Risk of Clinically Significant Chromosomal Microarray Analysis Findings in Fetuses With Nuchal Translucency From 3.0 mm Through 3.4 mm

First-Trimester Ultrasound Screening in Routine Obstetric Practice

Technologic advances and ultrasonographer-physician experience in fetal imaging have led to significant improvements in our ability to distinguish between normal and abnormal fetal structural development in the latter part of the first trimester. As a critical component of pregnancy care, assessment of fetal anatomy at the end of the first trimester with a standardized imaging protocol should be offered to all pregnant patients regardless of aneuploidy screening results because it has been demonstrated to identify approximately half of fetal structural malformations. Early identification of abnormalities allows focused genetic counseling, timely diagnostic testing, and subspecialist consultation. In addition, a normal ultrasound examination result offers some degree of reassurance to most patients. Use of cell-free DNA alone for aneuploidy screening while foregoing an accompanying early anatomic evaluation of the fetus will result in many anomalies that are typically detected in the first trimester not being identified until later in pregnancy, thus potentially diminishing the quality of obstetric care for pregnant individuals and possibly limiting their reproductive options, including pregnancy termination.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Ultrasonographic Fetal Nuchal Translucency Measurements and Cytogenetic Outcomes

Importance

Ultrasonographic measurement of fetal nuchal translucency is used in prenatal screening for trisomies 21 and 18 and other conditions. A cutoff of 3.5 mm or greater is commonly used to offer follow-up investigations, such as prenatal cell-free DNA (cfDNA) screening or cytogenetic testing. Recent studies showed a possible association with chromosomal anomalies for levels less than 3.5 mm, but extant evidence has limitations.

Objective

To evaluate the association between different nuchal translucency measurements and cytogenetic outcomes on a population level.

Design, Setting, and Participants

This population-based retrospective cohort study used data from the Better Outcomes Registry & Network, the perinatal registry for Ontario, Canada. All singleton pregnancies with an estimated date of delivery from September 1, 2016, to March 31, 2021, were included. Data were analyzed from March 17 to August 14, 2023.

Exposures

Nuchal translucency measurements were identified through multiple-marker screening results.

Main Outcomes and Measures

Chromosomal anomalies were identified through all Ontario laboratory-generated prenatal and postnatal cytogenetic tests. Cytogenetic testing results, supplemented with information from cfDNA screening and clinical examination at birth, were used to identify pregnancies without chromosomal anomalies. Multivariable modified Poisson regression with robust variance estimation and adjustment for gestational age was used to compare cytogenetic outcomes for pregnancies with varying nuchal translucency measurement categories and a reference group with nuchal translucency less than 2.0 mm.

Results

Of 414 268 pregnancies included in the study (mean [SD] maternal age at estimated delivery date, 31.5 [4.7] years), 359 807 (86.9%) had a nuchal translucency less than 2.0 mm; the prevalence of chromosomal anomalies in this group was 0.5%. An increased risk of chromosomal anomalies was associated with increasing nuchal translucency measurements, with an adjusted risk ratio (ARR) of 20.33 (95% CI, 17.58-23.52) and adjusted risk difference (ARD) of 9.94% (95% CI, 8.49%-11.39%) for pregnancies with measurements of 3.0 to less than 3.5 mm. The ARR was 4.97 (95% CI, 3.45-7.17) and the ARD was 1.40% (95% CI, 0.77%-2.04%) when restricted to chromosomal anomalies beyond the commonly screened aneuploidies (excluding trisomies 21, 18, and 13 and sex chromosome aneuploidies).

Conclusions and Relevance

In this cohort study of 414 268 singleton pregnancies, those with nuchal translucency measurements less than 2.0 mm were at the lowest risk of chromosomal anomalies. Risk increased with increasing measurements, including measurements less than 3.5 mm and anomalies not routinely screened by many prenatal genetic screening programs.

