Women's preference for non-invasive prenatal DNA testing versus chromosomal microarray after screening for Down syndrome: a prospective study

The importance of the trisomy 21 local cutoff value evaluation for prenatal screening in the second trimester of pregnancy

OBJECTIVE

The aim of this work was to compare different local cutoff values (LCV) and inline cutoff values (ICV) in pregnant women in the second trimester at high risk for carrying fetuses with trisomy 21.

METHODS

This retrospective cohort study analyzed prenatal screening outcomes in pregnant women (n = 311,561). The receiver operating characteristic curve was used to evaluate the diagnostic significance of the trisomy 21 risk value, alpha-fetoprotein, and free beta human chorionic gonadotropin multiple of the median for predicting trisomy 21 risk. The cutoff value corresponding to the maximal Youden index was taken as the LCV. The screening efficiency of both cutoff values was compared.

RESULTS

The LCV cutoff value was lower than the ICV cutoff value (1/643 vs 1/270). The sensitivity increased by 19.80%, the positive predictive value decreased by 0.20%, and the false-positive rate increased by 6.50%.

CONCLUSION

The LCV should be used to determine trisomy 21 risk, which can increase the detection rate of trisomy 21 in the second trimester.

[Differential expression profile of miRNAs in amniotic fluid exosomes from fetuses with Down syndrome]

OBJECTIVE

To investigate the role of miRNAs in amniotic fluid exosomes in growth and development of fetuses with Down syndrome (DS).

METHODS

Amniotic fluid were collected from 20 fetuses with DS and 20 normal fetuses (control) to extract amniotic exosome miRNA. MicroRNA sequencing technique was used to identify the differentially expressed miRNAs between the two groups, for which gene ontology (GO) and pathway analysis was performed. Three differentially expressed miRNAs with the strongest correlation with DS phenotype were selected for qPCR verification. Dual luciferase reporter assay was used to verify the activity of let-7d-5p for targeted regulation of BACH1.

RESULTS

We identified 15 differentially expressed miRNAs in DS as compared with the control group, among which 7 miRNAs were up-regulated and 8 were down-regulated. Target gene prediction results showed that the differentially expressed miRNAs targeted 17 DS-related genes. GO analysis revealed that the main functions of the target genes involved protein binding, protein transport, ATP binding, transferase activity and synapses. Pathway analysis revealed that the functional pathways were closely related with the development of the nervous system. qPCR results showed that the expression levels of miR-140-3p and let-7d-5p were significantly lower in DS group than in the control group (P < 0.05), as was consistent with miRNA sequencing results; the expression level of miR-4512 was significantly higher in DS group than in control group (P < 0.05), which was contrary to miRNA sequencing results. The results of double luciferase reporter gene assay confirmed that let-7d-5p was capable of targeted regulation of BACH1 expression.

CONCLUSION

Let-7d-5p in amniotic fluid exosomes may promote oxidative stress events in the brain of fetuses with DS by regulating BACH1 expression.

Utilization and uptake of clinical genetics services in high-income countries: A scoping review

Ongoing rapid growth in the need for genetic services has the potential to severely strain the capacity of the clinical genetics workforce to deliver this care. Unfortunately, assessments of the scale of this health policy challenge and potential solutions are hampered by the lack of a consolidated evidence base on the growth in genetic service utilization. To enable health policy research and strategic planning by health systems in this area, we conducted a scoping review of the literature on the utilization and uptake of clinical genetics services in high-income countries published between 2010 and 2018. One-hundred-and-ninety-five unique studies were included in the review. Most focused on cancer (85/195; 44%) and prenatal care (50/195; 26%), which are consistently the two areas with the greatest volume of genetic service utilization in both the United States and other high-income countries. Utilization and uptake rates varied considerably and were influenced by contextual factors including health system characteristics, provider knowledge, and patient preferences. Moreover, growth in genetic service utilization appears to be driven to a significant degree by technological advances and the integration of new tests into clinical care. Our review highlights both the policy challenge posed by the rapid growth in the utilization of genetic services and the variability in this trend across clinical indications and health systems.

The Emergence and Global Spread of Noninvasive Prenatal Testing

Since its introduction in 2011, noninvasive prenatal testing (NIPT) has spread rapidly around the world. It carries numerous benefits but also raises challenges, often related to sociocultural, legal, and economic contexts. This article describes the implementation of NIPT in nine countries, each with its own unique characteristics: Australia, Canada, China and Hong Kong, India, Israel, Lebanon, the Netherlands, the United Kingdom, and the United States. Themes covered for each country include the structure of the healthcare system, how NIPT is offered, counseling needs and resources, and cultural and legal context regarding disability and pregnancytermination. Some common issues emerge, including cost as a barrier to equitable access, the complexity of decision-making about public funding, and a shortage of appropriate resources that promote informed choice. Conversely, sociocultural values that underlie the use of NIPT vary greatly among countries. The issues described will become even more challenging as NIPT evolves from a second-tier to a first-tier screening test with expanded use.

