Copy Number Variations with Isolated Fetal Ventriculomegaly

Improving prenatal diagnosis with combined karyotyping, CNV-seq and QF-PCR: a comprehensive analysis of chromosomal abnormalities in high-risk pregnancies

Objective

This study aims to assess the diagnostic efficacy of a combined approach integrating chromosomal karyotyping, copy number variation sequencing (CNV-seq), and quantitative fluorescence polymerase chain reaction (QF-PCR) in detecting chromosomal abnormalities in high-risk pregnancies.

Methods

This retrospective study analyzed 617 high-risk pregnancies undergoing prenatal diagnosis from February 2023 to August 2024, with amniotic fluid samples concurrently analyzed using karyotyping, CNV-seq, and QF-PCR. We evaluated clinical characteristics, diagnostic yields, and inter-method concordance rates. Longitudinal follow-up assessed pregnancy outcomes and neonatal phenotypes, with particular emphasis on cases demonstrating diagnostic discrepancies or variants of uncertain clinical significance.

Results

The integrated approach detected chromosomal abnormalities in 12.5% (77/617) of cases, significantly higher than the rates achieved by karyotyping alone (9.7%) and CNV-seq/QF-PCR alone (8.3%) (p < 0.05). Karyotyping showed full concordance with CNV-seq and QF-PCR in detecting major chromosomal aneuploidies, identifying 21 cases of trisomy 21 and 4 cases of trisomy 18. CNV-seq uniquely identified additional pathogenic copy number variations in 2.1% of cases and variants of uncertain significance (VUS) in 3.2% of cases, both undetectable by conventional karyotyping. Subjects with high-risk non-invasive prenatal testing (NIPT) results had the highest abnormality detection rate (57.6%, p < 0.05). Follow-up data revealed pregnancy termination in 44 of 97 cases with chromosomal abnormalities. Notably, neonates carrying pathogenic CNVs inherited from asymptomatic parents demonstrated normal phenotypes.

Conclusion

The integration of karyotyping, CNV-seq, and QF-PCR provides superior diagnostic yield compared to individual testing strategies in high-risk pregnancies. Although karyotyping remains the gold standard for detecting major chromosomal aberrations, CNV-seq and QF-PCR enhance diagnostic precision through detection of submicroscopic variations. Multi-center studies with larger cohorts are needed to confirm these findings and clarify the clinical significance of uncertain variants.

Subgroup analysis of imaging scans, invasive examinations and prognosis in mild-to-moderate isolated foetal cerebral ventriculomegaly: a retrospective study in China

OBJECTIVE

This study aimed to analyse the causes of foetal mild-to-moderate isolated ventriculomegaly (IVM) and to evaluate the prognosis of neurological development in surviving children in different subgroups.

METHODS

We retrospectively studied mild-to-moderate IVM diagnosed by prenatal ultrasound scans in different subgroups according to the laterality of IVM, the degree of IVM and foetal sex independently. The results of foetal chromosomal microarray analysis, virological tests of umbilical cord blood or amniotic fluid, foetal magnetic resonance imaging and ultrasound were collected. Long-term follow-up was performed to assess the neurodevelopment of children within 66 months through telephone interviews and/or the Ages and Stages Questionnaire-3.

RESULTS

The moderate group showed more chromosomal abnormalities (16.2% vs. 4.1%) and greater structural anomalies in the brain (31.8% vs. 7.5%) than the mild group. Female foetuses showed more structural anomalies than male foetuses (25.0% vs. 7.2%). However, an adverse prognosis of children was not different across the different subgroups.

CONCLUSION

Moderate IVM may be more strongly associated with chromosomal aberrations and structural malformations than mild IVM. However, the adverse prognosis of children was similar between the different subgroups analysed.

Clinical characteristics and perinatal outcome of fetuses with ventriculomegaly

PURPOSE

To assess the incidence of associated structural anomalies, chromosomal/genetic abnormalities, infections, and perinatal outcomes of fetuses with ventriculomegaly (VM), also to evaluate the role of fetal magnetic resonance imaging (MRI) in detecting associated intracranial anomalies.

