Non-invasive prenatal testing for Down syndrome

Women's experiences with non-invasive prenatal testing in Switzerland: a qualitative analysis

BACKGROUND

Prenatal genetic testing, in particular non-invasive prenatal testing (NIPT), as well as screening for risks associated with pregnancy, and counseling, play pivotal roles in reproductive healthcare, offering valuable information about the health of the fetus to expectant parents. This study aims to delve into the perspectives and experiences of women considering genetic testing and screening during pregnancy, focusing on their decision-making processes and the implications for informed consent.

METHODS

A nationwide qualitative study was conducted in Switzerland, involving in-depth interviews with women who were 1 to 2 years post-partum, covered by basic compulsory Swiss insurance, including women with a migration background. Thematic analysis was employed to identify key themes and patterns in the data.

RESULTS

The findings underscore the significance of effective communication during prenatal counseling, suggesting that healthcare providers could not only convey technical information but also support women in their decision-making processes. Women need comprehensive information about genetic testing and its implications, as well as the reasons for screening during pregnancy, as there might be a need to bridge knowledge gaps and clarify misconceptions. Furthermore, the study highlights the multifaceted nature of decision-making, with women considering factors such as uncertainty, values, emotional responses, and societal support systems. The concept of acceptance emerged as a crucial theme, with some women expressing their readiness to love and accept their child, regardless of genetic anomalies or disabilities.

CONCLUSION

This study offers valuable insights into the perspectives and needs of women regarding prenatal genetic testing, screening, and counseling in Switzerland. It underscores the importance of enhancing the clinical interaction and informed consent process by providing comprehensive information, addressing misconceptions, and supporting women in decision-making about pregnancy management and the management of the child's health, following prenatal genetic testing, including NIPT. These findings can inform healthcare providers and policymakers in improving the quality of prenatal counseling, ensuring informed consent, and supporting women in making well-informed and meaningful decisions about genetic testing, and on the use of screening during pregnancy.

Immunoassay-Amplified Responses Using a Functionalized MoS2-Based SPR Biosensor to Detect PAPP-A2 in Maternal Serum Samples to Screen for Fetal Down's Syndrome

Background

Due to educational, social and economic reasons, more and more women are delaying childbirth. However, advanced maternal age is associated with several adverse pregnancy outcomes, and in particular a high risk of Down’s syndrome (DS). Hence, it is increasingly important to be able to detect fetal Down’s syndrome (FDS).

Methods

We developed an effective, highly sensitive, surface plasmon resonance (SPR) biosensor with biochemically amplified responses using carboxyl-molybdenum disulfide (MoS₂) film. The use of carboxylic acid as a surface modifier of MoS₂ promoted dispersion and formed specific three-dimensional coordination sites. The carboxylic acid immobilized unmodified antibodies in a way that enhanced the bioaffinity of MoS₂ and preserved biorecognition properties of the SPR sensor surface. Complete antigen pregnancy-associated plasma protein-A2 (PAPP-A2) conjugated with the carboxyl-MoS₂-modified gold chip to amplify the signal and improve detection sensitivity. This heterostructure interface had a high work function, and thus improved the efficiency of the electric field energy of the surface plasmon. These results provide evidence that the interface electric field improved performance of the SPR biosensor.

Results

The carboxyl-MoS₂-based SPR biosensor was used successfully to evaluate PAPP-A2 level for fetal Down’s syndrome screening in maternal serum samples. The detection limit was 0.05 pg/mL, and the linear working range was 0.1 to 1100 pg/mL. The women with an SPR angle >46.57 m° were more closely associated with fetal Down’s syndrome. Once optimized for serum Down’s syndrome screening, an average recovery of 95.2% and relative standard deviation of 8.5% were obtained. Our findings suggest that carboxyl-MoS₂-based SPR technology may have advantages over conventional ELISA in certain situations.

Conclusion

Carboxyl-MoS₂-based SPR biosensors can be used as a new diagnostic technology to respond to the increasing need for fetal Down’s syndrome screening in maternal serum samples. Our results demonstrated that the carboxyl-MoS₂-based SPR biosensor was capable of determining PAPP-A2 levels with acceptable accuracy and recovery. We hope that this technology will be investigated in diverse clinical trials and in real case applications for screening and early diagnosis in the future.

