A statistical investigation of parameters associated with low cell-free fetal DNA fraction in maternal plasma for noninvasive prenatal testing.

BACKGROUND: Noninvasive prenatal testing (NIPT) is the most common method for prenatal aneuploidy screening. Low fetal fraction (LFF) is the primary reason for NIPT failure. Consequently, factors associated with LFF should be elucidated for optimal clinical implementation of NIPT. METHODS: In this study, NIPT data from January 2019 to December 2022 from the laboratory records and obstetrical and neonatal data from the electronic medical records were collected and analyzed. Subjects with FF >3.50% were assigned to the control group, subjects with FF <3.50% once were assigned to the LFF group, and subjects with FF <3.50% twice were assigned to the repetitive low fetal fraction (RLFF) group. Factors, including body mass index (BMI), gestational age, maternal age, twin pregnancy, and in vitro fertilization (IVF) known to be associated with LFF were assessed by Kruskal-Wallis H test and logistic regression. Clinical data on first trimester pregnancy-associated plasma protein-A (PAPP-A), beta-human chorionic gonadotropin (ß-hCG), gestational age at delivery, birth weight at delivery, and maternal diseases were obtained from the hospital's prenatal and neonatal screening systems (twin pregnancy was not included in the data on gestational age at delivery and the control group did not include data on maternal diseases.), and were analyzed using Kruskal-Wallis H test and Chi-square test. RESULTS: Among the total of 63,883 subjects, 63,605 subjects were assigned to the control group, 197 subjects were assigned to the LFF group, and 81 subjects were assigned to the RLFF group. The median of BMI in the three groups was 22.43 kg/m2 (control), 25.71 kg/m2 (LFF), and 24.54 kg/m2 (RLFF). The median gestational age in the three groups was 130 days (control), 126 days (LFF), and 122/133 days (RLFF). The median maternal age in the three groups was 29 (control), 29 (LFF), and 33-years-old (RLFF). The proportion of twin pregnancies in the three groups was 3.3% (control), 10.7% (LFF), and 11.7% (RLFF). The proportion of IVF in the three groups was 4.7% (control), 11.7% (LFF), and 21.3% (RLFF). The factors significantly associated with LFF included BMI [2.18, (1.94, 2.45), p < 0.0001], gestational age [0.76, (0.67, 0.87), p < 0.0001], twin pregnancy [1.62, (1.02, 2.52), p = 0.0353], and IVF [2.68, (1.82, 3.86), p < 0.0001]. The factors associated with RLFF included maternal age [1.54, (1.17, 2.05), p = 0.0023] and IVF [2.55, (1.19, 5.54), p = 0.016]. Multiples of the median (MOM) value of ß-hCG and pregnant persons' gestational age at delivery were significantly decreased in the LFF and RLFF groups compared to the control group. CONCLUSION: According to our findings based on the OR value, factors associated strongly with LFF include a high BMI and the use of IVF. Factors associated less strongly with LFF include early gestational age and twin pregnancy, while advanced maternal age and IVF were independent risk factors for a second LFF result.

Body mass index, gestational age, maternal age, twin pregnancy, and in vitro fertilization are associated with fetal fraction. We added the repetitive low fetal fraction population and used a large normal population as a control to identify the main factors associated with low fetal fraction.

Performance Evaluation of Noninvasive Prenatal Testing in Screening Chromosome Disorders: A Single-Center Observational Study of 15,304 Consecutive Cases in China.

