Prenatal diagnosis by chromosomal microarray analysis

Prenatal diagnosis of chromosomal aberrations by chromosomal microarray analysis and pregnancy outcomes of fetuses with polyhydramnios

OBJECTIVES

To explore the prenatal clinical utility of chromosome microarray analysis (CMA) for polyhydramnios and evaluate the short and long-term prognosis of fetuses with polyhydramnios.

METHODS

A total of 600 singleton pregnancies with persistent polyhydramnios from 2014 to 2020 were retrospectively enrolled in this study. All cases received amniocentesis and were subjected to CMA results. All cases were categorized into two groups: isolated polyhydramnios and non-isolated polyhydramnios [with soft marker(s) or with sonographic structural anomalies]. All fetuses were followed up from 6 months to five years after amniocentesis to acquire short and long-term prognosis.

RESULTS

The detection rates of either aneuploidy or pathogenic copy number variants in fetuses with non-isolated polyhydramnios were significantly higher than those with isolated polyhydramnios (5.0 vs. 1.5%, p = 0.0243; 3.6 vs. 0.8%, p = 0.0288). The detection rate of total chromosomal abnormalities in the structural abnormality group was significantly higher than that in the isolated group (10.0 vs. 2.3%, p = 0.0003). In the CMA-negative cases, the incidence of termination of pregnancy, neonatal and childhood death, and non-neurodevelopmental disorders in fetuses combined with structural anomalies was significantly higher than that in fetuses with isolated polyhydramnios (p < 0.05). We did not observe any difference in the prognosis between the isolated group and the combined group of ultrasound soft markers. In addition, the risk of postnatal neurodevelopmental disorders was also consistent among the three groups (1.6 vs. 1.3 vs. 1.8%).

CONCLUSION

For low-risk pregnancies, invasive prenatal diagnosis of isolated polyhydramnios might be unnecessary. CMA should be considered for fetuses with structural anomalies. In CMA-negative cases, the prognosis of fetuses with isolated polyhydramnios was good, and polyhydramnios itself did not increase the risk of postnatal neurological development disorders. The worse prognosis mainly depends on the combination of polyhydramnios with structural abnormalities.

Comparison of exon-level copy number variants in CytoScan XON assay and next-generation sequencing in clinical samples

BACKGROUND AND AIMS

Next-generation sequencing (NGS)-based copy number variants (CNVs) have high false-positive rates. The fewer the exons involved, the higher the false-positive rate. A CytoScan XON assay was developed to assess exon-level CNVs.

MATERIALS AND METHODS

Twenty-three clinically relevant exon-level CNVs in 20 patient blood samples found in previous NGS studies were compared with the results from the CytoScan XON and multiplex ligation-dependent probe amplification (MLPA).

RESULTS

Fifteen of the 23 exon-level CNVs were consistent with the NGS results. Among these, eight were confirmed using MLPA. In six out of eight discrepancies between the CytoScan Xon and NGS, MLPA was performed, and three were negative, indicating that the CNVs in NGS were false positives. The CytoScan XON exhibits a sensitivity of 72.7% for small exon-level CNVs, along with a specificity of 100%. The assay could not detect the three exon-level CNVs in PKD1 and TSC2 that were detected using both NGS and MLPA. This could be due to the distribution of the probes in some areas, and the CNV-calling regions containing multiple exons.

CONCLUSION

The CytoScan XON assay is a promising complementary tool for the detection of exon-level CNVs, provided that the users carefully examine the distribution of probes and calling regions.

Exome sequencing in every pregnancy? Results of trio exome sequencing in structurally normal fetuses

OBJECTIVE

This study aimed to assess the detection rate of clinically significant results of prenatal exome sequencing (pES) in low-risk pregnancies and apparently normal fetuses in non-consanguineous couples.

METHODS

A retrospective analysis of pES conducted at a single center from January 2020 to September 2023 was performed. Genetic counseling was provided, and detailed medical histories were obtained. High-risk pregnancies were excluded due to major ultrasound anomalies, sonographic soft markers, abnormal maternal biochemical screening, or family history suggestive of monogenic diseases as well as cases with pathogenic and likely pathogenic (P/LP) chromosomal microarray results. Exome analysis focused on ∼2100 genes associated with Mendelian genetic disorders. Variant analysis and classification followed the American College of Medical Genetics and Genomics (ACMG) guidelines.

RESULTS

Among 1825 pES conducted, 1020 low-risk cases revealed 28 fetuses (2.7%) with potentially clinically significant variants indicating known monogenic diseases, primarily de novo dominant variants (64%). Among these 28 cases, 9 fetuses (0.9%) had the potential for severe phenotypes, including shortened lifespan and intellectual disability, and another 12 had the potential for milder phenotypes. Seven cases were reported with variants of uncertain significance (VUS) that, according to the ACMG criteria, leaned toward LP, constituting 0.7% of the entire cohort. Termination of pregnancy was elected in 13 out of 1020 cases (1.2%) in the cohort, including 7/9 in the severe phenotypes group, 2/12 in the milder phenotype group, and 4/7 in the VUS group.

CONCLUSION

The 2.7% detection rate highlights the significant contribution of pES in low-risk pregnancies. However, it necessitates rigorous analysis, and comprehensive genetic counseling before and after testing.

Prenatal Diagnosis of Chromosomal Mosaicism in 18,369 Cases of Amniocentesis

OBJECTIVE

 The prenatal diagnosis of chromosomal mosaicism is fraught with uncertainty. Karyotyping, chromosomal microarray analysis (CMA), and fluorescence in situ hybridization (FISH) are three commonly used techniques. In this study, we evaluated these techniques for the prenatal diagnosis of chromosomal mosaicism and its clinical outcome.

STUDY DESIGN

 A retrospective review of mosaicism was conducted in 18,369 pregnant women from January 2016 to November 2021. The subjects underwent amniocentesis to obtain amniotic fluid for G-band karyotyping with or without CMA/FISH. Cases diagnosed with chromosomal mosaicism were selected for further analysis.

RESULTS

 In total, 101 cases of chromosomal mosaicism were detected in 100 pregnant women (0.54%, 100/18,369). Four were lost during follow-up, 61 opted to terminate their pregnancy, and 35 gave birth to a healthy singleton or twins. Among these 35 cases, postnatal cytogenetic testing was performed on eight and two exhibited mosaicism; however, nothing abnormal was observed in the postnatal phenotype follow-up. Karyotyping identified 96 incidents of chromosomal mosaicism including 13 with level II mosaicism and 83 with level III mosaicism, FISH identified 37 cases of mosaicism, and CMA identified 17. The most common form of chromosomal mosaicism involved monosomy X, of which the mosaic fraction in cultured karyotyping appeared higher or comparable to uncultured FISH/CMA (p < 0.05). Discordant mosaic results were observed in 34 of 101 cases (33.7%), most of which resulted from the detection limit of different techniques and/or the dominant growth of a certain cell line.

CONCLUSION

 Based on the postnatal follow-up results from the babies born, we obtained a more hopeful result for the prognosis of chromosomal mosaicism. Although karyotyping was the most sensitive method for detecting chromosomal mosaicism, artifacts and bias resulting from culture should be considered, particularly for sex chromosomal abnormalities involving X monosomy, in which the combination with uncultured FISH was necessary.

KEY POINTS

· Karyotyping combined with uncultured FISH or CMA is beneficial for prenatal diagnosis of chromosomal mosaicism.. · Fetuses without ultrasound structural anomalies with chromosomal mosaicism often have optimistic prognosis..

The Diagnostic Yield of Chromosomal Microarray Analysis in Third-Trimester Fetal Abnormalities

OBJECTIVE

 This study aimed to determine the diagnostic yield of chromosomal microarray analysis (CMA) performed in cases of fetal abnormalities detected during the third trimester of pregnancy.

STUDY DESIGN

 A retrospective review of medical records was conducted for women who underwent amniocentesis at or beyond 28 weeks of gestation between January 2017 and February 2023. CMA results of pregnancies with abnormal sonographic findings not detected before 28 weeks were included.

RESULTS

 A total of 482 fetuses met the inclusion criteria. The average maternal age was 31.3 years, and the average gestational age at amniocentesis was 32.3 weeks. The overall diagnostic yield of CMA was 6.2% (30 clinically significant copy number variations [CNVs]). The yield was 16.4% in cases with two or more fetal malformations, while cases with a single anomaly revealed a diagnostic yield of 7.3%. Cases presenting isolated polyhydramnios or isolated fetal growth restriction had a lower yield of 9.3 and 5.4%, respectively. Of the 30 clinically significant cases, 19 (or 63.4%) exhibited recurrent CNVs. The remaining 11 cases (or 36.6%) presented unique CNVs. The theoretical yield of Noninvasive Prenatal Testing (NIPT) in our cohort is 2% for aneuploidy, which implies that it could potentially miss up to 70% of the significant findings that could be identified by CMA. In 80% of the fetuses (or 24 out of 30) with clinically significant CNVs, the structural abnormalities detected on fetal ultrasound examinations corresponded with the CMA results.

CONCLUSION

 The 6.2% detection rate of significant CNVs in late-onset fetal anomalies confirms the value of CMA in third-trimester amniocentesis. The findings underscore the necessity of CMA for detecting CNVs potentially overlooked by NIPT and emphasize the importance of thorough genetic counseling.

KEY POINTS

· CMA yields 6.2% for third-trimester anomalies.. · NIPT may miss 70% of CMA findings.. · Ultrasound matched 80% of CMA results..

Expert consensus on pediatric orthodontic therapies of malocclusions in children

Malocclusion, identified by the World Health Organization (WHO) as one of three major oral diseases, profoundly impacts the dental-maxillofacial functions, facial esthetics, and long-term development of ~260 million children in China. Beyond its physical manifestations, malocclusion also significantly influences the psycho-social well-being of these children. Timely intervention in malocclusion can foster an environment conducive to dental-maxillofacial development and substantially decrease the incidence of malocclusion or reduce the severity and complexity of malocclusion in the permanent dentition, by mitigating the negative impact of abnormal environmental influences on the growth. Early orthodontic treatment encompasses accurate identification and treatment of dental and maxillofacial morphological and functional abnormalities during various stages of dental-maxillofacial development, ranging from fetal stages to the early permanent dentition phase. From an economic and societal standpoint, the urgency for effective early orthodontic treatments for malocclusions in childhood cannot be overstated, underlining its profound practical and social importance. This consensus paper discusses the characteristics and the detrimental effects of malocclusion in children, emphasizing critical need for early treatment. It elaborates on corresponding core principles and fundamental approaches in early orthodontics, proposing comprehensive guidance for preventive and interceptive orthodontic treatment, serving as a reference for clinicians engaged in early orthodontic treatment.

