Expanding the application of non-invasive prenatal testing in the detection of foetal chromosomal copy number variations

The performance evaluation of NIPT for fetal chromosome microdeletion/microduplication detection: a retrospective analysis of 68,588 Chinese cases

Background

Chromosomal abnormalities are the main cause of birth defects in newborns. Since the inception of noninvasive prenatal testing (NIPT) technology, it has primarily been applied to the detection of common trisomy (T21, T18, T13). However, the application of NIPT in microdeletion and microduplication detection is still controversial.

Methods

This study retrospectively analyzed the data of 68,588 cases that underwent NIPT at Ganzhou Maternal and Child Health Hospital in China. These data were used to evaluate the performance of NIPT in fetal chromosome microdeletion/microduplication detection and to investigate the key factors affecting the NIPT performance.

Results

A total of 281 cases (0.41%) had positive NIPT results with copy number variants (CNVs), of which 161 were validated by karyotyping and chromosome microarray analysis (CMA). Among the 161 cases, 92 were confirmed as true positives through karyotyping or CMA, including 61 microdeletion cases and 31 microduplication cases, resulting in a positive predictive value (PPV) of 57.14%. Improvements in library construction methods increased the fraction of cell-free fetal DNA (cffDNA) from 13.76% to 18.44%, leading to a significant improvement in the detection rate (0.47% vs. 0.15%) and PPV (59.86% vs. 28.57%) of NIPT for CNVs.

Conclusion

This study proved the robust performance of NIPT for fetal chromosome microdeletion/microduplication detection. In addition, the cffDNA fraction is a key factor influencing NIPT, with increased cffDNA fraction improving the performance of NIPT.

Selection of prenatal screening with nuchal translucency > 95th centile and below 99th centile: a 4-year observational study with real-world data

OBJECTIVE

We sought to analyze the genetic outcomes of fetuses with nuchal translucency (NT) > 95th centile, and determine whether prenatal genetic counseling, chromosomal microarray analysis (CMA) or non-invasive prenatal testing (NIPT) are truly beneficial for the outcomes of fetuses with increased NT > 95th centile and below 99th centile.

MATERIALS AND METHODS

A total of 535 pregnant women were included in this study, with a fetal NT > 95th centile at 11-13+6 weeks of gestation from January 2017 to December 2020. 324 pregnant women with fetal NT > 95th centile and below 99th centile combined with other risk factors and NT > 99th centile received prenatal diagnostic karyotype analysis and CMA, and 211 pregnant women with fetal isolated increased NT > 95th centile and below 99th centile were selected to carry out NIPT.

RESULTS

A total of 211 pregnant women who underwent NIPT were included in the study, NIPT results showed that 8 high-risk cases were confirmed by prenatal diagnosis. Overall, the detection rate of NIPT was 3.79%. A total of 324 pregnant women with fetal NT > 95th centile and below 99th centile, along with other risk factors, and those with fetal NT > 99th centile, received karyotype analysis and CMA for prenatal diagnosis. Among them, a total of 73 genetic abnormalities were detected, including 45 cases of chromosomal aneuploidy, 7 cases of structural abnormalities, and 21 cases of copy number variations (CNVs) with a size of less than 10 Mb. In addition, the 73 women with genetic abnormalities are divided into three groups based on the NT measurement (Group 1: Fetuses with NT > 95th centile and below 99th centile, Group 2: Fetuses with NT > 99th centile, and Group 3: Fetuses with NT > 99th centile). 13.11% (8/61) of pathogenic genetic abnormalities (6 chromosomal aneuploidy, 1 structural abnormality, and 1 likely pathogenic CNV) will be missed if genetic counseling and prenatal genetic testing were not conducted in fetuses with increased NT > 95th centile and below 99th centile combined with other risks. Pathogenic CNVs were the most common abnormalities in group 3, and one likely pathogenic CNV was detected in group 1 and group 3, respectively, and a total of 14 CNVs of unknown clinical significance (VOUS) were detected.

CONCLUSIONS

Through this study, we demonstrated that the critical value of NT > 95th centile for invasive detection or NIPT. Invasive testing combined with CMA may be recommended for fetuses with NT > 95th centile and below 99th centile and with other risks. But when isolated NT > 95th centile and below 99th centile, NIPT would be appropriate.

