Genetics of congenital diaphragmatic hernia

Syndromic congenital diaphragmatic hernia: Current incidence and outcome. Analysis from the congenital diaphragmatic hernia study group registry

BACKGROUND

The aim of this study was to describe the incidence of Congenital Diaphragmatic Hernia, CDH, associated with known or clinically suspected syndromes, and the postnatal outcomes from a large database for CDH.

METHODS

Data from the multicenter, multinational database on infants with CDH (Congenital Diaphragmatic Hernia Study Group Registry) born from 1996 to 2020 were analyzed. Patients with known or suspected syndromes were grouped and outcome data were analyzed and compared to those without syndromic features.

RESULTS

A total of 12,553 patients were entered in the registry during the study period, and 421 had reported known syndromes, representing 3.4% of all CDH cases in the registry. A total of 50 different associated syndromes were reported. In addition to those with clinically suspected genetic conditions, a total rate of genetic syndromes with CDH was 8.2%. The overall survival to discharge for syndromic CDH was 34% and for non-syndromic CDH was 76.7%. The most common were syndromes Fryns syndrome (19.7% of all syndromes, 17% survival), trisomy 18 or Edward syndrome (17.5%, 9% survival), trisomy 21 or Down syndrome (9%, 47% survival), trisomy 13 or Patau syndrome (6.7%, 14% survival), Cornelia de Lange syndrome (6.4% of all syndromes, 22% survival) and Pallister-Killian syndrome (5.5% of all syndromes, 39.1% survival). In addition, 379 cases had reported chromosomal anomalies and 233 cases had clinically suspected syndromes, based on two more dysmorphic features or malformations in addition to CDH, but without molecular diagnosis. The syndromic CDH group had lower birth weight and gestational age at birth and increased incidence of bilateral CDH (2.9%) and rates of non-repair (53%). The length of hospital stay was longer, and larger number of patients needed O2 at 30 days. Extracorporeal life support was used only in 15% of the cases. Those who underwent surgical repair had survival to discharge rates of 73%.

CONCLUSION

Syndromic CDH is rare and only 3.4% of the reported cases of CDH have a known syndrome or association, but, if including patients with two dysmorphic features malformations, in addition to CDH, altogether as many as 8.2% have a diagnosed or suspected genetic condition. These children have with lower survival rates. Given higher rates of non-repair and decreased extracorporeal life support use, along with a high early mortality, decision-making regarding goals of care clearly influences outcomes. Survival varies depending on the genetic cause. Early genetic diagnosis is important and may influence the decision-making.

Risk of diaphragmatic hernia in patients with spontaneous pneumothorax

Background

Few studies have implied the incidence of diaphragmatic hernia (DH) after spontaneous pneumothorax (SP) with unknown mechanisms. The current study aimed to identify whether there is an association between the DH and SP.

Methods

We selected 46,897 patients with SP (SP cohort) and 46,897 without SP (non-SP matched cohort) from the National Health Insurance Database. Patients were frequency matched according to age, sex, and index year. The incidence of DH and its association with SP were assessed after stratifying different characteristics and comorbidities. Statistical analysis including chi-square test, t-test, cox proportional hazard model, and Kaplan–Meier method were used.

Results

The results suggested there were significant associations between SP and DH, especially in the subgroup of patients with older age (aged 40–64 years: 2.61-fold in adjusted hazard ratio (aHR), 95% confidence interval (CI): 1.27–5.36; aged > 65 years: 1.97-fold in aHR, 95% CI 1.43–2.71), male sex (2.11-fold in aHR, 95% CI 1.56–2.85), hypertension (2.05-fold in aHR, 95% CI 1.30–3.23), diabetes mellitus (2.58-fold in aHR, 95% CI 1.37–4.86), and smoking-related disease (1.86-fold in aHR, 95% CI 1.28–2.71). The SP cohort has significantly correlated with DH within 5-year follow-up (< 2 years: 3.22-fold in aHR, 95% CI 2.10–4.94; 2–5 years: 1.70-fold in aHR, 95% CI 1.05–2.75).

Conclusions

The SP cohort had a higher incidence of DH than the non-SP matched cohort. A prospective study of indications based on the findings of the current research should be performed.