Association analysis between chromosomal abnormalities and fetal ultrasonographic soft markers based on 15,263 fetuses

BACKGROUND

Soft markers are common prenatal ultrasonographic findings that indicate an increased risk for fetal aneuploidy. However, the association between soft markers and pathogenic or likely pathogenic copy number variations is still unclear, and clinicians lack clarity on which soft markers warrant a recommendation for invasive prenatal genetic testing of the fetus.

OBJECTIVE

This study aimed to provide guidance on ordering prenatal genetic testing for fetuses with different soft markers and to elucidate the association between specific types of chromosomal abnormalities and specific ultrasonographic soft markers.

STUDY DESIGN

Low-pass genome sequencing was performed for 15,263 fetuses, including 9123 with ultrasonographic soft markers and 6140 with normal ultrasonographic findings. The detection rate of pathogenic or likely pathogenic copy number variants among fetuses with various ultrasonographic soft markers were compared with that of fetuses with normal ultrasonography. The association of soft markers with aneuploidy and pathogenic or likely pathogenic copy number variants were investigated using Fisher exact tests with Bonferroni correction.

RESULTS

The detection rate of aneuploidy and pathogenic or likely pathogenic copy number variants was 3.04% (277/9123) and 3.40% (310/9123), respectively, in fetuses with ultrasonographic soft markers. An absent or a hypoplastic nasal bone was the soft marker in the second trimester with the highest diagnostic rate for aneuploidy of 5.22% (83/1591) among all isolated groups. Four types of isolated ultrasonographic soft markers, namely a thickened nuchal fold, single umbilical artery, mild ventriculomegaly, and absent or hypoplastic nasal bone, had higher diagnostic rates for pathogenic or likely pathogenic copy number variants (P<.05; odds ratio, 1.69-3.31). Furthermore, this study found that the 22q11.2 deletion was associated with an aberrant right subclavian artery, whereas the 16p13.11 deletion, 10q26.13-q26.3 deletion, and 8p23.3-p23.1 deletion were associated with a thickened nuchal fold, and the 16p11.2 deletion and 17p11.2 deletion were associated with mild ventriculomegaly (P<.05).

CONCLUSION

Ultrasonographic phenotype-based genetic testing should be considered in clinical consultations. Copy number variant analysis is recommended for fetuses with an isolated thickened nuchal fold, a single umbilical artery, mild ventriculomegaly, and an absent or a hypoplastic nasal bone. A comprehensive definition of genotype-phenotype correlations in aneuploidy and pathogenic or likely pathogenic copy number variants could provide better information for genetic counseling.

When NIPT meets WES, prenatal diagnosticians face the dilemma: genetic etiological analysis of 2,328 cases of NT thickening and follow-up of pregnancy outcomes

Objective: To assess the performance of diverse prenatal diagnostic approaches for nuchal translucency (NT) thickening and to investigate the optimal prenatal screening or diagnostic action with a NT thickening of 95th percentile-3.50 mm. Methods: A retrospective analysis of 2,328 pregnancies with NT ≥ 95th percentile through ultrasound-guided transabdominal chorionic villus sampling (CVS), amniocentesis, or cordocentesis obtained clinical samples (chorionic villi, amniotic fluid, and cord blood), and real-time quantitative fluorescent PCR (QF-PCR), chromosome karyotyping (CS), chromosome microarray analysis (CMA), or whole exome sequencing (WES) were provided to identify genetic etiologies. Results: In this study, the incidence of chromosomal defects increased with NT thickness. When NT ≥ 6.5 mm, 71.43% were attributed to genetic abnormalities. The 994 gravidas with fetal NT thickening underwent short tandem repeat (STR), CS, and CMA. In 804 fetuses with normal karyotypes, CMA detected 16 (1.99%) extra pathogenic or likely pathogenic copy number variations (CNVs). The incremental yield of CMA was only 1.16% (3/229) and 3.37% (10/297) in the group with NT 95th percentile-2.99 mm and NT 3.0-3.49 mm, separately. Among the 525 gravidas with fetal NT thickening who underwent STR, CMA, and WES, the incremental yield of WES was 4.09% (21/513). In the group of NT 95th percentile-2.99 mm, there were no additional single-nucleotide variations (SNVs) detected in WES, while in 143 cases with NT of 3.0-3.49 mm, the incremental yield of WES was 5.59% (8/143). Conclusion: In the group of NT 95th percentile-3.0 mm, since chromosomal aneuploidy and chromosomal copy number variation were the primary causes and the additional contribution of CMA and WES was not significant, we recommend NIPT-Plus for pregnant women with a NT thickening of 95th percentile-3.0 mm first. In addition, comprehensive prenatal genetic testing involving CMA and WES can benefit pregnancies with NT thickening of 3.0-3.49 mm.

