Noninvasive Prenatal Testing: Comparison of Two Mappers and Influence in the Diagnostic Yield

Objective. The aim of this study was to determine if the use of different mappers for NIPT may vary the results considerably. Methods. Peripheral blood was collected from 217 pregnant women, 58 pathological (34 pregnancies with trisomy 21, 18 with trisomy 18, and 6 with trisomy 13) and 159 euploid. MPS was performed following a manufacturer’s modified protocol of semiconductor sequencing. Obtained reads were mapped with two different software programs: TMAP and HPG-Aligner, comparing the results. Results. Using TMAP, 57 pathological samples were correctly detected (sensitivity 98.28%, specificity 93.08%): 33 samples as trisomy 21 (sensitivity 97.06%, specificity 99.45%), 16 as trisomy 18 (sensibility 88.89%, specificity 93.97%), and 6 as trisomy 13 (sensibility 100%, specificity 100%). 11 false positives, 1 false negative, and 2 samples incorrectly identified were obtained. Using HPG-Aligner, all the 58 pathological samples were correctly identified (sensibility 100%, specificity 96.86%): 34 as trisomy 21 (sensibility 100%, specificity 98.91%), 18 as trisomy 18 (sensibility 100%, specificity 98.99%), and 6 as trisomy 13 (sensibility 100%, specificity 99.53%). 5 false positives were obtained. Conclusion. Different mappers use slightly different algorithms, so the use of one mapper or another with the same batch file can provide different results.

Download Full-text

Unexplained False Negative Results in Noninvasive Prenatal Testing: Two Cases Involving Trisomies 13 and 18

Case Reports in Genetics ◽

10.1155/2015/926545 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

R. Hochstenbach ◽

G. C. M. L. Page-Christiaens ◽

A. C. C. van Oppen ◽

K. D. Lichtenbelt ◽

J. J. T. van Harssel ◽

...

Keyword(s):

False Negative ◽

Prenatal Testing ◽

High Sensitivity ◽

Trisomy 13 ◽

Maternal Weight ◽

Noninvasive Prenatal Testing ◽

Root Cause ◽

Negative Results ◽

False Negative Results ◽

Negative Case

Noninvasive prenatal testing (NIPT) validation studies show high sensitivity and specificity for detection of trisomies 13, 18, and 21. False negative cases have rarely been reported. We describe a false negative case of trisomy 13 and another of trisomy 18 in which NIPT was commercially marketed directly to the clinician. Both cases came to our attention because a fetal anatomy scan at 20 weeks of gestation revealed multiple anomalies. Karyotyping of cultured amniocytes showed nonmosaic trisomies 13 and 18, respectively. Cytogenetic investigation of cytotrophoblast cells from multiple placental biopsies showed a low proportion of nontrisomic cells in each case, but this was considered too small for explaining the false negative NIPT result. The discordant results also could not be explained by early gestational age, elevated maternal weight, a vanishing twin, or suboptimal storage or transport of samples. The root cause of the discrepancies could, therefore, not be identified. The couples involved experienced difficulties in accepting the unexpected and late-adverse outcome of their pregnancy. We recommend that all parties involved in caring for couples who choose NIPT should collaborate to clarify false negative results in order to unravel possible biological causes and to improve the process of patient care from initial counseling to communication of the result.

Download Full-text

A Novel Graphic-Aided Algorithm (gNIPT) Improves the Accuracy of Noninvasive Prenatal Testing

BioMed Research International ◽

10.1155/2020/4712657 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Qingwen Zhu ◽

Jing Wang ◽

Xiaoning Xu ◽

Shiying Zhou ◽

Zhengli Liao ◽

...

Keyword(s):