Clinical utility of expanded non-invasive prenatal screening and chromosomal microarray analysis in high-risk pregnancy

OBJECTIVE

To evaluate the utility of expanded non-invasive prenatal screening (NIPS), compared with chromosomal microarray analysis (CMA), for the detection of chromosomal abnormalities in high-risk pregnancies.

METHODS

This was a multicenter retrospective study of singleton pregnancies at high risk for chromosomal abnormality. Patients who underwent expanded NIPS and CMA sequentially during pregnancy from 2015 to 2019 were included in the analysis. Pregnancies with a positive result for sex chromosome aneuploidy were excluded as the full details could not be retrieved. The utility of expanded NIPS and CMA for detection of chromosomal abnormalities in this cohort was compared by assessing the concordance between the results.

RESULTS

Of the 774 included high-risk pregnancies, 550 (71.1%) had a positive NIPS result, while a positive CMA result was detected in 308 (39.8%) cases. The rate of full or partial concordance between NIPS and CMA was 82.2%, 59.6% and 25.0% for trisomies 21, 18 and 13, respectively. For rare aneuploidies and segmental imbalances, NIPS and CMA results were fully or partially concordant in 7.5% and 33.3% of cases, respectively. Copy-number variants < 5 Mb were detected more often by CMA, with an incidence of 7.9% (61/774) compared with 3.1% (24/774) by NIPS. A genetic aberration was detected by CMA in 1 in 17 (5.8%) high-risk pregnancies that had a negative or non-reportable NIPS result.

CONCLUSION

CMA allows for comprehensive detection of genome-wide chromosomal abnormalities in high-risk pregnancies. CMA should be offered instead of expanded NIPS for high-risk pregnancies. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Parental expectations of raising a child with disability in decision-making for prenatal testing and termination of pregnancy: A mixed methods study

OBJECTIVE

To examine attitudes toward prenatal testing and termination of pregnancy (TOP) among parents and obstetric providers in relation to their views on raising a child with disability.

METHODS

An explanatory sequential mixed methods study. A survey among 274 parents and 141 providers was followed by interviews with 26 parents and 10 providers. Using multivariate analysis, the relationships between attitudes were examined. Thematic analysis was used to identify the reasons behind the attitudes.

RESULTS

In comparison with providers, parents reported more positive attitudes toward raising a child with disability and more moral views about TOP. Providers reported more variations in attitudes toward offering prenatal testing and TOP. Significant associations were found between attitudes toward prenatal testing, raising a child with disability, reproductive autonomy, and TOP. Three major themes were identified: (1) meanings of parenthood from genetic tests; (2) views toward TOP and parental responsibility; and (3) implications of advanced extended prenatal genetic testing.

CONCLUSIONS

Perceived social-cultural norms of disabilities and parental expectations of raising a child with disability influence decision-making regarding TOP.

PRACTICE IMPLICATIONS

As more conditions of the fetus are able to be detected, the social-cultural implications of the technology and disabilities need to be addressed in antenatal care.

Next-generation sequencing: a follow-up of 36,913 singleton pregnancies with noninvasive prenatal testing in central China

PURPOSE

To evaluate the noninvasive prenatal testing (NIPT) results of 36,913 cases in Jiangxi province of central China and explore its application value in prenatal screening and diagnosis.

METHODS

This retrospective analysis included 36,913 singleton pregnant women who underwent NIPT because of moderate-/high-risk pregnancy or voluntary requirements between January 2017 and December 2019 in our hospital. Chromosomal abnormalities such as trisomies 21, 18, and 13 (T21, T18, T13) and sex chromosome aneuploidies (SCAs) were judged by standard Z-score analysis. Positive NIPT results were confirmed by amniocentesis and karyotyping. Pregnancy outcomes were followed up via telephone interview.

RESULTS

A total of 1.01% (371/36,913) positive cases were detected by NIPT, comprising 137, 46, 31, and 157 cases of T21, T18, T13, and SCAs, respectively. A total of 116 of T21, 27 of T18, 13 of T13, and 51 of SCAs were confirmed to be true positive; all normal cases that had been followed up were verified to be true negative. The NIPT sensitivity in T21, T18, T13, and SCAs was 100.00% individually, whereas the specificity was 99.94% (36,488/36,509), 99.95% (36,579/36,598), 99.95% (36,594/36,612), and 99.72% (36,472/36,574), respectively. Furthermore, the negative predictive values of T21, T18, T13, and SCAs were all 100%, while the positive predictive values were 84.67%, 58.70%, 41.94%, and 33.33%, respectively.