Unraveling Neuronal Identities Using SIMS: A Deep Learning Label Transfer Tool for Single-Cell RNA Sequencing Analysis

Large single-cell RNA datasets have contributed to unprecedented biological insight. Often, these take the form of cell atlases and serve as a reference for automating cell labeling of newly sequenced samples. Yet, classification algorithms have lacked the capacity to accurately annotate cells, particularly in complex datasets. Here we present SIMS (Scalable, Interpretable Machine Learning for Single-Cell), an end-to-end data-efficient machine learning pipeline for discrete classification of single-cell data that can be applied to new datasets with minimal coding. We benchmarked SIMS against common single-cell label transfer tools and demonstrated that it performs as well or better than state of the art algorithms. We then use SIMS to classify cells in one of the most complex tissues: the brain. We show that SIMS classifies cells of the adult cerebral cortex and hippocampus at a remarkably high accuracy. This accuracy is maintained in trans-sample label transfers of the adult human cerebral cortex. We then apply SIMS to classify cells in the developing brain and demonstrate a high level of accuracy at predicting neuronal subtypes, even in periods of fate refinement, shedding light on genetic changes affecting specific cell types across development. Finally, we apply SIMS to single cell datasets of cortical organoids to predict cell identities and unveil genetic variations between cell lines. SIMS identifies cell-line differences and misannotated cell lineages in human cortical organoids derived from different pluripotent stem cell lines. When cell types are obscured by stress signals, label transfer from primary tissue improves the accuracy of cortical organoid annotations, serving as a reliable ground truth. Altogether, we show that SIMS is a versatile and robust tool for cell-type classification from single-cell datasets.

Chromosome microarray analysis combined with karyotype analysis is a powerful tool for the detection in pregnant women with high-risk indicators

BACKGROUND

Karyotype analysis and fluorescence in situ hybridization (FISH) are commonly used for prenatal diagnosis, however they have many disadvantages. Chromosome microarray analysis (CMA) has the potential to overcome these disadvantages. This study aimed to evaluate the clinical value of CMA in the diagnosis of fetal chromosomal anomalies in southwest of China.

METHODS

A total of 3336 samples of amniotic fluid or umbilical cord blood from pregnant women with high-risk indicators at our center in southwest of China from June 2018 to January 2023 were included in the retrospective analysis. 3222 cases tested by CMA and karyotyping, 114 cases only tested by CMA.

RESULTS

3336 samples divided into 2911 cases with single and 425 cases with multiple high-risk indicators. The aneuploidy and pathogenic/likely pathogenic copy number variations (CNVs) of 2911 cases with single high-risk indicator were 4.43% (129/2911) and 2.44% (71/2911) respectively; the aneuploidy and pathogenic/likely pathogenic CNVs of 425 cases with multiple high-risk indicators were 6.82% (29/425) and 2.12% (9/425) respectively. The rate of aneuploidy increased significantly with pregnancy age or NT value. The detection rate of aneuploidy on cases with AMA combined NT ≥ 2.5 mm was significantly higher than that in cases only with AMA (p < 0.001); the detection rate of aneuploidy and pathogenic/likely pathogenic CNVs in cases with AMA combined NIPT high-risk were higher than that in cases only with AMA (p < 0.001, p < 0.05).

CONCLUSIONS

The combined application of CMA and karyotyping were recommended in prenatal diagnosis for providing a scientific and accurate genetic diagnosis and improving the quality of prenatal genetic counseling.

Clinical Potential of Expanded Noninvasive Prenatal Testing for Detection of Aneuploidies and Microdeletion/Microduplication Syndromes

OBJECTIVE

We aimed to evaluate the clinical performance of expanded noninvasive prenatal testing (NIPT-Plus) for the detection of aneuploidies and microdeletion/microduplication syndromes.

METHODS

A total of 7177 pregnant women were enrolled in the study from June 2020 to March 2022 at Xijing Hospital, China. Cases with NIPT-Plus-positive results were further confirmed by chromosomal karyotyping and a chromosomal microarray analysis.

