Favorable attitudes toward testing for chromosomal abnormalities via analysis of fetal cells in maternal blood

Overview of the impact of noninvasive prenatal testing on diagnostic procedures

Noninvasive prenatal testing (NIPT) has had a profound influence in the field of prenatal diagnosis since the 1997 discovery of cell-free fetal DNA in maternal blood. Research has progressed rapidly, with clinical data supporting laboratory studies showing that NIPT is highly sensitive and specific for fetal aneuploidy, resulting in marked uptake in the high-risk patient population. The superior accuracy of NIPT compared with conventional screening methods has led to significant decreases in the number of invasive diagnostic procedures, in addition to a concomitant decrease in the number of procedure-related fetal losses. Yet, NIPT has been described as a 'disruptive innovation' due to the considerable changes the technology has commanded on current prenatal screening and diagnostic practices. This review summarizes both institutional and global experience with NIPT uptake, its effect on reducing diagnostic invasive procedures, and the unique challenges that reduced procedural volume may have on physician and trainee proficiency, cytogenetic laboratories, and neonatal outcome.

Demographic and experiential correlates of public attitudes towards cell-free fetal DNA screening

This study seeks to inform clinical application of cell-free fetal DNA (cffDNA) screening as a novel method for prenatal trisomy detection by investigating public attitudes towards this technology and demographic and experiential characteristics related to these attitudes. Two versions of a 25-item survey assessing interest in cffDNA and existing first-trimester combined screening for either trisomy 13 and 18 or trisomy 21 were distributed among 3,164 members of the United States public. Logistic regression was performed to determine variables predictive of interest in screening options. Approximately 47% of respondents expressed an interest in cffDNA screening for trisomy 13, 18, and 21, with a majority interested in cffDNA screening as a stand-alone technique. A significantly greater percent would consider termination of pregnancy following a diagnosis of trisomy 13 or 18 (52%) over one of trisomy 21 (44%). Willingness to consider abortion of an affected pregnancy was the strongest correlate to interest in both cffDNA and first-trimester combined screening, although markedly more respondents expressed an interest in some form of screening (69% and 71%, respectively) than would consider termination. Greater educational attainment, higher income, and insurance coverage predicted interest in cffDNA screening; stronger religious identification also corresponded to decreased interest. Prior experience with disability and genetic testing was associated with increased interest in cffDNA screening. Several of these factors, in addition to advanced age and Asian race, were, in turn, predictive of respondents' increased willingness to consider post-diagnosis termination of pregnancy. In conclusion, divergent attitudes towards cffDNA screening--and prenatal options more generally--appear correlated with individual socioeconomic and religious backgrounds and experiences with disability and genetic testing. Clinical implementation and counseling for novel prenatal technologies should take these diverse stakeholder values into consideration.

Non-invasive prenatal testing: ethics and policy considerations

New technologies analyzing fetal DNA in maternal blood have led to the wide commercial availability of non-invasive prenatal testing (NIPT). We present here for clinicians the ethical and policy issues related to an emerging practice option. Although NIPT presents opportunities for pregnant women, particularly women who are at increased risk of having a baby with an abnormality or who are otherwise likely to access invasive prenatal testing, NIPT brings significant ethics and policy challenges. The ethical issues include multiple aspects of informed decision-making, such as access to counselling about the possible results of the test in advance of making a decision about participation in NIPT. Policy considerations include issues related to offering and promoting a privately available medical strategy in publicly funded institutions. Ethics and policy considerations merge in NIPT with regard to sex selection and support for persons living with disabilities.

Attitudes towards non-invasive prenatal testing for aneuploidy among US adults of reproductive age

OBJECTIVE

To determine how adults in the United States view non-invasive prenatal testing using cell-free fetal DNA (cffDNA testing) in order to help estimate uptake.

STUDY DESIGN

A national sample of 1861 US-based adults was surveyed using a validated online survey instrument. The survey was administered by a commercial survey research company. Respondents were randomized to receive a survey about prenatal testing for trisomy 13 and 18 or trisomy 21. Participants were asked to select among testing modalities, including cffDNA testing, and rank the features of testing that they considered most important to decision making.

RESULT

There was substantive interest in the use of cffDNA testing rather than traditional screening mechanisms, with a minority of respondents reporting that they would support the use of both methods in combination. The lower rates of false-negative and false-positive test results and the ability to use the test earlier in the pregnancy were the most highly rated benefits of cffDNA testing. Participants expressed strong support for diagnostic confirmation via invasive testing after a positive result from either screening or cffDNA testing. However, almost one-third of participants reported that they would not endorse the use of either invasive or non-invasive prenatal testing.

