Nonimmune hydrops fetalis: Genetic analysis and clinical outcome

Perinatal lethal form Gaucher disease with compound heterozygosity of single nucleotide variants and copy number variations presenting as nonimmune hydrops fetalis and cerebellar hypoplasia: A case report

OBJECTIVE

To present the ultrasound imaging and genetic diagnosis of a fetus with prenatal lethal form of Gaucher disease.

CASE REPORT

A 37-year-old primiparous woman was pregnant at her 23 weeks of gestation and the prenatal fetal ultrasound revealed hydrops fetalis, cerebellum hypoplasia, and fetal immobility. The pregnancy was terminated due to major fetal anomaly, and whole exome sequencing (WES) analysis of fetal tissue and parental blood unveiled a pathogenic variant in exon 10 of the GBA gene (NM_001005741.3: c.1265T > G: p.L422R) originating from the mother. Additionally, a novel CNV (chr1: 155204785-155205635 deletion, 0.85 kb) spanning exon 10-12 in the GBA gene was identified from the father. This compound heterozygosity confirmed the diagnosis of prenatal lethal form of Gaucher disease and was informative for genetic counseling.

CONCLUSION

WES is a powerful tool to detect pathogenic variants among fetuses with nonimmune hydrops fetalis and complex abnormality from prenatal ultrasound. Compound heterozygosity consisted of single nucleotide variants (SNV) and copy number variations (CNVs) may lead rare inherited metabolic disorders including prenatal lethal form of Gaucher disease.

RASopathies are the most common set of monogenic syndromes identified by exome sequencing for nonimmune hydrops fetalis: A systematic review and meta-analysis

RASopathies are a group of malformation syndromes known to lead to nonimmune hydrops fetalis (NIHF) in severe presentations. Pathogenic variants can be de novo or parentally inherited. Despite being a known frequent presentation, the fraction of monogenic NIHF cases due to RASopathies is limited in the literature. Also, the specific parental contribution of RASopathies to NIHF is not well described. Our objective was to review pooled exome sequencing (ES) diagnostic yield of RASopathies for NIHF and to determine the parental contribution of RASopathy to NIHF. We performed a systematic review of prenatal ES studies from January 1, 2000 to August 1, 2022. Thirty-six studies met inclusion criteria. Cases with RASopathy gene variants were reviewed. NIHF cases were further classified as isolated or non-isolated. Thirty-six ES studies including 46 pregnancies with NIHF and a diagnosed RASopathy were reviewed. Forty-four diagnostic variants and 2 variants of uncertain significance in 12 RASopathy genes were identified. Expanding on what was previously published, a total of 506 NIHF cases were extracted with 191 cases yielding a positive diagnosis by ES. The overall rate of RASopathy diagnosis in clinically diagnosed NIHF cases was 9% (44/506). The rate of RASopathy diagnosis among NIHF cases with positive genetic diagnosis by ES was 23% (44/191). Of the 46 cases identified, 13 (28%) variants were parentally inherited; specifically, 5/13 (38%) maternal, 3/13 (23%) paternal, 2/13 (15%) biparental, and 3/13 (23%) unspecified. Majority of NIHF cases 29/46 (63%) were isolated. Among NIHF cases with positive ES diagnoses, RASopathy diagnostic yield by ES was 23%. NIHF secondary to RASopathies was parentally inherited in 28% of cases. Most cases of NIHF due to RASopathy were isolated, with no prenatal detection of associated anomalies.

Isolated non-immune hydrops fetalis: an observational study on complete spontaneous resolution, perinatal outcome, and long-term follow-up

PURPOSE

The aim of our study was to investigate spontaneous resolution and postnatal outcome in non-immune hydrops fetalis (NIHF). We specifically studied NIHF cases that occurred without any other anomalies in the prenatal diagnostic workup, defined as isolated NIHF (iNIHF).

METHODS

To identify iNIHF we retrospectively classified prenatal findings of 700 NIHF singletons, diagnosed in our prenatal referral center between 1997 and 2016. We studied the occurrence of prenatal resolution in iNIHF and linked it to the perinatal outcome. We obtained long-term outcome by contacting the parents, children, and the pediatricians and listed all functional and structural anomalies and temporary logopedic, psychosocial and motoric impairments.