METHODS

Retrospective cohort study of 149 prenatally diagnosed pregnancies with fetal VM. VM was classified as mild (Vp = 10-12 mm), moderate (Vp = 12.1-15 mm), and severe (Vp > 15 mm). Fetal MRI was performed to 97 pregnancies.

RESULTS

The incidences of an associated CNS, non-CNS, chromosomal anomaly, genetic abnormality and fetal infection were 42.3%, 11.4%, 6.1%, 2.1% and 1.3%, respectively. Fetal MRI identified additional CNS anomalies in 6.7% of cases, particularly in severe VM. The incidences of perinatal outcomes were 18.8% termination of pregnancy, 4% intrauterine and 8.1% neonatal or infant death. The rates of fetuses alive at > 12 months of age with neurological morbidity were 2.6%, 11.1% and 76.9% for mild, moderate and severe isolated VM, respectively.

CONCLUSION

The prognosis of fetuses with VM mostly depends on the severity and the associated anomalies. Mild to moderate isolated VM generally have favorable outcomes. Fetal MRI is particularly valuable in fetuses with isolated severe VM.

Analysis of copy number variants detected by sequencing in spontaneous abortion

BACKGROUND

The incidence of spontaneous abortion (SA), which affects approximately 15-20% of pregnancies, is the most common complication of early pregnancy. Pathogenic copy number variations (CNVs) are recognized as potential genetic causes of SA. However, CNVs of variants of uncertain significance (VOUS) have been identified in products of conceptions (POCs), and their correlation with SA remains uncertain.

RESULTS

Of 189 spontaneous abortion cases, trisomy 16 was the most common numerical chromosome abnormality, followed by monosomy X. CNVs most often occurred on chromosomes 4 and 8. Gene Ontology and signaling pathway analysis revealed significant enrichment of genes related to nervous system development, transmembrane transport, cell adhesion, and structural components of chromatin. Furthermore, genes within the VOUS CNVs were screened by integrating human placental expression profiles, PhyloP scores, and Residual Variance Intolerance Score (RVIS) percentiles to identify potential candidate genes associated with spontaneous abortion. Fourteen potential candidate genes (LZTR1, TSHZ1, AMIGO2, H1-4, H2BC4, H2AC7, H3C8, H4C3, H3C6, PHKG2, PRR14, RNF40, SRCAP, ZNF629) were identified. Variations in LZTR1, TSHZ1, and H4C3 may contribute to embryonic lethality.

CONCLUSIONS

CNV sequencing (CNV-seq) analysis is an effective technique for detecting chromosomal abnormalities in POCs and identifying potential candidate genes for SA.

Prenatal diagnosis and pregnancy outcomes in fetuses with ventriculomegaly

Objective

Genetic etiology plays a critical role in fetal ventriculomegaly (VM). However, the studies on chromosomal copy number variants (CNVs) in fetal VM are limited. This study aimed to investigate the chromosomal CNVs in fetuses with mild to moderate VM, and explore its genotype-phenotype correlation.

Methods

A total of 242 fetuses with mild to moderate VM detected by prenatal ultrasound were enrolled in our study from October 2018 to October 2022. All cases underwent chromosomal microarray analysis (CMA) and G-banding simultaneously. All VM cases were classified different subgroups according to the maternal age, severity, VM distribution and presence/absence of other ultrasound abnormalities. The pregnancy outcomes and health conditions after birth were followed up. We also performed a pooled analysis regarding likely pathogenic and pathogenic CNVs (LP/P CNVs) for VM.

Results

The detection rate of chromosomal abnormalities by karyotyping was 9.1% (22/242), whereas it was 16.5% (40/242) when CMA was conducted (P < 0.05). The total detection rate of chromosomal abnormalities by karyotyping and CMA was 21.1% (51/242). A 12.0% incremental yield of CMA over karyotyping was observed. The detection rate of total genetic variants in fetuses with bilateral VM was significantly higher than in fetuses with unilateral VM (30.0% vs. 16.7%, P = 0.017). No significant differences were discovered between isolated VM and non-isolated VM, or between mild and moderate VM, or between advanced maternal age (AMA) and non-AMA (all P > 0.05). 28 fetuses with VM were terminated and 214 fetuses were delivered: one presented developmental delay and one presented congenital heart disease. The VM cases with both positive CMA and karyotypic results had a higher rate of termination of pregnancy than those with either a positive CMA or karyotypic result, or both negative testing results (P < 0.001).