CONCLUSION

There appears to be support for uptake of non-invasive prenatal tests. Clinical guidelines should therefore go forward in providing guidance on how to integrate non-invasive methods into the current standard of care. However, our findings indicate that even when accuracy, which is rated by patients as the most important aspect of prenatal testing, is significantly improved over existing screening methods and testing is offered non-invasively, the number of individuals who reported that they would decline any testing remained the same. Attention should therefore be directed at ensuring that the right of informed refusal of prenatal testing is not impacted by new, non-invasive methods.

Non-invasive prenatal testing for trisomy 21: a cross-sectional survey of service users' views and likely uptake

OBJECTIVE

To assess the views and likely uptake of non-invasive prenatal testing (NIPT) for trisomy 21 among potential service users in the UK.

DESIGN

Cross-sectional survey.

SETTING

Four antenatal clinics in England and two websites.

SAMPLE

A total of 1131 women and partners.

METHODS

Questionnaire conducted with women (and partners) recruited through antenatal clinics, a random sample of members of the website Mumsnet, and viewers of the website and Facebook page of the support group Antenatal Results and Choices (ARC).

MAIN OUTCOME MEASURES

Factors impacting decision-making towards prenatal testing; views on NIPT, including service delivery and likely uptake; hypothetical scenarios, focused on current screening, invasive testing, and NIPT offered to women with a high-risk screening result.

RESULTS

The vast majority (95.7%; 1071/1119; 95% CI 94.4-96.8%) thought NIPT was a positive development in prenatal care, with 88.2% (972/1103; 95% CI 86.1-90%) indicating that they would use the test, including respondents who would currently decline trisomy 21 screening (P < 0.001). Of the respondents who would have NIPT, 30.7% (299/973; 95% CI = 27.8-33.7%) said that they were 'likely' to terminate an affected pregnancy (including those who would currently decline screening or invasive testing), and 36.5% (355/973; 95% CI 33.5-39.6%) were 'not likely' to terminate an affected pregnancy. Respondents overwhelmingly indicated that safety for the baby was the most important attribute of NIPT (70.1%; 712/1015; 95% CI 67.2-73%).

CONCLUSION

Respondents were overwhelmingly positive towards the introduction of NIPT. Uptake is likely to be high, and includes women who currently decline screening as well as those who will use the test for information only. Pre-test counselling to ensure that women understand the implications of the test result is essential.

Non-invasive prenatal screening for trisomy 21: what women want and are willing to pay

OBJECTIVE

To investigate the attitude among pregnant women regarding non-invasive prenatal testing (NIPT) for detecting trisomy 21 (T21) and to quantify their willingness to pay for NIPT.

METHODS

A questionnaire was administered to pregnant women who received counselling for first-trimester screening (FTS) in two hospitals and nine midwife practices in the Netherlands.

RESULTS

A total of 147 women completed the questionnaire, yielding a response rate of 43%. If NIPT for detecting T21 were available, 81% stated they would choose to have this test, and 57% of women who elected not to undergo FTS in their current pregnancy would perform NIPT if available. Willingness to pay for NIPT was correlated with age and income, but not education level. The price that participants were willing to pay for NIPT was similar to the current price for FTS.

CONCLUSION

The pregnant women in our study had a positive attitude regarding NIPT for T21, and more than half of the women who rejected prenatal screening would receive NIPT if available.

PRACTICE IMPLICATIONS

Due to the elimination of iatrogenic miscarriage, caregivers should be aware that informed decision-making can change with respect to prenatal screening with the introduction of NIPT.

Public viewpoints on new non-invasive prenatal genetic tests

Prenatal screening programmes have been critiqued for their routine implementation according to clinical rationale without public debate. A new approach, non-invasive prenatal diagnosis (NIPD), promises diagnosis of fetal genetic disorders from a sample of maternal blood without the miscarriage risk of current invasive prenatal tests (e.g. amniocentesis). Little research has investigated the attitudes of wider publics to NIPD. This study used Q-methodology, which combines factor analysis with qualitative comments, to identify four distinct "viewpoints" amongst 71 UK men and women: 1. NIPD as a new tool in the ongoing societal discrimination against the disabled; 2. NIPD as a positive clinical application offering peace of mind in pregnancy; 3. NIPD as a medical option justified for severe disorders only; and 4. NIPD as a valid expansion of personal choice. Concerns included the "trivialisation of testing" and the implications of commercial/direct-to-consumer tests. Q-methodology has considerable potential to identify viewpoints and frame public debate about new technologies.