Birth defect co-occurrence patterns in the Texas Birth Defects Registry

BACKGROUND

The population-level landscape of co-occurring birth defects among infants without a syndromic diagnosis is not well understood.

METHODS

We analyzed data from 40,771 infants with two or more major birth defects in the Texas Birth Defects Registry (TBDR; 1999-2014). We calculated adjusted observed-to-expected (O/E) ratios for all two, three, four, and five-way combinations of 138 major defects.

RESULTS

Among 530 patterns with the highest adjusted O/E ratios (top 5% of 10,595 patterns), 66% included only defects co-occurring within one organ system and 28% were suggestive of known patterns (e.g., midline developmental defects). Of the remaining patterns, the combination of defects with the highest O/E ratio (193.8) encompassed the diaphragm, spine, spleen, and heart defects. Fourteen patterns involved heart and spine defects with or without rib defects. Ten additional patterns primarily involved two hallmark components of VACTERL association (specifically, vertebral defects, anal atresia, cardiac defects, renal, or limb defects, but not tracheoesophageal fistula).

CONCLUSIONS

Our analyses provide a description of the birth defect co-occurrence patterns in a multi-ethnic, population-based sample, and revealed several patterns of interest. This work complements prior work that has suggested etiologic connections between select defects (e.g., diaphragmatic hernia and heart and spleen anomalies; heart and spine defects).

IMPACT

In this large-scale, population-based study of birth defect co-occurrence patterns, we found several birth defect combinations of potential interest that warrant further investigation: congenital diaphragmatic hernia, heart, spine, and spleen defects and scimitar syndrome with vertebral defects. The majority of patterns of co-occurring defects observed more frequently than expected involved multiple defects within the same system and combinations suggestive of known associations. Nearly all of the top patterns (beyond the same system and those suggestive of known associations) involved organ systems that are components of the VACTERL association, with heart, spine, and rib defect patterns being the most common.

Underlying genetic etiologies of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is often detectable prenatally. Advances in genetic testing have made it possible to obtain a molecular diagnosis in many fetuses with CDH. Here, we review the aneuploidies, copy number variants (CNVs), and single genes that have been clearly associated with CDH. We suggest that array-based CNV analysis, with or without a chromosome analysis, is the optimal test for identifying chromosomal abnormalities and CNVs in fetuses with CDH. To identify causative sequence variants, whole exome sequencing (WES) is the most comprehensive strategy currently available. Whole genome sequencing (WGS) with CNV analysis has the potential to become the most efficient and effective means of identifying an underlying diagnosis but is not yet routinely available for prenatal diagnosis. We describe how to overcome and address the diagnostic and clinical uncertainty that may remain after genetic testing, and review how a molecular diagnosis may impact recurrence risk estimations, mortality rates, and the availability and outcomes of fetal therapy. We conclude that after the prenatal detection of CDH, patients should be counseled about the possible genetic causes of the CDH, and the genetic testing modalities available to them, in accordance with generally accepted guidelines for pretest counseling in the prenatal setting.

Genetically Modified Mouse Models of Congenital Diaphragmatic Hernia: Opportunities and Limitations for Studying Altered Lung Development

Congenital diaphragmatic hernia (CDH) is a relatively common and life-threatening birth defect, characterized by an abnormal opening in the primordial diaphragm that interferes with normal lung development. As a result, CDH is accompanied by immature and hypoplastic lungs, being the leading cause of morbidity and mortality in patients with this condition. In recent decades, various animal models have contributed novel insights into the pathogenic mechanisms underlying CDH and associated pulmonary hypoplasia. In particular, the generation of genetically modified mouse models, which show both diaphragm and lung abnormalities, has resulted in the discovery of multiple genes and signaling pathways involved in the pathogenesis of CDH. This article aims to offer an up-to-date overview on CDH-implicated transcription factors, molecules regulating cell migration and signal transduction as well as components contributing to the formation of extracellular matrix, whilst also discussing the significance of these genetic models for studying altered lung development with regard to the human situation.