Conclusion

The combination of CMA and karyotyping should be adopted to improve the positive detection rate of chromosomal abnormalities for VM. The total genetic abnormalities detected using both techniques would affect the final pregnancy outcomes. LP/P CNVs at 16p11.2, 17p13, and 22q11.21 were identified as the top three chromosomal hotspots associated with VM, which would enable genetic counselors to provide more precise genetic counseling for VM pregnancies.

The genetic landscape of chromosomal aberrations in 3776 Vietnamese fetuses with clinical anomalies during pregnancy

Background: Copy number variation sequencing (CNV-seq) is a powerful tool to discover structural genomic variation, but limitations associated with its retrospective study design and inadequate diversity of participants can be impractical for clinical application. Aim: This study aims to use CNV-seq to assess chromosomal aberrations in pregnant Vietnamese women. Materials & methods: A large-scale study was conducted on 3776 pregnant Vietnamese women with abnormal ultrasound findings. Results: Chromosomal aberrations were found in 448 (11.86%) women. Of these, 274 (7.26%) had chromosomal aneuploidies and 174 (4.61%) carried pathogenic/likely pathogenic CNVs. Correlations were established between chromosomal aberrations and various phenotypic markers. Conclusion: This comprehensive clinical study illuminates the pivotal role of CNV-seq in prenatal diagnosis for pregnancies featuring fetal ultrasound anomalies.

White matter changes in fetal brains with ventriculomegaly

Introduction

Ventriculomegaly (VM) is a fetal brain malformation which may present independently (isolated form) or in association with different cerebral malformations, genetic syndromes or other pathologies (non-isolated form).

Methods

This paper aims to study the effect of ventriculomegaly on the internal tridimensional architecture of fetal brains by way of Klingler's dissection. Ventriculomegaly was diagnosed using fetal ultrasonography during pregnancy and subsequently confirmed by necropsy. Taking into consideration the diameter of the lateral ventricle (measured at the level of the atrium), the brains were divided into two groups: moderate ventriculomegaly (with atrial diameter between 13 and 15 mm) and severe ventriculomegaly (with atrial diameter above 15 mm).

Results and discussion

The results of each dissection were described and illustrated, then compared with age-matched reference brains. In the pathological brains, fascicles in direct contact with the enlarged ventricles were found to be thinner and displaced inferiorly, the opening of the uncinate fasciculus was wider, the fornix was no longer in contact with the corpus callosum and the convexity of the corpus callosum was inverted. We have studied the prevalence of neurodevelopmental delay in children born with ventriculomegaly in the literature and discovered that a normal developmental outcome was found in over 90% of the mild VM cases, approximately 75% of the moderate and 60% in severe VM, with the correlated neurological impairments ranging from attention deficits to psychiatric disorders.

Molecular Approaches in Fetal Malformations, Dynamic Anomalies and Soft Markers: Diagnostic Rates and Challenges-Systematic Review of the Literature and Meta-Analysis

Fetal malformations occur in 2-3% of pregnancies. They require invasive procedures for cytogenetics and molecular testing. "Structural anomalies" include non-transient anatomic alterations. "Soft markers" are often transient minor ultrasound findings. Anomalies not fitting these definitions are categorized as "dynamic". This meta-analysis aims to evaluate the diagnostic yield and the rates of variants of uncertain significance (VUSs) in fetuses undergoing molecular testing (chromosomal microarray (CMA), exome sequencing (ES), genome sequencing (WGS)) due to ultrasound findings. The CMA diagnostic yield was 2.15% in single soft markers (vs. 0.79% baseline risk), 3.44% in multiple soft markers, 3.66% in single structural anomalies and 8.57% in multiple structural anomalies. Rates for specific subcategories vary significantly. ES showed a diagnostic rate of 19.47%, reaching 27.47% in multiple structural anomalies. WGS data did not allow meta-analysis. In fetal structural anomalies, CMA is a first-tier test, but should be integrated with karyotype and parental segregations. In this class of fetuses, ES presents a very high incremental yield, with a significant VUSs burden, so we encourage its use in selected cases. Soft markers present heterogeneous CMA results from each other, some of them with risks comparable to structural anomalies, and would benefit from molecular analysis. The diagnostic rate of multiple soft markers poses a solid indication to CMA.