RESULTS

A total of 112 positive cases (1.56%) were identified by NIPT-Plus, including 60 chromosome aneuploidies and 52 microdeletion/microduplication syndromes. Ninety-five cases were validated by amniocentesis, and 57 were confirmed with true-positive results, comprising 18 trisomy 21, 4 trisomy 18, 1 trisomy 13, 17 sex chromosome aneuploidies, 1 other aneuploidy, and 16 microdeletion/microduplication syndromes. The positive predictive value of total chromosomal abnormalities was 60% (57/95). For trisomy 21, trisomy 18, trisomy 13, sex chromosome aneuploidies, other aneuploidies and microdeletion/microduplication syndromes, the sensitivity was all 100%, the specificity was 100, 99.986, 100, 99.888, 99.958, and 99.636%, and the positive predictive value was 100, 80, 100, 68, 25, and 38.10%, respectively. For all clinical characteristics, the abnormal maternal serum screening group was found to have the highest prevalence of chromosomal abnormalities (1.54%), and the ultrasound abnormality group presented the highest positive predictive value (73.33%).

CONCLUSIONS

NIPT-Plus has great potential for the detection of aneuploidies and microdeletion/microduplication syndromes owing to its high sensitivity, safety, and specificity, which greatly reduces unnecessary invasive procedures and the risk of miscarriage and allows informed maternal choice.

Application of non-invasive prenatal testing to 91,280 spontaneous pregnancies and 3477 pregnancies conceived by in vitro fertilization

BACKGROUND

Many clinical studies based on spontaneous pregnancies (SPs) have demonstrated the superiority of non-invasive prenatal testing (NIPT), and the question of whether this technology is suitable for offspring conceived by assisted reproductive technology has attracted attention. This study aimed to evaluate the application value of NIPT in screening for trisomy (T)21, T18, T13 and sex chromosome aneuploidy (SCA) in pregnant women who conceived by in vitro fertilization (IVF).

RESULTS

In total, there were 804 high-risk cases [0.88% (804/91280), singleton = 795, twin = 9] in the SP group. Among the 558 invasive prenatal diagnosis (IPD) cases (singleton = 556, twin = 2), 343 (singleton = 342, twin = 1) were true positive, including 213 cases of T21, 28 of T18, 5 of T13 and 97 (singleton = 96, twin = 1) of SCA. The positive predictive values (PPVs) of T21, T18, T13, SCA and T21/T18/T13 combined in singleton pregnancy were 89.12% (213/239), 51.85% (28/54), 21.74% (5/23), 40.00% (96/240), and 77.85% (246/316), respectively, and the PPV of SCA in twin pregnancy was 100.00%. In the IVF group, IPD was performed in 19 (singleton = 16, twin = 3) of the 27 high-risk cases [0.78% (27/3477), singleton = 16, twin = 3], of which 9 (singleton = 8, twin = 1) were true positive, including 5 cases (singleton = 4, twin = 1) of T21 and 4 of SCA. The PPVs of singleton T21, SCA and T21/T18/T13 combined were 66.67% (4/6), 50.00% (4/8) and 57.14% (4/7), respectively, and the PPV of twin T21 was 100.00% (1/1). There were no significant differences in PPV among T21, SCA and T21/T18/T13 combined in singletons between the groups (89.12% vs. 66.67%, p = 0.09; 40.00% vs. 50.00%, p = 0.57; 77.85% vs. 57.14%, p = 0.20). The sensitivity and specificity were higher for singleton and twin pregnancies in the two groups. Based on follow-up results, 1 case of false negative T21 was found in the singleton SP group. Additionally, the mean foetal fraction (FF) of the IVF group was lower than that of the SP group (11.23% vs. 10.51%, p < 0.05).

CONCLUSION

NIPT has high sensitivity and specificity in screening chromosomal aneuploidies in both IVF pregnancy and spontaneous pregnancy, so it is an ideal screening method for IVF pregnancy.

Prenatal Screening for Microdeletions and Rare Autosomal Aneuploidies

Noninvasive prenatal screening with cell-free DNA is now considered a first-line screening for common aneuploidies. Advancements in existing laboratory techniques now allow to interrogate the entirety of the fetal genome, and many commercial laboratories have expanded their screening panels to include screening for rare autosomal aneuploidies and copy number variants. Here, we review the currently available data on the performance of fetal cell-free DNA to detect rare autosomal aneuploidies and copy number variants that are associated with clinically significant microdeletion and microduplication syndromes and the current position of medical societies on routine screening for these syndromes.