In utero Therapy for the Treatment of Sickle Cell Disease: Taking Advantage of the Fetal Immune System

Sickle Cell Disease (SCD) is an autosomal recessive disorder resulting from a β-globin gene missense mutation and is among the most prevalent severe monogenic disorders worldwide. Haematopoietic stem cell transplantation remains the only curative option for the disease, as most management options focus solely on symptom control. Progress in prenatal diagnosis and fetal therapeutic intervention raises the possibility of in utero treatment. SCD can be diagnosed prenatally in high-risk patients using chorionic villus sampling. Among the possible prenatal treatments, in utero stem cell transplantation (IUSCT) shows the most promise. IUSCT is a non-myeloablative, non-immunosuppressive alternative conferring various unique advantages and may also offer safer postnatal management. Fetal immunologic immaturity could allow engraftment of allogeneic cells before fetal immune system maturation, donor-specific tolerance and lifelong chimerism. In this review, we will discuss SCD, screening and current treatments. We will present the therapeutic rationale for IUSCT, examine the early experimental work and initial human experience, as well as consider primary barriers of clinically implementing IUSCT and the promising approaches to address them.

Decision making on antenatal screening results: A comparative Q-method study of women from two Chinese cities

Background

Although an integral part of ethical and quality health care, little is known about the informed decision making of Chinese women with different socioeconomic backgrounds within the context of antenatal testing.

Methods

To explore women's viewpoints on informed decision making regarding antenatal screening, a Q‐methodology study that combines both quantitative factor analysis and interviews was conducted between June 2016 and February 2017 in Shanghai and Duyun. A total of 169 women (84 Shanghai and 85 Duyun) participated in the study of 41 ranked statements along a Q‐sorting grid.

Results

Using by‐person factor analysis, five distinct viewpoints are identified: (a) choice is shared with the partner/husband, but the mother has the right to make the final decision; (b) having antenatal tests is not about choice but about a mother's responsibility; (c) choice is a shared decision led primarily by the partner/husband and secondarily by the doctors; (d) choice should be made using the advice of doctors, but the decision should be made with the partner/husband; and (e) choice is a responsibility shared with the partner, family and doctors.

Conclusions

The study reveals that women with better education and higher incomes demonstrate more autonomy than those with less education. The nuclear family clearly emerges as the main decision makers in health‐care services in China.

Patient and Public Contribution

The 169 participants shared their views and stories for at least an hour. They were debriefed after the interviews and contributed their thoughts on our study design and interpretation of the data.

Factors affecting cell-free DNA fetal fraction: statistical analysis of 13,661 maternal plasmas for non-invasive prenatal screening

Background

The identification of cell-free fetal DNA (cffDNA) facilitated non-invasive prenatal screening (NIPS) through analysis of cffDNA in maternal plasma. However, challenges regarding its clinical implementation become apparent. Factors affecting fetal fraction should be clarified to guide its clinical application.

Results

A total of 13,661 pregnant subjects with singleton pregnancies who undertook NIPS were included in the study. Relationship of gestational age, maternal BMI, and maternal age with the cffDNA fetal fraction in maternal plasmas for NIPS was investigated. Compared with 13 weeks (12.74%) and 14–18 weeks group (12.73%), the fetal fraction in gestational ages of 19–23 weeks, 24–28 weeks, and more than 29 weeks groups significantly increased to 13.11%, 16.14%, and 21.17%, respectively (P < 0.01). Compared with fetal fraction of 14.54% in the maternal BMI group of < 18.5 kg/m², the percentage of fetal fraction in the group of 18.5–24.9 kg/m² (13.37%), 25–29.9 kg/m² (12.20%), 30–34.9 kg/m² (11.32%), and 35–39.9 kg/m² (11.57%) decreased significantly (P < 0.01). Compared with the fetal fraction of 14.38% in the group of 18–24 years old, the fetal fraction in the maternal age group of 25–29 years old group (13.98%) (P < 0.05), 30–34 years old group (13.18%) (P < 0.01), 35–39 years old group (12.34%) (P < 0.01), and ≥ 40 years old (11.90%) group (P < 0.01) decreased significantly.

Conclusions

The percentage of fetal fraction significantly increased with increase of gestational age. Decreased fetal fraction with increasing maternal BMI was found. Maternal age was also negatively related to the fetal fraction.