Prenatal Diagnosis by Trio Clinical Exome Sequencing: Single Center Experience

Fetal anomalies, characterized by structural or functional abnormalities occurring during intrauterine life, pose a significant medical challenge, with a notable prevalence, affecting approximately 2-3% of live births and 20% of spontaneous miscarriages. This study aims to identify the genetic cause of ultrasound anomalies through clinical exome sequencing (CES) analysis. The focus is on utilizing CES analysis in a trio setting, involving the fetuses and both parents. To achieve this objective, prenatal trio clinical exome sequencing was conducted in 51 fetuseses exhibiting ultrasound anomalies with previously negative results from chromosomal microarray (CMA) analysis. The study revealed pathogenic variants in 24% of the analyzed cases (12 out of 51). It is worth noting that the findings include de novo variants in 50% of cases and the transmission of causative variants from asymptomatic parents in 50% of cases. Trio clinical exome sequencing stands out as a crucial tool in advancing prenatal diagnostics, surpassing the effectiveness of relying solely on chromosomal microarray analysis. This underscores its potential to become a routine diagnostic standard in prenatal care, particularly for cases involving ultrasound anomalies.

The yield of SNP microarray analysis for fetal ultrasound cardiac abnormalities

BACKGROUND

Chromosomal microarray analysis (CMA) has emerged as a critical instrument in prenatal diagnostic procedures, notably in assessing congenital heart diseases (CHD). Nonetheless, current research focuses solely on CHD, overlooking the necessity for thorough comparative investigations encompassing fetuses with varied structural abnormalities or those without apparent structural anomalies.

OBJECTIVE

This study sought to assess the relation of single nucleotide polymorphism-based chromosomal microarray analysis (SNP-based CMA) in identifying the underlying causes of fetal cardiac ultrasound abnormalities.

METHODS

A total of 2092 pregnant women who underwent prenatal diagnosis from 2017 to 2022 were included in the study and divided into four groups based on the presence of ultrasound structural abnormalities and the specific type of abnormality. The results of the SNP-Array test conducted on amniotic fluid samples from these groups were analyzed.

RESULTS

Findings from the study revealed that the non-isolated CHD group exhibited the highest incidence of aneuploidy, overall chromosomal abnormalities, and trisomy 18, demonstrating statistically significant differences from the other groups (p < 0.001). Regarding the distribution frequency of copy number variation (CNV) segment size, no statistically significant distinctions were observed between the isolated CHD group and the non-isolated CHD group (p > 0.05). The occurrence rates of 22q11.2 and 15q11.2 were also not statistically different between the isolated CHD group and the non-isolated congenital heart defect group (p > 0.05).

CONCLUSION

SNP-based CMA enhances the capacity to detect abnormal CNVs in CHD fetuses, offering valuable insights for diagnosing chromosomal etiology and facilitating genetic counseling. This research contributes to the broader understanding of the utility of SNP-based CMA in the context of fetal cardiac ultrasound abnormalities.

Clinical Experience of Prenatal Chromosomal Microarray Analysis in 6159 Ultrasonically Abnormal Fetuses

A single-center retrospective study of G-band karyotyping and chromosomal microarray analysis (CMA) for the invasive prenatal diagnosis of 6159 fetuses with ultrasound abnormalities was conducted. This study aimed to investigate the incidence rates of chromosomal abnormalities and pregnancy outcomes and postpartum clinical manifestations by long-term follow-up and to explore the correlation between different types of prenatal ultrasound abnormalities and pathogenic chromosomal abnormalities. The overall incidence of pathogenic chromosomal aberrations in fetuses with ultrasound abnormalities was 7.58% (467/6159), which comprised 41.7% (195/467) with chromosome number abnormalities, 57.6% (269/467) with pathogenic copy-number variations (pCNVs), and 0.64% (3/467) with uniparental disomy (UPD). In addition, 1.72% (106/6159) with likely pathogenic copy-number variations (lpCNVs) and 3.04% (187/6159) with variants of unknown significance (VOUS) were detected by CMA. Ultrasound abnormalities were categorized into structural anomalies and soft marker anomalies. The incidence rate of pathogenic and likely pathogenic chromosomal abnormalities was significantly higher among fetuses with structural anomalies than soft markers (11.13% vs 7.59%, p < 0.01). We retrospectively analyzed the prenatal genetic outcomes for a large cohort of fetuses with different types of ultrasound abnormalities. The present study showed that the chromosomal abnormality rate and clinical outcomes of fetuses with different types of ultrasound abnormalities varied greatly. Our data have important implications for prenatal genetic counseling for fetuses with different types of ultrasound abnormalities.

A rapid PCR-free next-generation sequencing method for comprehensive diagnosis of chromosome disease syndromes in prenatal samples

The aim of this study is to investigate the application performance of rapid copy number variation sequencing (rCNV-seq) technology for the detection of chromosomal abnormalities during prenatal diagnosis. Samples were collected from 424 pregnant women who were at high-risk for noninvasive prenatal screening in Kunming Maternal and Child Care Hospital from January 2018 to May 2022. rCNV-seq technique was used to detect fetal chromosome abnormalities and compare the results with that of chromosomal karyotype analysis. The Result showed that 330 (77.83%, 330/424) cases indicated chromosomal abnormalities among 424 high-risk pregnant women who underwent rCNV-seq. Moreover, 94 (22.17%, 94/424) cases were discovered to have copy number variations. Among the 330 fetuses with chromosomal abnormalities, common autosomal aneuploidy was observed in 203 cases (47.87%, 203/424) and sex chromosome aneuploidy was observed in 91 cases (21.46%, 91/424). Moreover, the abnormalities in multiple chromosomes were discovered in 33 cases (7.78%, 33/424), and the rare autosomal aneuploidy was observed in 3 cases (0.71%, 3/424). There were 63 fetuses (14.86%, 63/424) with pathogenic CNVs among the 94 fetuses with variable copy numbers. Of the 245 pregnant women who voluntarily selected G-band karyotyping, 1 fetus with copy number variation had normal karyotype results, and the remaining women were consistent with rCNV-seq. Our study revealed that rCNV-seq has higher accuracy in detecting common trisomy and can also detect chromosomal microdeletions or microduplications that cannot be detected by G-banding karyotype analysis. There is no effective treatment for chromosomal diseases, so it is particularly important to prevent chromosomal diseases through genetic counseling and prenatal diagnosis of chromosomal diseases.

Clinically significant findings in a decade-long retrospective study of prenatal chromosomal microarray testing

BACKGROUND

Chromosomal microarray (CMA) is commonly utilized in the obstetrics setting. CMA is recommended when one or more fetal structural abnormalities is identified. CMA is also commonly used to determine genetic etiologies for miscarriages, fetal demise, and confirming positive prenatal cell-free DNA screening results.

METHODS

In this study, we retrospectively examined 523 prenatal and 319 products-of-conception (POC) CMA cases tested at Nationwide Children's Hospital from 2011 to 2020. We reviewed the referral indications, the diagnostic yield, and the reported copy number variants (CNV) findings.

RESULTS

In our cohort, the diagnostic yield of clinically significant CNV findings for prenatal testing was 7.8% (n = 41/523) compared to POC testing (16.3%, n = 52/319). Abnormal ultrasound findings were the most common indication present in 81% of prenatal samples. Intrauterine fetal demise was the common indication identified in POC samples. The most common pathogenic finding observed in all samples was isolated trisomy 21, detected in seven samples.

CONCLUSION

Our CMA study supports the clinical utility of prenatal CMA for clinical management and identifying genetic etiology in POC arrays. In addition, it provides insight to the spectrum of prenatal and POC CMA results as detected in an academic hospital clinical laboratory setting that serves as a reference laboratory.

Identification of chromosomal abnormalities in miscarriages by CNV-Seq

OBJECTIVE

The primary object of this study is to analyze chromosomal abnormalities in miscarriages detected by copy number variants sequencing (CNV-Seq), establish potential pathways or genes related to miscarriages, and provide guidance for birth health in the following pregnancies.

METHODS

This study enrolled 580 miscarriage cases with paired clinical information and chromosomal detection results analyzed by CNV-Seq. Further bioinformatic analyses were performed on validated pathogenic CNVs (pCNVs).

RESULTS

Of 580 miscarriage cases, three were excluded as maternal cell contamination, 357 cases showed abnormal chromosomal results, and the remaining 220 were normal, with a positive detection rate of 61.87% (357/577). In the 357 miscarriage cases, 470 variants were discovered, of which 65.32% (307/470) were pathogenic. Among all variants detected, 251 were numerical chromosomal abnormalities, and 219 were structural abnormalities. With advanced maternal age, the proportion of numerical abnormalities increased, but the proportion of structural abnormalities decreased. Kyoto Encyclopedia of Genes and Genomes pathway and gene ontology analysis revealed that eleven pathways and 636 biological processes were enriched in pCNVs region genes. Protein-protein interaction analysis of 226 dosage-sensitive genes showed that TP53, CTNNB1, UBE3A, EP300, SOX2, ATM, and MECP2 might be significant in the development of miscarriages.

CONCLUSION

Our study provides evidence that chromosomal abnormalities contribute to miscarriages, and emphasizes the significance of microdeletions or duplications in causing miscarriages apart from numerical abnormalities. Essential genes found in pCNVs regions may account for miscarriages which need further validation.

Preimplantation genetic testing for X-linked chronic granulomatous disease induced by a CYBB gene variant: A case report

INTRODUCTION

X-linked recessive chronic granulomatous disease (XR-CGD) is a severe primary immunodeficiency principally caused by a CYBB (OMIM: 300481) gene variant. Recurrent fatal bacterial or fungal infections are the main clinical manifestations of XR-CGD.