CONCLUSION

NIPT is highly sensitive and has a low false positive rate in testing clinically significant fetal aneuploidies of general reproductive women. However, this technique cannot substitute for amniocentesis and karyotyping, and detailed genetic counseling is also essential for the high-risk group of NIPT.

Optimization Protocol of Fixation Method for Trophoblast Retrieval from the Cervix (TRIC): A Preliminary Study

Extravillous trophoblast cells (EVTs) secreted by the uterine cavity may help overcome limitations associated with prenatal testing currently in use. EVTs are isolated using a routine safe liquid-based Pap test (called ThinPrep); however, the ThinPrep solution contains alcohol that hinders the isolation of intact EVTs. We compared the trophoblastic cell isolation efficiency of two different methods of fixation: Thinprep (pre-fixation method) and formalin (post-fixation method). We analyzed EVTs from 20 pregnant women (5-20 weeks of gestation) who underwent invasive prenatal testing. The percentages of placental β-human chorionic gonadotropin (β-hCG)-expressing cells were calculated. The presence of XY chromosomes were used to confirm pure trophoblast cells by fluorescence in situ hybridization. The β-hCG-positive cells obtained from pre- and post-fixation were 66.4 ± 13.3% and 83.2 ± 8.1% (p = 0.003), respectively, and fluorescence-positive cells were 11.1 ± 2.1% and 23.8 ± 4.8%, respectively (p = 0.001). Post-fixation was found to be more efficient in isolating non-trophoblast cells than pre-fixation. For the successful clinical application of trophoblast retrieval and isolation from the cervix in prenatal genetic testing, each step should be optimized for consistent and reliable results.

Women's choices in non-invasive prenatal testing for aneuploidy screening: results from a single centre prior to introduction in England

OBJECTIVE

To evaluate patient choices and uptake of non-invasive prenatal testing (NIPT) for aneuploidy screening offered in a contingency model as part of routine care.

METHOD

We retrospectively reviewed data for all women with a singleton pregnancy attending for routine first trimester screening over an 18-month period. Women with a 'high-chance' of trisomy 21, 18 or 13 (≥1:150) were offered the choice of no further testing, NIPT or invasive testing, in line with the screening pathway recommended by the UK National Screening Committee.

RESULTS

Of 9342 women attending for a first trimester ultrasound scan, 7939 women were included in this study. Of these, 352 had a high-chance screening result for trisomy 21, and 291 (82.7%) opted for NIPT. The proportion of women opting for NIPT decreased as the chance of trisomy 21 increased: uptake was 93.2%, 90.0%, 77.1% and 47.2% for women with a chance of 1:100-150, 1:50-99, 1:10-49 and >1:10, respectively. 516 women (5.5%) accessed primary NIPT screening in the private sector, and 638 women (6.8%) declined any aneuploidy screening or testing.

CONCLUSION

Implementation of NIPT testing in a contingency model has a high uptake in a non-research National Health Service setting; the rate of uptake is related to the combined test risk result.

Characteristics and mode of inheritance of pathogenic copy number variants in prenatal diagnosis

BACKGROUND

Microdeletions and microduplications can occur in any pregnancy independent of maternal age. The spectrum and features of pathogenic copy number variants including the size, genomic distribution, and mode of inheritance are not well studied. These characteristics have important clinical implications regarding expanding noninvasive prenatal screening for microdeletions and microduplications.

OBJECTIVES

The aim was to investigate the spectrum and characteristics of pathogenic copy number variants in prenatal genetic diagnosis and to provide recommendations for expanding the scope of noninvasive prenatal screening for microdeletions and microduplications.

STUDY DESIGN

This was a retrospective study of 1510 pregnant women who underwent invasive prenatal diagnostic testing by chromosomal microarray analysis. Prenatal samples were retrieved by amniocentesis or chorionic villus sampling and sent to our prenatal genetic diagnosis laboratory for chromosomal microarray analysis. The risk of carrying a fetus with pathogenic copy number variants is stratified by the patients' primary indication for invasive testing. We searched the literature for published prenatal chromosomal microarray data to generate a large cohort of 23,865 fetuses. The characteristics and spectrum of pathogenic copy number variants including the type of aberrations (gains or losses), genomic loci, sizes, and the mode of inheritance were studied.

RESULTS

Overall, 375 of 23,865 fetuses (1.6%) carried pathogenic copy number variants for any indication for invasive testing, and 44 of them (11.7%) involve 2 or more pathogenic copy number variants. A total of 428 pathogenic copy number variants were detected in these fetuses, of which 280 were deletions and 148 were duplications. Three hundred sixty (84.1%) were less than 5 Mb in size and 68 (15.9%) were between 5 and 10 Mb. The incidence of carrying a pathogenic copy number variant in the high-risk group is 1 in 36 and the low-risk group is 1 in 125. Parental inheritance study results were available for 311 pathogenic copy number variants, 71 (22.8%) were maternally inherited, 36 (11.6%) were paternally inherited, and 204 (65.6%) occurred de novo.

