Prenatally diagnosed omphaloceles: Report of 92 cases and association with Beckwith-Wiedemann syndrome

The correlation with abnormal fetal outcome and a high level of amniotic fluid alpha-fetoprotein in mid-trimester

OBJECTIVE

To evaluate the correlation of high levels [>2.0 multiples of median (MoM)] of amniotic fluid alpha-fetoprotein (AFAFP) in midtrimester with abnormal fetal outcome.

MATERIALS AND METHODS

We retrospectively studied 6245 pregnant women with singleton pregnancy who had undergone amniocentesis between 15 and 27 weeks' gestation at Mackay Memorial Hospital between January 2014 and June 2020. Fifty-five cases had high AFAFP levels (>2.0 MoM). We investigated the abnormal fetal outcomes.

RESULTS

Among the fifty-five cases with high AFAFP levels (>2.0 MoM), thirty (54.5%) had fetal chromosomal abnormalities, major structural abnormalities, and/or adverse obstetric events. Eight cases (14.5%) had chromosomal abnormalities including trisomy 21 (3 cases), trisomy 18 (3 cases), mosaic trisomy 18 (1 cases), and mosaic ring 13 (1 case). Seventeen cases (30.9%) had major structural abnormalities including abdominal wall defect (6 cases) and central nervous system (5 cases), gastrointestinal tract (3 cases), cardiovascular (2 cases), and genitourinary tract (2 cases) abnormalities. Fifteen cases (27%) had adverse obstetric events, including preterm delivery (5 cases), intrauterine fetal demise (4 cases), small for gestational age (4 cases), preeclampsia (4 cases), gestational diabetes mellitus (2 cases), gestational hypertension (1 case), preterm prelabor rupture of membrane (1 case), prolonged labor (1 case), and preterm uterine contraction (1 case).

CONCLUSION

A high AFAFP level (>2.0 MoM) in midtrimester can be associated with abnormal fetal outcome, including chromosomal abnormalities, major structural abnormalities, and adverse obstetric events. Women with a prenatal diagnosis of high AFAFP levels (>2.0 MoM) should be alerted of the possibility of abnormal fetal outcomes, and further detailed genetic studies and serial sonographic examinations are recommended.

Prevalence of Beckwith Wiedemann Syndrome and Risk of Embryonal Tumors in Children Born with Omphalocele

AIM OF THE STUDY

Children with omphalocele have an increased prevalence of Beckwith Wiedemann syndrome (BWS) and thus a suspected increased risk of developing embryonal tumors, e.g. Wilms tumor, hepatoblastoma, neuroblastoma and rhabdomyosarcoma. The aim of this study was to examine the prevalence of BWS and the risk of embryonal tumors amongst patients born with omphalocele.

METHODS

A population-based cohort was used, including all children born in Sweden 1/1 1997-31/12 2016. Patients with omphalocele were identified through the Swedish National Patient Register and the Swedish Medical Birth Register. For each case of omphalocele ten age and sex matched individuals unexposed for omphalocele were randomly selected for comparison. Data on BWS and embryonal tumors were collected from the Swedish National Patient Register and the Swedish National Cancer Register.

MAIN RESULTS

Out of 207 cases of omphalocele, 15 (7.2%) were diagnosed with BWS. None of the children with omphalocele had yet developed any kind of embryonal tumor (median follow-up time 8 years). None of the 2070 controls were diagnosed with BWS but 3 (0.1%) of them had developed embryonal tumors during a median follow-up time of 10 years.

CONCLUSIONS

In this study the prevalence of BWS amongst children born with omphalocele is in the lower range of previously reported figures. Also, the prevalence of embryonal tumors amongst children with BWS is lower than expected and the risk of embryonal tumors in children with omphalocele and BWS might not be as high as previously stated. This must be taken into consideration when counseling parents prenatally.

TYPE OF STUDY

National register cohort study.

LEVEL OF EVIDENCE

II.

