Chromosomal microarray analysis in fetuses with aberrant right subclavian artery

Diagnostic yield of chromosomal microarray to examine the genetic factors associated with fetal aberrant right subclavian artery

PURPOSE

The primary objective was to find the risk factors that increase the probability of chromosomal abnormalities in fetal aberrant right subclavian artery (ARSA). Secondary objectives were to assess the factors which impact the adverse pregnancy outcomes in ARSA fetuses.

METHODS

This retrospective study included a total of 104 pregnant women whose fetuses were diagnosed with ARSA from January 2020 to July 2024, with subsequent chromosomal microarray analysis (CMA) performed.

RESULTS

Among the 104 cases of ARSA in this study, 46 (44.2%) were classified as isolated ARSA and 58 (55.8%) as non-isolated ARSA. Classification of non-isolated ARSA based on ultrasound soft marker abnormalities and structural abnormalities showed that an increase in the number of combined ultrasound soft marker abnormalities was associated with increased fetal chromosomal abnormalities and pathogenicity. In fetuses with structural abnormalities and ultrasonographic soft markers, they have more microarray abnormalities and higher pathogenicity compared to ARSA with only a single soft marker. The chromosomal abnormalities in ARSA fetuses predominantly manifest as trisomy 21, partial segmental microduplications, and microdeletions. Logistic regression analysis indicated that the presence of ultrasonographic soft marker abnormalities alongside ARSA serves as a risk factor for adverse pregnancy outcomes in ARSA fetuses.

CONCLUSION

In contrast to isolated ARSA, chromosomal disorders indicate a significant risk in ARSA accompanied by ultrasound abnormalities, and the risk is closely related to the number of ultrasonographic soft marker abnormalities. In addition, the combination of ultrasonographic soft marker abnormalities was a risk factor for adverse pregnancy outcomes in ARSA, while maternal age, structural abnormalities, polyhydramnios, and intrauterine growth restriction were not associated with it.

Aberrant right subclavian artery: the importance of distinguishing between isolated and non-isolated cases in prenatal diagnosis and clinical management

OBJECTIVES

This study aimed to evaluate the association of aberrant right subclavian artery (ARSA) with genetic abnormalities and postnatal symptomatology, by comparing isolated and non-isolated ARSA cases.

METHODS

Retrospective, descriptive and comparative study involving fetuses diagnosed with ARSA during routine fetal ultrasound scans, between 19 and 40 weeks, in a tertiary referral university hospital in Barcelona from January 2007 to December 2023.

RESULTS

Out of 154 fetuses diagnosed with ARSA, 75.3 % (116) were classified as isolated cases, while 24.7 % (38) had associated structural anomalies. Non-invasive prenatal testing with cell-free DNA was performed in 27.3 % (42) of cases, yielding low-risk results in 96.6 %, with only one case of trisomy 21 detected. Genetic evaluation was pursued in 15.6 % (24) of cases, revealing abnormalities in three fetuses: one with trisomy 21 and two with 22q11 deletion. All affected fetuses had associated structural defects. Overall, 151 fetuses survived after birth, there were two terminations of pregnancy and one stillbirth. Mild symptoms at birth were observed in 1.9 % (3) of newborns, all from the non-isolated ARSA group.

CONCLUSIONS

These findings emphasize the significance of distinguishing between isolated and non-isolated ARSA cases in prenatal diagnosis and clinical management, suggesting that isolated ARSA may be considered a normal vascular variation.

Aberrant right subclavian artery in the absence of other prenatal ultrasound findings: Should we still be concerned?

OBJECTIVE

To analyze the value of prenatal diagnostic genetic testing in cases with isolated aberrant right subclavian artery (ARSA).

METHODS

This is a retrospective cohort study, conducted between January 2015-January 2022 in a fetal medicine center. Women who had an ultrasound scan and diagnosed with fetal ARSA were included. Ultrasonographic characteristics, genetic, obstetric, and neonatal outcomes were collected and analyzed.

RESULTS

A total of 240 fetuses with ARSA were identified and included to the analysis. Eighty-two of the group had isolated ARSA (34.2%, 82/240), 57 had additional soft markers (23.8%, 57/240) and 101 had additional major ultrasonographic abnormalities (42.1%, 101/240). Genetic results were available in 196 cases (81.7%, 196/240). Seventy-four of isolated ARSA cases underwent genetic testing (90.2%, 74/82). A chromosomal abnormality was present in 60 cases; 54 (22.5%, 54/240) aneuploidies and 6 (2.5%, 6/240) copy number variants. Five (6.1%) of the isolated ARSA cases had chromosomal abnormalities. All of these five cases had prenatal genetic testing due to high-risk aneuploidy screening fetuses who had ARSA with at least one additional anomaly had the highest chromosomal abnormality rate (38.6%, 39/101). Seventy-seven of isolated ARSA cases were liveborn (93.9%, 77/82).

CONCLUSION

Our results supports the evidence from the literature that isolated ARSA confers a very low-risk for aneuploidy, if the aneuploidy screening tests are low-risk. Also, chromosomal microarray analysis did not yield any extra information in isolated ARSA.

Systematic review and meta-analysis of right subclavian artery variants and their correlation with cervical-thoracic clinical conditions

BACKGROUND

A high incidence of anatomical variations in the origin of the branches of the aortic arch has been reported, Nowadays, this variation is considered the most frequent in the aortic arch, its prevalence being estimated between 0.5% and 2.5% of the population. To understand its origin, knowledge of embryonic development is necessary.