The role of FREM2 and FRAS1 in the development of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) has been reported twice in individuals with a clinical diagnosis of Fraser syndrome, a genetic disorder that can be caused by recessive mutations affecting FREM2 and FRAS1. In the extracellular matrix, FREM2 and FRAS1 form a self-stabilizing complex with FREM1, a protein whose deficiency causes sac CDH in humans and mice. By sequencing FREM2 and FRAS1 in a CDH cohort, and searching online databases, we identified five individuals who carried recessive or double heterozygous, putatively deleterious variants in these genes which may represent susceptibility alleles. Three of these alleles were significantly enriched in our CDH cohort compared with ethnically matched controls. We subsequently demonstrated that 8% of Frem2ne/ne and 1% of Fras1Q1263*/Q1263* mice develop the same type of anterior sac CDH seen in FREM1-deficient mice. We went on to show that development of sac hernias in FREM1-deficient mice is preceded by failure of anterior mesothelial fold progression resulting in the persistence of an amuscular, poorly vascularized anterior diaphragm that is abnormally adherent to the underlying liver. Herniation occurs in the perinatal period when the expanding liver protrudes through this amuscular region of the anterior diaphragm that is juxtaposed to areas of muscular diaphragm. Based on these data, we conclude that deficiency of FREM2, and possibly FRAS1, are associated with an increased risk of developing CDH and that loss of the FREM1/FREM2/FRAS1 complex, or its function, leads to anterior sac CDH development through its effects on mesothelial fold progression.

Case series on anesthesia for video-assisted thoracoscopic surgery for congenital diaphragmatic hernia in children

Video-assisted thoracoscopic surgery (VATS) in the pediatric population is a challenging task for any anesthesiologist, moreover considering the high incidence of associated congenital anomalies which are individual predictors of poor prognosis. A thorough preoperative evaluation, knowledge of the physiology of one lung ventilation - pertaining to various methods of lung isolation, individualized meticulous planning, and continuous vigilance to detect any untoward event at the earliest with good communication between the anesthesiology and surgical teams contributes to a safe and successful surgery. We present a case series of anesthetic management of congenital diaphragmatic hernia with VATS.

Metabolic disturbances of the vitamin A pathway in human diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common life-threatening congenital anomaly resulting in high rates of perinatal death and neonatal respiratory distress. Some of the nonisolated forms are related to single-gene mutations or genomic rearrangements, but the genetics of the isolated forms (60% of cases) still remains a challenging issue. Retinoid signaling (RA) is critical for both diaphragm and lung development, and it has been hypothesized that subtle disruptions of this pathway could contribute to isolated CDH etiology. Here we used time series of normal and CDH lungs in humans, in nitrofen-exposed rats, and in surgically induced hernia in rabbits to perform a systematic transcriptional analysis of the RA pathway key components. The results point to CRPBP2, CY26B1, and ALDH1A2 as deregulated RA signaling genes in human CDH. Furthermore, the expression profile comparisons suggest that ALDH1A2 overexpression is not a primary event, but rather a consequence of the CDH-induced lung injury. Taken together, these data show that RA signaling disruption is part of CDH pathogenesis, and also that dysregulation of this pathway should be considered organ specifically.

FBN1 contributing to familial congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a relatively common, life--threatening birth defect. We present a family with recurrent CDH--paraesophageal and central--for whom exome sequencing (ES) revealed a frameshift mutation (c.4969_4970insA, p.Ile1657Asnfs*30) in the fibrillin 1 gene (FBN1) that causes Marfan syndrome. A diagnosis of Marfan syndrome had not been considered previously in this family. However, a review of the literature demonstrated that FBN1 mutations have an unusual pattern of CDH in which paraesophageal hernias are particularly common. Subsequent clinical evaluations revealed evidence for ectopia lentis in affected family members supporting a clinical diagnosis of Marfan syndrome. Since only two other cases of familial CDH have been described in association with FBN1 mutations, we investigated an oligogenic hypothesis by examining ES data for deleterious sequence changes in other CDH-related genes. This search revealed putatively deleterious sequence changes in four other genes that have been shown to cause diaphragm defects in humans and/or mice--FREM1, DES, PAX3 and MET. It is unclear whether these changes, alone or in aggregate, are contributing to the development of CDH in this family. However, their individual contribution is likely to be small compared to that of the frameshift mutation in FBN1. We conclude that ES can be used to identify both major and minor genetic factors that may contribute to CDH. These results also suggest that ES should be considered in the diagnostic evaluation of individuals and families with CDH, particularly when other diagnostic modalities have failed to reveal a molecular etiology.