Accelerated somatic mutation calling for whole-genome and whole-exome sequencing data from heterogenous tumor samples

Accurate detection of somatic mutations in DNA sequencing data is a fundamental prerequisite for cancer research. Previous analytical challenge was overcome by consensus mutation calling from four to five popular callers. This, however, increases the already nontrivial computing time from individual callers. Here, we launch MuSE2.0, powered by multi-step parallelization and efficient memory allocation, to resolve the computing time bottleneck. MuSE2.0 speeds up 50 times than MuSE1.0 and 8-80 times than other popular callers. Our benchmark study suggests combining MuSE2.0 and the recently expedited Strelka2 can achieve high efficiency and accuracy in analyzing large cancer genomic datasets.

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

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.

Noninvasive prenatal testing, ultrasonographic findings and poor prenatal diagnosis rates for twin pregnancies: a retrospective study

BACKGROUND

Noninvasive prenatal testing (NIPT) is increasingly used in the clinical prenatal screening of twin pregnancies, and its screening performance for chromosomal abnormalities requires further evaluation. For twin pregnancies with indications for prenatal diagnosis, there is a lack of clinical data to assess the prenatal diagnosis rate (PDR). The aim of this study was to evaluate the screening performance of NIPT for foetal chromosomal abnormalities in twin pregnancies and the PDR in the second and third trimesters.

METHODS

Ultrasound scans were carried out for all twin pregnancies between 11 and 13^+ 6 gestational weeks. For twin pregnancies with nuchal translucency thickness˂3.0 mm and no foetal structural malformations, NIPT was performed after blood sampling, followed by routine ultrasound monitoring. Women with twin pregnancies who underwent NIPT at the prenatal diagnostic centre of Xiangya Hospital from January 2018 to May 2022 were included in the study. Genetic counselling was offered to each pregnant woman when the NIPT result indicated a high risk of abnormalities or abnormal ultrasonographic (USG) findings were detected. We followed up twin pregnancies for NIPT results, USG findings, prenatal diagnosis results and pregnancy outcomes.

RESULTS

In 1754 twin pregnancies, the sensitivity, specificity and positive predictive value of NIPT for trisomy 21 were 100%, 99.9% and 75%, and the corresponding values for sex chromosome aneuploidy (SCA) were 100%, 99.9% and 50%, respectively. For the 14 twin pregnancies for which the NIPT results indicated a high risk of abnormalities, the PDR was 78.6% (11/14). For the 492 twin pregnancies for which the NIPT results indicated a low risk of abnormalities, the rate of USG findings in the second and third trimesters was 39.4% (194/492); of these pregnancies, prenatal diagnosis was recommended for 16.7% (82/492), but it was actually performed in only 8.3% (41/492), and the PDR was 50% (41/82). There was no significant difference in the PDR between the NIPT high-risk and low-risk groups.

CONCLUSIONS

The screening performance of NIPT for SCA in twin pregnancies needs to be further evaluated. When abnormal NIPT results or USG findings are used as the main prenatal diagnostic indicator in the second and third trimesters, the PDR is poor.

Positive cfDNA screening results for 22q11.2 deletion syndrome—Clinical and laboratory considerations

Introduction: Non-invasive prenatal screening (NIPS) via cell-free DNA (cfDNA) screens for fetal chromosome disorders using maternal plasma, including 22q11.2 deletion syndrome (22q11.2DS). While it is the commonest microdeletion syndrome and has potential implications for perinatal management, prenatal screening for 22q11.2DS carries some inherent technical, biological, and counseling challenges, including varying deletion sizes/locations, maternal 22q11.2 deletions, confirmatory test choice, and variable phenotype.

Materials and methods: This study addresses these considerations utilizing a retrospective cohort of 307 samples with screen-positive 22q11.2 NIPS results on a massively parallel sequencing (MPS) platform.

