats (STRs). The quantitative STR patterns obtained from samples of normal individuals are markedly different from those seen when patients with aneuploidies involving chromosome X, or trisomies of chromosomes 21 and 18, are tested. For example, while samples from normal subjects – tested with a chromosome 21‐derived STR (D21S11) – show two fluorescent PCR peaks with similar activities (...) in a 1:1 ratio, the analysis of samples from patients with trisomy 21 reveals the presence of either three peaks (ratio 1:1:1), or two peaks with a ratio of 2:1. The use of an internal non‐polymorphic marker allows identification of trisomic samples with three copies of the same allele. This rapid approach (24 hours) is particularly valuable when applied to prenatal diagnosis of chromosomal abnormalities since it reduces the time of anxiety of the parents waiting for the results of the conventional cytogenetic tests, which require several weeks. (shrink)

A striking feature of human female sexual reproduction is the high level of gametes that exhibit an aberrant number of chromosomes (aneuploidy). A high baseline observed in women of prime reproductive age is followed by a dramatic increase in older women. Proper chromosome segregation requires one or more DNA crossovers (COs) between homologous maternal and paternal chromosomes, in combination with cohesion between sister chromatid arms. In human females, CO designations occur normally, according to the dictates of CO interference, giving (...) early CO-fated intermediates. However, ≈25% of these intermediates fail to mature to final CO products. This effect explains the high baseline of aneuploidy and is predicted to synergize with age-dependent cohesion loss to explain the maternal age effect. Here, modern advances in the understanding of crossing over and CO interference are reviewed, the implications of human female CO maturation inefficiency are further discussed, and areas of interest for future studies are suggested. (shrink)

Loss of the Y‐chromosome is a common feature of species with chromosomal sex determination. However, our understanding of why some lineages frequently lose Y‐chromosomes while others do not is limited. The fragile Y hypothesis proposes that in species with chiasmatic meiosis the rate of Y‐chromosome aneuploidy and the size of the recombining region have a negative correlation. The fragile Y hypothesis provides a number of novel insights not possible under traditional models. Specifically, increased rates of Y aneuploidy may (...) impose positive selection for (i) gene movement off the Y; (ii) translocations and fusions which expand the recombining region; and (iii) alternative meiotic segregation mechanisms (achiasmatic or asynaptic). These insights as well as existing evidence for the frequency of Y‐chromosome aneuploidy raise doubt about the prospects for long‐term retention of the human Y‐chromosome despite recent evidence for stable gene content in older non‐recombining regions. (shrink)

Recent scientific advances mean the widespread introduction of non-invasive prenatal diagnosis (NIPD) for chromosomal aneuploidies may be close at hand, raising the question of how NIPD should be introduced as part of antenatal care pathways for pregnant women. In this paper, the authors examine the ethical implications of three hypothetical models for using NIPD for aneuploidy in state-funded healthcare systems and assess which model is ethically preferable. In comparing the models, the authors consider their respective timings; how each model (...) would fit with current screening and diagnostic tests offered to pregnant women; the implications of offering NIPD at different stages of pregnancy; and the potential for each model to support reproductive autonomy and informed decision-making. The authors conclude by favouring a model that would be offered at 11–13 weeks gestation, alongside existing combined screening, provided that this is accompanied by measures to maximise informed decision-making, for example, provision of adequate pretest and post-test counselling. (shrink)

Aneuploidy, an aberrant number of chromosomes in a cell, is a feature of several syndromes associated with cognitive and developmental defects. In addition, aneuploidy is considered a hallmark of cancer cells and has been suggested to play a role in neurodegenerative disease. To better understand the relationship between aneuploidy and disease, various methods to measure the chromosome numbers in cells have been developed, each with their own advantages and limitations. While some methods rely on dividing cells and (...) thus bias aneuploidy rates to that population, other, more unbiased methods can only detect the average aneuploidy rates in a cell population, cloaking cell‐to‐cell heterogeneity. Furthermore, some techniques are more prone to technical artefacts, which can result in over‐ or underestimation of aneuploidy rates. In this review, we provide an overview of several “traditional” karyotyping methods as well as the latest high throughput next generation sequencing karyotyping protocols with their respective advantages and disadvantages. (shrink)