METHODS

We searched the MEDLINE, Scopus, Web of Science, Google Scholar, Cumulative Index to Nursing and Allied Health Literature, and Latin-American literature and caribean of health sciences databases with dates ranging from their inception to June 2023. Study selection, data extraction, and methodological quality were assessed with the guaranteed tool for anatomical studies (Anatomical Quality Assurance). Finally, the pooled prevalence was estimated using a random effects model.

RESULTS

Thirty-nine studies were found that met the eligibility criteria. Twenty studies with a total of 41,178 subjects were included in the analysis. The overall prevalence of an ARSA variant was 1% (95% confidence interval = 1%-2%), the clinical findings found are that if ARSA is symptomatic it could produce changes in the hemodynamic function of the thoracocervical region in addition to other associated symptomatic complications in surrounding structures.

CONCLUSIONS

ARSA can cause several types of alterations in the cervical or thoracic region, resulting in various clinical complications, such as lusory dysphagia. Hence, knowing this variant is extremely important for surgeons, especially those who treat the cervico-thoracic region. The low prevalence of ARSA means that many professionals are completely unaware of its existence and possible course and origin. Therefore, this study provides detailed knowledge of ARSA so that professionals can make better diagnoses and treatment of ARSA.

Identification of copy number variations among fetuses with isolated ultrasound soft markers in pregnant women not of advanced maternal age

BACKGROUND

Pathogenic (P) copy number variants (CNVs) may be associated with second-trimester ultrasound soft markers (USMs), and noninvasive prenatal screening (NIPS) can enable interrogate the entire fetal genome to screening of fetal CNVs. This study evaluated the clinical application of NIPS for detecting CNVs among fetuses with USMs in pregnant women not of advanced maternal age (AMA).

RESULTS

Fetal aneuploidies and CNVs were identified in 6647 pregnant women using the Berry Genomics NIPS algorithm.Those with positive NIPS results underwent amniocentesis for prenatal diagnosis. The NIPS and prenatal diagnosis results were analyzed and compared among different USMs. A total of 96 pregnancies were scored positive for fetal chromosome anomalies, comprising 37 aneuploidies and 59 CNVs. Positive predictive values (PPVs) for trisomy 21, trisomy 18, trisomy 13, and sex chromosome aneuploidies were 66.67%, 80.00%, 0%, and 30.43%, respectively. NIPS sensitivity for aneuploidies was 100%. For CNVs, the PPVs were calculated as 35.59% and false positive rate of 0.57%. There were six P CNVs, two successfully identified by NIPS and four missed, of which three were below the NIPS resolution limit and one false negative. The incidence of aneuploidies was significantly higher in fetuses with absent or hypoplastic nasal bone, while that of P CNVs was significantly higher in fetuses with aberrant right subclavian artery (ARSA), compared with other groups.

CONCLUSIONS

NIPS yielded a moderate PPV for CNVs in non-AMA pregnant women with fetal USM. However, NIPS showed limited ability in identifying P CNVs. Positive NIPS results for CNVs emphasize the need for further prenatal diagnosis. We do not recommend the use of NIPS for CNVs screening in non-AMA pregnant women with fetal USM, especially in fetuses with ARSA.

Isolated aberrant right subclavian artery: an underlying clue for genetic anomalies

OBJECTIVE

Aberrant right subclavian artery (ARSA) is known to be associated with specific chromosomal abnormalities. However, there is no agreement regarding clinical decisions related to isolated ARSA. This study evaluated the association between ARSA and genetic abnormalities to provide evidence for prenatal consultation and the postpartum management of isolated ARSA.

METHODS

This single-center cross-sectional study involved fetuses diagnosed with ARSA between January 2014 and May 2021. A range of data was recorded for each patient, including screening ultrasound, fetal echocardiograms, genetic results, postnatal information, and follow-up records.

RESULTS

ARSA was detected in 151 fetuses, of which 136 were considered isolated cases. The remaining 9.9% (15/151) of cases had cardiac and/or extracardiac abnormalities or soft markers. Data from karyotype analysis and chromosomal microarray analysis (CMA) were available for 56 and 33 (out of 56) fetuses, respectively. Genetic abnormalities were detected in 10.7% of fetuses (6/56). Of these, 4.4% (2/45) and 36.4% (4/11) were associated with isolated and non-isolated ARSA, respectively, with a significant difference between these two groups regarding the frequency of genetic abnormality (p = 0.011). The analysis detected Klinefelter Syndrome (47, XXY) and 16p11.2 microdeletion in two isolated cases. One case each of trisomy 21 and 22q11.2 deletion, and another case of 47, XXY, were detected in fetuses with cardiac anomalies. Partial 5q deletion was found in a fetus with extracardiac malformations. In total, 141 of the fetuses survived after birth; termination of pregnancy was performed for 10 fetuses; only two fetuses had mild symptoms of dysphagia.

CONCLUSION

ARSA may be an underlying ultrasonic clue for genetic anomalies even in isolated ARSA. Fetuses with isolated ARSA cannot be ruled out for invasive antenatal diagnosis.

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.

