Efficiency of expanded noninvasive prenatal testing in the detection of fetal subchromosomal microdeletion and microduplication in a cohort of 31,256 single pregnancies

Antenatal reproductive screening for pregnant people including preconception: Provides the best reproductive opportunity for informed consent, quality, and safety

INTRODUCTION

This antenatal screening review will include reproductive screening evidence and approaches for pre-conception and post-conception, using first to third trimester screening opportunities.

METHODS

Focused antenatal screening peer-reviewed publications were evaluated and summarized.

RESULTS

Evidenced-based reproductive antenatal screening elements should be offered and discussed, with the pregnancy planning or pregnant person, during Preconception (genetic carrier screening for reproductive partners, personal and family (including reproductive partner) history review for increased genetic and pregnancy morbidity risks); First Trimester (fetal dating with ultrasound; fetal aneuploidy screening plus consideration for expanded fetal morbidity criteria, if appropriate; pregnant person preeclampsia screening; early fetal anatomy screening; early fetal cardiac screening); Second Trimester for standard fetal anatomy screening (18-22 weeks) including cardiac; pregnant person placental and cord pathology screening; pregnant person preterm birth screening with cervical length measurement); Third Trimester (fetal growth surveillance; continued preterm birth risk surveillance).

CONCLUSION

Antenatal reproductive screening has multiple elements, is complex, is time-consuming, and requires the use of pre- and post-testing counselling for most screening elements. The use of preconception and trimesters 'one to three' requires clear patient understanding and buy-in. Informed consent and knowledge transfer is a main goal for antenatal reproductive screening approaches.

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.

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.

Genetic analysis of chorionic villus tissues in early missed abortions

Chromosomal abnormalities are the most common etiology of early spontaneous miscarriage. However, traditional karyotyping of chorionic villus samples (CVSs) is limited by cell culture and its low resolution. The objective of our study was to investigate the efficiency of molecular karyotyping technology for genetic diagnosis of early missed abortion tissues. Chromosome analysis of 1191 abortion CVSs in early pregnancy was conducted from August 2016 to June 2021; 463 cases were conducted via copy-number variations sequencing (CNV-seq)/quantitative fluorescent-polymerase chain reaction (QF-PCR) and 728 cases were conducted using SNP array. Clinically significant CNVs of CVSs were identified to clarify the cause of miscarriage and to guide the couples' subsequent pregnancies. Among these, 31 cases with significant maternal cell contamination were removed from the study. Among the remaining 1160 samples, 751 cases (64.7%) with genetic abnormalities were identified, of which, 531 (45.8%) were single aneuploidies, 31 (2.7%) were multiple aneuploidies, 50 (4.3%) were polyploidies, 54 (4.7%) were partial aneuploidies, 77 (6.6%) had submicroscopic CNVs (including 25 with clinically significant CNVs and 52 had variants of uncertain significance), and 8 cases (0.7%) were uniparental disomies. Our study suggests that both SNP array and CNV-seq/QF-PCR are reliable, robust, and high-resolution technologies for genetic diagnosis of miscarriage.

Non-invasive prenatal testing: a revolutionary journey in prenatal testing

Non-invasive prenatal testing (NIPT) is a pioneering technique that has consistently advanced the field of prenatal testing to detect genetic abnormalities and conditions with the aim of decreasing the incidence and prevalence of inherited conditions. NIPT remains a method of choice for common autosomal aneuploidies, mostly trisomy 21, and several monogenic disorders. The advancements in gene sequencing techniques have expanded the panel of conditions where NIPT could be offered. However, basic research on the impact of several genetic conditions lags behind the methods of detection of these sequence aberrations, and the impact of the expansion of NIPT should be carefully considered based on its utility. With interest from commercial diagnostics and a lack of regulatory oversight, there remains a need for careful validation of the predictive values of different tests offered. NIPT comes with many challenges, including ethical and economic issues. The scientific evidence, technical feasibility, and clinical benefit of NIPT need to be carefully investigated before new tests and developments are translated into clinical practice. Moreover, the implementation of panel expansion of NIPT should accompany expert genetic counseling pre- and post-testing.

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.

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.

Prenatal diagnosis and outcomes in 320 fetuses with nasal bone anomalies

Object: To investigate the chromosome abnormalities associated with absent or hypoplastic fetal nasal bone. Methods: Patients with fetal nasal bone anomalies (NBA) referred to our center for prenatal diagnosis between 2017 and 2021 were retrospectively evaluated. All these patients underwent chromosomal microarray and/or karyotyping and received genetic counseling before and after testing. Results: Among 320 fetuses with NBA, chromosomal abnormalities were diagnosed in 89 (27.8%) cases, including 53 cases of trisomy 21, which was the most common type of chromosomal aneuploidy, accounting for 59.6% of all detected abnormalities. In addition to aneuploidies, 29 cases of copy number variants (CNVs) were detected. In cases of isolated NBA with low-risk screening results and without other risk factors, the incidence of fetal chromosomal aneuploidies and pathogenic CNVs is 5.3% (7 in 132 cases). Conclusion: This study suggests that parents of fetuses should be informed about the possibility of fetal aneuploidy and pathogenic CNVs and that discussion with the parents is also recommended, providing data support and reference for clinical counseling.