Objective: This study was to evaluate the performance of noninvasive prenatal testing (NIPT) in detecting fetal chromosome disorders in pregnant women. Methods: From October 1st, 2017, to December 31th, 2022, a total of 15,304 plasma cell free DNA-NIPT samples were collected for fetal chromosome disorders screening. The results of NIPT were validated by confirmatory invasive testing or clinical outcome follow-up. Further, NIPT performance between low-risk and high-risk groups, as well as singleton pregnancy and twin pregnancy groups was compared. Besides, analysis of 111 false-positive cases was performed. Results: Totally, NIPT was performed on 15,086 eligible venous blood samples, of which 179 (1.19%) showed positive NIPT results and 68 were further validated to be true positive samples via confirmatory invasive testing or follow-up of clinical outcomes. For common chromosome aneuploidies, sex chromosome abnormalities (SCA) and other chromosomal aneuploidies, the detection sensitivities of NIPT were all 100%, the specificities were 99.87%, 99.70%, and 99.68% and the positive predictive values (PPVs) were 65.45%, 31.82%, and 10.91%, respectively. No statistically significant variance in detection performance was observed among 2987 high-risk and 12,099 low-risk subjects, as well as singleton and twin pregnancy subjects. The concentration of cell-free fetal DNA of 111 false-positive cases ranged from 5.5% to 33.7%, which was higher than the minimum requirement of NIPT. Conclusion: With stringent protocol, NIPT shows high sensitivity and specificity for detecting fetal chromosome disorders in a large-scale clinical service, helping improving overall pregnancy management.

Clinical outcomes of screen-positive genome-wide cfDNA cases for trisomy 20: results from the global expanded NIPT Consortium.

Trisomy 20 has been shown to be one of the most frequent rare autosomal trisomies in patients that undergo genome-wide noninvasive prenatal testing. Here, we describe the clinical outcomes of cases that screened positive for trisomy 20 following prenatal genome-wide cell-free (cf.) DNA screening. These cases are part of a larger cohort of previously published cases. Members of the Global Expanded NIPT Consortium were invited to submit details on their cases with a single rare autosomal aneuploidy following genome-wide cfDNA screening for retrospective analysis. Clinical details including patient demographics, test indications, diagnostic testing, and obstetric pregnancy outcomes were collected. Genome-wide cfDNA screening was conducted following site-specific laboratory procedures. Cases which screened positive for trisomy 20 (n = 10) were reviewed. Clinical outcome information was available for 90% (9/10) of our screen-positive trisomy 20 cases; the case without diagnostic testing ended in a fetal demise. Of the nine cases with outcome information, one was found to have a mosaic partial duplication (duplication at 20p13), rather than a full trisomy 20. Only one case in the study cohort had placental testing; therefore, confined placental mosaicism could not be ruled out in most cases. Adverse pregnancy outcomes were seen in half of the cases, which could suggest the presence of underlying confined placental mosaicism or mosaic/full fetal trisomy 20. Based on our limited series, the likelihood of true fetal aneuploidy is low but pregnancies may be at increased risk for adverse obstetric outcomes and may benefit from additional surveillance.

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.

Early detection of active Human CytomegaloVirus (hCMV) infection in pregnant women using data generated for noninvasive fetal aneuploidy testing.

BACKGROUND: Prenatal hCMV infections can lead to severe embryopathy and neurological sequelae in neonates. Screening during pregnancy is not recommended by global societies, as there is no effective therapy. Recently, several groups showed that maternal-fetal hCMV transmission can be strongly reduced by administering anti-viral agents early in pregnancy. This calls for a screening method to identify at risk pregnancies at an appropriate gestational age, with the possibility for large-scale enrolment. Non-Invasive Prenatal Testing (NIPT) for fetal aneuploidy screening early in pregnancy is already implemented in many countries and performed on a large-scale basis. We investigated the use of whole genome cell-free DNA (cfDNA) sequencing data, generated for the purpose of NIPT, as (pre-)screening tool to identify women with active hCMV-infections, eligible for therapy. METHODS: Coded raw sequencing NIPT data from 204,818 pregnant women from three testing laboratories were analyzed for the presence of hCMV-cfDNA. Samples were stratified by cfDNA-hCMV load. For validation and interpretation, diagnostic hCMV-qPCR and serology testing were performed on a subset of cfDNA-hCMV-positive (n = 112) and -negative (n = 127) samples. FINDINGS: In 1930 samples (0.94%) hCMV fragments were detected. Validation by hCMV-qPCR showed that samples with high cfDNA-hCMV load tested positive and cfDNA-hCMV-negative samples tested negative. In 32/112 cfDNA-hCMV-positive samples (28.6%) the serological profile suggested a recent primary infection: this was more likely in samples with high cfDNA-hCMV load (78.6%) than in samples with low cfDNA-hCMV load (11.0%). In none of the cfDNA-hCMV-negative samples serology was indicative of a recent primary infection. INTERPRETATION: Our study shows that large-scale (pre-)screening for both genetic fetal aberrations and active maternal hCMV infections during pregnancy can be combined in one cfDNA sequencing test, performed on a single blood sample, drawn in the first trimester of pregnancy. FUNDING: This work was partly funded by the Prenatal Screening Foundation Nijmegen, the Netherlands.