RESULTS

Among 70 iNIHF cases, 54 (77.1%) resolved completely prenatally. The baby-take-home rate was 98.1% in these cases. In contrast, the baby-take-home rate in the subgroup without complete resolution was 25.0%. We achieved pediatric long-term outcome in 27 of 57 survivors (47.4%) of iNIHF with a mean follow-up period of 10.9 years. Among these 27 children, fetal hydrops had completely resolved prenatally in 26 cases and had regressed to a mild effusion in one case. In the pediatric development, two children had significant functional impairment and two children showed recurrent skin edema.

CONCLUSION

Complete spontaneous resolution was the most common intrauterine course of iNIHF in our collective. Completely resolved iNIHF had a favorable perinatal outcome in our study. Our data on the long-term outcomes are consistent with the assumption of an increased rate of functional impairments.

TRIAL REGISTRY

Internal study number of Heinrich-Heine-University, Duesseldorf: 6177R. Date of registration: December 2017.

Genetic disorders and pregnancy outcomes of non-immune hydrops fetalis in a tertiary referral center

OBJECTIVES

Non-immune hydrops fetalis (NIHF) is a non-specific symptom associated with a wide range of disorders. The prognosis of NIHF depends on the underlying etiology. In this study, we investigated the incidence of chromosomal abnormalities and Bart's hydrops fetalis in pregnancies associated with NIHF in South China.

METHODS

We conducted a retrospective review of NIHF pregnancies referred to the Fujian Provincial Maternity and Children's Hospital between 2014 and 2018, excluding pregnancies with maternal alloimmunization. Routine karyotyping was performed on all 129 enrolled patients, and chromosomal microarray analysis was performed for 35 cases with a normal karyotype. In addition, α-thalassemia genotyping was performed to confirm the presence of Bart's hydrops fetalis.

RESULTS

Chromosomal abnormalities were detected in 29.5% (38/129) of the cohort, including 37 cases with aneuploidy and one case with unbalanced structural rearrangement. Chromosomal microarray analysis performed on the 35 cases with a normal karyotype did not reveal any additional pathogenic variants. The proportions of chromosomal abnormalities declined with trimester progression, with frequencies of 65%, 30.1%, and 8.3% in the first, second, and third trimesters, respectively (p < 0.05). Bart's hydrops fetalis was detected in 34.9% (45/129) of the cohort. Among the 46 (35.6%) cases with unknown etiology, 23 cases had other ultrasonic abnormalities characterized by poor outcomes, whereas seven cases with multiple cavity effusions that resolved or remitted prior to birth showed normal development during the 3-4 years of follow-up.

CONCLUSIONS

In South China, Bart's hydrops fetalis and chromosomal abnormalities are the most common genetic etiologies of NIHF. Generalized skin edema and accompanying ultrasonic abnormalities are predictive of adverse outcomes, highlighting the need for intensive monitoring and better pregnancy management of NIHF patients.

Diagnostic yield from prenatal exome sequencing for non-immune hydrops fetalis: A systematic review and meta-analysis

Non-immune hydrops fetalis (NIHF) has multiple genetic etiologies diagnosable by exome sequencing (ES). We evaluated the yield of prenatal ES for NIHF, and the contribution of additional clinical findings and history. Systematic review was performed with PROSPERO tag 232951 using CINAHL, PubMed, and Ovid MEDLINE from January 1, 2000 through December 1, 2021. Selected studies performed ES to augment standard prenatal diagnostic approaches. Cases meeting a strict NIHF phenotype were tabulated with structured data imputed from papers or requested from authors. Genetic variants and diagnostic outcomes were harmonized across studies using current ACMG and ClinGen variant classification guidelines. Thirty-one studies reporting 445 NIHF cases had a 37% (95% CI: 32%-41%) diagnostic rate. There was no significant difference between isolated NIHF and NIHF with fetal malformations or between recurrent and simplex cases. Diagnostic rate was higher for consanguineous than non-consanguineous cases. Disease categories included RASopathies (24%), neuromuscular (21%), metabolic (17%), lymphatic (13%), other syndromes (9%), cardiovascular (5%), hematologic (2%), skeletal (2%), and other categories (7%). Inheritance patterns included recessive (55%), dominant (41%), and X-linked (4%). ES should be considered in the diagnostic workup of NIHF with and without associated ultrasound findings regardless of history of recurrence or consanguinity.