CONCLUSION

Collectively, pathogenic copy number variants are common in pregnancies. High-risk pregnancies should be offered invasive testing with chromosomal microarray analysis for the most comprehensive investigation. Detection limits on size, parental inheritance, and genomic distribution should be carefully considered before implementing copy number variant screening in expanded noninvasive prenatal screening.

Women's Attitudes Toward Invasive and Noninvasive Testing When Facing a High Risk of Fetal Down Syndrome

IMPORTANCE

Noninvasive prenatal testing (NIPT) using cell-free DNA in maternal blood is increasingly common compared with invasive testing (IT) in routine antenatal detection of Down syndrome (DS).

OBJECTIVE

To assess attitudes and decision making in pregnant women facing a risk of fetal DS greater than 1 in 250 as established by combined first trimester screening at 11 to 14 weeks of gestation.

DESIGN, SETTING, AND PARTICIPANTS

Survey study in which data were collected from pregnant women at high risk of fetal DS participating in a randomized clinical trial. Data were collected from April 8, 2014, to April 7, 2016, in 57 prenatal diagnosis centers in France. Data were analyzed in 2018.

INTERVENTIONS

Data on attitudes were collected prior to offering randomization between NIPT and IT, whereas data on decision making and test results were collected as part of the clinical trial.

MAIN OUTCOME AND MEASURES

The primary outcome related to attitudes. A hierarchical cluster analysis was conducted to identify clusters with contrasting attitudes. Logistic regression analyses were used to identify factors associated with attitudes.

RESULTS

All 2436 consecutive women to whom the study was proposed (mean [SD] age, 36.3 [5.0] years) answered the questionnaire: 515 (21.1%) expressed preference toward IT with complete karyotyping, whereas 1843 (75.7%) favored NIPT with almost certain but limited information. Hierarchical cluster analysis yielded 4 different clusters that mainly differed in attitudes toward risk taking and extent of information seeking. Factors likely associated with attitudes driven by risk aversion were mostly age and religious beliefs (adjusted odds ratio [aOR], 1.03; 95% CI, 1.00-1.05; P = .03 and aOR, 1.62; 95% CI, 1.29-2.04; P < .001, respectively), whereas higher nuchal translucency measurements by ultrasonography were associated with attitudes driven by ambiguity aversion (aOR, 1.67; 95% CI, 1.27-2.20; P < .001). For attitudes involving both risk and ambiguity aversion at different extents, lower education was associated with highly valuing all possibilities of getting information on pregnancy, whereas higher education was associated with highly valuing information on fetal DS as a primary concern (aOR, 0.54; 95% CI, 0.44-0.67; P < .001 and aOR, 1.44; 95% CI, 1.20-1.74; P < .001, respectively). In all, decision making was in line with attitudes.

CONCLUSIONS AND RELEVANCE

Aversion to risk of fetal loss related to IT and aversion to ambiguity generated by incomplete information from NIPT played a major role in shaping attitudes and decision making. Informed decision making should require pregnant women at high risk of DS to receive extensive information on targeted abnormalities by both tests.

The indications for early prenatal diagnosis of trisomy 18: a 7-year experience at mainland China

Objective: To report the experience with first-trimester prenatal detection of pregnancies complicated by trisomy 18.Study design: Proven cases of trisomy 18 identified between 11 and 14 weeks of gestation were retrospectively reviewed. Information on maternal demographics, prenatal sonographic findings, indications for prenatal diagnosis and chromosomal analysis results was obtained by reviewing medical records.Results: During the 7-year period from January 2011 to December 2017, 89 cases of full trisomy 18 had first-trimester indications for prenatal diagnosis at Guangzhou Women and Children's Medical Center. Eighty-five (95.5%) had abnormal sonographic findings in the first trimester. The most common finding was increased nuchal translucency (55.1%), followed by cystic hygroma (18.0%), omphalocele (14.6%), and fetalis hydrops (11.2%). Four cases (4.5%) were not associated with any abnormal first-trimester sonographic finding, and were diagnosed because of routine positive screening results for trisomy 18. A single case was diagnosed because of a positive cell-free DNA (cfDNA) result.Conclusion: These results demonstrate that a large number of fetuses with trisomy 18 have abnormal sonographic findings in the first trimester, and support the continued utility of first-trimester sonographic examination in the diagnosis of this trisomy even with the availability of cfDNA.