Prenatal genetic analysis of fetal aberrant right subclavian artery with or without additional ultrasound anomalies in a third level referral center

To evaluate the correlation between chromosomal abnormalities and fetal aberrant right subclavian artery (ARSA) with or without additional ultrasound anomalies (UAs). A total of 340 fetuses diagnosed with ARSA by ultrasound between December, 2015, and July, 2021, were included. All cases were subdivided into three groups: (A) 121 (35.6%) cases with isolated ARSA, (B) 91 (26.8%) cases with soft markers, and (C) 128 (37.6%) cases complicated with other UAs. Invasive testing was performed via amniotic fluid or cord blood karyotyping and chromosomal microarray analysis (CMA) in parallel, and pregnancy outcomes were followed. Karyotype abnormalities were identified in 18/340 (5.3%) patients. Karyotype abnormalities in Groups A, B, and C were 0/121 (0.0%), 7/91 (7.7%), and 11/128 (8.6%), respectively. CMA abnormalities with clinically significant variants were detected in 37/340 (10.9%) cases, of which 22q11.2 deletion syndrome and trisomy 21 accounted for 48.6% (18/37). The overall abnormal CMA with clinically significant variant detection rates in Groups A, B, and C were 3/121(2.5%), 13/91 (14.3%), and 21/128 (16.4%), respectively. There were significant difference in clinically significant CMA anomalies detection rate between Groups A and C (p < 0.05), as well as Groups A and B (p < 0.05). Comparing CMA to karyotyping showed a clinically significant incremental yield in Group C (7.8%, 10/128) compared to Groups A (2.5%, 3/121) and B (6.6%, 6/91) (p > 0.05). Fetal ARSA with additional UAs, concurred with cardiac and extra-cardiac anomalies, constitutes a high-risk factor for chromosomal aberrations, especially for pathogenic or likely pathogenic copy number variants.

Aberrant right subclavian artery: embryology, prenatal diagnosis and clinical significance

Introduction

The right subclavian artery normally arises as the first vessel from the brachiocephalic trunk. An aberrant right subclavian artery (ARSA) arises directly from the aortic arch and crosses behind the trachea towards the right arm. This variant occurs in approximately 1-2% of the population; however, the frequency increases in individuals with chromosomal abnormalities such as trisomy 21 and 22q11.2 microdeletion. Prenatal identification of ARSA therefore has a role in screening for such conditions.

Methods

Databases were searched for studies reporting the prenatal ultrasound evaluation of ARSA and its frequency in normal fetuses and in those with chromosomal abnormalities.

Results

A total of 23 studies were evaluated. Feasibility for the ultrasound evaluation of ARSA was 85-95%. The sonographic detection of ARSA is best in the three-vessel trachea view; however, sagittal and coronal imaging of the aortic arch may be useful. ARSA in isolation was not found to be associated with chromosomal abnormalities. The prevalence of ARSA in chromosomally abnormal fetuses was up to 24-fold higher than in normal fetuses, but the majority of chromosomally abnormal fetuses with ARSA had additional abnormal ultrasound findings, particularly cardiac abnormalities.

Conclusions

The prenatal detection of ARSA is a clinically useful prenatal marker for chromosomal abnormalities. In isolation, it is unlikely to be associated with pathogenic genetic variants. The ultrasound diagnosis of ARSA should prompt meticulous assessment of associated abnormalities. Invasive diagnostic testing should be offered to patients with non-isolated ARSA or in the presence of non-reassuring screening results or other risk factors.

Genetic abnormalities in fetal congenital heart disease with aberrant right subclavian artery

Fetal aberrant right subclavian artery (ARSA) is a relatively common sonographic finding. Congenital heart disease (CHD) is the most common structural abnormality in patients with ARSA. We aimed to assess the prevalence of genetic abnormalities, particularly sequence variants, in fetuses with CHD and ARSA. By clinical phenotyping and genomic sequencing, we retrospectively reviewed all fetuses with a prenatal diagnosis of CHD combined with ARSA at a single center. As a result, we identified 30 fetuses with ARSA combined with CHD, with conotruncal anomalies being the most common (n = 12, 40%), followed by left ventricular outflow tract obstruction (n = 6, 20%) and atrioventricular septal defects (n = 6, 20%). Overall, 18 (60%) cases had a genetic diagnosis. Copy number variation sequencing analysis identified six (20%) fetuses with aneuploidy and seven (23%) with pathogenic copy-number variants. Whole-exome sequencing (WES) analysis of the remaining 17 cases revealed diagnostic genetic variants in five (29%) cases, indicating that the diagnostic yield of WES for the entire cohort was 17% (5/30). Our findings reveal the high burden of genetic abnormalities in fetal CHD with ARSA. Single-gene disorders contribute substantially to the genetic etiology of fetal CHD with ARSA.

Identification of Novel Compound Heterozygous Variants of MMP9 in Fetus With Metaphyseal Anadysplasia Type 2

Matrix metalloproteinase 9 (MMP9) is an important member of the matrix metalloproteinase family and plays a key role in balancing extracellular matrix proteins. Studies have shown that the homozygous mutations in MMP9 can lead to metaphyseal anadysplasia type 2 (MANDP2, OMIM#613073). The clinical phenotype of this disease is limited and there were only five reported cases of MANDP2 associated with homozygous MMP9 mutations from three families. In this study, we described a case of a fetus with skeletal system malformation. The main clinical manifestations include the short bilateral femur, absence of right fibula, and curved ipsilateral tibia with short length. Importantly, two novel compound heterozygous variants of the MMP9 gene (NM_004,994.3: c.151C &gt; T and c.929del) were found through the trio whole exome sequencing and Sanger sequencing. This is the first report that identified the compound heterozygous variants of the MMP9 gene associated with metaphyseal dysplasia type 2.

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.

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.

Prenatal diagnosis of aberrant right subclavian artery: a literature review

The primary aim of this review is to estimate the prevalence of ARSA both in euploid fetuses as well as in fetuses with Down Syndrome. Secondary objectives were to estimate the association of ARSA with cardiac anomalies and chromosomal defects, especially trisomy 21 and 22q11 deletion (DiGeorge Syndrome). The incidence of ARSA in normal population varies from 0.35% to 3.5%, based on different studies. Since the first reported association between ARSA and trisomy 21 in 2015 until today, several studies have emerged to confirm different degrees of this correlation. Indeed, ARSA appears to be a clinically useful prenatal ultrasound marker for trisomy 21. Particularly, most recent studies concluded that ARSA as a non-isolated finding can be used as screening for Down syndrome. However, when ARSA is an isolated finding, various studies proved that there is no significant correlation with Down syndrome. Apart from these, ARSA appears to be associated with other chromosomal abnormalities, such as 22q11 deletion, cardiac defects and other morphological anomalies. As a conclusion ARSA should be characterized as isolated or non-isolated, as the non - isolated ARSA appears to be a clinically useful marker of Down syndrome and thus, additional testing is required when diagnosed.