[Management of isolated increased nuchal translucency: survey among the Pluridisciplinary Centers for Prenatal Diagnosis]

OBJECTIVES

The management for isolated increased nuchal translucency (NT) in the first trimester with a normal karyotype and normal Chromosomal Microarray Analysis (CMA) is not consensual. The aim was to perform a survey among the Pluridisciplinary Centers for Prenatal Diagnosis (CPDPN) in France regarding their management of increased NT in the first trimester.

METHODS

We conducted a multicenter descriptive survey between September 2021 and October 2021 among the 46 CPDPNs of France.

RESULTS

The response rate was 56.5% (n = 26/46). The NT thickness threshold for which invasive diagnosis testing is performed is 3.0mm in 23.1% of centers (n = 6/26) and 3.5mm in 76.9% of centers (n = 20/26). A CMA was performed alone in 26.9% of centers (n = 7/26) while 7.7% of centers (n = 2/26) did not perform a CMA. The gestational age for the first reference ultrasound scan was 16 to 18 WG in 88.5% of centers (n = 23/26), while it was not performed before 22 WG in 11.5% of centers (n = 3/26). Fetal echocardiography is proposed systematically in 73.1% of centers (n = 19/26).

CONCLUSION

There is heterogeneity in the management of increased NT in the first trimester among the CPDPNs in France. In case of increased NT on first trimester ultrasound scan, the NT thickness threshold for which invasive diagnosis testing is performed varies from 3.0 mm or 3.5mm depending on the center. Moreover, CMA and early reference morphological ultrasound scan between 16 and 18 WG were not systematically performed, despite the current data suggesting their interest.

Chromosomal abnormalities and structural defects in fetuses with increased nuchal translucency at a Chinese tertiary medical center

Objectives

To explore the pregnancy outcomes of fetuses with increased NT thickness.

Methods

This was a retrospective study of fetuses with increased NT (≥95th centile) at 11-14 weeks of gestation between January 2020 and November 2020.

Results

Among 264 fetuses with increased NT, the median of CRL and NT was 61.2 mm and 2.41 mm. Among them, 132 pregnancy women chose invasive prenatal diagnosis (43 cases of chorionic villus sampling (CVS), 89 cases of amniocentesis). Eventually, 16 cases of chromosomal abnormalities were discovered, including 6 cases (6.4%) of trisomy 21, 4 cases (3%) of trisomy 18, 1 case (0.8%) of 45, XO, 1 case (0.8%) of 47, XXY and 4 cases (3.03%) of CNV abnormalities. The major structural defects included hydrops (6.4%), cardiac defects (3%), and urinary anomalies (2.7%). The incidences of chromosomal abnormalities and structural defects in the NT < 2.5 mm group were 1.3 and 6%, while the incidences were 8.8 and 28.9% in the NT≥2.5 group.

Conclusion

Increased NT was associated with high risk of chromosomal abnormalities and structural anomalies. Chromosomal abnormalities and structural defects could be detected when NT thickness was between 95th centile and 2.5 mm.