Mothers of a child with Down syndrome: A qualitative analysis of the perspectives on non-invasive prenatal testing

OBJECTIVE

The introduction of non-invasive prenatal testing (NIPT) for Down syndrome (DS) has sparked social and ethical debates. To date, in-depth exploration of the voices of Australian mothers of a child with DS about NIPT has been lacking. The purpose of this study was to investigate the perspectives of Australian mothers of a child with DS towards the increasing availability of NIPT.

DESIGN AND SETTING

Fifteen mothers of children with DS aged 8 months-39 years participated in-depth interviews, conducted online via the software Zoom™. An inductive thematic analysis of interview data explored mothers' perceptions of NIPT.

FINDINGS

Mothers perspectives were nuanced and personal to each woman's circumstance. All mothers highlighted the inevitable association between testing and termination, the importance of autonomy and respecting [m]others' choices to test and to terminate, and that appropriate supports must be provided to ensure informed decision-making. These perspectives existed within an overarching theme of NIPT reflecting and reinforcing societal attitudes towards disability.

CONCLUSION

Mothers of a child with DS viewed informed decision-making as crucial both prior to undertaking NIPT and following a positive test result. This study adds a unique Australian perspective to the necessary ongoing social and ethical debate.

Aiding Risk Information learning through Simulated Experience (ARISE): A Comparison of the Communication of Screening Test Information in Explicit and Simulated Experience Formats

OBJECTIVE

To determine whether the use of Aiding Risk Information learning through Simulated Experience (ARISE) to communicate conditional probabilities about maternal serum screening results for Down syndrome promotes more accurate positive predictive value (PPV) estimates and conceptual understanding of screening, compared with explicitly providing individuals with this information via numerical summary or icon array.

METHOD

In experiment 1, 582 participants completed an online study in which they were asked to estimate the PPV and rate their attitudes toward a screening test when information was presented in either a description (required calculation of the PPV), explicit (PPV was provided and had to be identified), or an ARISE format (PPV was inferred through experience-based learning). In experiment 2, 316 participants estimated the PPV and rated their attitudes toward screening based on information presented in either an icon array (identify the icons that represent the PPV) or ARISE format.

RESULTS

In experiment 1, ARISE elicited the most accurate PPV estimates compared with the description and explicit formats, and both the explicit and ARISE formats led to more unfavorable attitudes toward screening. In experiment 2, both the icon array and ARISE resulted in similar PPV estimates; however, ARISE led to more negative attitudes toward screening.

CONCLUSIONS

These findings suggest that ARISE may be superior to other formats in the communication of PPV information for screening tests. However, differences in the complexity of the formats vary and require further investigation.

Non-Invasive Prenatal Testing: Review of Ethical, Legal and Social Implications

Non-invasive prenatal testing (NIPT) using cell-free fetal DNA (cffDNA) from maternal blood has recently entered clinical practice in many countries, including Canada. This test can be performed early during pregnancy to detect Down syndrome and other conditions. While NIPT promises numerous benefits, it also has challenging ethical, legal and social implications (ELSI). This paper reviews concerns currently found in the literature on the ELSI of NIPT. We make four observations. First, NIPT seems to exacerbate some of the already existing concerns raised by other prenatal tests (amniocentesis and maternal serum screening) such as threats to women’s reproductive autonomy and the potential for discrimination and stigmatization of disabled individuals and their families. This may be due to the likely upcoming large scale implementation and routinization of NIPT. Second, the distinction between NIPT as a screening test (as it is currently recommended) and as a diagnostic test (potentially in the future), has certain implications for the ELSI discussion. Third, we observed a progressive shift in the literature from initially including mostly conceptual analysis to an increasing number of empirical studies. This demonstrates the contribution of empirical bioethics approaches as the technology is being implemented into clinical use. Finally, we noted an increasing interest in equity and justice concerns regarding access to NIPT as it becomes more widely implemented.

What factors influence health professionals to use decision aids for Down syndrome prenatal screening?

Background

Health professionals are expected to engage pregnant women in shared decision making to help them make informed values-based decisions about prenatal screening. Patient decision aids (PtDAs) foster shared decision-making, but are rarely used in this context. Our objective was to identify factors that could influence health professionals to use a PtDA for decisions about prenatal screening for Down syndrome during a clinical pregnancy follow-up.