Prenatal phenotype of 22q11 micro-duplications: A systematic review and report on 12 new cases

The 22q11 region is prone to generating recurring Copy Number Variations (CNVs) as a result of the large numbers of Low Copy Repeats (LCRs). Typical duplications encompass the LCR-A-to-D region but atypical duplications of various sizes have also been reported. These duplications are responsible for highly variable phenotypes with incomplete penetrance and expressivity, which is challenging for adequate genetic counselling, especially in the prenatal period. To better delineate prenatal phenotypes associated with these CNVs, we report here a clinical and molecular description of twelve cases (9 foetuses and 3 deceased new-borns babies) carrying recurrent 22q11 duplications (diagnosed via aCGH), along with a review of the existing literature. 22q11 duplications were inherited from an apparently healthy parent in almost 60% of the cases. Other CNVs were diagnosed for 8% of the cases. Increased nuchal translucency and cardiac anomalies (CHD) were the most prominent phenotypes observed, along with mild renal and skeletal anomalies. Duplications encompassing the LCR-C-to-D region (and the CRKL gene) seemed more likely to generate CHDs and renal malformations. Cleft lip/palate were observed in foetuses with duplications encompassing the LCR-A-to-B region or the SPECC1L gene, as previously suggested. However, genotype-phenotype correlations remain difficult to ascertain. Second-hit point variants, epigenetic or environmental variations could play a role in the phenotypic variability of 22q11 duplications, but remain a challenge for assessment in the short period of pregnancy.

Fetal Aberrant Right Subclavian Artery: Associated Anomalies, Genetic Etiology, and Postnatal Outcomes in a Retrospective Cohort Study

BACKGROUND

Aberrant right subclavian artery (ARSA) is becoming increasingly common in fetuses. However, there are relatively fewer studies regarding the genetic etiology of ARSA. We performed a genetic analysis of fetuses with ARSA and followed up on the pregnancy outcomes to evaluate the prognosis of the fetuses, providing information for prenatal and eugenic consultations.

METHODS

This retrospective study included 112 pregnant females whose fetuses were diagnosed with ARSA from December 2016 to February 2021. Fetal karyotype analysis and single-nucleotide polymorphism (SNP) array were performed.

RESULTS

The 112 fetuses were divided into two groups: the isolated ARSA group (n = 48, 42.9%) and the non-isolated ARSA group (ARSA with other ultrasound abnormalities, n = 64, 57.1%). The total rate of pathogenic copy number variation (CNV) observed using karyotype analysis (3/8) and SNP array (5/8) was 7.1% (8/112). The rates of pathogenic CNV in the isolated and non-isolated ARSA groups were 4.2% (2/48) and 9.4% (6/64), respectively. No significant difference was observed between the two groups (P = 0.463). The results of genetic analysis influenced the parents' decision to terminate the pregnancy. During the follow-up examination, fetuses with ARSA without pathogenic CNV were found to have normal growth and development after birth.

CONCLUSION

Fetuses with isolated ARSA have a low probability of being diagnosed with pathogenic CNV. However, when ARSA is complicated with other ultrasound abnormalities, the risk of pathogenic CNV remarkably increases. Prenatal genetic counseling and SNP-array should be recommended for better assessment of fetal prognosis.

Aortic Arch Variants and Anomalies: Embryology, Imaging Findings, and Clinical Considerations

There is a wide spectrum of congenital anomalies or variations of the aortic arch, ranging from non-symptomatic variations that are mostly detected incidentally to clinically symptomatic variations that cause severe respiratory distress or esophageal compression. Some of these may be accompanied by other congenital heart diseases or chromosomal anomalies. The widespread use of multidetector computed tomography (CT) in clinical practice has resulted in incidental detection of several variations of the aortic arch in adults. Thus, radiologists and clinicians should be aware of the classification of aortic arch anomalies and carefully look for imaging features associated with a high risk of clinical symptoms. Understanding the embryological development of the aortic arch aids in the classification of various subtypes of aortic arch anomalies and variants. For accurate diagnosis and precise evaluation of aortic arch anomalies, cross-sectional imaging modalities, such as multidetector CT or magnetic resonance imaging, play an important role by providing three-dimensional reconstructed images. In this review, we describe the embryological development of the thoracic aorta and discuss variations and anomalies of the aortic arch along with their clinical implications.

Aberrant right subclavian artery as soft marker in the diagnosis of trisomy 21 during the first trimester of pregnancy

Purpose

Aberrant right subclavian artery is an anatomical variation with a prevalence of around 0.5–1.5% of the general population, being more frequently found among people with chromosomopathies, especially, trisomy 21. Despite being an anatomical finding, and thus, constant through the whole pregnancy, its value in the diagnosis of aneuploidies during the first trimester of pregnancy has been little studied. The aim of this study is to evaluate the reliability of the first-trimester ultrasound in the diagnosis of ARSA and its utility in the early diagnosis of aneuploidies.

Methods

This was a descriptive, observational, cross-sectional study that included all fetuses with sonographic diagnosis of ARSA between 2011 and 2018.