Clinical evaluation of noninvasive prenatal testing for sex chromosome aneuploidies in 9,176 Korean pregnant women: a single-center retrospective study.

BACKGROUND: To evaluate the clinical significance of noninvasive prenatal testing (NIPT) for detecting fetal sex chromosome aneuploidies (SCAs) in Korean pregnant women. METHODS: We retrospectively analyzed NIPT data from 9,176 women with singleton pregnancies referred to the CHA Biotech genome diagnostics center. Cell-free fetal DNA (cffDNA) was extracted from maternal peripheral blood, and high-throughput massively parallel sequencing was conducted. Subsequently, the positive NIPT results for SCA were validated via karyotype and chromosomal microarray analyses. RESULTS: Overall, 46 cases were SCA positive after NIPT, including 20, 12, 8, and 6 for Turner, triple X, Klinefelter, and Jacob syndromes, respectively. Among 37 women with invasive prenatal diagnosis, 19 had true positive NIPT results. The overall positive predictive value (PPV) of NIPT for detecting SCAs was 51.35%. The PPV was 18.75% for Turner, 88.89% for triple X, 71.43% for Klinefelter, and 60.00% for Jacob's syndromes. NIPT accuracy for detecting sex chromosome trisomies was higher than that for sex chromosome monosomy (P = 0.002). No significant correlation was observed between fetal SCA incidence and maternal age (P = 0.914), except for the borderline significance of Jacob's syndrome (P = 0.048). No significant differences were observed when comparing NIPT and karyotyping validation for fetal SCA according to pregnancy characteristics. CONCLUSION: Our data suggest that NIPT can reliably screen for SCAs, and it performed better in predicting sex chromosome trisomies compared with monosomy X. No correlation was observed between maternal age and fetal SCA incidence, and no association was observed between different pregnancy characteristics. The accuracy of these findings requires improvements; however, our study provides an important reference for clinical genetic counseling and further management. Larger scale studies, considering confounding factors, are required for accurate evaluation.

Comparison of Chromosomal Microarray Analysis and Noninvasive Prenatal Testing in Pregnant Women with Fetal Ultrasonic Soft Markers.