An Investigation of the Etiologies of Non-Immune Hydrops Fetalis in the Era of Next-Generation Sequence-A Single Center Experience

(1) Background: Numerous etiologies may lead to non-immune hydrops fetalis (NIHF). However, the causes remain unclear in half of NIHF cases following current standard assessment. The application of prenatal chromosomal microarray analysis (CMA) and exome sequencing (ES) can improve the identification of the etiologies. This study aimed to investigate the etiologies of NIHF in the era of next-generation sequence (NGS) following a unified prenatal work-up flow for diagnosis. (2) Methods: A retrospective analysis was conducted on NIHF cases that were collected prospectively to explore the underlying etiologies according to a unified prenatal diagnosis work-up flow at Shanghai First Maternity and Infant Hospital between Jan 2016 and Dec 2019. The medical records for all NIHF cases were reviewed, and the causes of NIHF were classified as confirmed (diagnostic), suspected, or unknown. (3) Results: Prenatal and postnatal medical records for a total of 145 NIHF cases were reviewed, 48.3% (70/145) of the cases were identified to be with confirmed etiologies, and 10.3% (15/145) with suspected etiologies. Among 85 cases with confirmed or suspected etiologies, 44.7% were diagnosed with genetic disorders, 20% with chylothorax/chyloascites diagnosed postnatally, 12.9% with fetal structural anomalies, 12.9% with fetal anemia, 7% (6 cases) with fetal arrhythmia, and 2.3% (2 cases) with placenta chorioangioma. In cases with genetic disorders, 8 aneuploidies were detected by CMA, and 30 cases had single-gene disorders identified by ES (29/30) or targeted gene panel (1/30). There were still 41.4% cases (60/145) with unknown causes after this unified prenatal diagnostic work-up flow. (4) Conclusions: In the era of NGS, the causes of NIHF were identified in 58.6% of cases, with genetic disorders being the most common ones. NGS is helpful in determining the genetic etiology of NIHF when CMA results cannot explain NIHF, but 41.4% of cases were still with unknown causes under the unified prenatal diagnostic work-up flow in this single-center study.

Cost-Effectiveness of Exome Sequencing versus Targeted Gene Panels for Prenatal Diagnosis of Fetal Effusions and Non-Immune Hydrops Fetalis

BACKGROUND

Although exome sequencing has a greater overall diagnostic yield than targeted gene panels in the evaluation of nonimmune hydrops fetalis and fetal effusions, the cost-effectiveness of this approach is not known.

OBJECTIVE

This study aimed to evaluate the costs and outcomes of targeted gene panels vs exome sequencing for prenatally diagnosed nonimmune hydrops fetalis and fetal effusions when next-generation sequencing is pursued following nondiagnostic standard nonimmune hydrops fetalis evaluations, including karyotype or chromosomal microarray.

STUDY DESIGN

A decision-analytical model was designed using TreeAge Pro to compare 10 genetic testing strategies, including a single test only (RASopathy, metabolic, or nonimmune hydrops fetalis-targeted gene panel or exome sequencing), sequential testing (RASopathy panel followed by nonimmune hydrops fetalis panel, metabolic panel followed by nonimmune hydrops fetalis panel, RASopathy panel followed by exome sequencing, metabolic panel followed by exome sequencing, and nonimmune hydrops fetalis panel followed by exome sequencing), and no additional genetic testing. Our theoretical cohort included cases with normal karyotype and/or microarray and excluded cases of alloimmunization and congenital viral infections. As nonimmune hydrops fetalis and fetal effusions can present throughout gestation, whereas pregnancy management options vary depending on gestational age, outcomes were calculated for 3 time intervals: 10 to 18, 18 to 22, and >22 weeks of gestation. The primary outcome was incremental cost per quality-adjusted life year. Additional outcomes included termination of pregnancy, stillbirth, neonatal death, and neonates born with mild, moderate, and severe or profound disease phenotypes. The cost-effectiveness threshold was $100,000 per quality-adjusted life year.

