Non-invasive Prenatal Testing Screening Research Articles

Combined first-trimester screening and invasive diagnostics for atypical chromosomal aberrations: Danish nationwide study of prenatal profiles and detection compared with NIPT.

Our aim was to examine the prenatal profiles of pregnancies affected by an atypical chromosomal aberration, focusing on pathogenic copy-number variants (pCNVs). We also wanted to quantify the performance of combined first-trimester screening (cFTS) and a second-trimester anomaly scan in detecting these aberrations. Finally, we aimed to estimate the consequences of a policy of using non-invasive prenatal testing (NIPT) rather than invasive testing with chromosomal microarray analysis (CMA) to manage pregnancies identified as high risk by cFTS. This was a retrospective review of the Danish Fetal Medicine Database of all pregnant women who underwent cFTS and a risk assessment for trisomy 21 between 1 January 2008 and 31 December 2018. Chromosomal aberrations diagnosed prenatally, postnatally or from fetal tissue following pregnancy loss or termination of pregnancy were identified. Chromosomal aberrations were grouped into one of six categories: triploidy; common trisomy (13, 18 or 21); monosomy X; other sex-chromosome aberration (SCA); pCNV; and rare autosomal trisomy (RAT) or mosaicism. The prevalence of each aberration category was stratified by the individual cFTS markers and trisomy 21 risk estimate, and the size of each pCNV diagnosed by CMA was calculated. We retrieved data on 565 708 pregnancies, of which 3982 (0.70%) were diagnosed with a fetal chromosomal aberration. cFTS identified 87% of the common trisomies, but it also performed well in identifying triploidies (86%), monosomy X (92%), atypical SCAs (58%) and RATs or mosaicisms (70%). pCNVs comprised 27% (n = 1091) of the chromosomal aberrations diagnosed overall, and the prevalence increased during the study period, as prenatal CMA was increasingly being performed. In pregnancies with a maternal age < 30 years, nuchal translucency (NT) thickness ≤ 95th centile, pregnancy-associated plasma protein-A (PAPP-A) ≥ 1 multiple of the median, or trisomy 21 risk of ≤ 1 in 1000, the prevalence of pCNVs exceeded significantly the prevalence of trisomies 21, 18 and 13. Pregnancies affected by a pCNV had significantly increased NT and decreased levels of the maternal biomarkers PAPP-A and β-human chorionic gonadotropin compared with unaffected pregnancies. However, only 23% of these pregnancies screened positive on cFTS and 51% of pCNVs were not detected until after birth. Among high-risk pregnancies, pCNVs comprised 14% of diagnosed aberrations, and when other atypical aberrations were considered, conventional NIPT (screening for trisomies 21, 18 and 13 and monosomy X) would miss 27% of all pathogenic aberrations diagnosed from invasive testing following a high-risk cFTS result. Thus, 1 in 26 pregnancies at high risk following cFTS would be affected by a chromosomal aberration despite a normal result from conventional NIPT. In a contingent screening model using NIPT for the 'intermediate'-risk group (trisomy 21 risk of 1 in 100-299), 50% of the aberrations would be missed. In our cohort, 79% of the pCNVs diagnosed were < 5Mb and therefore not detectable using current forms of 'genome-wide' NIPT. As a by-product of screening for trisomies 21, 18 and 13, most triploidies and the majority of atypical SCAs, RATs and mosaicisms are detected before birth. However, only 23% of pCNVs are associated with a high-risk result according to cFTS and only half are diagnosed before birth. Replacing invasive testing with NIPT for high-risk pregnancies would substantially decrease the first-trimester detection of pathogenic chromosomal anomalies. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

The Effect of Self-Reported Race on Noninvasive Prenatal Screening Test Characteristics.