Objective: This study aimed to assess the utility of chromosomal microarray analysis (CMA) and noninvasive prenatal testing (NIPT) in detecting clinically significant chromosomal abnormalities among fetuses presenting ultrasonic soft markers (USMs). Methods: A retrospective observational study, spanning from January 1, 2019, to September 30, 2022, enrolled 539 singleton pregnant women with fetal USMs at our center. Of these, 418 cases (77.6%) underwent NIPT, while 121 cases (22.4%) opted for invasive prenatal diagnosis post-appropriate genetic counseling. Cases with high-risk NIPT results proceeded to invasive prenatal diagnosis, where conventional karyotyping and CMA were concurrently performed. Further stratification was done based on the number of USMs, classifying cases into single-USM and multiple-USM groups. Results: Of the 24 cases (4.5%) exhibiting abnormal findings, 17 presented numerical chromosomal abnormalities, 2 featured clinically significant copy number variations (CNVs), 3 showed variants of unknown significance (VOUS), 1 displayed LOH, and 1 exhibited chromosome nine inversion. Notably, 18 cases (75%) theoretically detectable by karyotyping (eg, sizes above 10Mb) and 16 cases (66.7%) detectable by NIPT for five common aneuploidies were identified. Six submicroscopic findings (25%) were exclusively detectable by CMA. The predominant clinically relevant aberrations were observed in the thickened nuchal-translucency (TNT) group (9/35, 25.7%), followed by the multiple soft markers group (3/32, 9.3%). In the NIPT group, the false positive rate was 1.22%, and the false negative rate was 0%. Conclusion: The prevalence of chromosome aneuploidy exceeded that of submicroscopic chromosomal imbalance in pregnant women with fetal USMs. NIPT demonstrated efficacy, particularly for soft markers like echogenic intracardiac focus. However, for those with TNT and multiple soft markers, invasive prenatal diagnosis, including CMA testing, is recommended as the primary investigative approach.

The value of NIPT combined with serum cell-free DNA, estriol, AFP, and b-HCG levels in the recognition of trisomy 21 and 18 in the second trimester.

Background: This study aimed to evaluate the clinical application value of noninvasive prenatal testing from DNA (NIPT) and serum screening for screening in detecting fetal trisomy 21 and 18. Methods: As a retrospective analysis, we collected data from 1383 women (singleton pregnancy) who underwent serum screening and noninvasive prenatal testing from DNA (NIPT) in our department from May 2015 to September 2017 and calculated the diagnostic value of the two methods.

Fetal fraction of cell-free DNA in noninvasive prenatal testing and adverse pregnancy outcomes: a nationwide retrospective cohort study of 56,110 pregnant women.

BACKGROUND: Noninvasive prenatal testing by cell-free DNA analysis is offered to pregnant women worldwide to screen for fetal aneuploidies. In noninvasive prenatal testing, the fetal fraction of cell-free DNA in the maternal circulation is measured as a quality control parameter. Given that fetal cell-free DNA originates from the placenta, the fetal fraction might also reflect placental health and maternal pregnancy adaptation. OBJECTIVE: This study aimed to assess the association between the fetal fraction and adverse pregnancy outcomes. STUDY DESIGN: We performed a retrospective cohort study of women with singleton pregnancies opting for noninvasive prenatal testing between June 2018 and June 2019 within the Dutch nationwide implementation study (Trial by Dutch Laboratories for Evaluation of Non-Invasive Prenatal Testing [TRIDENT]-2). Multivariable logistic regression analysis was used to assess associations between fetal fraction and adverse pregnancy outcomes. Fetal fraction was assessed as a continuous variable and as <10th percentile, corresponding to a fetal fraction <2.5%. RESULTS: The cohort comprised 56,110 pregnancies. In the analysis of fetal fraction as a continuous variable, a decrease in fetal fraction was associated with increased risk of hypertensive disorders of pregnancy (adjusted odds ratio, 2.27 [95% confidence interval, 1.89-2.78]), small for gestational age neonates <10th percentile (adjusted odds ratio, 1.37 [1.28-1.45]) and <2.3rd percentile (adjusted odds ratio, 2.63 [1.96-3.57]), and spontaneous preterm birth from 24 to 37 weeks of gestation (adjusted odds ratio, 1.02 [1.01-1.03]). No association was found for fetal congenital anomalies (adjusted odds ratio, 1.02 [1.00-1.04]), stillbirth (adjusted odds ratio, 1.02 [0.96-1.08]), or neonatal death (adjusted odds ratio, 1.02 [0.96-1.08]). Similar associations were found for adverse pregnancy outcomes when fetal fraction was <10th percentile. CONCLUSION: In early pregnancy, a low fetal fraction is associated with increased risk of adverse pregnancy outcomes. These findings can be used to expand the potential of noninvasive prenatal testing in the future, enabling the prediction of pregnancy complications and facilitating tailored pregnancy management through intensified monitoring or preventive measures.