PATIENT CONCERNS

In the current case, in vitro fertilization (IVF) associated with preimplantation genetic testing for monogenic disorder (PGT-M) was applied for a Chinese couple who had given birth to a boy with XR-CGD.

DIAGNOSIS

Next-generation sequencing-based SNP haplotyping and Sanger-sequencing were used to detect the CYBB gene variant (c.804 + 2T>C, splicing) in this family.

INTERVENTIONS

The patient was treated with IVF and PGT-M successively.

OUTCOMES

In this IVF cycle, 7 embryos were obtained, and 2 of them were euploid and lacked the CYBB gene variant (c.804 + 2T>C). The PGT results were verified by prenatal diagnosis after successful pregnancy, and a healthy girl was eventually born.

CONCLUSION

PGT-M is an effective method for helping families with these fatal and rare inherited diseases to have healthy offspring. It can availably block the transmission of disease-causing loci to descendant.

Diagnostic yield of chromosomal microarray in the largest Latino clinical cohort

Copy number variants (CNVs) remain a major etiological cause of neurodevelopmental delay and congenital malformations. Chromosomal microarray analysis (CMA) represents the gold standard for CNVs molecular characterization. We applied CMA throughout the patient's clinical diagnostic workup, as the patient's medical provider requested. We collected CMA results of 3380 patients enrolled for 5 years (2016-2021). We found 830 CNVs in 719 patients with potential clinical significance, that is, (i) pathogenic, (ii) likely pathogenic, and (iii) variants of uncertain significance (VUS), from which 10.6% (predominantly involving chromosomes 15 and 22) were most likely the final cause underpinning the patients' clinical phenotype. For those associated with neurodevelopmental phenotypes, the rate of pathogenic or likely pathogenic findings among the patients with CNVs was 60.75%. When considering epileptic phenotypes, it was 59%. Interestingly, our protocol identified two gains harbored in 17q21.31 and 9q34.3, internationally classified initially as VUS. However, because of their high frequency, we propose that these two VUS be reclassified as likely benign in this widely heterogeneous phenotypic population. These results support the diagnostic yield efficiency of CMA in characterizing CNVs to define the final molecular cause of genetic diseases in this cohort of Colombian patients, the most significant sample of patients from a Latino population, and define new benign polymorphic CNVs.

The detection efficacy of noninvasive prenatal genetic testing (NIPT) for sex chromosome abnormalities and copy number variation and its differentiation in pregnant women of different ages

Objective

To analyze the efficacy of noninvasive prenatal genetic testing (NIPT) in detecting fetal sex chromosome abnormalities and copy number variation (CNV), compare the efficacy between NIPT and serological screening alone, and further analyze the fetal sex chromosome abnormalities and CNV differentiation in pregnant women of different ages, so as to provide a reference for the prevention and control of fetal birth defects.

Methods

Clinical data from 22,692 pregnant women admitted to our hospital from January 2013 to December 2022 were retrospectively analyzed. All participants underwent serological screening and NIPT screening to compare fetal chromosomal abnormalities between the two screening modalities. 145 women whose fetus were diagnosed as sex chromosome abnormalities and 36 women whose fetus were diagnosed as CNV abnormalities based on NIPT screening were selected for prenatal diagnosis by amniocentesis or karyotyping. Taking prenatal diagnosis as the standard, the four-grid table method was used to detect the positive predictive value of NIPT screening for fetal sex chromosomal abnormalities and CNV. According to the age, pregnant women were divided into 18-30 years old (n = 9844), 31-35 years old (n = 7612), >35 years old (n = 5236), and then the detection rates of sexual fetal chromosomal abnormalities, CNV and total chromosomal abnormalities were compared in pregnant women.

Results

Among the 22,692 pregnant women in this study, the high-risk proportion of serologic screening with 4.38% was higher than that of NIPT screening with 1.93% (P < 0.05). Among the 145 women with fetal sex chromosome abnormalities screened by NIPT, 122 cases of fetal sex chromosome abnormalities were diagnosed prenatally, including 45, X/47, XXX/47, XYY/47, XXY. The positive predictive values of NIPT screening were 25.00%, 58.82%, 85.71%, and 85.71%, respectively, with an overall predictive value of 44.26%. The positive predictive value of fetal sex chromosome abnormalities in NIPT screening was higher than that of serological screening (P < 0.05). Among the 36 pregnant women with fetal CNV, NIPT screening showed that CNVs≤10 Mb and CNVs>10 Mb were 33.33% and 66.67%, respectively. There were 12 cases of prenatal diagnosis of fetal CNV, among which the NIPT-screened positive predictive values of fetal copy number deletion, duplicate, deletion and duplicate were 50.00%, 57.14% and 100.00%, respectively, with an overall predictive value of 58.33%. The positive predictive value of CNV in NIPT screening was higher than that of serological screening without statistically significant difference (P > 0.05). The results of NIPT screening showed that the detection rate of fetal sex chromosome abnormalities and total abnormalities of pregnant women over 35 years of age was significantly higher than that of pregnant women aged 18-30 and 31-35 years (P < 0.05).

Conclusion

NIPT screening could greatly improve the detection efficacy of fetal sex chromosome abnormalities, CNV and other chromosome abnormalities, and decline the false positive rate. However, the positive predictive value of NIPT screening was relatively low, and further prenatal testing and genetic counseling are still required. In addition, NIPT screening for fetal sex chromosome abnormalities, and the detection rate of total abnormalities in pregnant women older than 35 years old were increased significantly, and pregnancy at an advanced age may be one of the risk factors for fetal chromosomal abnormalities.

Experience of copy number variation sequencing applied in spontaneous abortion

PURPOSE

We evaluated the value of copy number variation sequencing (CNV-seq) and quantitative fluorescence (QF)-PCR for analyzing chromosomal abnormalities (CA) in spontaneous abortion specimens.

METHODS

A total of 650 products of conception (POCs) were collected from spontaneous abortion between April 2018 and May 2020. CNV-seq and QF-PCR were performed to determine the characteristics and frequencies of copy number variants (CNVs) with clinical significance. The clinical features of the patients were recorded.

RESULTS

Clinically significant chromosomal abnormalities were identified in 355 (54.6%) POCs, of which 217 (33.4%) were autosomal trisomies, 42(6.5%) were chromosomal monosomies and 40 (6.2%) were pathogenic CNVs (pCNVs). Chromosomal trisomy occurs mainly on chromosomes 15, 16, 18, 21and 22. Monosomy X was not associated with the maternal or gestational age. The frequency of chromosomal abnormalities in miscarriages from women with a normal live birth history was 55.3%; it was 54.4% from women without a normal live birth history (P > 0.05). There were no significant differences among women without, with 1, and with ≥ 2 previous miscarriages regarding the rate of chromosomal abnormalities (P > 0.05); CNVs were less frequently detected in women with advanced maternal age than in women aged ≤ 29 and 30-34 years (P < 0.05).

CONCLUSION

Chromosomal abnormalities are the most common cause of pregnancy loss, and maternal and gestational ages are strongly associated with fetal autosomal trisomy aberrations. Embryo chromosomal examination is recommended regardless of the gestational age, modes of conception or previous abortion status.

Improving CNV Detection Performance in Microarray Data Using a Machine Learning-Based Approach

Copy number variation (CNV) is a primary source of structural variation in the human genome, leading to several disorders. Therefore, analyzing neonatal CNVs is crucial for managing CNV-related chromosomal disabilities. However, genomic waves can hinder accurate CNV analysis. To mitigate the influences of the waves, we adopted a machine learning approach and developed a new method that uses a modified log R ratio instead of the commonly used log R ratio. Validation results using samples with known CNVs demonstrated the superior performance of our method. We analyzed a total of 16,046 Korean newborn samples using the new method and identified CNVs related to 39 genetic disorders were identified in 342 cases. The most frequently detected CNV-related disorder was Joubert syndrome 4. The accuracy of our method was further confirmed by analyzing a subset of the detected results using NGS and comparing them with our results. The utilization of a genome-wide single nucleotide polymorphism array with wave offset was shown to be a powerful method for identifying CNVs in neonatal cases. The accurate screening and the ability to identify various disease susceptibilities offered by our new method could facilitate the identification of CNV-associated chromosomal disease etiologies.

Clinical application of single nucleotide polymorphism microarray analysis in pregnancy loss in Northwest China

Background: Spontaneous abortion is the most common complication of early pregnancy. In this study, we aim to investigate the clinical application value of genetic diagnosis using single nucleotide polymorphism (SNP) microarray analysis on the products of conception and to characterize the types of genetic abnormalities and their prevalence in pregnancy loss in Northwest China. Methods: Over 48 months, we selected 652 products of conception, which included chorionic villi, fetal tissues, germ cell samples, amniotic fluid samples, cord blood samples, and a cardiac blood sample. We analyzed the distribution of chromosomal abnormalities leading to fetal arrest or abortion using SNP array. The patients were then categorized divided into groups based on maternal age, gestational age, number of miscarriages, and maternal ethnic background. The incidences of various chromosomal abnormalities in each group were compared. Results: Of the 652 cases, 314 (48.16%) exhibited chromosomal abnormalities. These included 286 cases with numerical chromosomal abnormalities, 24 cases with copy number variation, and four cases with loss of heterozygosity. Among them, there were 203 trisomy cases, 55 monosomy cases, and 28 polyploidy cases. In the subgroup analysis, significant differences were found in the frequency of numerical chromosomal abnormalities and copy number variation between the advanced and younger maternal age group as well as between the early and late abortion groups. Furthermore, we identified significant differences in the frequency of numerical chromosomal abnormalities between the first spontaneous abortion and recurrent miscarriage groups. However, there were no significant differences in the frequency of numerical chromosomal abnormalities between the Han and Uighur groups. Conclusion: Our research highlights chromosomal abnormalities as the primary cause of spontaneous abortion, with a higher incidence in early pregnancy and among women of advanced age. The use of SNP array analysis emerges as an effective and reliable technique for chromosome analysis in aborted fetuses. This method offers a comprehensive and dependable genetic investigation into the etiology of miscarriage, establishing itself as a valuable routine selection for genetic analysis in cases of natural abortions.