Results

There were 257 cases of ARSA diagnosed. The first-trimester ultrasound showed the following results in the detection of ARSA: sensitivity of 68% (CI 95% 60.8%–74.5%), specificity of 99.9% (CI 95% 99.9%–100%), positive predictive value of 93.7% (CI 95% 88.1%–96.8%), and negative predictive value of 99.6% (CI 95% 99.5%–99.7%). Due to the presence of ARSA, two cases of trisomy 21, that would have been missed in the first trimester, were diagnosed, using ARSA as a soft marker and modifying the risk obtained by the combined screening as part of the genetic sonogram of the first trimester.

Conclusions

ARSA visualization during the first-trimester ultrasound is trustworthy and it can improve the detection of trisomy 21 in some cases of aneuploidy missed during the combined screening of the first trimester.

Chromosomal Microarray Analysis for the Fetuses with Aortic Arch Abnormalities and Normal Karyotype

Background

Aortic arch abnormalities (AAA) are abnormal embryologic developments of the aorta and its branches. Their outcomes often depend on their association with other congenital diseases and genetic testing results.

Objective

This study aimed to evaluate the yield of chromosomal microarray analysis (CMA) in fetuses with different patterns of AAA and normal karyotype.

Methods

Data from 158 pregnancies referred for prenatal CMA testing due to fetal AAA were obtained between April 2016 and April 2019. Fetuses with isolated AAA, AAA accompanied by soft ultrasound markers, and AAA with other ultrasound malformations were classified into groups A, B, and C, respectively. Cases with detectable karyotype aberrations were excluded from the study.

Results

Twenty cases (12.7%) of submicroscopic anomalies were detected in 158 cases with normal karyotype, comprising 16 cases (10.1%) of clinically significant variants, two cases (1.3%) of variants of unknown significance, and two variants (1.3%) that were likely benign. Microdeletion of 22q11.2 accounted for 25% (4/16) of the clinically significant variants. The overall incremental yields by CMA in group A, group B, and group C were 1.8%, 2.3%, and 24.1%, respectively. Except for double aortic arch, the incremental yield of clinical significant findings for each type of AAA in group C was much higher than that in group A and group B. In group A, a clinically significant variant was only detected in one fetus with right aortic arch (RAA) (1.8%, 1/57).

Conclusions

In addition to 22q11.2 microdeletion, many other clinically significant submicroscopic variants are present in fetuses with AAA, especially in fetuses with other ultrasound malformations. Although CMA is always recommended in the presence of any malformation in many countries, our results suggest insufficient evidence to recommend CMA in fetuses with isolated AAA, except for isolated RAA.

Prenatal Diagnosis of Aberrant Right Subclavian Artery: Association with Genetic Abnormalities

OBJECTIVE

 The objective of the present study was to determine the frequency of malformations and chromosomal abnormalities in a population of fetuses with an aberrant right subclavian artery (ARSA).

METHODS

 This is a 6-year retrospective study of fetuses with a prenatal diagnosis of ARSA conducted during the period between September 2013 and June 2019 at a fetal medicine unit. Data were collected from ultrasound, fetal echocardiograms, genetic studies, and neonatal records.

RESULTS

 An ARSA was diagnosed in 22 fetuses. An ARSA was an isolated finding in 18 out of 22 cases (82%). Associated abnormal sonographic findings were found in 4 cases. All cases underwent invasive testing. In 1 of the cases, a chromosomal abnormality was detected (mos 45,X [13]/46,X,e(X) (p22.1q22.1)). No cases of congenital heart disease were found in any of these fetuses. There were two cases in which the postnatal evaluation revealed a malformation: one case of hypospadias and 1 case of cleft palate.

CONCLUSION

 The presence of an isolated ARSA is benign and is not associated with chromosomal abnormalities. The finding of ARSA, however, warrants a detailed fetal ultrasound in order to exclude major fetal abnormalities and other soft markers.

Predictive value of aberrant right subclavian artery for fetal chromosome aneuploidy in women of advanced maternal age

Background

In the entire population, an aberrant right subclavian artery (ARSA) is closely associated with chromosomal abnormalities. ARSA with additional ultrasonic findings would increase risk of chromosomal abnormalities. The risk of fetal chromosomal abnormalities increased exponentially with the maternal age. These risks in the advanced maternal age (AMA) group are uncertain. This study aimed to determine the incidence of ARSA in Chinese AMA and non-AMA women and the frequency of aneuploidy among AMA and non-AMA women with ARSA.

Methods

This retrospective study included 13,690 singleton pregnancies, were divided into AMA and non-AMA groups. Integrated obstetric ultrasonic screening, biochemical screening, noninvasive prenatal screening, and fetal karyotype analysis were analyzed.

Results

The overall incidence of ARSA was 0.69%, with no difference between age groups. The incidence of chromosomal abnormalities in the AMA group (37 / 2860) was much higher than that of the non-AMA group. The risk of chromosomal abnormalities significantly increased with both ARSA detected and additional ultrasound findings. With combined ARSA and AMA, the likelihood of the incidence of chromosomal abnormalities increased. Chimerism (45X / 46XX) was found with isolated ARSA in AMA pregnancies.

Conclusion

There is a high prevalence of chromosomal abnormalities in fetuses of AMA women. ARSA increases the risk of chromosomal abnormalities in both age groups, especially combined with ARSA. When ARSA occurs in AMA women, it confers a high likelihood of chromosomal abnormalities.

PRENATAL IDENTIFICATION OF ABERRANT RIGHT SUBCLAVIAN ARTERY IN ISOLATION: THE NEED FOR FURTHER GENETIC WORK-UP?