Non-invasive prenatal testing for Down's syndrome: pregnant women's views and likely uptake

BACKGROUND

The introduction of non-invasive prenatal testing (NIPT) for Down's syndrome into routine state-funded antenatal care in the UK is approaching.

METHODS

We conducted qualitative one-to-one interviews with 40 pregnant women to ascertain their views on using NIPT for Down's syndrome.

RESULTS

The overwhelming majority of women viewed NIPT as a positive advancement in prenatal care, highlighting numerous practical and psychological advantages of a safe test that was highly accurate and could be conducted early in pregnancy. Concerns raised were that testing could become routinised, and that pressure to test might occur with women feeling less justified in declining a blood test that is available and offered by trusted health professionals; the impact on the disabled community and stigma for women who decline testing was also noted. Nevertheless, the vast majority of women said they would be likely to use NIPT, including half of the women who currently decline screening. Women's preference was for pre- and post-test counselling to be delivered by a midwife.

CONCLUSION

The successful introduction of NIPT into routine prenatal care will require guidelines and counselling strategies which ensure women are offered this test in a way which safeguards informed consent.

Non-invasive prenatal diagnosis for fetal sex determination: benefits and disadvantages from the service users' perspective

Prenatal fetal sex determination is clinically indicated for women who are at risk of having a child with a serious genetic disorder affecting a particular sex. Ultrasound has been the traditional method used, but early fetal sex determination using non-invasive prenatal diagnosis (NIPD) can now be performed using cell-free fetal DNA in maternal plasma. The study aim was to assess the views and experiences of service users who had used NIPD for fetal sex determination. In this paper, we report on the perceived benefits and disadvantages. A qualitative approach using semi-structured interviews was used. A total of 44 participants (38 women and 6 partners of participating women) were recruited. Participants' views and experiences of NIPD were overwhelmingly positive. Concerning benefits over traditional methods, three themes emerged: (1) technical aspects of technology; (2) timing; and (3) enhanced decision-making. Practical advantages of NIPD included avoiding miscarriage, and there were a number of psychological advantages associated with timing such as perceived control, early re-engagement, normalization of pregnancy and peace of mind. Participants also valued NIPD as it enabled a stepwise approach to decision-making. A number of disadvantages were discussed including concerns about social sexing and increased bonding at a time in pregnancy when miscarriage risk is high. However, participants felt these were fairly minor in comparison with the advantages of NIPD. Until definitive genetic diagnosis using NIPD is available, NIPD for fetal sex determination is perceived as a good interim measure with a number of notable advantages over traditional methods.

Variables influencing pregnancy termination following prenatal diagnosis of fetal chromosome abnormalities

The objective of this study was to identify variables that may influence the decision to terminate or continue a pregnancy affected by a chromosome abnormality. We performed a retrospective cohort analysis of 286 pregnancies diagnosed with a chromosome abnormality following genetic counseling and prenatal diagnosis. Data obtained included procedure type, chromosome results, ethnicity, maternal age, use of fertility treatments, and uptake of genetic counseling after results, among other factors. Wilcoxon rank sum test, Fisher's exact test, and univariate and multivariate logistic regression models were used for data analysis. The overall termination rate in this study was 82.9 %. A lower likelihood to terminate was found in pregnancies with a diagnosis of a sex chromosome abnormality (OR 0.05, p < .0001), Filipina race (OR 0.10, p = .03), and uptake of second genetic counseling session (OR 0.05, p < .0001). Prior history of termination was associated with increased likelihood to terminate (OR 8.6, p = .02). Factors revealing no statistically significant association with termination included maternal age, gestational age, clinic site, fetal gender, ultrasound anomalies, reason for referral and who informed the patient. Our data affirm the complexity of the decision making process and reinforce that providers should refrain from making assumptions regarding a patient's likelihood to terminate based on factors such as maternal age, gestational age, type of procedure, or ultrasound.

Noninvasive prenatal diagnosis: pregnant women's interest and expected uptake

OBJECTIVE

To investigate pregnant women's level of future interest in noninvasive prenatal diagnosis (NIPD) and what factors might affect expected uptake of this testing.