Placental, maternal, fetal, and technical origins of false-positive cell-free DNA screening results.

The introduction of noninvasive prenatal testing has resulted in substantial reductions to previously accepted false-positive rates of prenatal screening. Despite this, the possibility of false-positive results remains a challenging consideration in clinical practice, particularly considering the increasing uptake of genome-wide noninvasive prenatal testing, and the subsequent increased proportion of high-risk results attributable to various biological events besides fetal aneuploidy. Confined placental mosaicism, whereby chromosome anomalies exclusively affect the placenta, is perhaps the most widely accepted cause of false-positive noninvasive prenatal testing. There remains, however, a substantial degree of ambiguity in the literature pertaining to the clinical ramifications of confined placental mosaicism and its potential association with placental insufficiency, and consequentially adverse pregnancy outcomes including fetal growth restriction. Other causes of false-positive noninvasive prenatal testing include vanishing twin syndrome, in which the cell-free DNA from a demised aneuploidy-affected twin triggers a high-risk result, technical failures, and maternal origins of abnormal cell-free DNA such as uterine fibroids or unrecognized mosaicisms. Most concerningly, maternal malignancies are also a documented cause of false-positive screening results. In this review, we compile what is currently known about the various causes of false-positive noninvasive prenatal testing.

Clinical Experience with Noninvasive Prenatal Testing in Twin Pregnancy Samples at a Single Center in Germany.

In this study we wanted to determine the performance of a paired-end sequencing-based noninvasive prenatal testing (NIPT) assay in the detection of common fetal trisomies in twin pregnancy samples. Samples from patients with a twin pregnancy were collected from at least 10 weeks of gestation and analyzed at a single prenatal center in Germany. Results of Anomaly Detected (i.e., high risk) or No Anomaly Detected (i.e., low risk) for trisomy 21, trisomy 18, or trisomy 13 were reported. Follow-up confirmatory outcomes were requested for all cases. A total of 1,658 patients with twin pregnancies submitted samples during the study period; only two of these samples failed resulting in a low failure rate of 0.12%. Of the remaining 1,656 cases, there were 1,625 (98.1%) low-risk and 31 (1.9%) high-risk NIPT samples in our cohort. Of these, follow-up information was available for 301 (18.5%) of the low-risk samples and 19 (61.3%) of the high-risk samples. All of the low-risk cases with follow-up were determined to be true negatives giving an estimated negative predictive value of 100%. Seventeen of the 19 high-risk samples with follow-up were true positives, resulting in an overall positive predictive value of 89.5%. Sensitivities of > 99.9% were noted for both trisomy 21 and trisomy 18, with high specificities of ≥ 99.7% observed for all three trisomies. In conclusion, our study showed strong performance of the NIPT assay in the detection of common fetal trisomies in twin pregnancy samples, with high sensitivities, specificities, and positive predictive values observed based on known clinical outcomes along with a low failure rate.

Prenatal cfDNA Screening for Emanuel Syndrome and Other Unbalanced Products of Conception in Carriers of the Recurrent Balanced Translocation t(11;22): One Laboratory's Retrospective Experience.

Prenatal cell-free DNA screening (cfDNA) can identify fetal chromosome abnormalities beyond common trisomies. Emanuel syndrome (ES), caused by an unbalanced translocation between chromosomes 11 and 22, has lacked a reliable prenatal screening option for families with a carrier parent. A cohort of cases (n = 46) sent for cfDNA screening with indications and/or results related to ES was queried; diagnostic testing and pregnancy outcomes were requested and analyzed. No discordant results were reported or suspected; there were ten true positives with diagnostic confirmation, six likely concordant positives based on known translocations and consistent cfDNA data, and twenty-six true negatives, by diagnostic testing or birth outcomes. For cases with parental testing, all affected ES cases had maternal translocation carriers. Expanded cfDNA may provide reassurance for t(11;22) carriers with screen negative results, and screen positive results appear to reflect a likely affected fetus, especially with a known maternal translocation. Current society guidelines support the use of expanded cfDNA screening in specific circumstances, such as for translocation carriers, with appropriate counseling. Diagnostic testing is recommended for prenatal diagnosis of ES and other chromosome abnormalities in pregnancy. To our knowledge, this cohort is the largest published group of cases with prenatal screening for carriers of t(11;22).