Fetal mosaicism, should conventional karyotype always be performed?

BACKGROUND AND PURPOSE

The application of classical cytogenetic and DNA-based molecular techniques to detect cell lineages of mosaicism derived from cultured or noncultured fetal cells may result in discordant results. This retrospective study aimed to assess the inconsistent diagnostic outcomes, technical availability, and limitations of chromosomal microarray analysis (CMA) and karyotyping for mosaicism.

METHODOLOGY

A total of 75 fetuses diagnosed with mosaicism by karyotype analysis or CMA were selected, and the results from both the methods were compared and further analyzed.

RESULTS

A total of 42 (56%, 42/75) CMA results were consistent with karyotypes, consisting of 22 cases of mosaic sex chromosomal abnormalities, 8 routine autosomal aneuploidy cases, 8 other autosome aneuploidy cases, 3 large cryptic genomic rearrangements, and 1 small supernumerary marker chromosome. Discrepancy between karyotype analysis and CMA was observed in 33 (44%, 33/75) mosaicisms involving 15 sex chromosomal abnormalities, 1 routine autosomal aneuploidies, 5 other autosome aneuploidy cases, 8 large cryptic genomic rearrangements, and 4 small supernumerary marker chromosomes.

CONCLUSION

Considering the disparities between methods as well as the cell populations analyzed, both CMA and karyotype analysis have their own advantages and disadvantages. Therefore, CMA should ideally be used in combination with karyotyping to detect more cases of mosaicism than using either test alone.

Challenging diagnoses of tetraploidy/diploidy and trisomy 12: utility of first-tier prenatal testing methods

Introduction: Chromosome mosaicism and low-grade mosaicism present a challenge for diagnosis in the era of SNP array and NGS. Tetraploidy is a rare numerical chromosomal abnormality characterized by the presence of four copies of each chromosome. The prevalence of tetraploidy/diploidy mosaicism cases is extremely rare in the human population. Accurate estimates of the frequency of this chromosomal anomaly are lacking due to its classification as an extremely rare and difficult-to-detect condition. Methods: In this report, we describe two cases involving challenging diagnoses of tetraploidy/diploidy and trisomy 12. We utilized advanced genetic testing techniques, including SNP array, to examine the chromosomal abnormalities in these cases. We compared the results from SNP array to conventional G band karyotyping to assess the utility of first-tier prenatal testing methods. Results:Our analysis revealed two cases of tetraploidy/diploidy and trisomy 12 with atypical presentations. SNP array analysis provided higher resolution and more precise information about the chromosomal anomalies in these cases compared to conventional G band karyotyping. Additionally, the prevalence of tetraploidy/diploidy mosaicism was confirmed to be extremely rare in the population. Discussion: Low-level mosaicism is difficult to diagnose, and in many cases, it has traditionally been identified through techniques such as G band karyotype or FISH. Microarray has become an invaluable diagnostic tool for detecting chromosomal abnormalities, offering high-resolution insights. However, it may not always be able to detect rare occurrences of tetraploidy or tetraploidy/diploidy mosaicism. As a result, it is recommended to perform a G band karyotype analysis after obtaining a negative microarray result before considering other diagnostic methods with a potentially higher yield of diagnosis. For the detection of low-level mosaicism, combined diagnostic methods should be considered. The diagnosis of mosaicism is a multistep process that can be time-consuming, often requiring the application of more than one diagnostic technique. This approach is crucial for accurate diagnosis and comprehensive patient care. Further research is warranted to better understand the underlying mechanisms of these rare chromosomal anomalies and to develop more effective diagnostic strategies for challenging cases.

Next-generation sequencing through multi-gene panel testing for the diagnosis of a Chinese patient with atypical Cockayne syndrome

BACKGROUND

Cockayne syndrome (CS, OMIM #133540, #216400) is a rare autosomal recessive disease involving multiple systems, typically characterized by microcephaly, premature aging, growth retardation, neurosensory abnormalities, and photosensitivity. The age of onset is related to the severity of the clinical phenotype, which may lead to fatal outcomes.

METHODS

We report a 3-year-old girl who presented with photosensitivity, gait abnormalities, stunting, and microcephaly and showed atypical clinical classification due to mild clinical manifestations at an early onset age.

RESULTS

Next-generation sequencing reveals the frameshift mutation (c.394_398del, p.Leu132Asnfs*6) and a novel microdeletion of ERCC8 (exon4del, p.Arg92fs).

CONCLUSION

Therefore, it is still necessary to carry out next-generation sequencing for CS patients with atypical clinical manifestations, which is essential for diagnosis and accurate genetic counseling.

Prenatal diagnosis of 7q11.23 microdeletion: Two cases report and literature review

RATIONALE

Chromosome microdeletions within 7q11.23 can result in Williams-Beuren syndrome which is a rare autosomal dominant disorder. Williams-Beuren syndrome is usually associated with developmental delay, cardiovascular anomalies, mental retardation, and characteristic facial appearance.

PATIENT CONCERNS

Two pregnant women underwent amniocentesis for cytogenetic analysis and chromosomal microarray analysis (CMA) because of abnormal ultrasound findings. Case 1 presented subependymal cyst and case 2 presented intrauterine growth restriction, persistent left superior vena cava and pericardial effusion in clinical ultrasound examination.

DIAGNOSES

Cytogenetic examination showed that the 2 fetuses presented normal karyotypic results. CMA detected 1.536 Mb (case 1) and 1.409 Mb (case 2) microdeletions in the region of 7q11.23 separately.

INTERVENTIONS

Both couples opted for the termination of pregnancies based upon genetic counseling.

OUTCOMES

The deleted region in both fetuses overlapped with Williams-Beuren syndrome. To our knowledge, case 1 was the first reported fetus of Williams-Beuren syndrome with subependymal cyst.

LESSONS

The genotype-phenotype of Williams-Beuren syndrome is complicated due to the phenotypic diversity. For prenatal cases, clinicians should consider the combination of ultrasonography, traditional cytogenetic, and molecular diagnosis technology when genetic counseling.

Chromosomal abnormalities in fetuses with congenital heart disease: a meta-analysis

PURPOSE

The aim of this meta-analysis was to evaluate the risk of chromosomal abnormalities in fetuses with congenital heart disease (CHD).

METHODS

Four literature databases were searched until 17th January 2022 using the relevant medical subject heading terms, word variants, and keywords for "congenital heart defect, fetal, and chromosomal abnormalities". The prevalence of overall chromosomal abnormality, aneuploidy, 22q11 deletion, other copy number variants (CNVs), and variants of unknown significance (VOUS) was analyzed.

RESULTS

45 studies met the inclusion criteria for the analysis. The pooled proportion of overall chromosomal abnormalities, aneuploidy, 22q11 deletion, and other CNVs in fetuses with CHD was 23% (95% CI: 20-26%), 19% (95% CI, 16-22%), 2% (95% CI, 2-3%), and 4% (95% CI, 3-5%), respectively. The incidence of overall chromosomal abnormalities, aneuploidy, and other CNVs in non-isolated CHD was higher than in isolated CHD, with odds ratios of 3.08, 3.45, and 4.02, respectively. The incidence of overall chromosomal abnormalities in septal defects was higher than in conotruncal defects and other defects, with odds ratios of 1.60 and 3.61, respectively. In addition, the pooled proportion of VOUS in CHD was 4%.

CONCLUSION

CHD is commonly associated with chromosomal abnormalities. If karyotyping or fluorescence in situ hybridization is normal, chromosomal microarray should be performed to look for submicroscopic abnormalities, especially in fetuses with non-isolated CHD and septal defects.

Evaluation of the clinical effects of non-invasive prenatal screening for diseases associated with aneuploidy and copy number variation

BACKGROUND

To explore and compare the clinical effects of high-resolution non-invasive prenatal screening (NIPS-Plus) for common/uncommon chromosomal aneuploidy and microdeletion/microduplication syndromes (MMS).

METHODS

The current prospective study included a total of 25,380 pregnant women who performed NIPS-Plus, and amniocentesis was performed on women with MMS with the screening results to diagnose patients with suspected MMS.

RESULTS

There were 415 samples with positive results for NIPS-Plus, included 275 with aneuploidy and 140 with MMS. After diagnosis by amniocentesis, 188 cases were confirmed as true positive, included46 cases of T21, 9 cases of T18, 1 case of T13, 34 cases of SCA, 41 cases of other chromosomal euploidy and 57 cases of MMS. In addition, no false negative cases were found, MMS was classified with 5 Mb with the cutoff value, and the PPV of different fragment size was counted, respectively.

CONCLUSION

We found that the corresponding PPV was 44.66% with the fragment of copy number variation (CNV) being less than or equal to 5 Mb, and when it was greater than 5 Mb, the PPV was 29.73%, which suggested that NIPS-Plus was more suitable for screening the PPV of small fragment abnormalities. NIPS-Plus has a good application effect in routine aneuploidy screening and had the best detection effect for T21; moreover, it performed well in screening of MMS and had better detection effect on MMS with CNV fragment length less than 5 Mb. Based on the current results, we suggested that NIPS-Plus should be used as a comprehensive elementary prenatal screening method for all pregnant women, but for MMS caused by abnormal large fragment CNV, the detection method and efficiency still need to be improved.

Evaluation of the clinical utility of extended non-invasive prenatal testing in the detection of chromosomal aneuploidy and microdeletion/microduplication

BACKGROUND

With the development of whole-genome sequencing technology, non-invasive prenatal testing (NIPT) has been applied gradually to screen chromosomal microdeletions and microduplications that cannot be detected by traditional karyotyping. However, in NIPT, some false positives and false negatives occur. This study aimed to investigate the applicability of extended NIPT (NIPT-PLUS) in the detection of chromosomal aneuploidy and microdeletion/microduplication syndrome (MMS).

METHODS

A total of 452 pregnancies that underwent prenatal diagnostic testing (amniocentesis or chorionic villus sampling) by chromosomal microarray analysis (CMA), were screened by NIPT-PLUS from the peripheral blood sample of the pregnant women. The results of the two tested items were compared and analysed.