Array study in fetuses with nuchal translucency above the 95th percentile: a 4-year observational single-centre study

PURPOSE

To evaluate the performance of chromosomal microarray analysis (CMA) in fetuses with nuchal translucency (NT) > 95th percentile. Secondary objectives were to analyze these results according to NT thickness, below or above 3.5 mm, and those without associated anomalies.

METHODS

This observational single-cohort study was conducted between 2015 and 2018 in fetuses with NT > 95th percentile. Following an invasive test, quantitative fluorescence-polymerase chain reaction (QF-PCR) was performed, and if normal, CMA was performed. Pathogenic copy number variants (CNVs), non-reported pathogenic CNV, pathogenic autosomal recessive variants and variants of unknown significance (VUS) were analysed.

RESULTS

One-hundred and sixty-two fetuses with NT > 95th percentile, normal QF-PCR and CMA were included. Amongst 128 fetuses with NT between the 95th percentile and 3.5 mm, one (0.8%) had a pathogenic CNV, four (3.1%) had non-reported pathogenic CNV, one (0.8%) had pathogenic autosomal recessive variant and 13 (10.2%) had VUS. Amongst 34 fetuses with NT ≥ 3.5 mm, four (11.8%) had pathogenic CNV, one (2.9%) had non-reported pathogenic CNV, one (2.9%) had pathogenic autosomal recessive variant and four (11.8%) had VUS. Four in 162 (2.5%) fetuses had CNVs at the chromosome 16p13.11 region. Amongst 154 fetuses without structural abnormalities and normal QF-PCR, three (1.9%) had a pathogenic CNV, 5 (3.2%) had non-reported pathogenic CNV, one (0.6%) autosomal recessive pathogenic CNV and 16 (10.4%) had VUS.

CONCLUSION

Pathogenic CNVs were found in 1% of fetuses with an NT thickness between the 95^th percentile and 3.5 mm and in 12% of fetuses with NT ≥ 3.5 mm. CNVs were found at the 16p13.11 region in 2.5% of cases.

A Pain in the Neck: Lessons Learnt from Genetic Testing in Fetuses Detected with Nuchal Fluid Collections, Increased Nuchal Translucency versus Cystic Hygroma-Systematic Review of the Literature, Meta-Analysis and Case Series

Fetal Nuchal fluid collections can manifest with two distinct presentations attributable to the same phenotypic spectrum: increased nuchal translucency (iNT) and cystic hygroma. The prenatal detection of these findings should prompt an accurate assessment through genetic counseling and testing, including karyotype, chromosomal microarray analysis (CMA) and multigene RASopathy panel. We performed a systematic review of the literature and meta-analysis, to calculate diagnostic yields of genetic testing in fetuses with iNT and cystic hygroma. We compared the results with a cohort of 96 fetuses with these isolated findings. Fetuses with isolated NT ≥ 2.5 mm showed karyotype anomalies in 22.76% of cases and CMA presented an incremental detection rate of 2.35%. Fetuses with isolated NT ≥ 3 mm presented aneuploidies in 14.36% of cases and CMA had an incremental detection rate of 3.89%. When the isolated NT measured at least 3.5 mm the diagnostic yield of karyotyping was 34.35%, the incremental CMA detection rate was 4.1%, the incremental diagnostic rate of the RASopathy panel was 1.44% and it was 2.44% for exome sequencing. Interestingly, CMA presents a considerable diagnostic yield in the group of fetuses with NT ≥ 3.5 mm. Similarly, exome sequencing appears to show promising results and could be considered after a negative CMA result.

Does isolated nuchal translucency from 2.5 to 2.9 mm increase the risk of fetal chromosome disease?