Classic genetics studies found that genomic imbalance caused by changing the dosage of part of the genome (aneuploidy) has more detrimental effects than altering the dosage of the whole genome (ploidy). Previous analysis revealed global modulation of gene expression triggered by aneuploidy across various species, including maize (Zea mays), Arabidopsis, yeast, mammals, etc. Plant microRNAs (miRNAs) are a class of 20‐ to 24‐nt endogenous small noncoding RNAs that carry out post‐transcriptional gene expression regulation. That miRNAs and their putative (...) targets are preferentially retained as duplicates after whole‐genome duplication, as are many transcription factors and signaling components, indicates miRNAs are likely to be dosage‐sensitive and potentially involved in genomic balance networks. This review addresses the following questions regarding the role of miRNAs in genomic imbalance. (1) How do aneuploidy and polyploidy impact the expression of miRNAs? (2) Do miRNAs play a regulatory role in modulating the expression of their targets under genomic imbalance? (shrink)

Homologous centromeres compete for segregation to the secondary oocyte nucleus at female meiosis I. Centromeric repeats also compete with each other to populate centromeres in mitotic cells of the germline and have become adapted to use the recombinational machinery present at centromeres to promote their own propagation. Repeats are not needed at centromeres, rather centromeres appear to be hospitable habitats for the colonization and proliferation of repeats. This is probably an indirect consequence of two distinctive features of centromeric DNA. Centromeres (...) are subject to breakage by the mechanical forces exerted by microtubules and meiotic crossing‐over is suppressed. Centromeric proteins acting in trans are under selection to mitigate the costs of centromeric repeats acting in cis. Collateral costs of mitotic competition at centromeres may help to explain the high rates of aneuploidy observed in early human embryos. (shrink)

Recent data show that catastrophic events during one cell cycle can cause massive genome damage producing viable clones with unstable genomes. This is in contrast with the traditional view that tumorigenesis requires a long‐term process in which mutations gradually accumulate over decades. These sudden events are likely to result in a large increase in genomic diversity within a relatively short time, providing the opportunity for selective advantages to be gained by a subset of cells within a population. This genetic diversity (...) amplification, arising from a single aberrant cell cycle, may drive a population conversion from benign to malignant. However, there is likely a period of relative genome stability during the clonal expansion of tumors – this may provide an opportunity for therapeutic intervention, especially if mechanisms that limit tolerance of aneuploidy are exploited. (shrink)

Early embryogenesis is marked by a frail Spindle Assembly Checkpoint (SAC). The time of SAC acquisition varies depending on the species, cell size or a yet to be uncovered developmental timer. This means that for a specific number of divisions, biorientation of sister chromatids occurs unsupervised. When error‐prone segregation is an issue, an aneuploidy‐selective apoptosis system can come into play to eliminate chromosomally unbalanced cells resulting in healthy newborns. However, aneuploidy content can be too great to overcome, endangering (...) viability.SAC generates a diffusible signal to lengthen time spent in mitosis if needed, ensuring correct chromosome segregation, a fundamental factor in the generation of euploid cells. Thus, it remains puzzling what benefit could come from delaying SAC acquisition till later in the development. In this review, we describe what is known on SAC acquisition in distinct species and highlight pending research as well as potential applications for such knowledge. (shrink)

Sex chromosomes are advantageous to mammals, allowing them to adopt a genetic rather than environmental sex determination system. However, sex chromosome evolution also carries a burden, because it results in an imbalance in gene dosage between females (XX) and males (XY). This imbalance is resolved by X dosage compensation, which comprises both X chromosome inactivation and X chromosome upregulation. X dosage compensation has been well characterized in the soma, but not in the germ line. Germ cells face a special challenge, (...) because genome wide reprogramming erases epigenetic marks responsible for maintaining the X dosage compensated state. Here we explain how evolution has influenced the gene content and germ line specialization of the mammalian sex chromosomes. We discuss new research uncovering unusual X dosage compensation states in germ cells, which we postulate influence sexual dimorphisms in germ line development and cause infertility in individuals with sex chromosome aneuploidy. (shrink)