Methods

We planned to recruit a purposive sample of 45 health professionals (obstetrician-gynecologists, family physicians and midwives) involved in the care of pregnant women in three clinical sites (15 per site). Participating health professionals first watched a video showing two simulated consecutive prenatal follow-up consultations during which a pregnant woman, her partner and a health professional used a PtDA about Down syndrome prenatal screening. Participants were then interviewed about factors that would influence their use of the PtDA. Questions were based on the Theoretical Domains Framework. We performed content analyses of transcribed verbatim interviews.

Results

Out of 42 eligible health professionals approached, 36 agreed to be interviewed (86 % response rate). Of these, 27 were female (75 %), nine were obstetrician-gynecologists (25 %), 15 were family physicians (42 %), and 12 were midwives (33 %), with a mean age of 42.1 ± 11.6 years old. We identified 35 distinct factors reported by 20 % or more participants that were mapped onto 10 of the 12 of the Theoretical Domains Framework domains. The six most frequently mentioned factors influencing use of the PtDA were: 1) a positive appraisal (n = 29, 81 %, beliefs about consequences domain); 2) its availability in the office (n = 27, 75 %, environmental context and resources domain); 3) colleagues’ approval (n = 27, 75 %, social influences domain); 4) time constraints (n = 26, 72 %, environmental context and resources domain); 5) finding it a relevant source of information (n = 24, 67 %, motivation and goals domain); and 6) not knowing any PtDAs (n = 23, 64 %, knowledge domain).

Conclusions

Appraisal, PtDA availability, peer approval, time concerns, evidence and PtDA awareness all affect whether health professionals are likely to use a PtDA to help pregnant women make informed decision about Down syndrome screening. Implementation strategies will need to address these factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-1053-2) contains supplementary material, which is available to authorized users.

Cell-free DNA in pregnancy with choriocarcinoma and coexistent live fetus: A case report

BACKGROUND

This case report describes the use of analysis of cell-free DNA in the blood of a patient with a pregnancy with one live fetus and a choriocarcinoma diagnosed at 22 weeks of gestation.

RESULTS

The result of the analysis of 16 microsatellite loci on 14 chromosomes in the cell-free DNA in plasma was consistent with the result of the analysis of a tumor biopsy indicating biparental diploid origin of the genome. The DNA markers were discordant with the markers of the placenta indicating two separate conceptions.

CONCLUSION

Our results indicate that analysis of cell-free DNA in plasma allows determination of the origin of a choriocarcinoma without tissue biopsy, even in the presence of a co-existent pregnancy.

Cell-free DNA fragment-size distribution analysis for non-invasive prenatal CNV prediction

BACKGROUND

Non-invasive detection of aneuploidies in a fetal genome through analysis of cell-free DNA circulating in the maternal plasma is becoming a routine clinical test. Such tests, which rely on analyzing the read coverage or the allelic ratios at single-nucleotide polymorphism (SNP) loci, are not sensitive enough for smaller sub-chromosomal abnormalities due to sequencing biases and paucity of SNPs in a genome.

RESULTS

We have developed an alternative framework for identifying sub-chromosomal copy number variations in a fetal genome. This framework relies on the size distribution of fragments in a sample, as fetal-origin fragments tend to be smaller than those of maternal origin. By analyzing the local distribution of the cell-free DNA fragment sizes in each region, our method allows for the identification of sub-megabase CNVs, even in the absence of SNP positions. To evaluate the accuracy of our method, we used a plasma sample with the fetal fraction of 13%, down-sampled it to samples with coverage of 10X-40X and simulated samples with CNVs based on it. Our method had a perfect accuracy (both specificity and sensitivity) for detecting 5 Mb CNVs, and after reducing the fetal fraction (to 11%, 9% and 7%), it could correctly identify 98.82-100% of the 5 Mb CNVs and had a true-negative rate of 95.29-99.76%.

AVAILABILITY AND IMPLEMENTATION

Our source code is available on GitHub at https://github.com/compbio-UofT/FSDA CONTACT: : brudno@cs.toronto.edu.