Results: Approximately half of the cases reported ultrasound findings at some point during pregnancy. In 63.2% of cases with diagnostic testing, observed positive predictive values were 90.7%–99.4%. cfDNA identified deletions ranging from &lt;1 Mb to 3.55 Mb, with significant differences in confirmed fetal versus maternal deletion sizes; estimated cfDNA deletion size was highly concordant with microarray findings. Mosaicism ratio proved useful in predicting the origin of a deletion (fetal versus maternal). Prediction of deletion size, location, and origin may help guide confirmatory testing.

Discussion: The data shows that MPS-based NIPS can screen for 22q11.2DS with a high PPV, and that collaboration between the laboratory and clinicians allows consideration of additional metrics that may guide diagnostic testing and subsequent management.

The predictive value of prenatal cell-free DNA testing for rare autosomal trisomies: a systematic review and meta-analysis

OBJECTIVE

The diagnostic accuracy of cell-free fetal DNA in screening for rare autosomal trisomies is uncertain. We conducted a systematic review and meta-analysis aiming to determine the predictive value of cell-free DNA in screening for rare autosomal trisomies.

DATA SOURCES

PubMed, Embase, and Web of Science were searched from inception to January 2022.

STUDY ELIGIBILITY CRITERIA

All studies that reported on the diagnostic accuracy of cell-free DNA in the detection of rare autosomal trisomies were included. Case series were included if they contained at least 10 cases with diagnostic test results or postnatal genetic testing.

METHODS

Study appraisal was completed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Statistical analysis was performed using random-effects meta-analysis of double-arcsine transformed proportions of confirmed results in the fetus out of the positive tests to obtain a pooled estimate of the positive predictive value.

RESULTS

The search identified 7553 studies, of which 1852 were duplicates. After screening 5701 titles and abstracts, 380 studies proceeded to the full-text screen; 206 articles were retrieved for data extraction, of which another 175 articles were excluded. A total of 31 studies, with a total of 1703 women were included for analysis. The pooled positive predictive value of cell-free DNA for the diagnosis of rare autosomal trisomies was 11.46% (95% confidence interval, 7.80-15.65). Statistical heterogeneity was high (I²=82%). Sensitivity analysis restricted to 5 studies at low risk of bias demonstrated a pooled positive predictive value of 9.13% (95% confidence interval, 2.49-18.76). There were insufficient data to provide accurate ascertainment of sensitivity and specificity because most studies only offered confirmatory tests to women with high-risk results.

CONCLUSION

The positive predictive value of cell-free DNA in diagnosing rare autosomal trisomies is approximately 11%. Clinicians should provide this information when offering cell-free DNA for screening of conditions outside of common autosomal trisomies.

The accuracy of prenatal cell-free DNA screening for sex chromosome abnormalities: A systematic review and meta-analysis

OBJECTIVE

Although cell-free DNA screening for sex chromosome abnormalities is increasingly used in clinical practice, its diagnostic accuracy and clinical utility remain unclear. This systematic review and meta-analysis aimed to determine the performance of cell-free DNA in the detection of sex chromosome abnormalities.

DATA SOURCES

Medline and PubMed, Embase, and Web of Science were searched from inception to January 2022 for articles relating to cell-free DNA screening for sex chromosome abnormalities.

STUDY ELIGIBILITY CRITERIA

Original articles, randomized control trials, conference abstracts, cohort and case-control studies, and case series with more than 10 cases with diagnostic confirmation were considered for inclusion.

METHODS

Quality assessment of each included publication was performed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. The positive predictive value was calculated as the proportion of true positive cases among those who tested positive and underwent diagnostic testing. Sensitivity and specificity were pooled, and a summary receiver operating characteristic curve was produced using bivariate models that included studies that had diagnostic confirmation for high- and low-risk women.