Complete Hydatidiform Mole with a Coexisting Viable Male Fetus Detected by Cell-Free DNA.

Complete hydatidiform mole with coexisting fetus (CHMCF) is rare, and diagnosis is challenging due to limited data. Here, we present the case of a patient with noninvasive prenatal test (NIPT) resulting in "likely molar pregnancy" in the second trimester. Subsequent ultrasound confirmed a cystic appearing portion of the placenta. At 22 weeks, the patient delivered a demised fetus and two placentas. Pathology was consistent with CHMCF. This case is the first to show primary detection of a CHMCF with single-nucleotide polymorphism (SNP)-based NIPT prior to ultrasound identification. Our case suggests the use of SNP-based NIPT as an alternative noninvasive method to guide shared decision-making and clinical management for patients with this diagnosis.

Integrative preimplantation genetic testing analysis for a Chinese family with hereditary spherocytosis caused by a novel splicing variant of SPTB.

Hereditary spherocytosis (HS), the most common inherited hemolytic anemia disorder, is characterized by osmotically fragile microspherocytic red cells with a reduced surface area on the peripheral blood smear. Pathogenic variants in five erythrocyte membrane structure-related genes ANK1 (Spherocytosis, type 1; MIM#182900), SPTB (Spherocytosis, type 2; MIM#616649), SPTA1 (Spherocytosis, type 3; MIM#270970), SLC4A1 (Spherocytosis, type 4; MIM#612653) and EPB42 (Spherocytosis, type 5; MIM#612690) have been confirmed to be related to HS. There have been many studies on the pathogenic variants and mechanisms of HS, however, studies on how to manage the transmission of HS to the next-generation have not been reported. In this study, we recruited a patient with HS. Targeted next-generation sequencing with a panel of 208 genes related to blood system diseases detected a novel heterozygous variant in the SPTB: c.300+2dup in the proband. Sanger sequencing of variant alleles and haplotype linkage analysis of single nucleotide polymorphism (SNP) based on next-generation sequencing were performed simultaneously. Five embryos were identified with one heterozygous and four not carrying the SPTB variant. Single-cell amplification and whole genome sequencing showed that three embryos had varying degrees of trisomy mosaicism. One of two normal embryos was transferred to the proband. Ultimately, a healthy boy was born, confirmed by noninvasive prenatal testing for monogenic conditions (NIPT-M) to be disease-free. This confirmed our successful application of PGT in preventing transmission of the pathogenic variant allele in the HS family.

Clinical interpretation of cell-based non-invasive prenatal testing for monogenic disorders including repeat expansion disorders: potentials and pitfalls.