X chromosome centromeric drive may explain the prevalence of polycystic ovary syndrome and contribute to oocyte aneuploidy, menopause, and other conditions. The mammalian X chromosome may be vulnerable to meiotic drive because of X inactivation in the female germline. The human X pericentromeric region contains genes potentially involved in meiotic mechanisms, including multiple SPIN1 and ZXDC paralogs. This is consistent with a multigenic drive system comprising differential modification of the active and inactive X chromosome centromeres in female primordial germ (...) cells and preferential segregation of the previously inactivated X chromosome centromere to the polar body at meiosis I. The drive mechanism may explain differences in X chromosome regulation in the female germlines of the human and mouse and, based on the functions encoded by the genes in the region, the transmission of X pericentromeric genetic or epigenetic variants to progeny could contribute to preeclampsia, autism, and differences in sexual differentiation. (shrink)

The screening of in vitro embryos resulting from in vitro fertilization treatment for chromosomal abnormalities has as a primary aim to help patients achieve a successful pregnancy. Most IVF centers will not transfer aneuploid embryos, as they have an enhanced risk of leading to implantation failure and miscarriage. However, some aneuploidies, such as trisomy-21, can lead to viable pregnancies and to children with a variable health prognosis, and some prospective parents may request transfer of such embryos. I present two cases (...) where the testing for and detection of trisomy-21 can lead to conflicts between IVF professionals and patients and argue that in most such cases respect for choices of patients should prevail. (shrink)

Noninvasive prenatal screening using cell-free DNA, which analyzes placental DNA circulating in maternal blood to provide information about fetal chromosomal disorders early in pregnancy and without risk to the fetus, has been hailed as a potential “paradigm shift” in prenatal genetic screening. Commercial provision of cell-free DNA screening has contributed to a rapid expansion of the tests included in the screening panels. The tests can include screening for sex chromosome anomalies, rare subchromosomal microdeletions and aneuploidies, and most recently, the entire (...) fetal genome. The benefits of this screening tool are generally framed, by both providers and commercial laboratories, as enhancing reproductive autonomy and choice by providing an earlier, simpler, and more accurate screening while potentially reducing the need for invasive follow-up testing. The majority of the literature has explored these issues empirically or conceptually from a European or North American vantage point, one that assumes normative priorities such as individual reproductive autonomy and the clinical availability of maternal health care or prenatal screening programs within which cell-free DNA screening is offered. While its implementation has raised both challenges and opportunities, very little is known about real-world experiences and the implications of the rapid introduction of cell-free DNA screening outside of North America and Europe, especially in low- and middle-income countries. To begin addressing this gap in knowledge, we organized a four-day international workshop to explore the ethical, legal, social, economic, clinical, and practical implications of the global expansion of cell-free DNA screening. We describe eight key insights that arose from the workshop. (shrink)

Over the past decade, non-invasive prenatal testing (NIPT) has been adopted into routine obstetric care to screen for fetal sex, trisomies 21, 18 and 13, sex chromosome aneuploidies and fetal sex determination. It is predicted that the scope of NIPT will be expanded in the future, including screening for adult-onset conditions (AOCs). Some ethicists have proposed that using NIPT to detect severe autosomal AOCs that cannot be prevented or treated, such as Huntington’s disease, should only be offered to prospective parents (...) who intend to terminate a pregnancy in the case of a positive result. We refer to this as the ‘conditional access model’ (CAM) for NIPT. We argue against CAM for NIPT to screen for Huntington’s disease or any other AOC. Next, we present results from a study we conducted in Australia that explored NIPT users’ attitudes regarding CAM in the context of NIPT for AOCs. We found that, despite overall support for NIPT for AOCs, most participants were not in favour of CAM for both preventable and non-preventable AOCs. Our findings are discussed in relation to our initial theoretical ethical theory and with other comparable empirical studies. We conclude that an ‘unconditional access model’ (UAM), which provides unrestricted access to NIPT for AOCs, is a morally preferable alternative that avoids both CAM’s fundamental practical limitations and the limitations it places on parents’ reproductive autonomy. (shrink)