Low fetal fraction (FF) on cell-free DNA (cfDNA)-based noninvasive prenatal screening (NIPS) is a common etiology for indeterminate results. As maternal Black race is implicated as a risk factor for low FF and more indeterminate results, we sought to evaluate this association. This was a single-institution, retrospective cohort study of cfDNA-based NIPS performed between May 2017 and May 2022 with complete clinical data abstraction. We compared FF, indeterminate rates, and total cfDNA concentration among self-reported Black, White, and Other groups from NIPS results from 2017 to 2022 with full clinical data abstraction. Using linear regression and interaction testing, we evaluated associations between self-reported race, FF, indeterminate rate, and total cfDNA concentration. In total, 1,591 participants met the inclusion criteria; 70.8% (n = 1,126) self-identified as White, 6.9% (n = 110) as Black, and 22.3% (n = 355) self-identified with another race. Mean FF was not different between the White, Black, or Other groups (11.8 vs. 11.2 vs. 11.7%, respectively, p = 0.52). This remained true after adjusting for body mass index (BMI), gestational age (GA) at draw, and fetal sex (all p > 0.17). Interaction testing for FF and total cfDNA by race with BMI, GA at draw, and fetal sex demonstrated no effect modification. In our population, maternal self-identified race, particularly Black race, does not affect FF. Biological plausibility for race-based differences on clinical tests requires ongoing thoughtful consideration. · NIPS is widely used to screen for fetal aneuploidy.. · FF is an important test metric, and low FF is associated with adverse outcomes, like aneuploidy.. · In existing studies, Black race is implicated as a risk factor for lower FF.. · Our study found no differences in FF between groups by self-reported race.. · Biological plausibility for race-based differences on clinical tests requires ongoing consideration..

Should the scope of NIPT be limited by a 'threshold of seriousness'?

Non-invasive prenatal testing (NIPT) has the potential to screen for a wider range of genetic conditions than is currently possible at an early stage of pregnancy and with minimal risks. As such, there have been calls to apply a 'threshold of seriousness' to limit the scope of conditions being tested. This approach is based on concerns about society at large and the potential impact on specific groups within it. In this paper, we argue that limiting the scope of NIPT using the criterion of 'seriousness' is arbitrary, potentially stigmatises certain disabilities over others and fails to respect reproductive autonomy. We contend that concerns about expanded NIPT are more appropriately addressed by the provision of adequate information, counselling and consent procedures. We recommend a decision-making process that helps healthcare providers support prospective parents to make informed decisions about the nature and scope of NIPT screening based on their own values and social context. In addition to addressing concerns about expanded NIPT screening, this process would help clinicians to obtain legally valid consent and discharge their duty of care (including the duty to inform) in the prenatal context.

NIPT for adult-onset conditions: Australian NIPT users' views.

Noninvasive prenatal testing (NIPT) has become widely available in recent years. While initially used to screen for trisomies 21, 18, and 13, the test has expanded to include a range of other conditions and will likely expand further. This paper addresses the ethical issues that arise from one particularly controversial potential use of NIPT: screening for adult-onset conditions (AOCs). We report data from our quantitative survey of Australian NIPT users' views on the ethical issues raised by NIPT for AOCs. The survey ascertained support for NIPT for several traits and conditions including AOCs. Participants were then asked about their level of concern around implications of screening for AOCs for the future child and parent(s). Descriptive and comparative data analyses were conducted. In total, 109 respondents were included in data analysis. The majority of respondents expressed support for NIPT screening for preventable (70.9%) and nonpreventable AOCs (80.8%). Most respondents indicated concern around potential harmful impacts associated with NIPT for AOCs, including the psychological impact on the future child and on the parent(s). Despite this, the majority of participants thought that continuation of a pregnancy known to be predisposed to an AOC is ethically acceptable. The implications of these data are critically discussed and used to inform the normative claim that prospective parents should be given access to NIPT for AOCs. The study contributes to a body of research debating the ethical acceptability and regulation of various applications of NIPT as screening panels expand.

Clinical application of non-invasive prenatal testing for twin pregnancies

To evaluate the feasibility of non-invasive prenatal testing (NIPT) for the screening of fetal chromosome aneuploidies in twin pregnancies. A total of 2 745 women with twin-pregnancies were subjected for NIPT screening. Chromosomal karyotyping and chromosomal microarray analysis (CMA) were carried out on amniotic fluid samples from those with a high risk for fetal chromosome aneuploidies, and the diagnosis and pregnancy outcome were followed up. The sensitivity, specificity, positive predictive value and false positive rate of the NIPT were calculated. Compared with other chromosomal abnormalities, NIPT had a higher efficacy for trisomy 21 and sex chromosomal aneuploidy (SCA) in twin pregnancies (with sensitivity being 100%, 100%, and specificity being 99.93%, 99.9%, respectively). It is difficult to evaluate the efficacy for trisomies 18 and 13 due to the limited data. For chromosome microdeletions and microduplications spanning 15 ~ 21 Mb, NIPT also had a certain detection rate. Compared with women with natural conception, NIPT had a higher detection rate for those with twin pregnancies by assisted reproduction (P < 0.05). It is feasible to use NIPT for the detection of chromosome aneuploidies in women with twin pregnancies.