The objective of this study was to evaluate the association between aberrant right subclavian artery (ARSA) and chromosomal abnormalities. The study included 5211 women having attended our unit for fetal anatomic screening and fetal echocardiography from August 2016 until February 2019. After diagnosing ARSA, prenatal invasive testing was discussed with the patients. ARSA affected fetus was determined in 57 cases; of these, there were 38 cases of isolated ARSA and 19 cases of non-isolated ARSA but associated with soft markers and fetal anomalies. Nineteen patients underwent amniocentesis; Down syndrome was determined in two women, both of them from the non-isolated ARSA group, with fetal hydrops, atrioventricular septal defect and esophageal atresia. Fifteen of 38 patients who declined prenatal diagnostic testing, accepted karyotype analysis after delivery and none of these 15 cases had chromosomal abnormalities. Identification of ARSA should be followed by detailed ultrasound examination to ensure that there are no accompanying soft markers and/or structural defects. Isolated ARSA may not be an indication for karyotype analysis or 22q11.2 microdeletions. Non-ARSA implies a strong predictor of aneuploidy, and when additional findings are detected, invasive testing should be offered to the parents. The association between isolated ARSA and genetic disease should be evaluated in large powered prospective studies.

Is it useful to evaluate the presence of aberrant right subclavian artery in prenatal diagnosis ultrasounds?

AIM

Analyze if the evaluation of aberrant right subclavian artery in the prenatal echography has improved the detection of chromosomal, genetic and/or morphological abnormalities in our population.

METHODS

Descriptive, observational, cross-sectional study of the cases of aberrant right subclavian artery diagnosed in our Prenatal Diagnosis Unit between January of 2011 and December of 2018.

RESULTS

Two hundred and fifty-seven cases of aberrant right subclavian artery were diagnosed and among them, 179 were considered isolated cases and thus were confirmed after birth. The detection of aberrant right subclavian artery did not improve itself neither the diagnosis of trisomy 21 in the second trimester of pregnancy nor other chromosomal or genetic abnormalities, including the not isolated cases. There were two cases of trisomy 21 diagnosed in the second trimester that presented major sonographic disorders and an inadequate examination during the first trimester. When aberrant right subclavian artery was associated with soft markers of aneuploidy in the second trimester, any case was a trisomy 21. Aberrant right subclavian artery seems to be associated with some minor and major heart defects, especially ventriculoseptal defect and aneurismatic ductus, and in some cases, also with clubfeet.

CONCLUSION

When an adequate screening of aneuploidies and a thorough ultrasound have been performed during the first trimester, aberrant right subclavian artery hardly helps to perform other diagnosis in the second trimester.

The “No ARSA” Sign: A Novel Method of Prenatal Screening for Aberrant Right Subclavian Artery

An aberrant right subclavian artery (ARSA) can be overlooked by the conventional method as described by Chaoui et al., due to acoustic shadowing. The aim of this study was to evaluate the feasibility and accuracy of a novel screening method for ARSA by demonstrating the brachiocephalic artery bifurcation, referred to as the “No ARSA” sign. A prospective study conducted at a tertiary care center between 2018 and 2019 included unselected pregnant patients at a median gestational age of 15.1 (14.2–22.1; IQR (inter-quartile range)) weeks, who had been referred for a routine or targeted anomaly scan. All participants were scanned for the presence or absence of ARSA using both the conventional and the novel “No ARSA” methods for validation purposes. A total of 226 unselected patients were enrolled in the study. The “No ARSA” sign was visualized in 218 fetuses (96.5%). In the remaining 8 cases (3.5%), the “No ARSA” sign was not demonstrated. In these fetuses, an ARSA was visualized by the conventional method. The new method exhibited 100% feasibility and was in complete agreement with the conventional method. Intra- and inter-observer agreement was excellent (κ = 1). The results of the study suggest that the “No ARSA” sign is an efficient and reliable screening tool for ARSA.

Prenatal clubfoot increases the risk for clinically significant chromosomal microarray results - Analysis of 269 singleton pregnancies

OBJECTIVE

To examine the detection rate of clinically significant chromosomal microarray analysis (CMA) results in singleton pregnancies with clubfoot.

METHODS

Data from all CMA tests in singleton pregnancies with sonographic diagnosis of clubfoot (talipes equinovarus) performed between January 2013 and September 2017 were retrospectively obtained from the Israeli Ministry of Health computerized database. The rates of clinically significant CMA results in fetuses with clubfoot were compared to the general population risk, based on a local cohort of 5541 pregnancies with no major sonographic anomalies.

RESULTS

Of the 5750 CMA tests, a total of 269 (4.7%) were performed due to demonstration of fetal clubfoot. Of the 229 cases with isolated deformity, nine (3.9%) clinically significant CMA results were detected. This detection rate is significantly increased compared to the control population (RR 2.7 (95% CI 1.4-5.0)). In the 40 pregnancies with non-isolated clubfoot, seven (17.5%) clinically significant CMA results were detected, a significantly higher frequency compared to the control population and to isolated clubfoot cases.

DISCUSSION

Sonographic diagnosis of clubfoot, whether isolated or associated with additional sonographic defects, increases the risk for abnormal CMA findings. Thus, CMA analysis, in conjunction with thorough sonographic anatomic survey, should be recommended in such pregnancies.

Microarray analysis has no additional value in fetal aberrant right subclavian artery: description of 268 pregnancies and systematic literature review

OBJECTIVES

Fetal aberrant right subclavian artery (ARSA) is a relatively common sonographic finding. Several studies have reported a significant association between ARSA and Down syndrome, as well as 22q11.2 microdeletion. The objective of this study was to assess the risk of abnormal chromosomal microarray analysis (CMA) findings in a large cohort of pregnancies with fetal ARSA as an isolated, as well as a non-isolated, sonographic anomaly. A secondary objective was to review the literature, examining the frequency of chromosomal microarray aberrations in fetuses with isolated ARSA.