METHOD

Written questionnaires were administered to women in their third trimester.

RESULTS

One hundred fourteen women returned the questionnaire (80.9% response rate). Of these, 71.9% reported interest in NIPD, 22.7% were ambivalent, and 5.4% were uninterested. Safety of the fetus was the single most important factor in 75% of women's decisions. Factors associated with increased interest in NIPD included: older age (p = 0.036), higher education (p = 0.013), Caucasian or Asian ethnicity (p = 0.011), and higher likelihood to terminate an affected pregnancy (p = 0.002). Nearly 20% of women reported that they would do whatever their doctor recommended regarding NIPD, and 94.4% of women wished to meet with a genetic counselor at some point to discuss NIPD.

CONCLUSION

The majority of pregnant women report hypothetical interest in NIPD, primarily because of increased safety for the fetus, although a significant minority are uninterested or ambivalent. Discussions with healthcare providers regarding NIPD, and their recommendations, are likely to be an important factor in women's decisions about this testing. As such, adequate discussion of the implications of prenatal diagnostic testing will be critical.

Noninvasive prenatal diagnosis: 2010

Looking for fetal cells and now nucleic acids has been the holy grail of prenatal diagnosis for more than a century. The use of noninvasive diagnostics has potential far beyond aneuploidy; in fact, its use for Rhesus disease is already commonplace in Europe. Accurate segregation of fetal cells from maternal cells or identification of cell-free fetal (cff) DNA or RNA is critical to the development of fetal cells as a screening or diagnostic prenatal technique. The large number of approaches that have been used is testimony to the fact that none of them have been particularly successful. This article discusses the current status and challenges of noninvasive prenatal diagnosis.

Ethical aspects arising from non-invasive fetal diagnosis

Non-invasive prenatal diagnosis (NIPD) could significantly change the framework for testing and screening in pregnancy. This chapter reviews the ethical implications of this technology, including current issues in prenatal diagnosis, implications for informed consent, possible non-medical uses and options for regulation. The prospect of NIPD normalising screening and termination in pregnancy is raised as a concern. NIPD will also require monitoring to ensure women are making well-informed decisions, given that a risk to the pregnancy is absent. The question of whether NIPD will reduce anxiety needs to be established and the prospect that it will increase terminations on the grounds of disability should be recognised. The offer of NIPD external to any clinical oversight might give rise to wider social sex selection, paternity testing or testing 'for information'. The value assumptions of these uses of NIPD need to be addressed.

Psychosocial Correlates of Pregnant Women's Attitudes Toward Prenatal Maternal Serum Screening and Invasive Diagnostic Testing: Beyond Traditional Risk Status

This study examined whether psychosocial variables predict pregnant women's attitudes toward maternal serum screening and invasive diagnostic testing, beyond the influence of traditional obstetric risk status (based on advanced maternal age, history of genetic disorders, etc.). In a sample of 612 pregnant women (66.5% high risk, 33.5% low risk) we assessed responses to hypothetical scenarios of invasive testing following normal or abnormal maternal serum screening. We also assessed psychosocial variables stemming from the theory of planned behavior (e.g., knowledge, concern for fetus, attitudes toward termination, health locus of control). Overall, two thirds of the women would want serum screening. Follow-up invasive diagnostic testing would be sought by 37.2% of the women after a negative screening, and by 75.0% after a positive screening. As expected, traditional risk status predicted desire for screening and also invasive testing following either a negative or positive screen. Yet, controlling for risk status, many psychosocial variables predicted a women's interest in screening and in invasive testing: more knowledge about prenatal testing, concern about fetal health, willingness to terminate a pregnancy, and an internal or medical profession health locus of control. We conclude that psychosocial variables influence women's desire for screening or invasive testing beyond traditional risk status.

Automated detection of rare fetal cells in maternal blood: eliminating the false-positive XY signals in XX pregnancies

OBJECTIVE

The purpose of this study was to develop a new method to help differentiate XX from XY signals in maternal blood from women carrying XY fetuses.

STUDY DESIGN

We have developed a system to scan automatically for cells that bear X and Y fluorescence in situ hybridization signals. These XY target cells are identified by scans at low (x20) magnification, and all identified targets are revisited and verified at high (x100) magnification. The viewer software component of the system displays x20 images of all cells and intracellular fluorescence in situ hybridization signals that are present in each of the 4000 optical fields per slide, along with x100 images of automatically detected target cells.