Patient Perceptions on the Advancement of Noninvasive Prenatal Testing for Sickle Cell Disease among Black Women in the United States

Background Noninvasive prenatal testing (NIPT) designed to screen for fetal genetic conditions, is increasingly being implemented as a part of routine prenatal care screening in the United States (US). However, these advances in reproductive genetic technology necessitate empirical research on the ethical and social implications of NIPT among populations underrepresented in genetic research, particularly Black women with sickle cell disease (SCD). Methods Forty (N = 40) semi-structured interviews were conducted virtually with Black women in the US (19 participants with SCD; 21 participants without SCD) from June 2021 to January 2022. We employed a qualitative approach to examine the study participants’ perceptions of the potential advancement of NIPT for screening SCD in the fetus. Data were analyzed using NVivo 12 qualitative software. Results The themes revealed the complexities involving the intersectional lived experiences of SCD, prenatal care, lack of synergy among health providers, and NIPT decision-making. The results further revealed that even when Black women have shared commonalities in their lived experiences while navigating SCD and motherhood, their perceptions of NIPT screening technologies are divergent. Conclusion Expanding the ethical discourse on the social implications of NIPT is critical to fully elucidate how Black women perceive NIPT’s utility, particularly as NIPT advances to screen for SCD in the fetus. Neglecting to include Black women with genetic conditions in empirical studies on NIPT may contribute to ongoing health inequities and limit and constrain reproductive choices among Black women with and without SCD.

Efficiency of Non-Invasive Prenatal Testing in Detecting Fetal Copy Number Variation: A Retrospective Cohort Study.

Screening of pathological copy number variations (CNVs) is important for early-diagnosis of hereditary disease. This study was designed to investigate the efficiency of non-invasive prenatal testing (NIPT) in detecting fetal CNVs. This retrospective analysis included fetuses with CNVs between January 2018 and December 2020. Karyotype analysis and CNV sequencing (CNV-seq) were performed. We then analyzed the positive predictive values of the subchromosomal microdeletions and microduplications. Fifty-eight subjects with aberrant CNVs were screened after NIPT, among which 44 finally underwent amniocentesis. CNV-seq confirmed the presence of CNVs in 24 cases. This indicated that false positivity rate of NIPT was 45.5%. Among 24 cases with CNVs after CNV-seq, only 4 showed consistent findings with karyotype analysis, which showed that karyotyping analysis yielded a missed diagnosis rate of 83.3% for the genome CNV. Positive predictive value (PPV) was 50.0% for CNVs with a length of <5 Mb after NIPT screening. PPV for CNVs with a length of 5 Mb-10 Mb was 33.3%, while that for CNVs with a length of ≥10Mb was 60%. For CNVs duplication after NIPT, the PPV was 65.2%, while that for deletion was 36.4%. For CNVs detected after NIPT, it should be combined with ultrasonographic findings, karyotype analysis, CNV-seq or CMA to determine the pregnancy outcome. Expanding NIPT may increase the risk of unnecessary invasive surgery and unintended selective termination of pregnancy.

Rapid non-invasive prenatal screening test for trisomy 21 based on digital droplet PCR

Non-invasive prenatal tests for the detection of fetal aneuploidies are predominantly based on the analysis of cell-free DNA (cfDNA) from the plasma of pregnant women by next-generation sequencing. The development of alternative tests for routine genetic laboratories is therefore desirable. Multiplex digital droplet PCR was used to detect 16 amplicons from chromosome 21 and 16 amplicons from chromosome 18 as the reference. Two fluorescently labeled lock nucleic acid probes were used for the detection of reaction products. The required accuracy was achieved by examining 12 chips from each patient using Stilla technology. The plasma cfDNA of 26 pregnant women with euploid pregnancies and 16 plasma samples from pregnancies with trisomy 21 were analyzed to determine the cutoff value for sample classification. The test was validated in a blind study on 30 plasma samples from pregnant patients with a risk for trisomy 21 ranging from 1:4 to 1:801. The results were in complete agreement with the results of the invasive diagnostic procedure (sensitivity, specificity, PPV, and NPV of 100%). Low cost, and speed of analysis make it a potential screening method for implementation into the clinical workflow to support the combined biochemical and ultrasound results indicating a high risk for trisomy 21.