RESULTS

The search identified 7553 results. Of these, 380 proceeded to the full-text screening, of which 94 articles were included in the meta-analysis with a total of 1,531,240 women tested. All studies reported a confirmatory genetic test. The pooled positive predictive value was 49.4% (95% confidence interval, 45.8-53.1). The pooled positive predictive value was 32.0% (95% confidence interval, 27.0%-37.3%) for monosomy X, 67.6% (95% confidence interval, 62.5%-72.5%) for XXY, 57.5% (95% confidence interval, 51.7%-63.1%) for XXX, and 70.9% (95% confidence interval, 63.9%-77.1%) for XYY. The pooled sensitivity and specificity of cell-free DNA for sex chromosome abnormalities were 94.1% (95% confidence interval, 90.8%-96.3%) and 99.5% (95% confidence interval, 99.0%-99.7%), respectively, with an area under the summary receiver operating characteristic curve of 0.934 (95% confidence interval, 0.907-0.989).

CONCLUSION

Although the sensitivity and specificity of cell-free DNA for sex chromosome abnormalities are high, the positive predictive value was approximately 50%. The positive predictive value was higher for sex chromosome abnormalities with a supernumerary Y chromosome and lower for monosomy X. Clinicians should inform couples about these findings when offering cell-free DNA for sex chromosome abnormalities.

The role of non-invasive prenatal testing and ultrasound in prenatal screening of fetal chromosomal abnormalities in singleton: a retrospective study

Background

Non-invasive prenatal testing (NIPT) has good screening performance for common chromosomes, but it may have false positive (FP) and false negative (FN) results for various reasons. For abnormal NIPT results, the combination of fetal ultrasound phenotypes will provide more fetal information for prenatal diagnosis. The aim of this study was to combine NIPT and ultrasound phenotypes to analyze their complementary roles in prenatal screening of fetal chromosome abnormalities.

Methods

From January 2018 to December 2021, 12,803 pregnant women with singleton who successfully underwent NIPT/expanded NIPT (NIPT-Plus) at Xiangya Hospital of Central South University, of which 111 cases were positive results and one case was FN result. We retrospectively collected the clinical features, ultrasonographic findings, prenatal diagnosis, and pregnancy outcomes of these 112 pregnant women and analyzed the ultrasonic manifestations of different chromosomal abnormalities in detail.

Results

The positive predictive values (PPVs) of NIPT/NIPT-Plus for trisomy (T)21, T18, sex chromosome abnormality (SCA), microdeletion/microduplication syndrome (MMS), T13, and rare autosomal trisomy (RAT) were 100.0%, 85.7%, 57.1%, 44.4%, 40.0%, and 7.7%, respectively. The total termination rates of pregnancy for T21, T18, T13, SCA, pathogenic MMS, and RAT were 93.5%, 100.0%, 100.0%, 66.7%, 100.0%, and 100.0%, respectively. From the karyotypes of SCA live-born fetuses, 47,XYY and 47,XXX were more likely to be selected for continued pregnancy. The ultrasound phenotypes of T21 were diverse, including normal, soft marker, and structural malformation. Both T18 and T13 had structural malformations as the main phenotypes. Most ultrasound phenotypes of FP T21, T18, and T13 were normal but occasionally manifested as fetal growth restriction (FGR). The ultrasound phenotypes of SCA, MMS, and RAT were relatively mild and manifested as normal, soft marker, FGR, or polyhydramnios, and the ultrasound phenotypes were similar between FP and true positive (TP) cases.

Conclusions

Ultrasound phenotypes are helpful in identifying FP NIPT/NIPT-Plus results, especially for T18 and T13. Given its mild ultrasound phenotypes, NIPT-Plus has important clinical significance in reducing the missed diagnosis of SCA, MMS, and RAT, but its screening performance needs to be further improved.

The accuracy of cell-free DNA screening for fetal segmental copy number variants: A systematic review and meta-analysis

BACKGROUND

The performance of cell-free DNA (cfDNA) screening for microscopic copy number variants (CNVs) is unclear.

OBJECTIVES

This was a systematic review and meta-analysis to investigate the sensitivity, specificity and positive predictive value (PPV) of cfDNA screening for CNVs.

SEARCH STRATEGY

Articles published in EMBASE, PubMed or Web of Science before November 2022 were screened for inclusion. This protocol was registered with PROSPERO (23 March 2021, CRD42021250849) prior to initiation.

SELECTION CRITERIA

Articles published in English, detailing diagnostic outcomes for at least 10 high-risk CNV results with cfDNA were considered for inclusion.