RESULTS

Of the 452 cases, 335 (74.12%) had positive CMA results, and 117 (25.88%) had no abnormal results. A total of 86 cases of trisomy 21, 18 and 13 and sex chromosome aneuploidy (SCA) were detected by CMA and NIPT-PLUS, with a detection rate of 96.51% (83/86). Among them, the detection rates of T18, T13; 47, XXY; 47, XXX and 47 XYY were 100%, and the detection rates of T21 and 45 XO were 96.55% and 90%, respectively. The detection sensitivity of rare chromosomal trisomy (RAT) was 80% (4/5). The positive predictive values of NIPT-PLUS for chromosome aneuploidy T21, T18 and T13 and for SCA and RAT were 90.32%, 87.50%, 25.00%, 88.89% and 50%, respectively. A total of 249 cases (74.32%) of chromosomal MMS were detected by CMA. The detection rate of NIPT-PLUS was 63.86% (159/249), and 90 cases (36.14%) were missed. The larger the MMS fragment, the higher the NIPT-PLUS detection sensitivity. In addition, most small fragments were of maternal origin.

CONCLUSION

The comparison between the CMA and NIPT-PLUS techniques shows that NIPT-PLUS has high sensitivity for detecting chromosomal aneuploidy and chromosomal copy number variations (CNVs) with fragments > 5 M. However, the sensitivity of CNV for fragments < 5 M is low, and the missed detection rate is high. Additionally, confined placental mosaicism and foetal mosaicism are the key factors causing false negatives in NIPT-PLUS, while maternal chromosomal abnormalities and confined placental mosaicism are key contributors to false positives, so appropriate genetic counselling is especially important for pregnant women before and after NIPT-PLUS testing.

Prenatal phenotypes and pregnancy outcomes of fetuses with recurrent 1q21.1 microdeletions and microduplications

Objective

Chromosomal 1q21.1 deletions and duplications are genomic disorders that are usually diagnosed postnatally. However, the genotype-phenotype correlations of 1q21.1 copy number variants (CNVs) during the prenatal period are still not clear. This study aimed to provide a systematic summary of prenatal phenotypes for such genomic disorders.

Methods

In total, 26 prenatal amniotic fluid samples diagnosed with 1q21.1 microdeletions/microduplications were obtained from pregnant women who opted for invasive prenatal testing. Karyotypic analysis and chromosomal microarray analysis (CMA) were performed for all cases simultaneously. The pregnancy outcomes and health conditions after birth in all cases were followed up. Meanwhile, prenatal cases with 1q21.1 microdeletions or microduplications in the literature were retrospectively collected.

Results

In total, 11 pregnancies (11/8,252, 0.13%) with 1q21.1 microdeletions and 15 (15/8,252, 0.18%) with 1q21.1 microduplications were identified. Among these 1q21.1 CNVs, 4 cases covered the thrombocytopenia-absent radius (TAR) region, 16 cases covered the 1q21.1 recurrent microdeletion/microduplication region, and 6 cases covered all regions mentioned above. The prenatal abnormal ultrasound findings were recorded in four participants with 1q21.1 deletions and seven participants with 1q21.1 duplications. Finally, three cases with 1q21.1 deletions and five with 1q21.1 duplications terminated their pregnancies.

Conclusion

In the prenatal setting, 1q21.1 microdeletions were associated with increased nuchal translucency (NT), anomalies of the urinary system, and cardiovascular abnormalities, while 1q21.1 microduplications were correlated with cardiovascular malformations, nasal bone dysplasia, and increased NT. In addition, cerebral ventriculomegaly might be correlated with 1q21.1 microduplications. Considering the variable expressivity and incomplete penetrance of 1q21.1 CNVs, long-term follow-up after birth should be carried out in these cases.

The Effect of Resolution Level and Targeted Design in the Diagnostic Performance of Prenatal Chromosomal Microarray Analysis

INTRODUCTION

This study was performed to assess the optimal resolution for prenatal testing by array comparative genomic hybridization (aCGH), aiming to balance between maximum diagnostic yield and minimal detection of variants of uncertain significance (VOUS).

METHODS

This was a prospective study using data of 2,336 fetuses that underwent invasive prenatal diagnosis, and the samples were analyzed by aCGH. In total, six different aCGH platforms were studied; four different resolutions (0.18 Mb, 0.5 Mb, 1 Mb, and 2 Mb) and two platform designs (whole-genome [WG] and targeted). The results of these designs were compared based on their diagnostic yield and VOUS rate. The performance of the different designs was further analyzed according to indication for invasive testing.

RESULTS

The diagnostic yield of copy number variants increased with increasing level of analysis. The detection rates of clinically significant chromosomal abnormalities were almost the same across our targeted array designs; 7.2% with 0.18 Mb backbone/0.05 Mb versus 7.1% with 0.5 Mb backbone/0.05 Mb (p >0.05). However, a significant difference in the rate of VOUS was observed; 9.4% with 0.18 Mb backbone/0.05 Mb versus 6% with 0.5 Mb backbone/0.05 Mb (p <0.001). After analyzing the results across different indications for testing, we found that the application of non-targeted platform designs and lower levels of resolution analysis (such as 1 Mb WG or 0.5 MbL/1 MbG WG) would offer similar diagnostic yield in most cases with major congenital anomalies, with lower VOUS rates. However, the sample size for many indication groups was too small to extract robust associations.

CONCLUSION

It appears that the targeted array platform with 0.5 Mb backbone resolution and 0.05 Mb on targeted gene-rich regions is optimal for routine chromosomal microarray analysis use in prenatal diagnosis. It may be beneficial to individualize the minimum resolution in specific referral indications as the indications for invasive prenatal testing may be quite heterogeneous.

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

BACKGROUND

Next-generation sequencing for copy number variants is often used as a follow-up investigation of unusual fetal ultrasound results and is capable of detecting copy number variations with a resolution of ∼0.1 Mb. In a prenatal setting, observation and subsequent management of pregnancies with a fetal variant of uncertain significance remains problematic for counseling.

OBJECTIVE

This study aimed to follow the decision-making processes in pregnancies with a fetal variant of uncertain significance and prospectively assess copy number variation interpretations and implications under the newer 2020 American College of Medical Genetics and Genomics guidelines.

STUDY DESIGN

In a single prenatal unit, prospective chromosome testing using copy number variation sequencing for 8030 fetuses with unexpected noninvasive findings identified 139 pregnancies with a copy number variation classified as a variant of uncertain significance according to the 2015 American College of Medical Genetics and Genomics guidelines current at the time. Parent-of-origin testing was subsequently performed to determine if the copy number variation was inherited or de novo. All couples were offered specialized genetic counseling to assist in pregnancy management decisions. For the continued pregnancies that reached term, newborns were clinically assessed for evidence of any disease at 0 to 10 months and/or at 2 to 4 years of age.

RESULTS

Of the 139 variants of uncertain significance found, most (78%) were inherited with no evidence of disease in the carrier parent. On the basis of primary ultrasound findings combined with results from noninvasive prenatal screening tests, most inherited variant of uncertain significance pregnancies were continued, whereas most pregnancies involving de novo variants of uncertain significance were terminated. From clinical follow-up of the 113 live births, only 5 showed any evidence of a phenotype that was not apparently related to the original variant of uncertain significance. Prospective reanalysis of the 139 variants of uncertain significance using recent 2020 American College of Medical Genetics and Genomics guidelines changed the status of 24 variants of uncertain significance, with 15 reclassified as benign and 9 as pathogenic. However, the 5 children born with an inherited variant of uncertain significance reclassified as pathogenic showed no evidence of a disease phenotype on clinical follow-up.

CONCLUSION

The severity of fetal ultrasound findings combined with results from parent-of-origin testing were the key drivers in pregnancy management decisions for patients. According to birth outcomes from continued pregnancies, most variants of uncertain significance proved to be apparently benign in nature and potentially of low risk of adverse disease outcome. There was a discordance rate of 17% for variant of uncertain significance scoring between the 2015 and 2020 American College of Medical Genetics and Genomics guidelines for defining a variant of uncertain significance, suggesting that difficulties remain for predicting true pathogenicity. Nonetheless, with increasing knowledge of population copy number variation polymorphisms, and a more complete assessment for alternative genetic causes, patients having prenatal assessments should feel less anxious when a fetal variant of uncertain significance is identified.

Advanced maternal age: copy number variations and pregnancy outcomes

Objective: Adverse pregnancy outcomes are closely related to advanced maternal age (AMA; age at pregnancy ≥35 years). Little research has been reported on aneuploid abnormalities and pathogenic copy number variations (CNVs) affecting pregnancy outcomes in women with AMA. The purpose of this study was to assess CNVs associated with AMA in prenatal diagnosis to determine the characteristics of pathogenic CNVs and assist with genetic counseling of women with AMA. Methods: Among 277 fetuses of women with AMA, 218 (78.7%) were isolated AMA fetuses and 59 (21.3%) were non-isolated AMA fetuses and showed ultrasound anomalies from January 2021 to October 2022. Isolated AMA was defined as AMA cases without sonographic abnormalities. Non-isolated AMA was defined as AMA cases with sonographic abnormalities such as sonographic soft markers, widening of the lateral ventricles, or extracardiac structural anomalies. The amniotic fluid cells underwent routine karyotyping followed by single nucleotide polymorphism array (SNP-array) analysis. Results: Of the 277 AMA cases, karyotype analysis identified 20 chromosomal abnormalities. As well as 12 cases of chromosomal abnormalities corresponded to routine karyotyping, the SNP array identified an additional 14 cases of CNVs with normal karyotyping results. There were five pathogenetic CNVs, seven variations of uncertain clinical significance (VOUS), and two benign CNVs. The detection rate of abnormal CNVs in non-isolated AMA cases was increasing (13/59; 22%) than in isolated AMA cases (13/218; 5.96%) (p < 0.001). We also determined that pathogenic CNVs affected the rate of pregnancy termination in women with AMA. Conclusion: Aneuploid abnormalities and pathogenic CNVs affect pregnancy outcomes in women with AMA. SNP array had a higher detection rate of genetic variation than did karyotyping and is an important supplement to karyotype analysis, which enables better informed clinical consultation and clinical decision-making.