Chromosomal microarray analysis vs. karyotyping for fetal ventriculomegaly: a meta-analysis

BACKGROUND

Chromosomal abnormalities are important causes of ventriculomegaly (VM). In mild and isolated cases of fetal VM, obstetricians rarely give clear indications for pregnancy termination. We aimed to calculate the incidence of chromosomal abnormalities and incremental yield of chromosomal microarray analysis (CMA) in VM, providing more information on genetic counseling and prognostic evaluation for fetuses with VM.

METHODS

The Chinese language databases Wanfang Data, China National Knowledge Infrastructure, and China Biomedical Literature Database (from January 1, 1991 to April 29, 2020) and English language databases PubMed, Embase, and Cochrane Library (from January 1, 1945 to April 29, 2020) were systematically searched for articles on fetal VM. Diagnostic criteria were based on ultrasonographic or magnetic resonance imaging (MRI) assessment of lateral ventricular atrium width: ≥10 to <15 mm for mild VM, and ≥15 mm for severe VM. Isolated VM was defined by the absence of structural abnormalities other than VM detected by ultrasonography or MRI. R software was used for the meta-analysis to determine the incidence of chromosomal abnormalities and incremental yield of CMA in VM, and the combined rate and 95% confidence interval (CI) were calculated.

RESULTS

Twenty-three articles involving 1635 patients were included. The incidence of chromosomal abnormalities in VM was 9% (95% CI: 5%-12%) and incremental yield of CMA in VM was 11% (95% CI: 7%-16%). The incidences of chromosomal abnormalities in mild, severe, isolated, and non-isolated VM were 9% (95% CI: 4%-16%), 5% (95% CI: 1%-11%), 3% (95% CI: 1%-6%), and 13% (95% CI: 4%-25%), respectively.

CONCLUSIONS

Applying CMA in VM improved the detection rate of abnormalities. When VM is confirmed by ultrasound or MRI, obstetricians should recommend fetal karyotype analysis to exclude chromosomal abnormalities. Moreover, CMA should be recommended preferentially in pregnant women with fetal VM who are undergoing invasive prenatal diagnosis. CMA cannot completely replace chromosome karyotype analysis.

Classifying and Evaluating Fetuses With Ventriculomegaly in Genetic Etiologic Studies

The association between genetics and fetuses with ventriculomegaly (VM) is unknown. This study aimed to classify and evaluate abnormal copy number variations (CNVs) in fetuses with VM. From December 2016 to September 2020, amniotic fluid or umbilical cord blood from 293 pregnant women carrying fetuses with VM was extracted for single-nucleotide polymorphism microarray (SNP array). Among 293 fetuses with VM, 31 were detected with abnormal CNVs, including 22 with pathogenic CNVs (7.51%) and nine with variation of uncertain clinical significance (VUS) CNVs (3.07%). Of the 22 fetuses with pathogenic CNVs, 13 had known disease syndromes. Among the 293 fetuses, 133 had mild isolated VM [pathogenic CNVs, 7/133 (5.26%)]; 142 had mild non-isolated VM [pathogenic CNVs, 13/142 (9.15%)]; 12 had severe isolated VM [pathogenic CNVs, 2/12 (16.67%)]; and six had severe non-isolated VM (no abnormal CNVs was detected). There was no statistical significance in the rate of pathogenic CNVs among the four groups (P = 0.326, P > 0.05). Among the 267 fetuses with successful follow-up, 38 were terminated (of these, 21 had pathogenic CNVs). Of the 229 fetuses, two had developmental delay and the remaining 227 had a good prognosis after birth. Overall, the results are useful for the detection of fetal microdeletion/microduplication syndrome and for the accurate assessment of fetal prognosis in prenatal consultation.