Report content and prenatal diagnosis of non-invasive prenatal testing for sex chromosome aneuploidy

Objective: To analyze the report content, the methods and results of prenatal diagnosis of high risk of sex chromosome aneuploidy (SCA) in non-invasive prenatal testing (NIPT). Methods: A total of 227 single pregnancy pregnant women who received genetic counseling and invasive prenatal diagnosis at Drum Tower Hospital Affiliated to the Medical School of Nanjing University from January 2015 to April 2022 due to the high risk of SCA suggested by NIPT were collected. The methods and results of prenatal diagnosis were retrospectively analyzed, and the results of chromosome karyotype analysis and chromosome microarray analysis (CMA) were compared. The relationship between NIPT screening and invasive prenatal diagnosis was analyzed. Results: (1) Prenatal diagnosis methods for 277 SCA high risk pregnant women included 73 cases of karyotyping, 41 cases of CMA and 163 cases of karyotyping combined with CMA, of which one case conducted amniocentesis secondly for further fluorescence in situ hybridization (FISH) testing. Results of invasive prenatal diagnosis were normal in 166 cases (59.9%, 166/277), and the abnormal results including one case of 45,X (0.4%, 1/277), 18 cases of 47,XXX (6.5%, 18/277), 36 cases of 47,XXY (13.0%, 36/277), 20 cases of 47,XYY (7.2%, 20/277), 1 case of 48,XXXX (0.4%, 1/277), 20 cases of mosaic SCA (7.2%, 20/277), 5 cases of sex chromosome structural abnormality or large segment abnormality (1.8%, 5/277), and 10 cases of other abnormalities [3.6%, 10/277; including 9 cases of copy number variation (CNV) and 1 case of balanced translocation]. Positive predictive value (PPV) for SCA screening by NIPT was 34.7% (96/277). (2) Among the 163 cases tested by karyotyping combined with CMA, 11 cases (6.7%, 11/163) showed inconsistent results by both methods, including 5 cases of mosaic SCA, 1 case of additional balanced translocation detected by karyotyping and 5 cases of additional CNV detected by CMA. (3) NIPT screening reports included 149 cases of "sex chromosome aneuploidy"(53.8%, 149/277), 54 cases of "number of sex chromosome increased" (19.5%, 54/277), and 74 cases of "number of sex chromosome or X chromosome decreased" (26.7%, 74/277). The PPV of "number of sex chromosome increased" and "number of sex chromosome or X chromosome decreased" were 72.2% (39/54) and 18.9% (14/74), respectively, and the difference was statistically significant (χ2=34.56, P<0.01). Conclusions: NIPT could be served as an important prenatal screening technique of SCA, especially for trisomy and mosaicism, but the PPV is comparatively low. More information of NIPT such as the specific SCA or maternal SCA might help improving the confidence of genetic counseling and thus guide clinic management. Multi technology platforms including karyotyping, CMA and FISH could be considered in the diagnosis of high risk of SCA by NIPT.

The predictive value of noninvasive prenatal screening for copy number variations: a cohort study and a systematic meta-analysis

ABSTRACT Objective To assess the diagnostic accuracy of noninvasive prenatal screening (NIPS) in screening for copy number variations (CNVs). Methods We conducted a systematic review and meta-analysis by combining our study results with those reported in other articles. We retrospectively collected the data of pregnant women with NIPS testing in the Hangzhou Women’s Hospital from December 2019 to February 2022. Simultaneously, a systematic search of PubMed, EMBASE, and Web of Science was carried out to identify all relevant peer-reviewed publications. Statistical analysis was performed based on the random-effects model to determine a pooled estimate of the positive predictive value (PPV). Results A total of 29 studies involving 2,667 women were included for analysis. The pooled PPV of NIPS in the detection of CNVs was 32.86% (95% confidence interval [24.61–41.64]). Statistical heterogeneity was high, while no significant publication bias was found in this meta-analysis. There were insufficient data to accurately determine sensitivity and specificity, as most studies only performed confirmatory tests on high-risk women. Conclusions The PPV of NIPS in screening for CNVs was approximately 33%. Cautions should be kept in mind for the pretest guidance and subsequent after-test counseling when offering such genome-wide NIPS tests.