Challenges and Pragmatic Solutions in Pre-Test and Post-Test Genetic Counseling for Prenatal Exome Sequencing

The yield of genetic prenatal diagnosis has been notably improved by introducing whole genome chromosomal microarray (CMA) and prenatal exome sequencing (pES). However, together with increased numbers of diagnoses made, the need to manage challenging findings such as variants of unknown significance (VUS) and incidental findings (IF) also increased. We have summarized the current guidelines and recommendations and we have shown current solutions used in our tertiary center in the Netherlands. We discuss four of the most common clinical situations: fetus with normal pES results, fetus with a pathogenic finding explaining the fetal phenotype, fetus with a variant of uncertain clinical significance fitting the phenotype and fetus with a variant leading to an incidental diagnosis. Additionally, we reflect on solutions in order to facilitate genetic counseling in an NGS-era.

Copy Number Variation and Structural Genomic Findings in 116 Cases of Sudden Unexplained Death between 1 and 28 Months of Age

In sudden unexplained death in pediatrics (SUDP) the cause of death is unknown despite an autopsy and investigation. The role of copy number variations (CNVs) in SUDP has not been well-studied. Chromosomal microarray (CMA) data are generated for 116 SUDP cases with age at death between 1 and 28 months. CNVs are classified using the American College of Medical Genetics and Genomics guidelines and CNVs in our cohort are compared to an autism spectrum disorder (ASD) cohort, and to a control cohort. Pathogenic CNVs are identified in 5 of 116 cases (4.3%). Variants of uncertain significance (VUS) favoring pathogenic CNVs are identified in 9 cases (7.8%). Several CNVs are associated with neurodevelopmental phenotypes including seizures, ASD, developmental delay, and schizophrenia. The structural variant 47,XXY is identified in two cases (2/69 boys, 2.9%) not previously diagnosed with Klinefelter syndrome. Pathogenicity scores for deletions are significantly elevated in the SUDP cohort versus controls (p = 0.007) and are not significantly different from the ASD cohort. The finding of pathogenic or VUS favoring pathogenic CNVs, or structural variants, in 12.1% of cases, combined with the observation of higher pathogenicity scores for deletions in SUDP versus controls, suggests that CMA should be included in the genetic evaluation of SUDP.

Detection of cryptic balanced chromosomal rearrangements using high-resolution optical genome mapping

BACKGROUND

Chromosomal rearrangements have profound consequences in diverse human genetic diseases. Currently, the detection of balanced chromosomal rearrangements (BCRs) mainly relies on routine cytogenetic G-banded karyotyping. However, cryptic BCRs are hard to detect by karyotyping, and the risk of miscarriage or delivering abnormal offspring with congenital malformations in carrier couples is significantly increased. In the present study, we aimed to investigate the potential of single-molecule optical genome mapping (OGM) in unravelling cryptic chromosomal rearrangements.

METHODS

Eleven couples with normal karyotypes that had abortions/affected offspring with unbalanced rearrangements were enrolled. Ultra-high-molecular-weight DNA was isolated from peripheral blood cells and processed via OGM. The genome assembly was performed followed by variant calling and annotation. Meanwhile, multiple detection strategies, including FISH, long-range-PCR amplicon-based next-generation sequencing and Sanger sequencing were implemented to confirm the results obtained from OGM.

RESULTS

High-resolution OGM successfully detected cryptic reciprocal translocation in all recruited couples, which was consistent with the results of FISH and sequencing. All high-confidence cryptic chromosomal translocations detected by OGM were confirmed by sequencing analysis of rearrangement breakpoints. Moreover, OGM revealed additional complex rearrangement events such as inverted aberrations, further refining potential genetic interpretation.

CONCLUSION

To the best of our knowledge, this is the first study wherein OGM facilitate the rapid and robust detection of cryptic chromosomal reciprocal translocations in clinical practice. With the excellent performance, our findings suggest that OGM is well qualified as an accurate, comprehensive and first-line method for detecting cryptic BCRs in routine clinical testing.

Evaluation and Analysis of Absence of Homozygosity (AOH) Using Chromosome Analysis by Medium Coverage Whole Genome Sequencing (CMA-seq) in Prenatal Diagnosis

OBJECTIVE

Absence of homozygosity (AOH) is a genetic characteristic known to cause human diseases mainly through autosomal recessive or imprinting mechanisms. The importance and necessity of accurate AOH detection has become more clinically significant in recent years. However, it remains a challenging task for sequencing-based methods thus far.

METHODS

In this study, we developed and optimized a new bioinformatic algorithm based on the assessment of minimum sequencing coverage, optimal bin size, the Z-score threshold of four types of allele count and the frequency for accurate genotyping using 28 AOH negative samples, and redefined the AOH detection cutoff value. We showed the performance of chromosome analysis by five-fold coverage whole genome sequencing (CMA-seq) for AOH identification in 27 typical prenatal/postnatal AOH positive samples, which were previously confirmed by chromosomal microarray analysis with single nucleotide polymorphism array (CMA/SNP array).

RESULTS

The blinded study indicated that for all three forms of AOH, including whole genomic AOH, single chromosomal AOH and segmental AOH, and all kinds of sample types, including chorionic villus sampling, amniotic fluid, cord blood, peripheral blood and abortive tissue, CMA-seq showed equivalent detection power to that of routine CMA/SNP arrays (750K). The subtle difference between the two methods is that CMA-seq is prone to detect small inconsecutive AOHs, while CMA/SNP array reports it as a whole.

CONCLUSION

Based on our newly developed bioinformatic algorithm, it is feasible to detect clinically significant AOH using CMA-seq in prenatal diagnosis.

How to choose a test for prenatal genetic diagnosis: a practical overview

Establishing the diagnosis of a fetal genetic disease in utero expands decision-making opportunities for individuals during pregnancy and enables providers to tailor prenatal care and surveillance to disease-specific risks. The selection of prenatal genetic tests is guided by key details from fetal imaging, family and obstetrical history, suspected diagnoses and mechanisms of disease, an accurate understanding of what abnormalities each test is designed to detect, and, at times, the gestational age at which testing is initiated. Pre- and posttest counseling, by or in conjunction with providers trained in genetics, ensure an accurate understanding of genetic tests, their potential results and limitations, estimated turnaround time for results, and the clinical implications of their findings. As prenatal diagnosis and testing options continue to expand rapidly, it is increasingly important for obstetrical providers to understand how to choose appropriate genetic testing and contextualize the clinical implications of their results.

Prenatal diagnosis by trio exome sequencing in fetuses with ultrasound anomalies: A powerful diagnostic tool

Introduction: Prenatal ultrasound (US) anomalies are detected in around 5%-10% of pregnancies. In prenatal diagnosis, exome sequencing (ES) diagnostic yield ranges from 6% to 80% depending on the inclusion criteria. We describe the first French national multicenter pilot study aiming to implement ES in prenatal diagnosis following the detection of anomalies on US. Patients and methods: We prospectively performed prenatal trio-ES in 150 fetuses with at least two US anomalies or one US anomaly known to be frequently linked to a genetic disorder. Trio-ES was only performed if the results could influence pregnancy management. Chromosomal microarray (CMA) was performed before or in parallel. Results: A causal diagnosis was identified in 52/150 fetuses (34%) with a median time to diagnosis of 28 days, which rose to 56/150 fetuses (37%) after additional investigation. Sporadic occurrences were identified in 34/56 (60%) fetuses and unfavorable vital and/or neurodevelopmental prognosis was made in 13/56 (24%) fetuses. The overall diagnostic yield was 41% (37/89) with first-line trio-ES versus 31% (19/61) after normal CMA. Trio-ES and CMA were systematically concordant for identification of pathogenic CNV. Conclusion: Trio-ES provided a substantial prenatal diagnostic yield, similar to postnatal diagnosis with a median turnaround of approximately 1 month, supporting its routine implementation during the detection of prenatal US anomalies.

Case report: A reciprocal translocation-free and pathogenic DUOX2 mutation-free embryo selected by complicated preimplantation genetic testing resulted in a healthy live birth

Preimplantation genetic testing (PGT) is an effective approach to improve clinical outcomes and prevent transmission of genetic imbalances by selecting embryos free of disease-causing genes and chromosome abnormalities. In this study, PGT was performed for a challenging case in which a couple simultaneously carried a maternal subchromosomal reciprocal translocation (RecT) revealed by fluorescence in situ hybridization involving the chromosome X (ChrX) and heterozygous mutations in dual oxidase 2 (DUOX2). Carriers of RecT are at increased risk for infertility, recurrent miscarriages, or having affected children due to the unbalanced gametes produced. DUOX2 mutation results in congenital hypothyroidism. Pedigree haplotypes for DUOX2 was constructed after the mutations were verified by Sanger sequencing. Since male carriers of X-autosome translocations may exhibit infertility or other abnormalities, pedigree haplotype for chromosomal translocation was also constructed to identify embryo with RecT. Three blastocysts were obtained by in vitro fertilization and underwent trophectoderm biopsy, whole genomic amplification, and next-generation sequencing (NGS). A blastocyst lacking copy number variants and RecT but carrying the paternal gene mutation in DUOX2, c.2654G>T (p.R885L) was used for embryo transfer, resulting in a healthy female infant whose genetic properties were confirmed by amniocentesis. Cases containing RecT and single gene disorder are rare. And the situation is more complicated when the subchromosomal RecT involving ChrX cannot be identified with routine karyotype analysis. This case report contributes significantly to the literature and the results have shown that the NGS-based PGT strategy may be broadly useful for complex pedigrees.