Increased fetal nuchal translucency (NT) is a common ultrasonic manifestation during pregnancy. Many studies have confirmed that NT ≥ 3 mm is a high risk factor for adverse pregnancy outcome. However, when NT is between 2.5 and 2.9 mm, will it increase the risk of fetal chromosome abnormalities and other diseases? What is the most appropriate method for prenatal chromosome evaluation? At present, it has not been widely reported in the literature, and the conclusion is also controversial. This prospective cohort study included fetal samples from women who underwent amniocentesis from 2017 to 2020. The samples of the experimental group were fetuses with NT ≥ 2.5 mm at 11 to 13 + 6 weeks of gestation, with or without ultrasonographic anomaly. The control group contained fetal NT < 2.5 mm without ultrasonographic anomalies. All amniotic fluid samples were tested by copy number variants sequencing. In 262 fetal samples with isolated NT from 2.5 to 2.9 mm, the detection rate of aneuploidy was 3.4% (9/262), and the risk of aneuploidy was significantly higher than that of the control group (1.4%, 32/2331) (relative risk 2.5, 95% CI 1.2-5.2). The detection rates of other pathogenic/likely pathogenic copy number variants in the two groups were 0.8% (2/262) and 1.3% (31/2331), respectively, which was not statistically significant (relative risk 0.6, 95% CI 0.1-2.4). Our results showed that isolated NT from 2.5 to 2.9 mm increased the risk of fetal chromosome aneuploidy. Therefore, noninvasive prenatal screening is recommended as the first choice for prenatal chromosome evaluation in this population.

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.

Gene Differential Expression and Interaction Networks Illustrate the Biomarkers and Molecular Mechanisms of Atherosclerotic Cerebral Infarction

Atherosclerotic cerebral infarction (ACI) seriously threatens the health of the senile patients, and the strategies are urgent for the diagnosis and treatment of ACI. This study investigated the mRNA profiling of the patients with ischemic stroke and atherosclerosis via excavating the datasets in the GEO database and attempted to reveal the biomarkers and molecular mechanism of ACI. In this study, GES16561 and GES100927 were obtained from Gene Expression Omnibus (GEO) database, and the related differentially expressed genes (DEGs) were analyzed with R language. Furthermore, the DEGs were analyzed with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Besides, the protein-protein interaction (PPI) network of DEGs was analyzed by STRING database and Cytoscape. The results showed that 133 downregulated DEGs and 234 upregulated DEGs were found in GES16561, 25 downregulated DEGs and 104 upregulated DEGs were found in GSE100927, and 6 common genes were found in GES16561 and GES100927. GO enrichment analysis showed that the functional models of the common genes were involved in neutrophil activation, neutrophil degranulation, neutrophil activation, and immune response. KEGG enrichment analysis showed that the DEGs in both GSE100927 and GSE16561 were connected with the pathways including Cell adhesion molecules (CAMs), Cytokine-cytokine receptor interaction, Phagosome, Antigen processing and presentation, and Staphylococcus aureus infection. The PPI network analysis showed that 9 common DEGs were found in GSE100927 and GSE16561, and a cluster with 6 nodes and 12 edges was also identified by PPI network analysis. In conclusion, this study suggested that FCGR3A and MAPK pathways were connected with ACI.

Isolated Increased Nuchal Translucency in First Trimester Ultrasound Scan: Diagnostic Yield of Prenatal Microarray and Outcome of Pregnancy