Performance of Chromosomal Microarray Analysis for Detection of Copy Number Variations in Fetal Echogenic Bowel

BACKGROUND

Fetal echogenic bowel (FEB) is associated with an increased risk of poor pregnant outcomes; however, karyotyping fails to detect copy number variations (CNVs) in FEB. This study aimed to evaluate the performance of chromosomal microarray analysis (CMA) for detection of FEB.

METHODS

The medical records of 147 pregnant women with FEB recruited during December 2015 to December 2018 were retrospectively reviewed, and prenatal samples were collected for karyotyping and CMA. The detection of chromosomal abnormality was compared between karyotyping and CMA.

RESULTS

Karyotyping identified eight cases with abnormal karyotypes (5.44% prevalence), including four fetuses with pathogenic aneuploidy, three with chromosome polymorphism and one with balanced chromosome translocation. CMA identified 13 abnormal CNVs (8.84% prevalence), including 4 fetuses with pathogenic aneuploidy as detected by karyotyping and 9 additional CNVs with normal karyotypes; however, CMA failed to detect chromosome polymorphism and balanced chromosome translocation. In fetuses with isolated FEB, no cases presented pathogenic findings and CMA detected two cases with variants of uncertain significance (VOUS). In cases presenting FEB along with other ultrasound abnormalities, CMA detected three cases with pathogenic CNVs and four cases with VOUS in addition to four cases with aneuploidy. There was no significant difference in the detection of abnormal CNVs between the fetuses with echogenic bowel alone and along with other ultrasound abnormalities (10% vs 8.67%, P > 0.05). Except 9 fetuses lost to the follow-up, the other 138 fetuses with echogenic bowel were successfully followed up. Pregnancy was terminated in 5 fetuses with chromosomal abnormality, 2 with pathogenic CNVs and 1 with VOUS, and other 16 with normal karyotypes and CMA findings but showing ultrasound abnormalities or multiple malformations.

CONCLUSION

Isolated FEB is associated with a good prognosis, and a satisfactory pregnant outcome is expected for fetuses with echogenic bowel that are negative for chromosomal anomalies and other severe structure abnormalities. CMA shows an important value in the genetic diagnosis of FEB. As a supplement to karyotyping, CMA may improve the accuracy of prenatal diagnosis of fetal intestinal malformations in pregnant women with FEB.

Detection of copy number variation associated with ventriculomegaly in fetuses using single nucleotide polymorphism arrays

Etiopathogenesis of fetal ventriculomegaly is poorly understood. Associations between fetal isolated ventriculomegaly and copy number variations (CNVs) have been previously described. We investigated the correlations between fetal ventriculomegaly-with or without other ultrasound anomalies-and chromosome abnormalities. 222 fetuses were divided into four groups: (I) 103 (46.4%) cases with isolated ventriculomegaly, (II) 41 (18.5%) cases accompanied by soft markers, (III) 33 (14.9%) cases complicated with central nervous system (CNS) anomalies, and (IV) 45 (20.3%) cases with accompanying anomalies. Karyotyping and single nucleotide polymorphism (SNP) array were used in parallel. Karyotype abnormalities were identified in 15/222 (6.8%) cases. Karyotype abnormalities in group I, II, III, and IV were 4/103 (3.9%), 2/41 (4.9%), 4/33 (12.1%), and 5/45 (11.1%), respectively. Concerning the SNP array analysis results, 31/222 (14.0%) were CNVs, CNVs in groups I, II, III, and IV were 11/103 (10.7%), 6/41 (14.6%), 9/33 (27.3%), and 5/45 fetuses (11.1%), respectively. Detections of clinical significant CNVs were higher in non-isolated ventriculomegaly than in isolated ventriculomegaly (16.81% vs 10.7%, P = 0.19). SNP arrays can effectively identify CNVs in fetuses with ventriculomegaly and increase the abnormal chromosomal detection rate by approximately 7.2%, especially ventriculomegaly accompanied by CNS anomalies.

Correlation between mild fetal ventriculomegaly, chromosomal abnormalities, and copy number variations

BACKGROUND

Lateral ventriculomegaly is the most common abnormality of the fetal nervous system. This study investigated the incidence of chromosomal abnormalities and copy number variations (CNVs) in fetuses with mild ventriculomegaly (MV) based on various ultrasonic manifestations, identifying their corresponding features via ultrasound examination.