Copy Number Variation ◽

Copy Number ◽

False Negative ◽

Prenatal Testing ◽

Maternal Blood ◽

Negative Control ◽

Trisomy 13 ◽

Singleton Pregnancy ◽

Noninvasive Prenatal Testing ◽

Number Variation

Noninvasive Prenatal Testing (NIPT) has advanced the detection of fetal chromosomal aneuploidy by analyzing cell-free DNA in peripheral maternal blood. The statistic Z-test that it utilizes, which measures the deviation of each chromosome dosage from its negative control, is now widely accepted in clinical practice. However, when a chromosome has loss and gain regions which offset each other in the z-score calculation, merely using the Z-test for the result tends to be erroneous. To improve the performance of NIPT in this aspect, a novel graphic-aided algorithm (gNIPT) that requires no extra experiment procedures is reported in this study. In addition to the Z-test, this method provides a detailed analysis of each chromosome by dividing each chromosome into multiple 2 Mb size windows, calculating the z-score and copy number variation of each window, and visualizing the z-scores for each chromosome in a line chart. Data from 13537 singleton pregnancy women were analyzed and compared using both the normal NIPT (nNIPT) analysis and the gNIPT method. The gNIPT method had significantly improved the overall positive predictive value (PPV) of nNIPT (88.14% vs. 68.00%, p=0.0041) and the PPV for trisomy 21 (T21) detection (93.02% vs. 71.43%, p=0.0037). There were no significant differences between gNIPT and nNIPT in PPV for trisomy 18 (T18) detection (88.89% vs. 63.64%, p=0.1974) and in PPV for trisomy 13 (T13) detection (57.14% vs. 50.00%, p=0.8004). One false-negative T18 case in nNIPT was detected by gNIPT, which demonstrates the potency of gNIPT in discerning chromosomes that have variation in multiple regions with an offsetting effect in z-score calculation. The gNIPT was also able to detect copy number variation (CNV) in chromosomes, and one case with pathogenic CNV was detected during the study. With no additional test requirement, gNIPT presents a reasonable solution in improving the accuracy of normal NIPT.

Download Full-text

A Case of False Negative NIPT for Down Syndrome-Lessons Learned

Case Reports in Genetics ◽

10.1155/2014/823504 ◽

2014 ◽

Vol 2014 ◽

pp. 1-3 ◽

Cited By ~ 12

Author(s):

Meagan Smith ◽

Kimberly M. Lewis ◽

Alexandrea Holmes ◽

Jeannie Visootsak

Keyword(s):

Down Syndrome ◽

Genetic Counseling ◽

Case Report ◽

Prenatal Care ◽

Trisomy 21 ◽

False Negative ◽

Prenatal Testing ◽

Lessons Learned ◽

Noninvasive Prenatal Testing ◽

Common Cause

Down syndrome or trisomy 21 is the most common cause of prenatal chromosome abnormalities with approximately 50% of all reported chromosome conditions. With the successful introduction of noninvasive prenatal testing (NIPT) for Down syndrome into routine prenatal care, it is important to understand the risks, benefits, and limitations in order to guide patients in making an informed decision. Herein, we describe the first published case report of a patient whose fetus tested “negative” for Trisomy 21 by NIPT but was diagnosed postnatally with trisomy 21. We present the importance of proper pretest and posttest genetic counseling to ensure prenatal patients are able to make informed decisions and are educated appropriately about NIPT.

Download Full-text

Expanded noninvasive prenatal testing for fetal aneuploidy and copy number variations and parental willingness for invasive diagnosis in a cohort of 18,516 cases

BMC Medical Genomics ◽

10.1186/s12920-021-00955-6 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Yunsheng Ge ◽

Jia Li ◽

Jianlong Zhuang ◽

Jian Zhang ◽

Yanru Huang ◽

...

Keyword(s):