Non-invasive prenatal testing for fetal chromosome abnormalities: review of clinical and ethical issues

Genomics-based non-invasive prenatal screening using cell-free DNA (cfDNA screening) was proposed to reduce the number of invasive procedures in current prenatal diagnosis for fetal aneuploidies. We review here the clinical and ethical issues of cfDNA screening. To date, it is not clear how cfDNA screening is going to impact the performances of clinical prenatal diagnosis and how it could be incorporated in real life. The direct marketing to users may have facilitated the early introduction of cfDNA screening into clinical practice despite limited evidence-based independent research data supporting this rapid shift. There is a need to address the most important ethical, legal, and social issues before its implementation in a mass setting. Its introduction might worsen current tendencies to neglect the reproductive autonomy of pregnant women.

Non-invasive prenatal testing for trisomy 21 based on analysis of cell-free fetal DNA circulating in the maternal plasma

OBJECTIVE

By-the-book implementation of non-invasive prenatal test and clinical validation for trisomy 21.

STUDY DESIGN

Publicly funded prospective study of 225 cases. Women at risk for trisomy 21 > 1/250 based on combined ultrasound and serum markers during first or second trimester were eligible following an informed consent. The technique was established from the available literature and performed on 10 mL of venous blood collected prior to chorionic villus sampling or amniocentesis. Investigators were blinded to the fetal karyotype. Results were expressed in Z-scores of the percentage of each chromosome.

RESULTS

Among 976 eligible cases, 225 were processed: 8 were used for pretesting phase and 23 to build a reference set. One hundred thirty six euploid cases and 47 with trisomy 21 were then run randomly. Eleven cases yielded no result (4.8%). Z-scores were above 3 (7.58+/-2.41) for chromosome 21 in all 47 trisomies and in none of the euploid cases (0.11+/-1.0). Z-scores were within normal range for the other chromosomes in both groups. Using a cut-off of 3, sensitivity and specificity were of 100% 95% CI [94.1, 100] and 100% 95% CI [98, 100], respectively.

CONCLUSION

Non-invasive prenatal test for trisomy 21 is a robust strategy that can be translated from seminal publications. Publicly funded studies should refine its indications and cost-effectiveness in prenatal screening and diagnosis. © 2015 John Wiley & Sons, Ltd.

Classifying aging as a disease in the context of ICD-11

Aging is a complex continuous multifactorial process leading to loss of function and crystalizing into the many age-related diseases. Here, we explore the arguments for classifying aging as a disease in the context of the upcoming World Health Organization's 11th International Statistical Classification of Diseases and Related Health Problems (ICD-11), expected to be finalized in 2018. We hypothesize that classifying aging as a disease with a "non-garbage" set of codes will result in new approaches and business models for addressing aging as a treatable condition, which will lead to both economic and healthcare benefits for all stakeholders. Actionable classification of aging as a disease may lead to more efficient allocation of resources by enabling funding bodies and other stakeholders to use quality-adjusted life years (QALYs) and healthy-years equivalent (HYE) as metrics when evaluating both research and clinical programs. We propose forming a Task Force to interface the WHO in order to develop a multidisciplinary framework for classifying aging as a disease with multiple disease codes facilitating for therapeutic interventions and preventative strategies.

Uptake of non-invasive prenatal testing in Chinese women: money matters

OBJECTIVE

To determine the influence of free invasive prenatal testing on the uptake of non-invasive prenatal testing (NIPT).

STUDY DESIGN

Over a 2-year period at a Chinese tertiary prenatal diagnostic unit, women at risk of fetal trisomy were given the option of NIPT or invasive prenatal testing. Invasive prenatal testing was offered free of charge to women with a local Hukou (household registration); however, women without a local Hukou were charged for invasive prenatal testing. Both women with and without a local Hukou were charged for NIPT.

RESULTS

During the first year, 2647 women with a positive trisomy 21 screening test were referred (474 women with a local Hukou and 2173 women without a local Hukou). Only 1.6% of the women with a local Hukou underwent NIPT, while this proportion was 20.6% in the women without a local Hukou. During the second year, the price of NIPT was reduced. The total number of women referred was 3047 (502 women with a local Hukou and 2545 women without a local Hukou). The uptake of NIPT in women without a local Hukou doubled, but the uptake of NIPT remained stable in women with a local Hukou.