RESULTS

Among women <18 weeks of gestation, exome sequencing alone was the dominant strategy associated with the lowest costs ($221 million) and the highest quality-adjusted life years (10,288). Strategies with exome sequencing alone or as a sequential test resulted in more terminations but fewer stillbirths, neonatal deaths (NNDs), and affected infants than strategies without exome sequencing. Among women between 18 and 22 weeks of gestation, exome sequencing alone was also associated with the lowest costs ($188 million) and the highest quality-adjusted life years (8734), and similar trends were observed in pregnancy outcomes. Among patients >22 weeks of gestations, when termination was not available, exome sequencing was associated with lower costs ($300 million) and the highest quality-adjusted life years (8492). Exome sequencing was cost-effective up to a cost per test of $50,451 at <18 weeks of gestation, $50,423 at 18 to 22 weeks of gestation, and $9530 at >22 weeks of gestation. Targeted genetic panels and exome sequencing were cost-effective strategies compared with no additional genetic testing.

CONCLUSION

For cases of nonimmune hydrops fetalis and fetal effusions with nondiagnostic karyotype or microarray, next-generation sequencing was cost-effective compared with a strategy without additional genetic testing. For those that undergo next-generation sequencing, exome sequencing was the cost-effective strategy compared with all other testing strategies using targeted gene panels, leading to lower costs and fewer adverse perinatal outcomes. Exome sequencing was cost-effective in a setting without the option for pregnancy termination. These data supported the routine use of exome sequencing when next-generation sequencing is pursued for establishing a genetic diagnosis underlying otherwise unexplained nonimmune hydrops fetalis and fetal effusions.

Diagnostic yield using whole-genome sequencing and in-silico panel of 281 genes associated with non-immune hydrops fetalis in clinical setting

OBJECTIVE

To investigate the diagnostic yield of clinical whole-genome sequencing (WGS) in prenatally diagnosed non-immune hydrops fetalis (NIHF).

METHODS

This was a retrospective study of 23 fetuses with prenatally diagnosed NIHF, negative for trisomies and copy-number variants, referred for analysis by WGS with an in-silico panel of 281 genes associated with hydrops fetalis. Due to identification of a high proportion of causative variants in the HRAS gene in the main cohort, Sanger sequencing of HRAS was performed in a replication cohort, consisting of 24 additional fetuses with NIHF that were negative for trisomies and copy-number variants and had not undergone WGS.

RESULTS

Of the 23 fetuses in the main cohort, a molecular diagnosis was achieved in 12 (52.2%). Pathogenic or likely pathogenic variants were identified in seven genes: HRAS (n = 5), RIT1 (n = 2), FOXP3 (n = 1), GLB1 (n = 1), MAP2K1 (n = 1), PTPN11 (n = 1) and RASA1 (n = 1). The inheritance pattern of the 12 causative variants was autosomal dominant in 10 cases (HRAS, MAP2K1, PTPN11, RASA1, RIT1), autosomal recessive in one (GLB1) and X-linked recessive in one (FOXP3). Of the 24 fetuses in the replication cohort, a pathogenic variant in HRAS was identified in one, resulting in an overall frequency of causative HRAS variants of 12.8% (6/47) in our two cohorts.

CONCLUSIONS

We demonstrate a diagnostic yield of 52% with clinical WGS in NIHF using an in-silico panel of 281 genes. However, the high diagnostic yield may be attributed to the small sample size and possible over-representation of severe phenotypes in the included fetuses. Bearing in mind that chromosomal abnormalities were excluded in our cohorts, a detection rate of up to 75% is possible in prenatally diagnosed NIHF when WGS analysis includes calling of chromosomal aberrations. © 2022 The Authors. Ultrasound in Obstetrics &amp; Gynecology published by John Wiley &amp; Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

A single center experience in 90 cases with nonimmune hydrops fetalis: diagnostic categories ‒ mostly aneuploidy and still often idiopathic

OBJECTIVES

The prognosis of nonimmune hydrops fetalis (NIHF) is still poor with a high mortality and morbidity rate despite progress in perinatal care. This study was designed to investigate etiology and outcome of NIHF.

METHODS

A retrospective review of 90 NIHF cases from 2007 to 2019 was conducted at University Medical Center of the Johannes Gutenberg University, Mainz, Germany. Demographics, genetic results, prenatal and postnatal outcomes including one year survival as well as autopsy data were extracted. Etiology of hydrops was classified using 13 previously established categories. In 4 patients observed between 2016 and 2019, we used a next-generation-sequencing (NGS) panel for genetic evaluation.