Exploration of factors for failure of non-invasive prenatal testing based on Logistic regression analysis

To explore the factors for the failure of non-invasive prenatal testing (NIPT) through multifactorial unconditional Logistic regression analysis. A total of 3 410 pregnant women who had visited Dalian Women and Children Medical Group from July 2019 to June 2020 were selected as the study subjects and divided into first success NIPT group (n = 3 350) and first failed group (n = 60). Clinical data including age, weight, body mass index (BMI), gestational week, type of pregnancy (singleton/twin), history of delivery, heparin treatment, and conception method [natural conception/assisted reproductive technology (ART)] were collected. Independent sample t-test and Chi-square test were carried out for comparing the two groups, and multi-factorial unconditional Logistic regression analysis was carried out to explore the factors for the failure of NIPT, and receiver operating characteristic curve (ROC) analysis was used to evaluate the diagnosis and predictive effects. Among the 3 410 pregnant women, 3 350 were assigned to the first success NIPT group, and 60 were assigned to the first failed group, and the first-time failure rate was 1.76% (60/3 410). No significant difference was found in age, weight, BMI and method of conception between the two groups (P > 0.05). Compared with first success group, first failed group had lower sampling gestational weeks, lower proportion of women with previous history of delivery, and higher proportion of twin pregnancies and heparin treatment (P < 0.05). Multi-factorial unconditional Logistic regression analysis indicated that sampling gestational week (OR = 0.931, 95%CI: 0.845 ~ 1.026, P < 0.001) and history of heparin use (OR = 8.771, 95%CI: 2.708 ~ 28.409, P < 0.001) are independent factors for first failed NIPT. One-way unconditional Logistic regression analysis for sampling gestational weeks indicated that the regression equation for NIPT screening failure was Logit (P) = -9.867 + 0.319 × sampling gestational week, with the area under the ROC curve being 0.742, a Jordan index of 0.427, and a cutoff value of 16.36 weeks. Gestational week and heparin treatment are independent factors for the first failed NIPT. A regression equation has been established and determined the optimal sampling gestational week to be 16.36 weeks, which may provide a reference for the timing of NIPT screening.

Noninvasive prenatal screening and maternal malignancy: role of imaging.

Noninvasive prenatal screening (NIPS) tests for fetal chromosomal anomalies through maternal blood sampling. It is becoming widely available and standard of care for pregnant women in many countries. It is performed in the first trimester of pregnancy, usually between 9 and 12weeks. Fragments of fetal cell-free deoxyribonucleic acid (DNA) floating in maternal plasma are detected and analyzed by this test to assess for chromosomal aberrations. Similarly, maternal tumor-derived cell-free DNA (ctDNA) released from the tumor cells also circulates in the plasma. Hence, the presence of genomic anomalies originating from maternal tumor-derived DNA may be detected on the NIPS-based fetal risk assessment in pregnant patients. Presence of multiple aneuploidies or autosomal monosomies are the most commonly reported NIPS abnormalities detected with occult maternal malignancies. When such results are received, the search for an occult maternal malignancy begins, in which imaging plays a crucial role. The most commonly detected malignancies via NIPS are leukemia, lymphoma, breast and colon cancers. Ultrasound is a reasonable radiation-free modality for imaging during pregnancy, specially when there are localizing symptoms or findings, such as palpable lumps. While there are no consensus guidelines on the imaging evaluation for these patients, when there are no localizing symptoms or clinically palpable findings, whole body MRI is recommended as the radiation-free modality of choice to search for an occult malignancy. Based on clinical symptoms, practice patterns, and available resources, breast ultrasound, chest radiographs, and targeted ultrasound evaluations can also be performed initially or as a follow-up for MRI findings. CT is reserved for exceptional circumstances due to its higher radiation dose. This article intends to increase awareness of this rare but stressful clinical scenario and guide imaging evaluation for occult malignancy detected via NIPS during pregnancy.

Clinical application of noninvasive prenatal testing in twin pregnancies: a single-centre experience

Objectives To evaluate the clinical efficiency of non-invasive prenatal testing (NIPT) for fetal chromosomal aneuploidy screening in twin pregnancies. Methods A total of 1650 women with twin pregnancies were enrolled in the study, which underwent NIPT at the Southwest Hospital, Army Medical University, Chongqing, China from January 2013 to June 2022. Fetal karyotyping analysis was conducted in high-risk patients, with subsequent follow-up on pregnancy outcomes. Results In 1650 pregnancies, NIPT results showed ten cases of the fetal chromosome aneuploidy, of which six cases were true positive and four cases were false positive. The sensitivity, specificity, positive predictive value (PPV), and false-positive rate (FPR) of trisomy 21 were 100%, 99.79%, 57.14%, and 0.18%, respectively. Sensitivity, specificity, PPV, and FPR of trisomy 18 were 100%, 99.94%, 50%, and 0.06%, respectively. The sensitivity, specificity, PPV, and FPR of trisomy 13 were 100%, 100%, 100%, and 0%, respectively. No false negatives were detected and the negative predictive value (NPV) was 100% of the total. Eleven pregnancies failed the NIPT test with no-call due to the low fetal fraction (< 4%). Conclusions NIPT is a high-performing routine primary prenatal screening test in twin pregnancies, with high sensitivity and specificity in screening for fetal aneuploidy.