METHODS

A retrospective analysis was performed on ultrasound and neurosonogram (NSG) manifestations and genetic profiles of 334 cases with MV and invasive prenatal diagnosis.

RESULTS

Three hundred thirty-four cases with fetal MV were assessed via karyotyping. Further chromosomal microarray analysis (CMA) was performed in 182 cases with normal chromosome karyotypes; pathogenic chromosomal copy number variations (CNVs) were found in eight cases with a prevalence of 4.4% (8/182). In this study, the incidence rate of pathogenic abnormalities of chromosomes and CNVs was 5.7% (19/334). Based on whether lateral ventriculomegaly was complicated with other ultrasonic features, the 334 patients were divided into two groups: (1) 175 cases exhibited isolated ventriculomegaly (IVM; 52.4%, 175/334 group A) including two (1.1%, 2/175) with pathogenic chromosomal karyotype abnormalities-both trisomy 21; (2) 159 cases exhibited non-isolated ventriculomegaly (N-IVM; 47.6%, 159/334) with pathogenic chromosomal abnormalities and CNVs detected in17 cases (10.7%, 17/159). The N-IVM group was further divided into two groups: 105 cases exhibited MV with undetermined ultrasonic abnormalities (31.4%, 105/334, group B) with pathogenic chromosomal abnormalities and CNVs detected in eight cases (7.6%, 8/105); 54 cases exhibited MV with structural malformations (16.2%, 54/334, group C) of which nine cases (16.7%, 9/54) presented both pathogenic chromosomal abnormalities and CNVs, and five cases (55.6%, 5/9) were diagnosed with various cortical malformations. The pathogenicity rates of the IVM and N-IVM groups were statistically different (χ ²=14.159, p = 0.000). There were significant differences (χ²=7.992, p = 0.005) among groups A, B, and C.

CONCLUSIONS

Combinations of various ultrasonic abnormalities significantly affect the risk of pathogenic chromosomal abnormalities and CNVs in fetuses with MV. Cases involving cortical malformations require particular attention to the occurrence of pathogenic genetic abnormalities. When fetal MV is detected, a comprehensive ultrasound examination focusing on undetermined ultrasonic abnormalities is critical. Fetal NSG should be conducted to detect potential cerebral cortical malformation easily missed by routine ultrasound.

Prenatal diagnosis of chromosomal aberrations by chromosomal microarray analysis in foetuses with ventriculomegaly

Ventriculomegaly is considered to be linked to abnormal neurodevelopment outcome. The aim of this retrospective study was to investigate the current applications of chromosomal microarray analysis (CMA) in foetuses with ventriculomegaly. A total of 548 foetuses with ventriculomegaly detected by prenatal ultrasound underwent single nucleotide polymorphism (SNP) array testing and were subjected to long-term follow-up. The overall prevalence of chromosomal aberrations was 7.30% (40/548), including 4.20% (23/548) with pathogenic/likely pathogenic copy number variants. The incidence of chromosomal aberrations was significantly higher in foetuses with bilateral ventriculomegaly than in those with unilateral ventriculomegaly (10.56% vs. 5.71%, P = 0.040), in foetuses with non-isolated ventriculomegaly than in those with isolated ventriculomegaly (12.99% vs. 2.38%, P < 0.0001), and in foetuses with severe ventriculomegaly than in those with mild-to-moderate ventriculomegaly (23.08% vs. 6.51%, P = 0.005). The outcome in foetuses with mild ventriculomegaly was significantly better than in those with moderate ventriculomegaly (95.60% vs. 84.00%, P = 0.003). Thus, CMA should be regarded as the first-tier test for prenatal diagnosis of foetal ventriculomegaly, especially in foetuses with bilateral or non-isolated ventriculomegaly. The outcome of foetuses with mild ventriculomegaly is favourable; however, there is an increased risk of neurodevelopmental disabilities in foetuses with moderate ventriculomegaly.