Evaluation of the trachea in fetuses with double aortic arch using prenatal ultrasound: a retrospective cohort study

BACKGROUND

Double aortic arch is the most common form of complete vascular ring. The trachea and/or esophagus could be compressed by the complete vascular ring, which may lead to early respiratory and/or esophageal symptoms in children with double aortic arch. Accurate prenatal assessment of tracheal compression could provide relevant information for perinatal clinical management of double aortic arch and emergency treatment of infants with double aortic arch. The fetal trachea is filled with amniotic fluid and can be clearly visualized with prenatal ultrasound. Previous studies reported the use of prenatal ultrasound to measure the tracheal internal diameters in normal fetuses and showed a linear correlation between the fetal tracheal internal diameters and gestational age. However, to the best of our knowledge, few studies have quantitatively evaluated tracheal compression in fetuses with double aortic arch using ultrasound.

OBJECTIVE

This study aimed to evaluate the tracheal compression caused by the vascular ring in fetuses with double aortic arch using prenatal ultrasound and to analyze the relationship between tracheal compression and postnatal clinical symptoms.

STUDY DESIGN

The data of fetuses with double aortic arch diagnosed with prenatal ultrasound at 2 institutions from January 2011 to April 2021 were retrospectively analyzed. Singleton pregnancies with normal fetuses as the control group were prospectively recruited. The tracheal compression-evaluated by comparing the tracheal internal diameter z scores against the gestational age-was assessed in fetuses with double aortic arch and in normal fetuses. The live-born infants with double aortic arch were divided into symptomatic and asymptomatic groups for the comparison of z scores. The receiver operating characteristic curve for the tracheal internal diameter z score cutoffs and prediction of symptomatic infants with double aortic arch was plotted. Intraobserver and interobserver agreements were investigated.

RESULTS

A total of 26 fetuses with double aortic arch were diagnosed, and 14 fetuses (53.8%) with double aortic arch were delivered alive. Among the 14 live-born infants, 7 (50.0%) were symptomatic, whereas 7 (50.0%) were asymptomatic. The tracheal internal diameter z scores were significantly lower in the double aortic arch group than in the normal groups (-0.62±1.36 vs 0.00±0.78; P<.001). The tracheal internal diameter z scores were significantly lower in the symptomatic group than in the asymptomatic group (-1.42±0.92 vs -0.49±0.96; P=.018). The area under the curve was 0.878 (95% confidence interval, 0.689-1.000). Using a tracheal internal diameter z scores cutoff of -1.21, the sensitivity was 71%, and the specificity was close to 100%. The intraclass correlation coefficients of interobserver and intraobserver agreements were 0.987 (95% confidence interval, 0.980-0.992) and 0.975 (95% confidence interval, 0.955-0.987), respectively.

CONCLUSION

The clinical symptoms in infants with double aortic arch were associated with prenatal tracheal compression, which can be prenatally evaluated using ultrasound. If fetuses are diagnosed with double aortic arch, prenatal surveillance of the tracheal internal diameters and comparison with z score reference ranges could provide pertinent information that would aid perinatal clinical management.

The Value of a Comprehensive Genomic Evaluation in Prenatal Diagnosis of Genetic Diseases: A Retrospective Study

Currently, there are still many challenges in prenatal diagnosis, such as limited or uncertain fetal phenotyping, variant interpretation, and rapid turnaround times. The aim of this study was to illustrate the value of a comprehensive genomic evaluation in prenatal diagnosis. We retrospectively reviewed 20 fetuses with clinically significant copy number variants (CNVs) detected by chromosomal microarray analysis (CMA) and no further exome sequencing testing in our tertiary center between 2019 and 2020. The residual DNA from the prenatal cases was used for the parallel implementation of CNV sequencing (CNV-seq) and trio-based clinical exome sequencing (trio-CES). CMA revealed 26 clinically significant CNVs (18 deletions and eight duplications) in 20 fetuses, in which five fetuses had two or more CNVs. There were eight fetuses with pathogenic CNVs (e.g., del 1p36), nine fetuses with likely pathogenic CNVs (e.g., dup 22q11.21), and three fetuses with variants of unknown significance (VOUS, e.g., dup 1q21.1q21.2). Trio-CES identified four fetuses with likely pathogenic mutations (SNV/InDels). Of note, a fetus was detected with a maternally inherited hemizygous variant in the SLX4 gene due to a 16p13.3 deletion on the paternal chromosome. The sizes of CNVs detected by CNV-seq were slightly larger than that of the SNP array, and four cases with mosaic CNVs were all identified by CNV-seq. In conclusion, microdeletion/duplication syndromes and monogenic disorders may co-exist in a subject, and CNV deletion may contribute to uncovering additional recessive disease alleles. The application of a comprehensive genomic evaluation (CNVs and SNV/InDels) has great value in the prenatal diagnosis arena. CNV-seq based on NGS technology is a reliable and a cost-effective technique for identifying CNVs.

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

Noninvasive prenatal testing (NIPT) is widely used to screen for common fetal chromosomal aneuploidies. However, the ability of NIPT-Plus to detect copy number variation (CNV) is debatable. Accordingly, we assessed the efficiency of NIPT-Plus to detect clinically significant fetal CNV. We performed a prospective analysis of 31,260 singleton pregnancies, included from June 2017 to December 2020. Cell-free fetal DNA was directly sequenced using the semiconductor sequencing platform for women with high-risk CNV with clinically significant results. Fetal karyotyping and chromosomal microarray analysis (or next-generation sequencing) are recommended for invasive diagnostic procedures. Women at low risk with no other abnormal results continued their pregnancies. We analyzed the expanded NIPT results, diagnostic test results, and follow-up information to evaluate its performance in detecting fetal CNV. Of the 31,260 pregnant women who received NIPT-Plus, 31,256 cases were tested successfully, a high risk of clinically significant CNV was detected in 221 cases (0.71%); 18 women refused further diagnosis; 203 women underwent invasive prenatal diagnosis; and 78 true positive cases and 125 false positive cases, with an overall positive predictive value (PPV) of 38.42% and a false positive rate of 0.40%. For known microdeletion/microduplication syndromes (n = 27), the PPVs were 75% DiGeorge syndrome (DGS), 80% 22q11.22 microduplication, 50% Prader-Willi syndrome, and 50% cri-du-chat. For the remaining clinically significant fetal CNVs (n = 175), the combined PPVs were 46.5% (CNVs > 10 Mb) and 28.57% (CNVs ≤ 10 Mb). NIPT-Plus screening for CNV has certain clinical value. NIPT-Plus yielded relatively high PPVs for 22q11.2 microduplication syndrome and DGS, and low to moderate PPVs for other CNVs.

Prenatal Diagnosis and Outcomes in Fetuses with Hemivertebra

Background: There are few studies on the burden of chromosomal abnormalities and single gene disorders in fetal hemivertebra (HV). We aim to investigate the cytogenetic and monogenic risk and evaluate prenatal outcomes of fetal HV. Method: This study included fetuses diagnosed with HV divided into two groups: isolated HV and non-isolated HV. Data on other sonographic structural anomalies, chromosomal and sub-chromosomal abnormalities, monogenic variations detected by WES, and prenatal outcomes are recorded and reviewed. Results: Among 109 fetal HV cases, forty-seven (43.1%) non-isolated HV cases were associated with structural anomalies. Chromosomal test results were available in 58 cases, identifying six (10.3%) chromosomal aberrations involved in four isolated and two non-isolated HV. WES identified four (likely) pathogenic variants in three cases among 16 fetuses with HV, involving three novel variants, 1250G > T and c.1277G> inherited from parents, respectively, in DLL3 and c.7213C > A ** in the FLNB. The live birth rate (LB) was higher in the isolated fetal HV group than in the non-isolated group (67.7% (42/62) vs. 12.5% (12/47), p < 0.001). Conclusion: This study emphasizes the risk of cytogenetic abnormalities in isolated HV. WES yields a diagnostic rate of 18.3% in HV with normal CMA, probably aiding the prenatal counseling and management of fetal HV.

Potentials and challenges of chromosomal microarray analysis in prenatal diagnosis

Introduction: For decades, conventional karyotyping analysis has been the gold standard for detecting chromosomal abnormalities during prenatal diagnosis. With the development of molecular cytogenetic methods, this situation has dramatically changed. Chromosomal microarray analysis (CMA), a method of genome-wide detection with high resolution, has been recommended as a first-tier test for prenatal diagnosis, especially for fetuses with structural abnormalities.

Methods: Based on the primary literature, this review provides an updated summary of the application of CMA for prenatal diagnosis. In addition, this review addresses the challenges that CMA faces with the emergence of genome sequencing techniques, such as copy number variation sequencing, genome-wide cell-free DNA testing, and whole exome sequencing.

Conclusion: The CMA platform is still suggested as priority testing methodology in the prenatal setting currently. However, pregnant women may benefit from genome sequencing, which enables the simultaneous detection of copy number variations, regions of homozygosity and single-nucleotide variations, in near future.

Prenatal Diagnosis Using Chromosomal Microarray Analysis in High-Risk Pregnancies

Background: To assess the value of chromosomal microarray analysis (CMA) during the prenatal diagnosis of high-risk pregnancies. Methods: Between January 2016 and November 2021, we included 178 chorionic villi and 859 amniocentesis samples from consecutive cases at a multiple tertiary hospital. Each of these high-risk singleton pregnancies had at least one of the following indications: (1) advanced maternal age (AMA; ≥35 years; 546, 52.7%); (2) fetal structural abnormality on ultrasound (197, 19.0%); (3) high-risk first- or second-trimester Down syndrome screen (189, 18.2%), including increased nuchal translucency (≥3.5 mm; 90, 8.7%); or (4) previous pregnancy, child, or family history (105, 10.1%) affected by chromosomal abnormality or genetic disorder. Both G-banding karyotype analysis and CMA were performed. DNA was extracted directly and examined with oligonucleotide array-based comparative genomic hybridization. Results: Aneuploidies were detected by both G-banding karyotyping and CMA in 42/1037 (4.05%) cases. Among the 979 cases with normal karyotypes, 110 (10.6%) cases had copy number variants (CNVs) in CMA, including 30 (2.9%) cases with reported pathogenic and likely pathogenic CNVs ≥ 400 kb, 37 (3.6%) with nonreported VOUS, benign, or likely benign CNVs ≥ 400 kb, and 43 (4.1%) with nonreported CNVs < 400 kb. Of the 58 (5.6%) cases with aneuploidy rearrangements, 42 (4.1%) were diagnosed by both G-banding karyotyping and CMA; four inversions, six balanced translocations, and six low mosaic rates were not detected with CMA. Conclusions: CMA is an effective first step for the prenatal diagnosis of high-risk pregnancies with fetal structural anomalies found in ultrasonography or upon positive findings.