Prenatal Diagnosis ◽

High Risk ◽

Pregnant Women ◽

Copy Number ◽

Prenatal Testing ◽

Copy Number Variations ◽

Trisomy 13 ◽

Noninvasive Prenatal Testing ◽

Predictive Values ◽

Parental Willingness

Abstract Background Noninvasive prenatal testing (NIPT) has been wildly used to screen for common aneuplodies. In recent years, the test has been expanded to detect rare autosomal aneuploidies (RATs) and copy number variations (CNVs). This study was performed to investigate the performance of expanded noninvasive prenatal testing (expanded NIPT) in screening for common trisomies, sex chromosomal aneuploidies (SCAs), rare autosomal aneuploidies (RATs), and copy number variations (CNVs) and parental willingness for invasive prenatal diagnosis in a Chinese prenatal diagnosis center. Methods A total of 24,702 pregnant women were retrospectively analyzed at the Women and Children’s Hospital from January 2013 to April 2019, among which expanded NIPT had been successfully conducted in 24,702 pregnant women. The high-risk expanded NIPT results were validated by karyotype analysis and chromosomal microarray analysis. All the tested pregnant women were followed up for pregnancy outcomes. Results Of the 24,702 cases, successful follow-up was conducted in 98.77% (401/446) of cases with common trisomies and SCAs, 91.95% (80/87) of RAT and CNV cases, and 76.25% (18,429/24,169) of cases with low-risk screening results. The sensitivity of expanded NIPT was 100% (95% confidence interval[CI], 97.38–100%), 96.67%(95%CI, 82.78–99.92%), and 100%(95%CI, 66.37–100.00%), and the specificity was 99.92%(95%CI, 99.87–99.96%), 99.96%(95%CI, 99.91–99.98%), and 99.88% (95%CI, 99.82–99.93%) for the detection of trisomies 21, 18, and 13, respectively. Expanded NIPT detected 45,X, 47,XXX, 47,XXY, XYY syndrome, RATs, and CNVs with positive predictive values of 25.49%, 75%, 94.12%, 76.19%, 6.45%, and 50%, respectively. The women carrying fetuses with Trisomy 21/Trisomy 18/Trisomy 13 underwent invasive prenatal diagnosis and terminated their pregnancies at higher rates than those at high risk for SCAs, RATs, and CNVs. Conclusions Our study demonstrates that the expanded NIPT detects fetal trisomies 21, 18, and 13 with high sensitivity and specificity. The accuracy of detecting SCAs, RATs, and CNVs is still relatively poor and needs to be improved. With a high-risk expanded NIPT result, the women at high risk for common trisomies are more likely to undergo invasive prenatal diagnosis procedures and terminate their pregnancies than those with unusual chromosome abnormalities.

Download Full-text

Performance of Cell-Free DNA Screening for Fetal Common Aneuploidies and Sex Chromosomal Abnormalities: A Prospective Study from a Less Developed Autonomous Region in Mainland China

Genes ◽

10.3390/genes12040478 ◽

2021 ◽

Vol 12 (4) ◽

pp. 478

Author(s):

Yunli Lai ◽

Xiaofan Zhu ◽

Sheng He ◽

Zirui Dong ◽

Yanqing Tang ◽

...

Keyword(s):

Sex Chromosome ◽

Chromosomal Abnormalities ◽

False Negative ◽

Prenatal Testing ◽

Read Depth ◽

Trisomy 13 ◽

Prognostic Information ◽

Aneuploidy Screening ◽

Predictive Values ◽

Risk Result

To evaluate the performance of noninvasive prenatal screening (NIPS) in the detection of common aneuploidies in a population-based study, a total of 86,262 single pregnancies referred for NIPS were prospectively recruited. Among 86,193 pregnancies with reportable results, follow-up was successfully conducted in 1160 fetuses reported with a high-risk result by NIPS and 82,511 cases (95.7%) with a low-risk result. The screen-positive rate (SPR) of common aneuploidies and sex chromosome abnormalities (SCAs) provided by NIPS were 0.7% (586/83,671) and 0.6% (505/83,671), respectively. The positive predictive values (PPVs) for Trisomy 21, Trisomy 18, Trisomy 13 and SCAs were calculated as 89.7%, 84.0%, 52.6% and 38.0%, respectively. In addition, less rare chromosomal abnormalities, including copy number variants (CNVs), were detected, compared with those reported by NIPS with higher read-depth. Among these rare abnormalities, only 23.2% (13/56) were confirmed by prenatal diagnosis. In total, four common trisomy cases were found to be false negative, resulting in a rate of 0.48/10,000 (4/83,671). In summary, this study conducted in an underdeveloped region with limited support for the new technology development and lack of cost-effective prenatal testing demonstrates the importance of implementing routine aneuploidy screening in the public sector for providing early detection and precise prognostic information.

Download Full-text

Cell-Free DNA Analysis of Targeted Genomic Regions in Maternal Plasma for Non-Invasive Prenatal Testing of Trisomy 21, Trisomy 18, Trisomy 13, and Fetal Sex

Clinical Chemistry ◽

10.1373/clinchem.2015.252502 ◽

2016 ◽

Vol 62 (6) ◽

pp. 848-855 ◽

Cited By ~ 29

Author(s):

George Koumbaris ◽

Elena Kypri ◽

Kyriakos Tsangaras ◽

Achilleas Achilleos ◽

Petros Mina ◽

...