Introduction: Circulating fetal cells isolated from maternal blood can be used for prenatal testing, representing a safe alternative to invasive testing. The present study investigated the potential of cell-based noninvasive prenatal testing (NIPT) for diagnosing monogenic disorders dependent on the mode of inheritance. Methods: Maternal blood samples were collected from women opting for prenatal diagnostics for specific monogenic disorders (N = 7). Fetal trophoblasts were enriched and stained using magnetic activated cell sorting and isolated by fluorescens activated single-cell sorting. Individual cells were subject to whole genome amplification, and cells of fetal origin were identified by DNA-profiling using short tandem repeat markers. The amplified fetal DNA was input for genetic testing for autosomal dominant-, autosomal recessive-, X-linked and repeat expansion disorders by direct variant analysis and haplotyping. The cell-based NIPT results were compared with those of invasive testing. Results: In two cases at risk of skeletal dysplasia, caused by variants in the FGFR3 gene (autosomal dominant disorders), cell-based NIPT correctly stated an affected fetus, but allelic dropout of the normal alleles were observed in both cases. Cell-based NIPT gave an accurate result in two cases at risk of autosomal recessive disorders, where the parents carried either different diastrophic dysplasia causing variants in the SLC26A2 gene or the same cystic fibrosis disease-causing variant in the CFTR gene. Cell-based NIPT accurately identified an affected male fetus in a pregnancy at risk of Duchenne muscular dystrophy (DMD gene, X-linked recessive disorders). In two cases at risk of the myotonic dystrophy type 1 (DMPK gene, repeat expansion disorder), cell-based NIPT correctly detected an affected and an unaffected fetus, respectively. Discussion: Circulating fetal cells can be used to detect both maternally- and paternally inherited monogenic disorders irrespective of the type of variant, however, the risk of allelic dropout must be considered. We conclude that the clinical interpretation of the cell-based NIPT result thus varies depending on the disorders' mode of inheritance.

Complete trisomy 9 detected by noninvasive prenatal testing and confirmed by amniocentesis.

Complete chromosome 9 trisomy (T9) is a rare and fatal chromosomal disorder. We performed non-invasive prenatal testing (NIPT) in a patient with threatened abortion symptoms and found that the fetal was at risk for complete chromosome 9 trisomy. This shows that NIPT has certain accuracy in detecting trisomy of chromosome 9, which provide options for prenatal diagnosis of rare chromosomal abnormalities.

Change in client choice under multiple prenatal genetic testing options including noninvasive prenatal testing (NIPT) after genetic counseling in a Japanese maternity hospital.

OBJECTIVE: This study examined how clients' selection and preference for noninvasive prenatal testing (NIPT) for aneuploidy changed with genetic counseling (GC) performed by certified geneticists at a primary hospital specializing in obstetrics, where other multiple prenatal genetic tests options were available. METHODS: A total of 334 couples who underwent GC between 2017 and 2019 were included in the study. The average age of the pregnant women who underwent GC was 35.1 years. RESULTS: Among the 95 couples (28.4%) who wanted NIPT at the start of GC, 10 (10.5%) switched to other tests, and 4 (4.2%) chose not to undergo any test. Among the 106 (31.7%) couples who wanted the combination of ultrasonography and the serum marker test, 12 (11.3%) chose not to undergo the test. Among the 92 (27.5%) couples who were undecided before GC, 21 (22.8%) wanted NIPT, 31 (33.7%) selected combined tests, and 18 (19.6%) did not undergo any test. CONCLUSION: We have demonstrated the significance of GC before prenatal genetic testing under widespread use of NIPT. Ideally, obstetric facilities should provide GC, or at least, pre-counseling at their own facilities, and offer multiple prenatal genetic testing options or refer to other facilities for the same.

A high Z-score might increase the positive predictive value of cell-free noninvasive prenatal testing for singleton-pregnant women.

OBJECTIVE: To explore the positive predictive value (PPV) in noninvasive prenatal testing (NIPT)-positive cases and analyze the effect of the Z-score intervals on PPV performance. METHODS: In this retrospective study, 26,667 pregnant women underwent NIPT from November 2014 to August 2022, of which 169 were NIPT-positive cases. NIPT-positive cases were divided into three groups according to the Z-score: 3 ≤ Z < 6, 6 ≤ Z < 10, and Z ≥ 10. RESULTS: The PPVs of NIPT were 91.26% (94/103) for trisomy (T) 21, 80.65% (25/31) for T18, and 36.84% (7/19) for T13. The PPVs for the 3 ≤ Z < 6, 6 ≤ Z < 10, and Z ≥ 10 groups were 50%, 84.62%, and 87.95%, respectively. A higher PPV was found in the NIPT results when the Z-score was larger, with significant differences. The PPVs for T21/T18/T13 were 71.43%/42.86%/25% for 3 ≤ Z < 6, 90.32%/85.71%/57.14% for 6 ≤ Z < 10, and 93.85%/100%/25% for Z ≥ 10. For T21, T18, and T13, the correlations between the Z-score and fetal fraction concentration in true positives were r = 0.85, r = 0.59, and r = 0.71 (all p < .001), respectively. CONCLUSION: Z-score is associated with the PPV performance of NIPT in fetal T13, T18, and T21. The possibility of false positives caused by placental chimerism should be considered when determining whether high Z-values lead to high PPVs.