Prenatal screening pathways, as nowadays offered in most Western countries consist of similar tests. First, a risk‐assessment test for major aneuploides is offered to pregnant women. In case of an increased risk, invasive diagnostic tests, entailing a miscarriage risk, are offered. For decades, only conventional karyotyping was used for final diagnosis. Moreover, several foetal ultrasound scans are offered to detect major congenital anomalies, but the same scans also provide relevant information for optimal support of the pregnancy and the delivery.Recent developments (...) in prenatal screening include the application of microarrays that allow for identifying a much broader range of abnomalities than karyotyping, and non‐invasive prenatal testing (NIPT) that enables reducing the number of invasive tests for aneuploidies considerably. In the future, broad NIPT may become possible and affordable.This article will briefly address the ethical issues raised by these technological developments. First, a safe NIPT may lead to routinisation and as such challenge the central issue of informed consent and the aim of prenatal screening: to offer opportunity for autonomous reproductive choice. Widening the scope of prenatal screening also raises the question to what extent ‘reproductive autonomy’ is meant to expand. Finally, if the same test is used for two different aims, namely detection of foetal anomalies and pregnancy‐related problems, non‐directive counselling can no longer be taken as a standard. Our broad outline of the ethical issues is meant as an introduction into the more detailed ethical discussions about prenatal screening in the other articles of this special issue. (shrink)

BackgroundThe clinical introduction of non-invasive prenatal testing for fetal aneuploidies is currently transforming the landscape of prenatal screening in many countries. Since it is noninvasive, safe and allows the early detection of abnormalities, NIPT expanded rapidly and the test is currently commercially available in most of the world. As NIPT is being introduced globally, its clinical implementation should consider various challenges, including the role of the surrounding social and cultural contexts. We conducted a qualitative study with healthcare professionals in Lebanon (...) and Quebec as case studies, to highlight the relevance of cultural contexts and to explore the concerns that should be taken into account for an ethical implementation of NIPT.MethodsWe conducted semi-structured interviews with 20 healthcare professionals (HCPs), 10 from each country, practicing in the field of prenatal screening and follow up diagnostic testing, including obstetricians and gynecologists, nurses, medical geneticists and, genetic counselors. We aimed to 1) explore HCPs’ perceptions and views regarding issues raised by NIPT and 2) to shed light on ways in which the introduction of the same technology (NIPT) in two different contexts (Lebanon and Quebec) raises common and different challenges that are influenced by the cultural norms and legal policies in place.ResultsWe identified challenges to the ethical implementation of NIPT. Some are common to both contexts, including financial/economic, social, and organizational/ educational challenges. Others are specific to each context. For example, challenges for Lebanon include abortion policy and financial profit, and in Quebec challenges include lobbying by Disability rights associations and geographical access to NIPT.ConclusionsOur findings highlight the need to consider specific issues related to various cultural contexts when developing frameworks that can guide an ethically sound implementation of NIPT. Further, they show that healthcare professional education and training remain paramount in order to provide NIPT counseling in a way that supports pregnant women and couples’ choice. (shrink)

Bowman-Smart et al. (2023) outlined the scenario that with the content expansion of noninvasive prenatal testing (NIPT) in the future, its application is not limited to the screening for aneuploidi...

Faithful DNA replication and accurate chromosome segregation are the key machineries of genetic transmission. Disruption of these processes represents a hallmark of cancer and often results from loss of tumor suppressors. PTEN is an important tumor suppressor that is frequently mutated or deleted in human cancer. Loss of PTEN has been associated with aneuploidy and poor prognosis in cancer patients. In mice, Pten deletion or mutation drives genomic instability and tumor development. PTEN deficiency induces DNA replication stress, confers stress (...) tolerance, and disrupts mitotic spindle architecture, leading to accumulation of structural and numerical chromosome instability. Therefore, PTEN guards the genome by controlling multiple processes of chromosome inheritance. Here, we summarize current understanding of the PTEN function in promoting high-fidelity transmission of genetic information. We also discuss the PTEN pathways of genome maintenance and highlight potential targets for cancer treatment. PTEN is a guardian of the genome. However, the role of PTEN in guarding the genome has not been revealed until recently. PTEN controls multiple fundamental processes of genomic transmission. By physically interacting with key molecules in DNA replication, DNA repair/decatenation, and chromosome segregation during the cell cycle, PTEN maintains genomicintegrity and fitness. (shrink)