Clinical application and evaluation of health economics for non-invasive prenatal testing of fetuses in Tianjin

To assess the clinical efficacy and health economic value of non-invasive prenatal testing (NIPT) for the prenatal screening of common fetal chromosomal aneuploidies. 10 612 pregnant women from October 2017 to December 2019 presented at the antenatal screening clinic of the General Hospital of Tianjin Medical University were selected as the study subjects. Results of NIPT and invasive prenatal diagnosis and follow-up outcome for the 10 612 pregnant women were retrospectively analyzed and compared. Meanwhile, NIPT data for two periods were analyzed for assessing the health economic value of NIPT as the second- or first-tier screening strategy for the prenatal diagnosis of fetal trisomies 21, 18 and 13. The NIPT was successful in 10 528 (99.72%) subjects, with the sensitivity for fetal trisomies 21, 18 and 13 being 100%, 92.86% and 100%, and the positive predictive value (PPV) being 89.74%, 61.90% and 44.44%, respectively. The PPV of NIPT for sex chromosome aneuploidies was 34.21%. Except for one false negative case of trisomy 18, the negative predictive value for trisomy 21, trisomy 13 and other chromosomal abnormalities were 100%. For pregnant women with high risk by serological screening, advanced maternal age or abnormal ultrasound soft markers, NIPT has yielded a significantly increased high risk ratio. There was no statistical difference in the PPV of NIPT among pregnant women from each subgroup. NIPT would have higher health economic value as a second-tier screening until 2019, while compared to 2015 ~ 2017, its incremental cost-effectiveness ratio as a first-tier screening had declined clearly. The screening efficacy of NIPT for trisomies 21, 18 and 13 for a mixed population is significantly better than conventional serological screening, but it is relatively low for sex chromosomal abnormalities. NIPT can also be recommended for populations with relatively high risks along with detailed pre- and post-test genetic counselling. From the perspective of health economics, except for open neural tube defects, it is possible for NIPT to replace the conventional serological screening in the future as its cost continues to decrease.

The uncertainty of copy number variants: pregnancy decisions and clinical follow-up

Next-generation sequencing for copy number variants is often used as a follow-up investigation of unusual fetal ultrasound results and is capable of detecting copy number variations with a resolution of ∼0.1 Mb. In a prenatal setting, observation and subsequent management of pregnancies with a fetal variant of uncertain significance remains problematic for counseling. This study aimed to follow the decision-making processes in pregnancies with a fetal variant of uncertain significance and prospectively assess copy number variation interpretations and implications under the newer 2020 American College of Medical Genetics and Genomics guidelines. In a single prenatal unit, prospective chromosome testing using copy number variation sequencing for 8030 fetuses with unexpected noninvasive findings identified 139 pregnancies with a copy number variation classified as a variant of uncertain significance according to the 2015 American College of Medical Genetics and Genomics guidelines current at the time. Parent-of-origin testing was subsequently performed to determine if the copy number variation was inherited or de novo. All couples were offered specialized genetic counseling to assist in pregnancy management decisions. For the continued pregnancies that reached term, newborns were clinically assessed for evidence of any disease at 0 to 10 months and/or at 2 to 4 years of age. Of the 139 variants of uncertain significance found, most (78%) were inherited with no evidence of disease in the carrier parent. On the basis of primary ultrasound findings combined with results from noninvasive prenatal screening tests, most inherited variant of uncertain significance pregnancies were continued, whereas most pregnancies involving de novo variants of uncertain significance were terminated. From clinical follow-up of the 113 live births, only 5 showed any evidence of a phenotype that was not apparently related to the original variant of uncertain significance. Prospective reanalysis of the 139 variants of uncertain significance using recent 2020 American College of Medical Genetics and Genomics guidelines changed the status of 24 variants of uncertain significance, with 15 reclassified as benign and 9 as pathogenic. However, the 5 children born with an inherited variant of uncertain significance reclassified as pathogenic showed no evidence of a disease phenotype on clinical follow-up. The severity of fetal ultrasound findings combined with results from parent-of-origin testing were the key drivers in pregnancy management decisions for patients. According to birth outcomes from continued pregnancies, most variants of uncertain significance proved to be apparently benign in nature and potentially of low risk of adverse disease outcome. There was a discordance rate of 17% for variant of uncertain significance scoring between the 2015 and 2020 American College of Medical Genetics and Genomics guidelines for defining a variant of uncertain significance, suggesting that difficulties remain for predicting true pathogenicity. Nonetheless, with increasing knowledge of population copy number variation polymorphisms, and a more complete assessment for alternative genetic causes, patients having prenatal assessments should feel less anxious when a fetal variant of uncertain significance is identified.