Keyword(s):

Trisomy 21 ◽

Dna Analysis ◽

Prenatal Testing ◽

Cost Effective ◽

Maternal Plasma ◽

Trisomy 13 ◽

Cell Free Dna ◽

Free Dna ◽

Genomic Regions ◽

Fetal Fraction

Abstract BACKGROUND There is great need for the development of highly accurate cost effective technologies that could facilitate the widespread adoption of noninvasive prenatal testing (NIPT). METHODS We developed an assay based on the targeted analysis of cell-free DNA for the detection of fetal aneuploidies of chromosomes 21, 18, and 13. This method enabled the capture and analysis of selected genomic regions of interest. An advanced fetal fraction estimation and aneuploidy determination algorithm was also developed. This assay allowed for accurate counting and assessment of chromosomal regions of interest. The analytical performance of the assay was evaluated in a blind study of 631 samples derived from pregnancies of at least 10 weeks of gestation that had also undergone invasive testing. RESULTS Our blind study exhibited 100% diagnostic sensitivity and specificity and correctly classified 52/52 (95% CI, 93.2%–100%) cases of trisomy 21, 16/16 (95% CI, 79.4%–100%) cases of trisomy 18, 5/5 (95% CI, 47.8%–100%) cases of trisomy 13, and 538/538 (95% CI, 99.3%–100%) normal cases. The test also correctly identified fetal sex in all cases (95% CI, 99.4%–100%). One sample failed prespecified assay quality control criteria, and 19 samples were nonreportable because of low fetal fraction. CONCLUSIONS The extent to which free fetal DNA testing can be applied as a universal screening tool for trisomy 21, 18, and 13 depends mainly on assay accuracy and cost. Cell-free DNA analysis of targeted genomic regions in maternal plasma enables accurate and cost-effective noninvasive fetal aneuploidy detection, which is critical for widespread adoption of NIPT.

Download Full-text

Noninvasive prenatal testing for chromosome aneuploidies and subchromosomal microdeletions/microduplications in a cohort of 42,910 single pregnancies with different clinical features

Human Genomics ◽

10.1186/s40246-019-0250-2 ◽

2019 ◽

Vol 13 (1) ◽

Cited By ~ 17

Author(s):

Yibo Chen ◽

Qi Yu ◽

Xiongying Mao ◽

Wei Lei ◽

Miaonan He ◽

...

Keyword(s):

Clinical Features ◽

Sex Chromosome ◽

Prenatal Testing ◽

Maternal Plasma ◽

Trisomy 13 ◽

Noninvasive Prenatal Testing ◽

Detection Rates ◽

Non Invasive ◽

Cell Free Fetal Dna ◽

Sex Chromosome Aneuploidies

Abstract Background Since the discovery of cell-free DNA (cfDNA) in maternal plasma, it has opened up new approaches for non-invasive prenatal testing. With the development of whole-genome sequencing, small subchromosomal deletions and duplications could be found by NIPT. This study is to review the efficacy of NIPT as a screening test for aneuploidies and CNVs in 42,910 single pregnancies. Methods A total of 42,910 single pregnancies with different clinical features were recruited. The cell-free fetal DNA was directly sequenced. Each of the chromosome aneuploidies and the subchromosomal microdeletions/microduplications of PPV were analyzed. Results A total of 534 pregnancies (1.24%) were abnormal results detected by NIPT, and 403 pregnancies had underwent prenatal diagnosis. The positive predictive value (PPV) for trisomy 21(T21), trisomy 18 (T18), trisomy 13 (T13), sex chromosome aneuploidies (SCAs), and other chromosome aneuploidy was 79.23%, 54.84%, 13.79%, 33.04%, and 9.38% respectively. The PPV for CNVs was 28.99%. The PPV for CNVs ≤ 5 Mb is 20.83%, for within 5–10 Mb 50.00%, for > 10 Mb 27.27% respectively. PPVs of NIPT according to pregnancies characteristics are also different. Conclusion Our data have potential significance in demonstrating the usefulness of NIPT profiling not only for common whole chromosome aneuploidies but also for CNVs. However, this newest method is still in its infancy for CNVs. There is still a need for clinical validation studies with accurate detection rates and false positive rates in clinical practice.

Download Full-text