CONCLUSION

The financial impact on the uptake of NIPT should not be underestimated.

Advantages and Disadvantages of Different Implementation Strategies of Non-Invasive Prenatal Testing in Down Syndrome Screening Programmes

BACKGROUND

Implementation of non-invasive prenatal testing (NIPT) in Down syndrome screening programmes requires health policy decisions about its combination with other tests and its timing in pregnancy.

AIM

Our aim was to aid health policy decision makers by conducting a quantitative analysis of different NIPT implementation strategies.

METHODS

Decision trees were created to illustrate all plausible alternatives in a theoretical cohort of 100,000 pregnant women in five screening programmes: classical screening by the first-trimester combined test (FCT), pre-selection of high-risk women prior to NIPT by the FCT, NIPT as the first screening test at 10 weeks and at 13 weeks, and the simultaneous conductance of NIPT and the FCT.

RESULTS

Pre-selection by FCT prior to NIPT reduces the number of amniocenteses to a minimum because of a reduction of false-positive NIPT results. If NIPT is the first screening test, it detects almost all fetal Down syndrome cases. NIPT at 10 weeks reassures women early in pregnancy, while NIPT at 13 weeks prevents unnecessary tests due to spontaneous miscarriages and allows for immediate confirmation by amniocentesis.

CONCLUSION

Every implementation strategy has its advantages and disadvantages. The most favourable implementation strategy may be NIPT as the first screening test at 13 weeks, offering the most accurate screening test for Down syndrome, when the risk for spontaneous miscarriage has declined remarkably and timely confirmation by amniocentesis can be performed.

Physician liability and non-invasive prenatal testing

Although non-invasive prenatal testing (NIPT) marks a notable development in the field of prenatal genetic testing, there are some physician liability considerations raised by this technology. As NIPT is still emerging as the standard of care and is just starting to receive provincial funding, the question arises of whether physicians are obligated to disclose the availability of NIPT to eligible patients as part of the physician-patient discussion about prenatal screening and diagnosis. If NIPT is discussed with patients, it is important to disclose the limitations of this technology with respect to its accuracy and the number of disorders that it can detect when compared with invasive diagnostic options. A failure to sufficiently disclose these limitations could leave patients with false assurances about the health of their fetuses and could raise informed consent and liability issues, particularly if a child is born with a disability as a result.

Biomarkers to detect Wilms tumors in pediatric patients: where are we now?

Wilms tumor (WT) is the most common pediatric renal tumor. Survival rates are high, whether treated according to the European protocols (SIOP-RTSG) that use prenephrectomy chemotherapy or the Children's Oncology Group (COG) protocols, with immediate nephrectomy. However, the more intensive treatment given to higher risk subgroups may result in late effects. Current risk stratification does not identify all tumors that relapse and loss of heterozygosity of 16q and 1p are the only molecular biomarkers used in risk stratification. In this review we describe recent new genetic and epigenetic findings in WT and discuss their potential use as biomarkers. We discuss approaches to ensure representative sampling of WTs including the potential for 'liquid biopsy' to circumvent intratumoral heterogeneity.

Acceptability of prenatal testing and termination of pregnancy in Pakistan

This study aimed to assess acceptability of prenatal testing (PNT) and termination of pregnancy (TOP) for a range of conditions in Pakistani parents with and without a child with a genetic condition. A structured questionnaire assessing acceptability of PNT and TOP for 30 conditions was completed by 400 Pakistani participants: 200 parents with a child with a genetic condition (100 fathers and 100 mothers) and 200 parents without an affected child (100 fathers and 100 mothers). There was a high level of interest in PNT, where over 80 % of parents in all four study groups would want PNT for the majority of the conditions. There was comparatively less interest in TOP for the same conditions (ranging from 5 to 70 % of parents, with mothers of an affected child being most interested). Parents were most likely to be interested in TOP for conditions at the serious end of the continuum. More than half of the participants in each group would consider TOP for anencephaly and quadriplegia. The interest in PNT and TOP for a range of conditions suggests that rapidly developing PNT technologies are likely to be acceptable in Pakistan, a low-middle income level and Muslim country. The comparatively lower level of interest in TOP for the same conditions highlights ethical dilemmas that such technologies are likely to raise.