METHODS

Data from all pregnancies referred for invasive testing and CMA due to sonographic diagnosis of fetal ARSA, between 2013 and 2017, were obtained retrospectively from the computerized database of the Israeli Ministry of Health. The rate of clinically significant CMA findings in these fetuses was compared to that in a local control population of 2752 low-risk pregnancies with normal ultrasound and serum screening results. In addition, a literature search was conducted in PubMed, from inception to February 2018, of original studies in the English language describing the frequency and nature of microscopic and submicroscopic aberrations in fetuses with isolated ARSA.

RESULTS

Of 246 pregnancies with isolated ARSA that underwent CMA analysis, a clinically significant finding was detected in one (0.4%) pregnancy (trisomy 21). This rate did not differ significantly from that in the control population (P = 0.1574). Of 22 fetuses with non-isolated ARSA, one (4.5%) additional case of trisomy 21 was noted. The frequency of trisomy 21 in this cohort also did not differ from that in the control population (relative risk, 5.5 (95% CI, 0.8-37.6)). The literature search yielded 13 additional relevant papers, encompassing 333 cases of isolated ARSA. Of 579 cases overall (including those of the present study), 13 (2.2%) cases of trisomy 21 were detected, with no cases of 22q11.2 microdeletion.

CONCLUSION

While an association may exist between non-isolated ARSA and Down syndrome, isolated ARSA might better serve as a soft marker for Down syndrome, rather than a routine indication for invasive prenatal testing. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Is fetal isolated double renal collecting system an indication for chromosomal microarray?

Introduction: Duplication of the renal collecting system is one of the most common variants of urinary tract anatomy. The objective of our study was to examine the risk for chromosomal aberrations in this isolated prenatal sonographic finding.Methods: Data from all chromosomal microarray analyses (CMA) reported to the Ministry of Health between January 2013 and September 2017 were retrospectively obtained from a computerized database. All pregnancies with a sonographic diagnosis of the isolated duplex renal collecting system and documentation of CMA result were included. Rate of abnormal CMA findings was compared to the general population risk, based on a systematic review encompassing 9272 cases with normal ultrasound and a local data of 5541 pregnancies undergoing CMA due to maternal request.Results: Two pathogenic CMA finding was found amongst 143 pregnancies with double collecting system (1.4%), not significantly different from the risk for abnormal CMA results in the general population. In addition, five variants of unknown significance were demonstrated (3.5%).Conclusion: To our best knowledge, this analysis is the first report describing the rate of chromosomal anomalies in pregnancies with isolated duplex renal collecting system. Its results suggest that routine invasive prenatal testing with CMA analysis in such cases is no more useful than in the general population. Prospective well-adjusted studies are needed to guide the optimal management of these pregnancies.

Noninvasive screening by cell-free DNA for 22q11.2 deletion: Benefits, limitations, and challenges

Cell-free DNA (cfDNA) testing for fetal aneuploidy is one of the most important technical advances in prenatal care. Additional chromosome targets beyond common aneuploidies, including the 22q11.2 microdeletion, are now available because of this clinical testing technology. While there are numerous potential benefits, 22q11.2 microdeletion screening using cfDNA testing also presents significant limitations and pitfalls. Practitioners who are offering this test should provide comprehensive pretest and posttest prenatal counselling. The discussion should include the possibility of an absence of a result, as well as the risk of possible discordance between cfDNA screening results and the actual fetal genetic chromosomal constitution. The goal of this review is to provide an overview of the cfDNA testing technologies for 22q11.2 microdeletions screening, describe the current state of test validation and clinical experience, review "no results" and discordant findings based on differing technologies, and discuss management options.

Chromosomal microarray findings in pregnancies with an isolated pelvic kidney

Objective To examine the risk for abnormal chromosomal microarray analysis (CMA) results among fetuses with an apparently isolated pelvic kidney. Methods Data from all CMA analyses performed due to an isolated pelvic kidney reported to the Israeli Ministry of Health between January 2013 and September 2016 were retrospectively obtained. Risk estimation was performed comparing the rate of abnormal observed CMA findings to the general population risk, based on a systematic review encompassing 9272 cases and on local data of 5541 cases. Results Of 120 pregnancies with an isolated pelvic kidney, two gain-of-copy number variants suggesting microduplication syndromes were demonstrated (1.67%). In addition, three variants of unknown significance were detected (2.5%). Conclusion The risk for clinically significant CMA findings among pregnancies with an isolated single pelvic kidney was not significantly different compared to both control populations. The results of our study question the practice of routine CMA analysis in fetuses with an isolated pelvic kidney.

Clinical value of chromosomal microarray analysis in prenatally diagnosed dextro-transposition of the great arteries

Objectives: To evaluate the usefulness of chromosomal microarray analysis (CMA) in fetuses with dextro-transposition of the great arteries (d-TGA).Methods: Thirty-two fetuses with d-TGA were examined for submicroscopic copy number variations (CNVs) using CMA.Results: Among the 32 d-TGA fetuses, 23 had isolated lesions (71.9%) and nine had other cardiac or extracardiac anomalies (28.1%). CNVs were detected in 16/32 (50%) of the fetuses, including benign CNVs detected in nine fetuses (28.1%), pathogenic CNVs detected in three fetuses (9.4%), and variants of unknown significance (VOUS) detected in four fetuses (12.5%). There was no significant difference in the detection rates of pathogenic CNVs between the isolated and nonisolated groups. All four VOUS were found in the nonisolated group.Conclusion: CMA might be an effective tool for identifying submicroscopic chromosomal aberrations in fetuses with d-TGA.

