Prenatal Diagnosis of the Right Aortic Arch: Change in Detection Rate, the Status of Associated Anomalies, and Perinatal Outcomes in 137 Fetuses

Prenatal diagnosis in fetal right aortic arch using chromosomal microarray analysis and whole exome sequencing: a Chinese single-center retrospective study

BACKGROUND

Right aortic arch (RAA) is a common congenital aortic arch abnormality. Fetuses with RAA frequently have good outcomes after birth. However, chromosomal abnormalities and genetic syndromes suggest poor prognosis for these patients. So far the underlying genetic etiology is still not identified in most RAA patients based on traditional genetic techniques and a problem is still debated whether fetuses with isolated RAA should be referred for CMA. Our study aims to investigate the genetic etiology of fetuses with right aortic arch (RAA) by chromosomal microarray analysis (CMA) and whole exome sequencing (WES) and evaluate the efficacy of CMA in fetal isolated RAA.

RESULTS

Among these 153 fetuses, 99 (64.7%) with isolated RAA and 54 (35.3%) with non-isolated RAA; 25.5% (39/153) with additional intracardiac anomalies (ICA), and 19.0% (29/153) with extracardiac anomalies (ECA). Tetralogy of Fallot (n = 10) and persistent left superior vena cava (n = 11) are the most common ICA and ECA, respectively. CMA detected 15 clinically significant copy number variations (CNVs) in 14 cases (9.2%); microdeletion of 22q11.21 was the most common pathogenic CNVs (7.8%). The chromosomal abnormalities rate was higher in non-isolated RAA and RAA with ICA groups than in isolated RAA group (16.7% vs. 5.1%; 20% vs. 5.1%, both p < 0.05). From five cases further undergoing WES, a diagnostic variant in MTOR gene (c.7255G > A, de novo) was first reported in prenatal, extending the prenatal manifestation of Smith-Kingsmore syndrome (OMIM: 616638); a clinically relevant variant c.3407A > T in STAG2 was identified, being inherited from the healthy mother. Moreover, the premature birth and termination rates were higher in non-isolated RAA group than in isolated RAA group (11.1% vs. 1.0%; 37.0% vs. 2.0%, both p < 0.01).

CONCLUSIONS

We demonstrate that CMA and WES are useful diagnostic tools for fetal RAA, particularly non-isolated RAA, and all fetuses with RAA should be referred for CMA. The data probably aids in prenatal diagnosis and prenatal counseling of fetal RAA.

Prenatal diagnosis of right aortic arch: associated anomalies and fetal prognosis according to different subtypes

OBJECTIVES

Right aortic arch (RAA) is a rare anomaly with an incidence of 0.1 % in the adult population and low-risk fetuses. Our aim in this study was to evaluate associated anomalies and conditions according to subtypes.

METHODS

This was a retrospective study examining consecutive pregnancies diagnosed with RAA in our hospital between 2018 and 2022. Fetuses with RAA were divided into three groups, RAA with right-sided ductus arteriosus (RAA-RDA), RAA with left-sided ductus arteriosus (RAA-LDA), and RAA with a double aortic arch (RAA-DAA).

RESULTS

A total of 81 fetuses were diagnosed as having RAA during the study period. The rate of cardiac anomalies (82.8 %) in the RAA-RDA group was higher than in the RAA-LDA (17.6 %) and RAA-DAA (22.2 %) groups (p<0.001). No statistically significant difference was found between the groups in terms of maternal age, diagnosis week, pregnancy outcome, extracardiac anomalies, and genetic anomalies. Three (8 %) of 36 fetuses with isolated RAA who resulted in live birth developed symptoms related to the vascular ring, and one (2.7 %) newborn with RAA-DAA underwent surgery.

CONCLUSIONS

The incidence of cardiac anomalies is high in fetuses with RAA-RDA. Ultrasound examinations should be performed for cardiac anomalies and additional structural anomalies. Vascular ring formation is a rare but important complication due to compression risk to the trachea and esophagus.

[Prenatally detected aortic arch anomalies and their consequences after birth]

INTRODUCTION

Aortic arch anomalies are frequently associated with cardiac or extracardiac malformations, chromosomal aberrations and postpartum esophagus/trachea compression.

OBJECTIVE

We aimed to establish the prevalence of associated cardiac and extracardiac malformations, the frequency of chromosomal aberrations in fetuses with the diagnosis of aortic arch anomalies and to assess the pregnancy and the postnatal outcome.

METHOD

Retrospective cohort study of all fetuses with aortic arch anomalies and genetic diagnosis in a tertiary referral obstetric and fetal cardiology centre between 2016 and 2020. Postpartum data were collected within 24 months after birth.

RESULTS

In a cohort of 11.380 pregnant women, the prevalence of aortic arch anomalies was 0.25%. Among 28 cases of right aortic arch anomalies, in 27 fetuses prenatal genetic diagnosis was available. We diagnosed 4 fetuses with mirror-image branching (right sided V-sign) and 23 fetuses with U-sign (4 fetuses with complete double aortic arch). 18 cases (66%) were isolated. Associated anomalies were cardiac in 3 cases and extracardiac in 7 cases (33%). The most frequent cardiac anomaly was tetralogy of Fallot (2/27), the extracardiac anomalies were thymus hypoplasia, single umbilical artery and subclavian artery malformations. In 1 case (3.7%), fluorescent in situ hybridization diagnosed 22q11.2 microdeletion. 75% of fetuses with right sided V-sign were associated with conotruncal malformations. Pregnancy and postpartum outcome were known in 24 pregnancies. Postnatal diagnosis was different from prenatal in 2 cases, the concordance rate was 93%. Isolated cases resulted in live birth in 17/18 pregnancies (93%). The frequency of postpartum trachea/esophagus compression was 42,9% (9 cases) due to vascular ring, in 6 children (28,6%) operation was necessary.

CONCLUSION

Fetal aortic arch anomalies are multidisciplinary diseases to be diagnosed by proper prenatal ultrasound examination. Associated fetal anomalies necessitate extended obstetric and cardiac sonography, invasive prenatal testing should be offered, and thorough postnatal long-term follow-up is recommended. Orv Hetil. 2023; 164(28): 1111-1120.