RESULTS

Ninety NIHF cases were identified, with a median gestational age (GA) at diagnosis of 14 weeks. There were 25 live-born infants with a median GA of 34 weeks at birth, 15 patients survived to one year. There was aneuploidy in more than one third of the cases. All 90 cases were subclassified into etiologic categories with chromosomal 35, idiopathic 15, syndromic 11, cardiovascular 9, inborn errors of metabolism 6, lymphatic dysplasia 3, thoracic 3, infections 3, gastrointestinal 3 and hematologic 2. The NGS panel was used in 4 cases and 4 diagnoses were made.

CONCLUSIONS

In 90 cases with NIHF we identified an aneuploidy in more than one third of the cases. Improved techniques, such as possibly specific genetic analysis, could reduce the high rate of unexplained cases of NIHF.

Diagnostic yield of exome sequencing for prenatal diagnosis of fetal structural anomalies: A systematic review and meta-analysis

Objectives

We conducted a systematic review and meta‐analysis to determine the diagnostic yield of exome sequencing (ES) for prenatal diagnosis of fetal structural anomalies, where karyotype/chromosomal microarray (CMA) is normal.

Methods

Following electronic searches of four databases, we included studies with ≥10 structurally abnormal fetuses undergoing ES or whole genome sequencing. The incremental diagnostic yield of ES over CMA/karyotype was calculated and pooled in a meta‐analysis. Sub‐group analyses investigated effects of case selection and fetal phenotype on diagnostic yield.

Results

We identified 72 reports from 66 studies, representing 4350 fetuses. The pooled incremental yield of ES was 31% (95% confidence interval (CI) 26%–36%, p < 0.0001). Diagnostic yield was significantly higher for cases pre‐selected for likelihood of monogenic aetiology compared to unselected cases (42% vs. 15%, p < 0.0001). Diagnostic yield differed significantly between phenotypic sub‐groups, ranging from 53% (95% CI 42%–63%, p < 0.0001) for isolated skeletal abnormalities, to 2% (95% CI 0%–5%, p = 0.04) for isolated increased nuchal translucency.

Conclusion

Prenatal ES provides a diagnosis in an additional 31% of structurally abnormal fetuses when CMA/karyotype is non‐diagnostic. The expected diagnostic yield depends on the body system(s) affected and can be optimised by pre‐selection of cases following multi‐disciplinary review to determine that a monogenic cause is likely.

What's already known about this topic?

Prenatal exome sequencing (ES) increases genetic diagnoses in fetuses with structural abnormalities and a normal karyotype and chromosomal microarray.

Published diagnostic yields from ES are varied and may be influenced by study size, case selection and fetal phenotype.

What does this study add?

This study provides a comprehensive systematic review of the literature to date and investigates the diagnostic yield of ES for a range of isolated system anomalies, to support clinical decision‐making on how to offer prenatal ES.

Hydrops fetalis-trends in associated diagnoses and mortality from 1997-2018

OBJECTIVES

To describe and evaluate trends in the etiology and mortality risk in neonates admitted for neonatal intensive care with hydrops fetalis.

STUDY DESIGN

A retrospective review of de-identified patient data in the Pediatrix Clinical Data Warehouse from 1997 to 2018.

RESULTS

We identified 2144 infants diagnosed with hydrops fetalis. The most common diagnoses were congenital heart disease (n = 325, 15.2%), genetic diagnoses (n = 269, 12.5%) and cardiac arrhythmia (n = 176, 8.2%). Of 2144 neonates, 988 (46%) survived to hospital discharge and 775 (36%) died prior to discharge. Mortality rate was highly variable across diagnoses, ranging from 90% in infants with congenital diaphragmatic hernia to 0% in infants with atrial flutter. Over the study period, more infants were diagnosed with trisomies and fewer with twin-to-twin transfusion. Mortality decreased by 5% from 1997-2007 to 2008-2018.

CONCLUSIONS

The risk of death among neonates with hydrops fetalis is highly dependent on the underlying cause, with increasing risk of mortality at lower gestational ages.