RESULTS

We initially examined 36,000 fields from 18 slides in 12 pregnancies (6 male and 6 female) using our system that is based on fluorescence in situ hybridization with a single probe for the X-chromosome and a single probe for the Y-chromosome and found XY nuclei in all samples, regardless of fetal gender. In the second phase of the study, a refinement of the approach that incorporated 2 independent probes for the Y-chromosome resulted in a false-positive rate for detection of XY nuclei in XX cases <0.00005%.

CONCLUSION

Our data suggest that this system may allow for excellent "signal to noise" separation, which is required absolutely for fetal cell methods to differentiate aneuploid from normal pregnancies. Quantitation of fetal cells in the maternal circulation and standardization of processes that have been developed for their enrichment are crucial to moving fetal cell assessment from esoteric basic science to applied new technology.

Screening for Fragile X Syndrome: Parent attitudes and perspectives

PURPOSE

This study examined the attitudes and beliefs of 442 parents of children with fragile X syndrome (FXS) regarding different screening options for FXS.

METHODS

A survey was administered to parents of children with FXS across the U.S.

RESULTS

Parents indicated their support for voluntary screening for FXS, especially carrier and newborn screening. They also thought advantages of widespread screening to be more likely than disadvantages.

CONCLUSION

Parents' support for FXS screening is at odds with current screening criteria, but as new genetic knowledge and technologies reconfigure these criteria, it will be important to take parents' perspectives into account.

Non-invasive prenatal diagnosis: on the horizon?

The launch of the genomics and postgenomics era has greatly expanded our understanding of the genetic basis of many diseases. In conjunction with the sociocultural trend to delay childbirth and to maintain smaller family units, extra demand may be placed on the existing prenatal diagnostic services. The inherent risk of fetal loss associated with current prenatal diagnostic procedures, such as amniocentesis and chorionic villus sampling, has spurred research into non-invasive prenatal diagnosis. Much research has been conducted on the exploitation of fetal genetic material present in the maternal circulation. The initial focus was on the isolation of intact fetal cells and subsequently, the existence of extracellular fetal DNA in maternal plasma was realized. Exciting developments have been achieved in recent years. A large-scale trial to evaluate the clinical utility of fetal cell isolation from maternal blood for fetal aneuploidy diagnosis was launched and data were recently published. Much has taken place in the research of fetal DNA analysis in maternal plasma and in one example, namely prenatal RhD determination, this type of analysis has been used in the clinical setting. This paper reviews the technological developments in non-invasive prenatal diagnosis.

Fetal gender and aneuploidy detection using fetal cells in maternal blood: analysis of NIFTY I data. National Institute of Child Health and Development Fetal Cell Isolation Study

OBJECTIVES

The National Institute of Child Health and Human Development Fetal Cell Isolation Study (NIFTY) is a prospective, multicenter clinical project to develop non-invasive methods of prenatal diagnosis. The initial objective was to assess the utility of fetal cells in the peripheral blood of pregnant women to diagnose or screen for fetal chromosome abnormalities.

METHODS

Results of fluorescence in situ hybridization (FISH) analysis on interphase nuclei of fetal cells recovered from maternal blood were compared to metaphase karyotypes of fetal cells obtained by amniocentesis or chorionic villus sampling (CVS). After the first 5 years of the study we performed a planned analysis of the data. We report here the data from 2744 fully processed pre-procedural blood samples; 1292 samples were from women carrying singleton male fetuses.

RESULTS

Target cell recovery and fetal cell detection were better using magnetic-based separation systems (MACS) than with flow-sorting (FACS). Blinded FISH assessment of samples from women carrying singleton male fetuses found at least one cell with an X and Y signal in 41.4% of cases (95% CI: 37.4%, 45.5%). The false-positive rate of gender detection was 11.1% (95% CI: 6.1,16.1%). This was higher than expected due to the use of indirectly labeled FISH probes in one center. The detection rate of finding at least one aneuploid cell in cases of fetal aneuploidy was 74.4% (95% CI: 76.0%, 99.0%), with a false-positive rate estimated to be between 0.6% and 4.1%.

CONCLUSIONS

The sensitivity of aneuploidy detection using fetal cell analysis from maternal blood is comparable to single marker prenatal serum screening, but technological advances are needed before fetal cell analysis has clinical application as part of a multiple marker method for non-invasive prenatal screening. The limitations of the present study, i.e. multiple processing protocols, are being addressed in the ongoing study.