Proposal for Practical Approach in Prenatal Diagnosis of Beckwith–Wiedemann Syndrome and Review of the Literature

Background: Beckwith–Wiedemann syndrome (BWS) is a phenotypically and genetically heterogeneous disorder associated with epigenetic/genetic aberrations on chromosome 11p15.4p15.5. There is no consensus criterion for prenatal diagnosis of BWS. Methods: Three BWS patients with their clinical histories, prenatal ultrasonographic features, and results of molecular diagnosis were presented. Likewise, by incorporating the findings of our cases and literature review, the phenotypic spectrum and genotype–phenotype correlations of fetal BWS were summarized, and a practical approach in prenatal diagnosis of BWS was proposed. Results: A total of 166 BWS cases with prenatal features were included for analysis. Common fetal features include abdominal wall defects (42.8%), polyhydramnios (33.1%), and macrosomia (32.5%). Molecular pathologies include methylation changes in imprinting control region 1 and 2 (ICR1 and ICR2), paternal uniparental disomy of chromosome 11p15.5, copy number change involving 11p15, etc. Some genotype–phenotype correlations were observed. However, the broad phenotypic spectrum but limited features manifested by affected fetuses rendering ultrasonographic diagnosis not easy. Conclusions: Molecular tests are used for prenatal diagnosis of BWS suspected by ultrasonography. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) is recommended as the first-line molecular tool because it simultaneously detects ICR1/ICR2 methylation statuses and copy numbers that solve the majority of clinical cases in the prenatal scenario.

Prenatal genetic diagnosis of omphalocele by karyotyping, chromosomal microarray analysis and exome sequencing

OBJECTIVES

The aim of this study is to share our experience in the prenatal diagnosis of omphalocele by karyotyping, chromosomal microarray analysis (CMA) and whole exome sequencing (WES).

METHODS

In this retrospective study, 81 cases of omphalocele were identified from 2015 to 2020. Associated anomalies and prenatal diagnosis based on karyotyping, CMA and WES were analysed.

RESULTS

Fifty-eight (71.6%) of the 81 foetuses had other ultrasound anomalies. Giant omphalocele was present in 11 cases (13.6%) and small omphalocele was present in 70 cases (86.4%). Chromosomal abnormalities were found in 24 foetuses (29.6%, 24/81), the most common of which were trisomy 18 (58.8%, 11/24) and trisomy 13 (29.2%, 7/24). Compared to isolated omphalocele, non-isolated omphalocele was accompanied by an increased prevalence of chromosomal abnormalities (4.3% (1/23) vs. 39.7% (23/58), χ2 = 8.226, p = .004). All chromosomal abnormalities were found in small omphalocele. Aside from aneuploidy, CMA showed one pathogenic copy number variants (CNVs) for a detection rate of 1.2%, one variants of unknown significance (VOUS) and one instance of loss of heterozygosity (LOH). WES was performed on 3 non-isolated cases, and one was found to have pathogenic variants.

CONCLUSIONS

The most common genetic cause of omphalocele is aneuploidy and the prevalence of chromosomal abnormalities is increased with non-isolated and small omphalocele. CMA and WES can be useful for providing further genetic information to assist in prenatal counselling and pregnancy management.

Characteristics Associated with Tumor Development in Individuals Diagnosed with Beckwith-Wiedemann Spectrum: Novel Tumor-(epi)Genotype-Phenotype Associations in the BWSp Population

Beckwith–Wiedemann Spectrum (BWSp) is the most common epigenetic childhood cancer predisposition disorder. BWSp is caused by (epi)genetic changes affecting the BWS critical region on chromosome 11p15. Clinically, BWSp represents complex molecular and phenotypic heterogeneity resulting in a range of presentations from Classic BWS to milder features. The previously reported tumor risk based on Classic BWS cohorts is 8–10% and routine tumor screening has been recommended. This work investigated the tumor risk and correlation with phenotype within a cohort of patients from Classic BWS to BWSp using a mixed-methods approach to explore phenotype and epigenotype profiles associated with tumor development through statistical analyses with post-hoc retrospective case series review. We demonstrated that tumor risk across BWSp differs from Classic BWS and that certain phenotypic features are associated with specific epigenetic causes; nephromegaly and/or hyperinsulinism appear associated with cancer in some patients. We also demonstrated that prenatal and perinatal factors that are not currently part of the BWSp classification may factor into tumor risk. Additionally, blood testing results are not necessarily synonymous with tissue testing results. Together, it appears that the current understanding from Classic BWS of (epi)genetics and phenotype correlations with tumors is not represented in the BWSp. Further study is needed in this complex population.