Fetal hydrops and the Incremental yield of Next-generation sequencing over standard prenatal Diagnostic testing (FIND) study: prospective cohort study and meta-analysis

OBJECTIVE

To determine the incremental yield of exome sequencing (ES) over chromosomal microarray analysis (CMA) or karyotyping in prenatally diagnosed non-immune hydrops fetalis (NIHF).

METHODS

A prospective cohort study (comprising an extended group of the Prenatal Assessment of Genomes and Exomes (PAGE) study) was performed which included 28 cases of prenatally diagnosed NIHF undergoing trio ES following negative CMA or karyotyping. These cases were combined with data from a systematic review of the literature. MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov databases were searched electronically (January 2000 to October 2020) for studies reporting on the incremental yield of ES over CMA or karyotyping in fetuses with prenatally detected NIHF. Inclusion criteria for the systematic review were: (i) at least two cases of NIHF undergoing sequencing; (ii) testing initiated based on prenatal ultrasound-based phenotype; and (iii) negative CMA or karyotyping result. The incremental diagnostic yield of ES was assessed in: (i) all cases of NIHF; (ii) isolated NIHF; (iii) NIHF associated with an additional fetal structural anomaly; and (iv) NIHF according to severity (i.e. two vs three or more cavities affected).

RESULTS

In the extended PAGE study cohort, the additional diagnostic yield of ES over CMA or karyotyping was 25.0% (7/28) in all NIHF cases, 21.4% (3/14) in those with isolated NIHF and 28.6% (4/14) in those with non-isolated NIHF. In the meta-analysis, the pooled incremental yield based on 21 studies (306 cases) was 29% (95% CI, 24-34%; P < 0.00001; I²  = 0%) in all NIHF, 21% (95% CI, 13-30%; P < 0.00001; I²  = 0%) in isolated NIHF and 39% (95% CI, 30-49%; P < 0.00001; I²  = 1%) in NIHF associated with an additional fetal structural anomaly. In the latter group, congenital limb contractures were the most prevalent additional structural anomaly associated with a causative pathogenic variant, occurring in 17.3% (19/110) of cases. The incremental yield did not differ significantly according to hydrops severity. The most common genetic disorders identified were RASopathies, occurring in 30.3% (27/89) of cases with a causative pathogenic variant, most frequently due to a PTPN11 variant (44.4%; 12/27). The predominant inheritance pattern in causative pathogenic variants was autosomal dominant in monoallelic disease genes (57.3%; 51/89), with most being de novo (86.3%; 44/51).

CONCLUSIONS

Use of prenatal next-generation sequencing in both isolated and non-isolated NIHF should be considered in the development of clinical pathways. Given the wide range of potential syndromic diagnoses and heterogeneity in the prenatal phenotype of NIHF, exome or whole-genome sequencing may prove to be a more appropriate testing approach than a targeted gene panel testing strategy. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Utility of fetal whole exome sequencing in the etiological evaluation and outcome of nonimmune hydrops fetalis

INTRODUCTION

Nonimmune hydrops fetalis (NIHF) has varied etiology. We assessed the etiological spectrum and evaluated the utility of fetal whole exome sequencing (fWES) for the diagnosis of NIHF.

METHODS

In this prospective cohort study, we evaluated antenatally diagnosed fetuses with NIHF between July 2018 and December 2019 according to the routine diagnostic algorithm. Fetuses that remained undiagnosed after routine NIHF workup were subjected to fetal chromosomal microarray and/or WES. Pregnancies were followed up for clinical outcomes.

RESULTS

Of the 45 fetuses, consanguinity and recurrent hydrops fetalis were observed in 13.3% (6/45) and 28.8% (13/45), respectively. Overall, an etiological diagnosis was possible in 75.5% (34/45) of fetuses, while the cause remained unknown in 24.4% (11/45). A genetic etiology was identified in 46.6% (21/45): aneuploidy and monogenic disorders in 28.8% (13/45) and 17.8% (8/45), respectively. fWES on 19 fetuses detected disease-causing variants in 42.1% (8/19). Nine novel variants were detected in RAPSN, ASCC1, NEB, PKD1L1, GUSB, and PIEZO1. Only 8.8% (4/45) of the cohort survived without morbidity.

CONCLUSIONS

This study describes the etiological spectrum and the disease-causing variants in an Indian cohort of hydropic fetuses.