Should chromosomal microarray be offered to fetuses with ultrasonographic soft markers in second trimester: A prospective cohort study and meta-analysis

OBJECTIVE

To evaluate whether chromosomal microarray (CMA) should be offered to fetuses with ultrasonographic soft markers (USMs) in the second trimester.

METHODS

A prospective cohort study and meta-analysis were conducted. In the prospective cohort study, 564 fetuses with USMs were enrolled. In the meta-analysis, eligible articles describing copy number variations in fetuses with USMs were included.

RESULTS

In the prospective cohort study, the diagnostic yields of CMA over non-invasive prenatal testing (NIPT) and karyotyping were significantly higher in fetuses with mild ventriculomegaly (MVM) than those in local control cohorts with normal ultrasound. However, the yields of CMA over NIPT and karyotyping in fetuses with other USMs were similar to controls. About ten studies, involving 405 fetuses with MVM and 1412 fetuses with other USMs, were included in the meta-analysis. The pooled diagnostic yields of CMA over NIPT and karyotyping in fetuses with MVM were 4.9% and 3.2%, respectively. In fetuses with other USMs, the yields of CMA over NIPT and karyotyping were 1.2% and 0.4%, respectively.

CONCLUSION

It is reasonable to offer CMA as a first-tier test to fetuses with MVM. However, for fetuses with other USMs, the considerations to perform CMA should not differ from pregnancies with normal ultrasound.

Prenatal genetic considerations in congenital ventriculomegaly and hydrocephalus

BACKGROUND

Fetal ventriculomegaly (VM) is a frequent finding in prenatal ultrasound. Rather than a proper diagnosis, VM is a sonographic sign, making prenatal counseling a complex and challenging undertaking. VM can range from severe pathologic processes leading to severe neurodevelopmental delay to normal variants.

DISCUSSION

A growing number of genetic conditions with different pathophysiological mechanisms, inheritance patterns, and long-term prognosis have been associated both to isolated and complex fetal VM. These include chromosomal abnormalities, copy number variants, and several single gene diseases. In this review, we describe some of the most common genetic conditions associated with fetal VM and provide a simplified diagnostic workflow for the clinician.

Prenatal detection of 1p36 deletion syndrome: ultrasound findings and microarray testing results

OBJECTIVE

Only a small number of reports have been made on the prenatal ultrasound findings observed in 1p36 deletion syndrome. We explored prenatal diagnosis of 1p36 deletion by ultrasound as well as chromosomal microarray (CMA), and delineated the fetal presentation of this syndrome.

STUDY DESIGN

This was a retrospective analysis of 10 new prenatal cases of 1p36 deletion identified by CMA at a single Chinese medical center. Clinical data were reviewed for these cases, including maternal demographics, indications for invasive testing, sonographic findings, CMA results and pregnancy outcomes.

RESULTS

One case was diagnosed because of a positive cell-free DNA (cfDNA) testing result for terminal 1p deletion, and the remaining nine cases were identified because of an abnormal ultrasound findings, including early miscarriage, structural abnormalities and fetal growth restriction. CMA revealed 1p36 deletions to be terminal in six cases, and interstitial in four cases. Deletion sizes ranged from 1.7 to 42.7 Mb.

CONCLUSIONS

Prenatal findings such as cardiac malformations, especially Ebstein anomaly, and fetal growth retardation should warrant the diagnosis of 1p36 deletion and invasive genetic testing using CMA.

Copy number variations and fetal ventriculomegaly

PURPOSE OF REVIEW

Ventriculomegaly is one of the most common abnormal sonographic findings, which is associated with congenital infection, chromosomal and additional structural abnormalities. Currently, karyotype analysis is the primary method to detect chromosomal abnormalities in fetuses with ventriculomegaly. Recently, with the introduction of chromosomal microarray analysis (CMA) in prenatal diagnosis, copy number variations (CNVs) have been identified in cases of ventriculomegaly. The purpose of this review is to summarize the current knowledge about the genetic cause of fetal ventriculomegaly, with particular attention to primary articles regarding the association between CNVs and fetal ventriculomegaly.