Background: Increased nuchal translucency (NT) is associated with aneuploidy. When the karyotype is normal, fetuses are still at risk for structural anomalies and genetic syndromes. Our study researched the diagnostic yield of prenatal microarray in a cohort of fetuses with isolated increased NT (defined as NT ≥ 3.5 mm) and questioned whether prenatal microarray is a useful tool in determining the adverse outcomes of the pregnancy. Materials and Methods: A prospective study was performed, in which 166 women, pregnant with a fetus with isolated increased NT (ranging from 3.5 to 14.3 mm with a mean of 5.4 mm) were offered karyotyping and subsequent prenatal microarray when karyotype was normal. Additionally, all ongoing pregnancies of fetuses with normal karyotype were followed up with regard to postnatal outcome. The follow-up time after birth was maximally 4 years. Results: Totally, 149 of 166 women opted for prenatal testing. Seventy-seven fetuses showed normal karyotype (52%). Totally, 73 of 77 fetuses with normal karyotype did not show additional anomalies on an early first trimester ultrasound. Totally, 40 of 73 fetuses received prenatal microarray of whom 3 fetuses had an abnormal microarray result: two pathogenic findings (2/40) and one incidental carrier finding. In 73 fetuses with an isolated increased NT, 21 pregnancies showed abnormal postnatal outcome (21/73, 28.8%), 29 had a normal outcome (29/73, 40%), and 23 were lost to follow-up (23/73, 31.5%). Seven out of 73 live-born children showed an adverse outcome (9.6%). Conclusions: Prenatal microarray in fetuses with isolated increased NT had a 5% (2/40) increased diagnostic yield compared to conventional karyotyping. Even with a normal microarray, fetuses with an isolated increased NT had a 28.8% risk of either pregnancy loss or an affected child.

The yield of chromosomal microarray in pregnancies with congenital cardiac defects and normal noninvasive prenatal screening

BACKGROUND

Evidence comparing the yield of chromosomal microarray analysis to noninvasive prenatal screening in pregnancies with congenital heart anomalies is currently limited.

OBJECTIVE

This study aimed to examine the residual risk of clinically significant chromosomal microarray analysis results in fetuses with congenital heart defects by its various subtypes following a normal noninvasive prenatal screening.

STUDY DESIGN

Using a population-based, countrywide computerized database, we retrieved the reports of all pregnancies undergoing chromosomal microarray analysis because of congenital heart defects through the years 2013-2019. We examined the risk of clinically significant (pathogenic and likely pathogenic) chromosomal microarray analysis results and compared it with the results of a local cohort of low-risk pregnancies. Of 5541 fetuses, 78 (1.4%) showed abnormal results. The residual risk of abnormal chromosomal microarray analysis results was calculated using several options-trisomies 21, 18, and 13; sex chromosome aneuploidies; 22q11.2 deletion, and deletions and duplications of at least 10 MB in size (genome-wide noninvasive prenatal screening)-following the exclusion of theoretically detectable noninvasive prenatal screening anomalies.

RESULTS

Of the 1728 fetuses with congenital heart defects, 93 (5.4%) showed clinically significant chromosomal microarray analysis results (relative risk, 2.7; 95% confidence interval, 2.3-3.1). The result of pregnancies with fetuses with congenital heart defects was compared with the results of the control population. Unique variants were found in 15 pregnancies (16.1%). The detection rate of noninvasive prenatal screening in isolated congenital heart defects varied from 1.0% (aimed at 3 common trisomies) to 2.2% (aimed at 5 common aneuploidies and 22q11.2 deletion) using noninvasive prenatal screening. In nonisolated congenital heart defects, the noninvasive prenatal screening detection rates ranged from 7.8% (aimed at common autosomal trisomies) to 9.2% using genome-wide noninvasive prenatal screening. The residual risk of clinically significant chromosomal microarray analysis results following normal noninvasive prenatal screening ranged from 2.0% to 2.8% in isolated congenital heart defects and 4.5% to 5.9% in nonisolated cases and was significantly higher than those of the control cohort in all noninvasive prenatal screening options. In addition, the residual risk following noninvasive prenatal screening aimed at chromosomes 13, 18, 21, X, and Y was significantly higher than those of the control cohort for most specific congenital heart defect subtypes, except for ventricular septal defects and aberrant right subclavian artery.

CONCLUSION

The residual risk of clinically significant chromosomal microarray analysis results in pregnancies with fetuses with congenital heart defects following normal noninvasive prenatal screening was higher than those in pregnancies with normal ultrasound in most isolated and nonisolated congenital heart defect subtypes. This information should be taken into account by obstetricians and genetic counselors when considering the option of diagnostic testing.