Non-invasive prenatal testing for everybody or contingent screening?

To compare the advantages and disadvantages of two main implementation strategies for non-invasive prenatal testing (NIPT) for the detection of trisomies 21, 13 and 18 in public healthcare settings. These concern NIPT as a first-tier screening test for all pregnant women, or NIPT contingent on an increased risk first-trimester combined test (FCT) result. Comparison based on (un)published data and literature. Despite the lower prevalence of trisomies in the low-risk population, data show that the positive predictive value (PPV) and detection-miscarriage ratio of first-tier NIPT are comparable to NIPT used as contingency test. Advantages of NIPT as a first-tier test compared to FCT with contingent NIPT are that there is no time-window for testing, sensitivity is higher, fewer women need follow-up testing (PPV of NIPT is higher than PPV of FCT), less anxiety for pregnant women and partners. When given the choice, pregnant women prefer first-tier NIPT. Although contingency testing still seems to be the cheaper option, the differences in costs are becoming increasingly smaller and might soon disappear. We argue that NIPT should preferably be offered as a first-tier test for the detection of fetal aneuploidies for all pregnant women, provided that women are supported to make informed decisions. This article is protected by copyright. All rights reserved.

Clinical evaluation of true and false positive Z values among high-risk cases screened by non-invasive prenatal testing

To analyze the Z values of true and false positive cases by non-invasive prenatal testing (NIPT) in order to improve its accuracy in clinical practice. Results of 24 384 NIPT tests were reviewed. For cases with high risks for trisomies 21, 18 and 13, the range of Z values in true and false positive cases was analyzed and discussed. A total of 335 high-risk cases were identified by NIPT, among which 256 had elected prenatal diagnosis, 153 (59.77%) were verified as true positives, and 103 (40.23%) were false positives, and the area under the curve (AUC) was 0.9994. For NIPT screening, the positive predictive value (PPV) for trisomy 21 was 100% when Z>13, regardless if the pregnant woman was over 35. When 3<Z<13, the PPV for trisomy 21 was 80% (8/10) for those>35 and about 41.6% (5/12) for those<35. For trisomy 18, the PPV was 100% when Z>13, and only 14.3% (1/7) when 3<Z<13. NIPT showed that the positive predictive value of trisomy 13 was only 6.67% (1/15) when the trisomy 13 Z value was more than 20, the positive predictive value was 100% , and the trisomy 13 Z value was 3<Z<20. NIPT is a technique similar to prenatal diagnosis and has a high positive predictive value for trisomies 18 and 21. Proper classification and division of the high-risk Z value of NIPT can further improve the positive predictive values for trisomies 21, 18 and 13 in different intervals, and is more helpful to guide clinicians in genetic counseling for high-risk pregnant women. Meanwhile, the compliance of prenatal diagnosis in high risk NIPT pregnant women with Z value between 3~13 was improved.

A study on non-invasive prenatal screening for the detection of aneuploidy.

To explore the feasibility of clinical application of non-invasive prenatal screening to detect aneuploidy diseases. A total of 14,574 singleton pregnant women who underwent Non-invasive prenatal testing (NIPT) in the Southern Hospital from 2015 to June 2017 were selected, and 6471 pregnant women with twin pregnancy who underwent NIPT in the laboratory of Bei Rui He Kang Southern Hospital from June 2016 to October 2017 were included in this study. We analyzed NIPT screening efficiency (sensitivity, specificity) in twin pregnancies and singleton pregnancies, compared the positive detection rate of NIPT in patients with or without clinical symptoms. All NIPT high-risk results were validated by karyotyping, which were further verified by the follow-up physical examination of the neonatal. A total of 68 cases of twin pregnancy abnormalities were detected by NIPT, including 18 cases of trisomy 21, 6 cases of trisomy 18, 1 case of trisomy 13, 39 cases of Spinocerebellar ataxias (SCAs), and 4 cases of other chromosomal abnormalities. The sensitivity for trisomy 21, 18, and 13 and sex chromosome abnormality was 100%; the specificity for trisomy 21, 18, and 13 and sex chromosome abnormality was 99.97%, 99.95%, 99.97%, and 99.91% respectively. The screening efficiency was similar to that of singleton pregnancy, indicating that the NIPT technology in our laboratory for screening for aneuploidy diseases in twin pregnancy has reached the accuracy level of singleton pregnancy screening. There was a statistical difference between the risk group and the non-risk group in pregnant women with singleton pregnancy. The screening efficiency of NIPT was higher in pregnant women in the risk group, which implies that the clinical application of NIPT is inclined to detect high-risk group. Non-invasive prenatal testing (NIPT) is a rapid and safe screening method with high efficiency. Non-invasive prenatal testing (NIPT) is used for the screening of aneuploidy in twin pregnancy. The efficiency is similar to that of singleton pregnancy, indicating the feasibility of clinical application. However, the efficiency of NIPT screening tends to favor the detection in high-risk groups.