Case Report: Preimplantation Genetic Testing for X-Linked Severe Combined Immune Deficiency Caused by IL2RG Gene Variant

Preimplantation genetic testing (PGT) has been increasingly used to prevent rare inherited diseases. In this study, we report a case where PGT was used to prevent the transmission of disease-caused variant in a SCID-X1 (OMIM:300400) family. SCID-X1 is an X-linked recessive inherited disease whose major clinical manifestation of immune deficiency is the significant reduction in the number of T-cells and natural killer cells. This family gave birth to a boy who was a hemizygous proband whose IL2RG gene was mutated (c.315T > A, p(Tyr105*), NM_000206.3, CM962677). In this case, Sanger sequencing for mutated allele and linkage analysis based on single-nucleotide polymorphism (SNP) haplotype via next-generation sequencing were performed simultaneously. After PGT for monogenic disorder, we detected the aneuploidy and copy number variation (CNV) for normal and female carrier embryos. Four embryos (E02, E09, E10, and E11) were confirmed without CNVs and inherited variants at the IL2RG gene. Embryo E02 (ranking 4BB) has been transferred after considering the embryo growth rate, morphology, and PGT results. Prenatal genetic diagnosis was used to detect amniotic fluid cells, showing that this fetus did not carry the variant of the IL2RG gene (c.315T > A). Ultimately, a healthy girl who had not carried disease-causing variants of SCID-X1 confirmed by prenatal diagnosis was born, further verifying our successful application of PGT in preventing mutated allele transmission for this SCID family.

Validity and Utility of Non-Invasive Prenatal Testing for Copy Number Variations and Microdeletions: A Systematic Review

Valid data on prenatal cell-free DNA-based screening tests for copy number variations and microdeletions are still insufficient. We aimed to compare different methodological approaches concerning the achieved diagnostic accuracy measurements and positive predictive values. For this systematic review, we searched the Scopus and PubMed databases and backward citations for studies published between 2013 and 4 February 2022 and included articles reporting the analytical and clinical performance of cfDNA screening tests for CNVs and microdeletions. Of the 1810 articles identified, 32 met the criteria. The reported sensitivity of the applied tests ranged from 20% to 100%, the specificity from 81.62% to 100%, and the PPV from 3% to 100% for cases with diagnostic or clinical follow-up information. No confirmatory analysis was available in the majority of cases with negative screening results, and, therefore, the NPVs could not be determined. NIPT for CNVs and microdeletions should be used with caution and any developments regarding new technologies should undergo strict evaluation before their implementation into clinical practice. Indications for testing should be in correlation with the application guidelines issued by international organizations in the field of prenatal diagnostics.

Abnormal chromosomes identification using chromosomal microarray

In this study, we presented a case series to highlight the chromosomal microarray (CMA) in identifying chromosomal abnormalities which is undetectable by conventional karyotyping or known abnormal chromosomes without clear diagnosis. Extensive studies showed that CMA was gradually accepted as a prenatal invasive testing during pregnancy. The aim of this study was to evaluate the diagnostic effect of CMA for foetuses with abnormal chromosomes unrecognised by conventional karyotyping. Pregnant women who need prenatal diagnosis with all indications were enrolled in this study. For aberrant cytogenetic findings that cannot be defined by routine karyotyping, single nucleotide polymorphism array (SNP-array) was used. Six cases with abnormal karyotype were included in the study. With higher resolution of translocation breakpoints, CMA could detect smaller chromosomal imbalances that were undetectable by karyotyping. This study highlights the value of CMA for the detection of submicroscopic abnormalities in foetuses that cannot be detected by conventional karyotyping. Impact StatementWhat is already known on this subject? Chromosomal microarray (CMA) offers additional diagnostic benefits by revealing submicroscopic imbalances or copy number variations (CNVs) that are too small to be identified on a standard G-banded chromosome preparation.What do the results of this study add? We added a case series to highlight the CMA in identifying chromosomal abnormalities not detectable by conventional karyotyping or known abnormal chromosomes without clear diagnosis.What are the implications of these findings for clinical practice and/or further research? This study highlights the value of CMA in the case of associated foetuses with submicroscopic abnormalities that cannot detect by conventional karyotyping.

Combining Z-Score and Maternal Copy Number Variation Analysis Increases the Positive Rate and Accuracy in Non-Invasive Prenatal Testing

Objective: To evaluate positive rate and accuracy of non-invasive prenatal testing (NIPT) combining Z-score and maternal copy number variation (CNV) analysis. To assess the relationship between Z-score and positive predictive value (PPV). Methods: This prospective study included 61525 pregnancies to determine the correlation between Z-scores and PPV in NIPT, and 3184 pregnancies to perform maternal CNVs analysis. Positive results of NIPT were verified by prenatal diagnosis and/or following-up after birth. Z-score grouping, logistic regression analysis, receiver operating characteristic (ROC) curves, and S-curve trends were applied to correlation analysis of Z-scores and PPV. The maternal CNVs were classified according to the technical standard for the interpretation of ACMG. Through genetic counseling, fetal and maternal phenotypes and family histories were collected. Results: Of the 3184 pregnant women, 22 pregnancies were positive for outlier Z-scores, suggesting fetal aneuploidy. 12 out of 22 pregnancies were true positive (PPV = 54.5%). 17 pregnancies were found maternal pathogenic or likely pathogenic CNVs (> 0.5 Mb) through maternal CNV analysis. Prenatal diagnosis revealed that 7 out of 11 fetuses carried the same CNVs as the mother. Considering the abnormal biochemical indicators during pregnancy and CNV-related clinical phenotypes after birth, two male fetuses without prenatal diagnosis were suspected to carry the maternally-derived CNVs. Further, we identified three CNV-related family histories with variable phenotypes. Statistical analysis of the 61525 pregnancies revealed that Z-scores of chromosomes 21 and 18 were significantly associated with PPV at 3 ≤ Z ≤ 40. Notably, three pregnancies with Z > 40 were both maternal full aneuploidy. At Z < -3, fetuses carried microdeletions instead of monosomies. Sex chromosome trisomy was significantly higher PPV than monosomy. Conclusion: The positive rate of the NIPT screening model combining Z-score and maternal CNV analysis increased from 6.91‰ (22/3184) to 12.25‰ (39/3184) and true positives increased from 12 to 21 pregnancies. We found that this method could improve the positive rate and accuracy of NIPT for aneuploidies and CNVs without increasing testing costs. It provides an early warning for the inheritance of pathogenic CNVs to the next generation.

The Use of Genetics for Reaching a Diagnosis in XY DSD

Reaching a firm diagnosis is vital for the long-term management of a patient with a difference or disorder of sex development (DSD). This is especially the case in XY DSD where the diagnostic yield is particularly low. Molecular genetic technology is playing an increasingly important role in the diagnostic process, and it is highly likely that it will be used more often at an earlier stage in the diagnostic process. In many cases of DSD, the clinical utility of molecular genetics is unequivocally clear, but in many other cases there is a need for careful exploration of the benefit of genetic diagnosis through long-term monitoring of these cases. Furthermore, the incorporation of molecular genetics into the diagnostic process requires a careful appreciation of the strengths and weaknesses of the evolving technology, and the interpretation of the results requires a clear understanding of the wide range of conditions that are associated with DSD.

Chromosomal Microarray Analysis in Fetuses Detected with Isolated Cardiovascular Malformation: A Multicenter Study, Systematic Review of the Literature and Meta-Analysis

Cardiovascular malformations (CVM) represent the most common structural anomalies, occurring in 0.7% of live births. The CVM prenatal suspicion should prompt an accurate investigation with fetal echocardiography and the assessment through genetic counseling and testing. In particular, chromosomal microarray analysis (CMA) allows the identification of copy number variations. We performed a systematic review and meta-analysis of the literature, studying the incremental diagnostic yield of CMA in fetal isolated CVM, scoring yields for each category of heart disease, with the aim of guiding genetic counseling and prenatal management. At the same time, we report 59 fetuses with isolated CVM with normal karyotype who underwent CMA. The incremental CMA diagnostic yield in fetuses with isolated CVM was 5.79% (CI 5.54–6.04), with conotruncal malformations showing the higher detection rate (15.93%). The yields for ventricular septal defects and aberrant right subclavian artery were the lowest (2.64% and 0.66%). Other CVM ranged from 4.42% to 6.67%. In the retrospective cohort, the diagnostic yield was consistent with literature data, with an overall CMA diagnostic yield of 3.38%. CMA in the prenatal setting was confirmed as a valuable tool for investigating the causes of fetal cardiovascular malformations.

Chromosomal Copy Number Variation Analysis in Pregnancy Products from Recurrent and Sporadic Miscarriage Using Next-Generation Sequencing

Chromosomal abnormality is one of the causes of fetal miscarriage. The potential differences of fetal chromosomal abnormalities in sporadic miscarriage (SM) and recurrent miscarriage (RM) remain unclear. The purpose of this study was to investigate copy number variations (CNVs) in SM and RM to provide useful genetic guidance for pregnancy and prenatal diagnosis. Four hundred eight samples of aborted fetuses were analyzed by CNV sequencing, and further functional enrichment analysis was performed. Chromosomal abnormalities were identified in 218 (53.4%) fetuses. There were 62 cases (15.2%) with structural chromosomal abnormalities, including 41 with VUS CNVs, 8 with pathogenic CNVs (pCNVs), and 5 with likely pCNVs. Duplications or deletions of 7p22, 8p22, 8p23, and Xp22.31 were significantly more common in RM cases and therefore believed to be related to RM. A total of 289 genes were identified, and 29 different functions were enriched as potential RM candidate genes and functions, which were mainly concentrated in 4 functional categories: chemokines and chemotaxis, protease activity and protein modification, defense response to bacterial and fungal infections, and immune response. The results of this study may improve our understanding of the etiology of RM and contribute to the establishment of a population-based genetic marker information for RM.