Decision making during reproduction is complex for a variety of medical and social reasons. Anyone who has had a conversation with a family member about the “best time” to have a baby can attest to this — there is no “best time” or “best way.” Multiple pressures from any number of sources combine in a minefield of hazards made ever more complicated by restrictive laws in the US. Add to this a screening result of potential chromosomal aneuploidy and decision (...) making becomes ever more complex. Societal stigma and lack of adequate and accurate information during counseling certainly plays a role in the high number of terminations in the setting of diagnosed chromosomal aneuploidy, yet other factors also push families in this direction including medical considerations and the abysmal lack of social support programs. (shrink)

L’implantation d’une nouvelle technologie est une étape de la translation d’une découverte vers une application clinique. De nombreux modèles ont été proposés pour étudier une telle translation ; celui de Goering, Holland et Kelley met de l’avant des priorités qui résonnent avec la bioéthique. Nous proposons l’application d’un outil issu des sciences de l’implantation, le Consolidated Framework for Implementation Research (CFIR), pour identifier les enjeux éthiques d’une nouvelle technologie. Cet outil est conçu pour identifier les barrières et facilitateurs de l’implantation (...) d’une technologie, et par le fait même s’inscrit dans le modèle de la recherche translationnelle. Nous prenons en exemple le test génomique prénatal non invasif (TGPNI). Ce test est offert dans certaines provinces du Canada en deuxième intention pour les personnes enceintes ayant une haute probabilité d’avoir un foetus avec une aneuploïdie. Des innovations potentielles du TGPNI sont de l’offrir comme test de première intention et d’étendre le nombre de conditions génétiques dépistées. Nous proposons donc d’utiliser le CFIR pour identifier les enjeux éthiques qui découlent des barrières et facilitateurs de ces innovations du TGPNI. En identifiant les barrières et facilitateurs de l’implantation d’une technologie, cet outil permet aux bioéthiciens de recourir à un outil éprouvé d’une autre discipline pour étudier des enjeux éthiques. Les bioéthiciens peuvent alors se tourner vers leurs outils traditionnels pour identifier les enjeux éthiques que soulèvent ces éléments. Notre proposition est un exemple parmi d’autres possibles de ce que cette approche peut accomplir : identifier d’une manière innovatrice des enjeux éthiques d’une nouvelle technologie. (shrink)

Detection of genetic aberrations in prenatal samples, obtained through amniocentesis or chorion villus biopsy, is increasingly performed using chromosomal microarray (CMA), a technique that can uncover both aneuploidies and copy number variants throughout the genome. Despite the obvious benefits of CMA, the decision on implementing the technology is complicated by ethical issues concerning variant interpretation and reporting. In Belgium, uniform guidelines were composed and a shared database for prenatal CMA findings was established. This Belgian approach sparks discussion: it is evidence-based, (...) prevents inconsistencies and avoids parental anxiety, but can be considered paternalistic. Here, we reflect on the cultural and moral bases of the Belgian reporting system of prenatally detected variants. (shrink)

Cytogenetic research has had a major impact on the field of reproductive medicine, providing an insight into the frequency of chromosomal abnormalities that occur during gametogenesis, embryonic development and pregnancy. In humans, aneuploidy has been found to be relatively common during fetal life, necessitating prenatal screening of high‐risk pregnancies. Aneuploidy rates are higher still during the preimplantation stage of development. An increasing number of IVF laboratories have attempted to improve pregnancy rates by using preimplantation genetic diagnosis (PGD) to (...) ensure that the embryos transferred to the mother are chromosomally normal. This paper reviews some of the techniques that are key to the detection of aneuploidy in reproductive samples including comparative genomic hybridization (CGH). CGH has provided an unparalleled insight into the nature of chromosome imbalance in human embryos and polar bodies. The clinical application of CGH for the purposes of PGD and the future extensions of the methodology, including DNA microarrays, are discussed. BioEssays 25:289–300, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Prenatal screening pathways, as nowadays offered in most Western countries consist of similar tests. First, a risk-assessment test for major aneuploides is offered to pregnant women. In case of an increased risk, invasive diagnostic tests, entailing a miscarriage risk, are offered. For decades, only conventional karyotyping was used for final diagnosis. Moreover, several foetal ultrasound scans are offered to detect major congenital anomalies, but the same scans also provide relevant information for optimal support of the pregnancy and the delivery. Recent (...) developments in prenatal screening include the application of microarrays that allow for identifying a much broader range of abnomalities than karyotyping, and non-invasive prenatal testing that enables reducing the number of invasive tests for aneuploidies considerably. In the future, broad NIPT may become possible and affordable. This article will briefly address the ethical issues raised by these technological developments. First, a safe NIPT may lead to routinisation and as such challenge the central issue of informed consent and the aim of prenatal screening: to offer opportunity for autonomous reproductive choice. Widening the scope of prenatal screening also raises the question to what extent ‘reproductive autonomy’ is meant to expand. Finally, if the same test is used for two different aims, namely detection of foetal anomalies and pregnancy-related problems, non-directive counselling can no longer be taken as a standard. Our broad outline of the ethical issues is meant as an introduction into the more detailed ethical discussions about prenatal screening in the other articles of this special issue. (shrink)