O59 - Psychological benefits and harms of Non-Invasive Prenatal Screening (NIPS): Women’s perspectives

Non-invasive prenatal screening (NIPS) is being increasingly used by expectant parents. Much provision of this test in Australia is occurring in clinical settings where specialised genetic counselling is unavailable. Potential psychosocial consequences of NIPS remain largely unexplored. This study aimed to understand potential psychosocial consequences from prenatal genetic screening tests. We conducted a thematic analysis of semi-structured qualitative interviews with 16 women who received an increased-chance prenatal screening (NIPS, combined first trimester screening, or morphology scan) result. All participants had NIPS as a first line screening test (n=12) or contingent screening test after receiving an increased chance results from another screening test (n=4). Women held positive opinions of NIPS and discussed the need for it to be covered by Medicare. However, some received inadequate pre-test counselling which potentially contributed to negative psychosocial consequences, including increased self-reported anxiety and distress. Several women were unaware of the conditions that NIPS screened for, particularly SCA and microdeletions and were subsequently surprised when they received increased-chance results. False positive results caused some women to feel that bonding with their baby had been significantly disrupted in the period between receiving an increased chance screening result and receiving their contingent NIPS and/or diagnostic testing results. Women discussed several strategies that would have made their experience receiving an increased-chance screening result easier, including better information provision about the conditions tested for, and the possible consequences of an increased-chance screening result, particularly for conditions beyond the three common trisomies. Our results indicate that some expectant parents are not fully informed of the scope and implications of NIPS prior to testing. This may prevent them from making fully considered choices that reflect their personal values and aspirations for parenthood. Better pre-test counselling may facilitate informed decision-making and improve prospective parents’ experiences.

False-positives and false-negatives in non-invasive prenatal testing (NIPT): what can we learn from a meta-analyses on > 750,000 tests?

BackgroundNon-invasive prenatal testing (NIPT) has had an incomparable triumph in prenatal diagnostics in the last decade. Over 1400 research articles have been published, predominantly praising the advantages of this test.MethodsThe present study identified among the 1400 papers 24 original and one review paper, which were suited to re-evaluate the efficacy of > 750,000 published NIPT-results. Special attention was given to false-positive and false-negative result-rates. Those were discussed under different aspects—mainly from a patient-perspective.ResultsA 27: 1 rate of false-positive compared to false-negative NIPT results was found. Besides, according to all reported, real-positive, chromosomally aberrant NIPT cases, 90% of those would have been aborted spontaneously before birth. These findings are here discussed under aspects like (i) How efficient is NIPT compared to first trimester screening? (ii) What are the differences in expectations towards NIPT from specialists and the public? and (iii) There should also be children born suffering from not by NIPT tested chromosomal aberrations; why are those never reported in all available NIPT studies?ConclusionsEven though much research has been published on NIPT, unbiased figures concerning NIPT and first trimester screening efficacy are yet not available. While false positive rates of different NIPT tests maybe halfway accurate, reported false-negative rates are most likely too low. The latter is as NIPT-cases with negative results for tested conditions are yet not in detail followed up for cases with other genetic or teratogenic caused disorders. This promotes an image in public, that NIPT is suited to replace all invasive tests, and also to solve the problem of inborn errors in humans, if not now then in near future. Overall, it is worth discussing the usefulness of NIPT in practical clinical application. Particularly, asking for unbiased figures concerning the efficacy of first trimester-screening compared to NIPT, and for really comprehensive data on false-positive and false-negative NIPT results.