Performance of noninvasive prenatal testing for twin pregnancies in South China.

OBJECTIVE: The purpose of this study was to evaluate the performance of noninvasive prenatal testing (NIPT) for the detection of chromosomal aneuploidies and copy number variations (CNVs) in twin pregnancies. METHOD: A cohort of 2010 women with twin pregnancies was recruited. 1331 patients opted for NIPT, and 679 patients opted for expanded NIPT (NIPT-plus). All high-risk patients were advised to undergo invasive prenatal diagnosis. All participants were followed up until 6 months after birth. RESULTS: Twenty-two cases were predicted to have a high risk of chromosome abnormalities by NIPT, of which 14 pregnant women underwent invasive prenatal diagnosis. The 14 cases included 3 cases of trisomy 21, 1 case of trisomy 18, 1 case of trisomy 7, 2 cases of sex chromosome aneuploidies (SCAs), and 7 cases of CNVs, of which the confirmed cases numbered 2, 1, 0, 1, and 0, respectively. Twenty cases were predicted to have a high risk of chromosome abnormalities by NIPT-plus, of which 16 pregnant women underwent invasive prenatal diagnosis. The 16 cases included 1 case of trisomy 21, 1 case of trisomy 7, 7 cases of SCAs, and 7 cases of CNVs, of which were confirmed in 1, 0, 3, and 2, respectively. No false-negative result was reported during the follow-up period. CONCLUSION: The NIPT/NIPT-plus has excellent performance in the detection of chromosome aneuploidies in twin pregnancies. But for CNVs, the effectiveness of NIPT is poor, and the NIPT-plus have a certain detection efficiency. It is worth noting that pre- and post-genetic counseling is especially important, and the chorionicity, mode of conception, clinical indications, and fetal fraction should be considered as influencing factors.

The Clinical Application and Accuracy Evaluation of Noninvasive Prenatal Testing for Common Trisomy and Sex Chromosome Aneuploidy.

BACKGROUND: Noninvasive prenatal testing (NIPT) has been widely adopted in prenatal examination for fetal chromosomal aneuploidy. The present study aimed to evaluate the clinical features of NIPT for both common trisomy and sex chromosome aneuploidy (SCA). METHODS: A total of 24,164 pregnant women with NIPT testing from July 2020 to June 2022 were recruited at the Linping Maternity and Child Health Care Hospital. RESULTS: Ninety cases showed high risk of trisomy 21/18/13 with karyotype results available, and the sensitivity, specificity, and positive predictive value (PPV) were 98.41%, 99.88% and 68.89%, respectively. The three most important reasons for screening were advanced maternal age (AMA, 28.06%), intermediate risk of prenatal screening (20.34%) and Multiple of medium (MoM) abnormality of prenatal screening (17.38%). High risk of NIPT results with Z-score ≥15 have a higher PPV when compared to those with 3 ≤ Z-score < 10, and 10 ≤ Z-score < 15. Meanwhile, 97 pregnant women received positive results for fetal sex chromosome aneuploidy (SCA) in NIPT. In addition, the rate for further diagnostics of SCA was 64.95% and the PPV of SCA was 50.79%. CONCLUSIONS: Our data show that NIPT has a promising future in prenatal screening for genetic abnormalities of the fetus, and that the accuracy of NIPT is closely related to Z-score.