Prenatal microarray analysis in right aortic arch-a retrospective cohort study and review of the literature

OBJECTIVE

To examine the risk for clinically significant chromosomal microarray analysis (CMA) findings in fetal right aortic arch (RAA).

METHODS

Data from all CMA analyses performed owing to isolated RAA reported to the Israeli Ministry of Health between January 2013 and September 2016 were evaluated retrospectively. Risk for abnormal CMA findings was compared with two control populations, based on both previously described 9272 pregnancies with normal ultrasound, and on a local cohort of 5541 pregnancies undergoing CMA testing owing to maternal request. In addition, Pubmed database search was conducted for original researches examining this issue.

RESULTS

Of 94 CMA analyses performed owing to isolated RAA, six (6.4%) pathogenic findings were detected (47,XX + 21; 45,X; two 22q11.2 microdeletions; 10p15.3 microdeletion and 16p11.2 duplication). Compared with control groups, an isolated RAA yielded a significantly increased relative risk for abnormal CMA results. Literature search yielded two additional retrospective studies describing microarray testing in RAA and encompassing 57 cases. The overall risk for clinically significant CMA findings was 6.62% (10/151).

CONCLUSIONS

CMA testing is indicated in cases of prenatal isolated RAA, even in the era of advanced sonographic equipment, routine biochemical screening for Down syndrome and available non-invasive prenatal testing.

Microarray analysis in pregnancies with isolated echogenic bowel

INTRODUCTION

Fetal echogenic bowel is a frequent sonographic finding, demonstrated in about 1% of pregnancies. The advised evaluation of fetal echogenic bowel includes maternal serology, genetic testing for cystic fibrosis, detailed sonographic anatomic survey, and invasive prenatal testing for fetal chromosomal aberrations. The objective of our study was to evaluate the risk for clinically significant chromosomal microarray analysis (CMA) findings in pregnancies with isolated echogenic bowel.

METHODS

Data from all CMA analyses performed due to isolated echogenic bowel reported to the Israeli Ministry of Health between January 2013 and September 2016 were retrospectively obtained. Risk estimation was performed comparing the rate of abnormal microarray findings to the control population, based on a systematic review of 9272 pregnancies and a large local cohort of 5541 fetuses with normal ultrasound, undergoing CMA testing due to maternal request.

RESULTS

Of 103 CMA analyses performed due to isolated echogenic bowel, two (1.94%) pathogenic findings were detected (47,XYY and 16p11.2 duplication). This risk was not significantly elevated compared to the control groups. In addition, three variants of unknown significance were demonstrated.

CONCLUSIONS

To our best knowledge, our study is the first report describing the rate of clinically significant copy number variants in pregnancies with isolated echogenic bowel. According to our results, it seems that pregnancies with isolated echogenic bowel do not have an increased risk for abnormal CMA compared to fetuses with no evidence of sonographic anomalies. Our findings suggest that the consideration to perform CMA analysis in such pregnancies should not differ from any pregnancy with normal ultrasound.

Non-visualization of fetal gallbladder in microarray era - a retrospective cohort study and review of the literature

OBJECTIVE

The objective of this study is to examine the frequency of abnormal Chromosomal Microarray (CMA) analyses among fetuses with isolated non-visualization of fetal gallbladder.

METHODS

Data from CMA analyses performed due to isolated non-visualization of fetal gallbladder between January 2013 and September 2016 were retrospectively acquired from a computerized database of the Israeli Ministry of Health. The results were compared with the rate for clinically significant CMA findings in general population, based on a large cohort of 5541 pregnancies undergoing CMA due to maternal request, and a systematic review of 9272 cases with normal ultrasound.

RESULTS

Of 45 pregnancies with isolated non-visualization of fetal gallbladder, CMA testing yielded one (2.22%) gain-of-copy-number variant at 16p11.2, categorized as "pathogenic". In addition, one finding of unknown significance was demonstrated. The risk for clinically meaningful CMA findings among pregnancies with isolated absent gallbladder was not significantly increased compared to control population.

CONCLUSIONS

To the best of our knowledge, this study is the first report describing the rate of pathogenic CMA results in fetuses with isolated non-visualization of fetal gallbladder. The results, in conjunction with previous studies, show that the risk for abnormal CMA results in pregnancies diagnosed with non-visualized gallbladder is not significantly different from pregnancies with normal ultrasound.

Isolated fetal horseshoe kidney does not seem to increase the risk for abnormal chromosomal microarray results

OBJECTIVE

To examine the risk for clinically significant chromosomal microarray analysis (CMA) among fetuses with apparently isolated horseshoe kidney.

METHODS

Data from all CMA analyses performed due to isolated horseshoe kidney reported to the Israeli Ministry of Health between January 2013 and September 2016 were retrospectively obtained from a computerized database. Risk estimation was performed comparing the rate of abnormal CMA findings to the general population, based on a systematic review encompassing 9272 pregnancies with normal ultrasound, and local data cohort of 5541 pregnancies undergoing CMA due to maternal request.

RESULTS

Of 82 pregnancies with isolated horseshoe kidney, one loss-of-copy-number variant compatible with 16p13.11 microdeletion syndrome was demonstrated (1.2%). In addition, two variants of unknown significance (VOUS) were detected (2.4%). The relative risk for pathogenic CMA findings among pregnancies with isolated single horseshoe kidney was not significantly different from the control population (1.03-1.39%).

DISCUSSION

To our best knowledge, our study is the first report describing the rate of clinically significant CMA findings in fetuses with isolated horseshoe kidney. The detection of one pathogenic CMA findings in our cohort implies that the value of CMA analysis in such pregnancies is similar to the general population.