Detection of hypermethylation at H19DMR at amniocentesis in a fetus with overgrowth, distended abdomen and Beckwith-Wiedemann syndrome

OBJECTIVE

We present detection of hypermethylation at H19 differentially methylated region (DMR) at amniocentesis in a fetus with overgrowth, distended abdomen and Beckwith-Wiedemann syndrome (BWS).

CASE REPORT

A 31-year-old, gravida 2, para 1, woman was referred for genetic counseling at 22 weeks of gestation because of fetal overgrowth with fetal biometry equivalent to 24 weeks of gestation and a distended abdomen with an abdominal circumference equivalent to 26 weeks of gestation. She did not undergo any assisted reproductive technology during this pregnancy. Amniocentesis was performed at 23 weeks of gestation. Conventional cytogenetic analysis revealed a karyotype of 46,XX. Array comparative genomic hybridization analysis on the DNA extracted from uncultured amniocytes revealed no genomic imbalance. Methylation analysis on the DNA extracted from amniocytes revealed hypermethylation at H19DMR [imprinting center 1 (IC1)] and normal methylation at KvDMR1 (IC2). The methylation test confirmed the diagnosis of BWS in the fetus. The parents decided to continue the pregnancy. At 36 weeks of gestation, a 4000-g female baby was delivered with macroglossia, ear tags and creases, and an enlarged liver, consistent with the phenotype of BWS.

CONCLUSION

Prenatal diagnosis of fetal overgrowth should include a differential diagnosis of BWS, and methylation analysis of H19DMR (IC1) and KvDMR1 (IC2) is useful under such a circumstance.

Identifying biomarkers for prenatal diagnosis of neural tube defects based on "omics"

Neural tube defects (NTDs) are the most severe birth defects and the main cause of newborn death; posing a great challenge to the affected children, families, and societies. Presently, the clinical diagnosis of NTDs mainly relies on ultrasound images combined with certain indices, such as alpha-fetoprotein levels in the maternal serum and amniotic fluid. Recently, the discovery of additional biomarkers in maternal tissue has presented new possibilities for prenatal diagnosis. Over the past 20 years, "omics" techniques have provided the premise for the study of biomarkers. This review summarizes recent advances in candidate biomarkers for the prenatal diagnosis of fetal NTDs based on omics techniques using maternal biological specimens of different origins, including amniotic fluid, blood, and urine, which may provide a foundation for the early prenatal diagnosis of NTDs.

Usefulness of Postnatal Echocardiograms in Patients with Omphaloceles Who Previously Had a Normal Fetal Echocardiogram

INTRODUCTION

Neonates with omphaloceles routinely have a transthoracic echocardiogram (TTE) performed due to a high association with congenital heart defects (CHD). The utility of a TTE in these patients with a normal fetal echocardiogram is unknown. The primary objective of this study was to determine whether a critical CHD diagnosis was missed in patients with an omphalocele who had a normal fetal echocardiogram. The secondary objective of the study was to determine whether any CHD diagnosis was missed postnatally when a fetal echocardiogram was read as normal.

METHODS

A retrospective chart review was performed of patients with omphaloceles born between January 1, 2008, and June 30, 2020. Patients were included if they had a fetal echocardiogram that was read as normal and had a postnatal echocardiogram performed. Baseline demographics, postnatal data echocardiographic findings, and hospital course were collected. Critical CHD was defined as CHD requiring neonatal cardiac intervention.

RESULTS

Fifty-six fetal echocardiograms on patients with omphaloceles were performed, of which 24 patients met the inclusion criteria. No patient was diagnosed with a critical CHD postnatally (negative predictive value [NPV] = 100%). Two patients were diagnosed with ventricular septal defects (VSD) postnatally (NPV = 91.7%). One of the VSDs required closure with a patch at 4 months of life, while the other, a small muscular VSD, closed spontaneously within the first year of life. Both patients had a murmur on exam during their initial hospital stay. The patient that required surgery also had an abnormal electrocardiogram and chest X-ray. There were no mortalities due to cardiac causes in these patients.

CONCLUSION

Critical CHD was not missed on any patient with an omphalocele who had a normal fetal echocardiogram. All other patients with omphaloceles who had CHD diagnosed postnatally had an abnormal clinical finding on postnatal evaluation. The routine performance of a postnatal TTE in patients with an omphalocele who had a normal fetal echocardiogram may not be needed in those with a normal clinical workup. Further studies evaluating echocardiographic imaging recommendations are needed to maximize care and optimize resource allocation in this complex patient population.