RECENT FINDINGS

Recent studies have disclosed that in addition to numerical chromosomal abnormalities and large chromosomal imbalances, pathogenic CNVs are another important genetic cause of fetal ventriculomegaly, which may be involved in the pathological process of fetal ventriculomegaly as well as postnatal neurodevelopmental disorders. Furthermore, it is reported that the incidences of pathogenic CNVs in fetuses with ventriculomegaly were associated with the presence of other structural anomalies, but were irrelevant to the severity of ventriculomegaly.

SUMMARY

CNVs are an important cause of fetal ventriculomegaly and CMA should be offered to all fetuses with ventriculomegaly, regardless of the degree of ventriculomegaly or whether combined with other structural anomalies.

Identification of copy number variations among fetuses with ultrasound soft markers using next-generation sequencing

A prospective analysis investigating the associations between pathogenic copy number variations (pCNVs) and ultrasound soft markers (USMs) in fetuses and evaluating the clinical value of copy number variation sequencing (CNV-seq) in such pregnancy studies was carried out. 3,398 unrelated Chinese women with singleton pregnancies and undergone amniocentesis at 18–36 weeks of gestation for fetal CNV-seq were included. According to the prenatal fetal ultrasound screening results, the samples were divided into 3 groups: normal ultrasound (n = 2616), solitary USM (n = 663), and two or more USMs (n = 119). CNV-seq was performed successfully using all samples. The prevalence of pCNVs in fetuses with normal ultrasound and USMs was 3.03% (79/2616) and 2.94% (23/782), respectively. The risk of segmental aneuploidies was significantly higher in the two or more USMs group (5/119, 4.20%) than in the normal ultrasound (27/2616, 1.04%) or solitary USM (9/663, 1.36%) groups (p = 0.002 and p = 0.031, respectively). Assuming that the resolution of karyotyping is ~5 Mb, a cytogenetic analysis would miss 33 of 102 (32.35%) pCNVs in these samples. Our results suggest an association between pCNVs and fetal USMs; multiple USMs indicate an increased risk of fetal segmental aneuploidies. In prenatal diagnostic testing, CNV-Seq identified additional, clinically significant cytogenetic information.

Prenatal chromosomal microarray analysis in fetuses with congenital heart disease: a prospective cohort study

BACKGROUND

Currently, chromosomal microarray analysis is considered the first-tier test in pediatric care and prenatal diagnosis. However, the diagnostic yield of chromosomal microarray analysis for prenatal diagnosis of congenital heart disease has not been evaluated based on a large cohort.

OBJECTIVE

Our aim was to evaluate the clinical utility of chromosomal microarray as the first-tier test for chromosomal abnormalities in fetuses with congenital heart disease.

STUDY DESIGN

In this prospective study, 602 prenatal cases of congenital heart disease were investigated using single nucleotide polymorphism array over a 5-year period.

RESULTS

Overall, pathogenic chromosomal abnormalities were identified in 125 (20.8%) of 602 prenatal cases of congenital heart disease, with 52.0% of them being numerical chromosomal abnormalities. The detection rates of likely pathogenic copy number variations and variants of uncertain significance were 1.3% and 6.0%, respectively. The detection rate of pathogenic chromosomal abnormalities in congenital heart disease plus additional structural anomalies (48.9% vs 14.3%, P < .0001) or intrauterine growth retardation group (50.0% vs 14.3%, P = .044) was significantly higher than that in isolated congenital heart disease group. Additionally, the detection rate in congenital heart disease with additional structural anomalies group was significantly higher than that in congenital heart disease with soft markers group (48.9% vs 19.8%, P < .0001). No significant difference was observed in the detection rates between congenital heart disease with additional structural anomalies and congenital heart disease with intrauterine growth retardation groups (48.9% vs 50.0%), congenital heart disease with soft markers and congenital heart disease with intrauterine growth retardation groups (19.8% vs 50.0%), or congenital heart disease with soft markers and isolated congenital heart disease groups (19.8% vs 14.3%). The detection rate in fetuses with congenital heart disease plus mild ventriculomegaly was significantly higher than in those with other types of soft markers (50.0% vs 15.6%, P < .05).

CONCLUSION

Our study suggests chromosomal microarray analysis is a reliable and high-resolution technology and should be used as the first-tier test for prenatal diagnosis of congenital heart disease in clinical practice.