Background Non-invasive prenatal testing (NIPT), which can screen for aneuploidies such as trisomy 21, is being implemented in several public healthcare systems across Europe. Comprehensive communication and information have been highlighted in the literature as important elements in supporting women’s reproductive decision-making and addressing relevant ethical concerns such as routinisation. Countries such as England and France are adopting broadly similar implementation models, offering NIPT for pregnancies with high aneuploidy probability. However, we do not have a deeper understanding of how (...) professionals’ counselling values and practices may differ between these contexts. Methods In this paper, we explore how professionals in England and France support patient decision-making in the provision of NIPT and critically compare professional practices and values. We draw on data from semi-structured interviews with healthcare professionals. Results Both English and French professionals emphasised values relating to patient choice and consent. However, understandings and application of these values into the practice of NIPT provision differed. English interviewees placed a stronger emphasis on interpreting and describing the process of counselling patients and clinical care through a “principle” lens. Their focus was on non-directiveness, standardisation, and the healthcare professional as “decision-facilitator” for patients. French interviewees described their approach through a “procedural” lens. Their focus was on formal consent, information, and the healthcare professional as “information-giver”. Both English and French professionals indicated that insufficient resources were a key barrier in effectively translating their values into practice. Conclusion Our findings illustrate that supporting patient choice in the provision of NIPT may be held as an important value in common on a surface level, but can be understood and translated into practice in different ways. Our findings can guide further research and beneficially inform practice and policy around NIPT provision. (shrink)

SummaryMis‐regulation (e.g. overproduction) of the human Ndc80/Hec1 outer kinetochore protein has been associated with aneuploidy and tumourigenesis, but the genetic basis and underlying mechanisms of this phenomenon remain poorly understood. Recent studies have identified the ubiquitous Ndc80 internal loop as a protein‐protein interaction platform. Binding partners include the Ska complex, the replication licensing factor Cdt1, the Dam1 complex, TACC‐TOG microtubule‐associated proteins (MAPs) and kinesin motors. We review the field and propose that the overproduction of Ndc80 may unfavourably absorb these (...) interactors through the internal loop domain and lead to a change in the equilibrium of MAPs and motors in the cells. This sequestration will disrupt microtubule dynamics and the proper segregation of chromosomes in mitosis, leading to aneuploid formation. Further investigation of Ndc80 internal loop‐MAPs interactions will bring new insights into their roles in kinetochore‐microtubule attachment and tumourigenesis. (shrink)

Meiotic defects cause abnormal chromosome segregation leading to aneuploidy in mammalian oocytes. Chromosome segregation is particularly error‐prone in human oocytes, but the mechanisms behind such errors remain unclear. To explain the frequent chromosome segregation errors, recent investigations have identified multiple meiotic defects and explained how these defects occur in female meiosis. In particular, we review the causes of cohesin exhaustion, leaky spindle assembly checkpoint (SAC), inherently unstable meiotic spindle, fragmented kinetochores or centromeres, abnormal aurora kinases (AURK), and clinical genetic (...) variants in human oocytes. We mainly focus on meiotic defects in human oocytes, but also refer to the potential defects of female meiosis in mouse models. (shrink)