DATA COLLECTION AND ANALYSIS

The PPV was calculated and pooled with random-effects models for double-arcsine transformed proportions, using cases with diagnostic confirmation. Overall sensitivity, specificity and a summary receiver-operating characteristics (ROC) curve were calculated using bivariate models. The risk of bias was assessed using QUADAS-2.

MAIN RESULTS

In all, 63 articles were included in the final analysis, detailing 1 591 459 cfDNA results. The pooled PPV was 37.5% (95% confidence interval [CI] 30.6-44.8), with substantial statistical heterogeneity (I²  = 93.9%). Bivariate meta-analysis estimated sensitivity and specificity to be 77.4% (95% CI 65.7-86.0) and 99.4% (95% CI 98.0-99.8), respectively, with an area under the summary ROC curve of 0.947 (95% CI 0.776-0.984).

CONCLUSIONS

Approximately one-third of women who screen high-risk for CNVs with cfDNA will have an affected fetus. This value is of importance for screening counselling.

A retrospective single-center analysis of prenatal diagnosis and follow-up of 626 chinese patients with positive non-invasive prenatal screening results

This study explored the diagnostic efficiency of different prenatal diagnostic approaches for women with positive non-invasive prenatal screening (NIPS) results by analyzing their clinical information and pregnancy outcomes. We collected data on 626 NIPS-positive pregnant women from January 2017 to June 2021 and arranged subsequent prenatal diagnostic operations for them after genetic counseling, along with long-term intensive follow-up. A total of 567 women accepted invasive prenatal diagnosis (IPD) (90.58%), and 262 cases were confirmed as true positives for NIPS. The positive predictive values for trisomies 21 (T21), 18 (T18), and 13 (T13); sex chromosome aneuploidies (SCAs); rare autosomal trisomies (RATs); and microdeletion and microduplication syndromes (MMS) were 81.13%, 37.93%, 18.42%, 48.83%, 18.37%, and 41.67%, respectively. Discordant results between NIPS and IPD were observed in 48 cases, with the discordance rate being 8.47%. Additionally, there were 43 cases with discordant results between karyotyping and chromosomal microarray analysis (CMA)/copy number variation sequencing. Additional reporting of RATs and MMS with routine NIPS that only detects T21/T18/T13 and SCAs can yield more accurate diagnoses. However, NIPS cannot be used as a substitute for IPD owing to its high false positive rate and discordance with other diagnostic methods. Therefore, we recommend CMA combined with karyotyping as the preferred method for accurately diagnosing NIPS-positive women.

Physical activity and risk of infection, severity and mortality of COVID-19: a systematic review and non-linear dose-response meta-analysis of data from 1 853 610 adults

OBJECTIVE

To quantify the association between physical activity and risk of SARS-CoV-2 infection, COVID-19-associated hospitalisation, severe illness and death due to COVID-19 in adults.

DESIGN

A systematic review and meta-analysis.

DATA SOURCES

Three databases were systematically searched through March 2022.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Peer-reviewed articles reporting the association between regular physical activity and at least one COVID-19 outcome in adults were included. Risk estimates (ORs, relative risk (RR) ratios or HRs) were extracted and pooled using a random-effects inverse-variance model.

RESULTS

Sixteen studies were included (n=1 853 610). Overall, those who engaged in regular physical activity had a lower risk of infection (RR=0.89; 95% CI 0.84 to 0.95; I2=0%), hospitalisation (RR=0.64; 95% CI 0.54 to 0.76; I2=48.01%), severe COVID-19 illness (RR=0.66; 95% CI 0.58 to 0.77; I2=50.93%) and COVID-19-related death (RR=0.57; 95% CI 0.46 to 0.71; I2=26.63%) as compared with their inactive peers. The results indicated a non-linear dose-response relationship between physical activity presented in metabolic equivalent of task (MET)-min per week and severe COVID-19 illness and death (p for non-linearity <0.001) with a flattening of the dose-response curve at around 500 MET-min per week.

CONCLUSIONS

Regular physical activity seems to be related to a lower likelihood of adverse COVID-19 outcomes. Our findings highlight the protective effects of engaging in sufficient physical activity as a public health strategy, with potential benefits to reduce the risk of severe COVID-19. Given the heterogeneity and risk of publication bias, further studies with standardised methodology and outcome reporting are now needed.

PROSPERO REGISTRATION NUMBER

CRD42022313629.

A Critical Evaluation of Validation and Clinical Experience Studies in Non-Invasive Prenatal Testing for Trisomies 21, 18, and 13 and Monosomy X

Non-invasive prenatal testing (NIPT) for trisomies 21, 18, 13 and monosomy X is widely utilized with massively parallel shotgun sequencing (MPSS), digital analysis of selected regions (DANSR), and single nucleotide polymorphism (SNP) analyses being the most widely reported methods. We searched the literature to find all NIPT clinical validation and clinical experience studies between January 2011 and January 2022. Meta-analyses were performed using bivariate random-effects and univariate regression models for estimating summary performance measures across studies. Bivariate meta-regression was performed to explore the influence of testing method and study design. Subgroup and sensitivity analyses evaluated factors that may have led to heterogeneity. Based on 55 validation studies, the detection rate (DR) was significantly higher for retrospective studies, while the false positive rate (FPR) was significantly lower for prospective studies. Comparing the performance of NIPT methods for trisomies 21, 18, and 13 combined, the SNP method had a higher DR and lower FPR than other methods, significantly so for MPSS, though not for DANSR. The performance of the different methods in the 84 clinical experience studies was consistent with validation studies. Clinical positive predictive values of all NIPT methods improved over the last decade. We conclude that all NIPT methods are highly effective for fetal aneuploidy screening, with performance differences across methodologies.

Positive predictive value estimates for noninvasive prenatal testing from data of a prenatal diagnosis laboratory and literature review

Objective

Since 2011, noninvasive prenatal testing (NIPT) has undergone rapid expansion, with both utilization and coverage. However, conclusive data regarding the clinical validity and utility of this testing tool are lacking. Thus, there is a continued need to educate clinicians and patients about the current benefits and limitations in order to inform pre- and post-test counseling, pre/perinatal decision making, and medical risk assessment/management.

Methods

This retrospective study included women referred for invasive prenatal diagnosis to confirm positive NIPT results between January 2017 and December 2020. Prenatal diagnosis testing, including karyotyping, chromosomal microarray analysis (CMA) were performed. Positive predictive values (PPVs) were calculated.

Results

In total, 468 women were recruited. The PPVs for trisomies 21, 18, and 13 were 86.1%, 57.8%, and 25.0%, respectively. The PPVs for rare chromosomal abnormalities (RCAs) and copy number variants (CNVs) were 17.0% and 40.4%, respectively. The detection of sex chromosomal aneuploidies (SCAs) had a PPV of 20% for monosomy X, 23.5% for 47,XXX, 68.8% for 47,XXY, and 62.5% for 47,XYY. The high-risk groups had a significant increase in the number of true positive cases compared to the low- and moderate-risk groups.

Conclusions

T13, monosomy X, and RCA were associated with lower PPVs. The improvement of cell-free fetal DNA screening technology and continued monitoring of its performance are important.

Analysis of 17 Prenatal Cases with the Chromosomal 1q21.1 Copy Number Variation

Copy number variations (CNVs) at the chromosomal 1q21.1 region represent a group of hot-spot recurrent rearrangements in human genome, which have been detected in hundreds of patients with variable clinical manifestations. Yet, report of such CNVs in prenatal scenario was relatively scattered. In this study, 17 prenatal cases involving the 1q21.1 microdeletion or duplication were recruited. The clinical survey and imaging examination were performed; and genetic detection with karyotyping and CNV analysis using chromosomal microarray (CMA) or CNVseq were subsequently carried out. These cases were all positive with 1q21.1 CNV, yet presented with exceedingly various clinical and utrasonographic indications. Among them, 12 pregnancies carried 1q21.1 deletions, while the other 5 carried 1q21.1 duplications, all of which were within the previously defined breaking point (BP) regions. According to the verification results, 9 CNVs were de novo, 7 were familial, and the other 1 was not certain. We summarized the clinical information of these cases, and the size and distribution of CNVs, and attempted to analyze the association between these two aspects. The findings in our study may provide important basis for the prenatal diagnosis and genetic counseling on such conditions in the future.