Nontraumatic Liver Herniation through a Right–Sided Congenital Diaphragmatic Hernia of Morgagni: An Autopsy Case Report with a Review of Liver Herniations through the Defect and a Review of the Defect

Congenital diaphragmatic hernia of Morgagni (CMH) is a rare developmental defect that develops during the development of the human diaphragm. It is usually right-sided and tends to produce symptoms in later life when abdominal viscera herniate into the chest cavities.

Herniations of the liver through this defect into the chest cavities are rare and are often not clinically suspected even when they are associated with symptoms. The amounts of liver tissue involved are usually small, do not cause symptoms and are often an incidental finding during imaging studies of the chest for unrelated symptoms.

This case report documents a clinically unrecognized incidental herniation of the liver into the right chest cavity through a CMH. The report also reviews previously reported cases of liver herniations through a CMH and the possible causes of the defect.

Current concepts on the pathogenesis and etiology of congenital diaphragmatic hernia

This review outlines research that has advanced our understanding of the pathogenesis and etiology of congenital diaphragmatic hernia (CDH). The majority of CDH cases involve incomplete formation of the posterolateral portion of the diaphragm, clinically referred to as a Bochdalek hernia. The hole in the diaphragm allows the abdominal viscera to invade the thoracic cavity, thereby impeding normal lung development. As a result, newborns with CDH suffer from a combination of severe pulmonary hypoplasia and pulmonary hypertension. Despite advances in neonatal intensive care, mortality and serious morbidity remain high. Systematic studies using rat and transgenic mouse models in conjunction with analyses of human tissue are providing insights into the embryological origins of the diaphragmatic defect associated with CDH and abnormalities of developmentally regulated signaling cascades.

Variants in GATA4 are a rare cause of familial and sporadic congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is characterized by incomplete formation of the diaphragm occurring as either an isolated defect or in association with other anomalies. Genetic factors including aneuploidies and copy number variants are important in the pathogenesis of many cases of CDH, but few single genes have been definitively implicated in human CDH. In this study, we used whole exome sequencing (WES) to identify a paternally inherited novel missense GATA4 variant (c.754C>T; p.R252W) in a familial case of CDH with incomplete penetrance. Phenotypic characterization of the family included magnetic resonance imaging of the chest and abdomen demonstrating asymptomatic defects in the diaphragm in the two "unaffected" missense variant carriers. Screening 96 additional CDH patients identified a de novo heterozygous GATA4 variant (c.848G>A; p.R283H) in a non-isolated CDH patient. In summary, GATA4 is implicated in both familial and sporadic CDH, and our data suggests that WES may be a powerful tool to discover rare variants for CDH.

Deficiency of FRAS1-related extracellular matrix 1 (FREM1) causes congenital diaphragmatic hernia in humans and mice

Congenital diaphragmatic hernia (CDH) is a common life-threatening birth defect. Recessive mutations in the FRAS1-related extracellular matrix 1 (FREM1) gene have been shown to cause bifid nose with or without anorectal and renal anomalies (BNAR) syndrome and Manitoba oculotrichoanal (MOTA) syndrome, but have not been previously implicated in the development of CDH. We have identified a female child with an isolated left-sided posterolateral CDH covered by a membranous sac who had no features suggestive of BNAR or MOTA syndromes. This child carries a maternally-inherited ~86 kb FREM1 deletion that affects the expression of FREM1's full-length transcripts and a paternally-inherited splice site mutation that causes activation of a cryptic splice site, leading to a shift in the reading frame and premature termination of all forms of the FREM1 protein. This suggests that recessive FREM1 mutations can cause isolated CDH in humans. Further evidence for the role of FREM1 in the development of CDH comes from an N-ethyl-N-nitrosourea -derived mouse strain, eyes2, which has a homozygous truncating mutation in Frem1. Frem1(eyes2) mice have eye defects, renal agenesis and develop retrosternal diaphragmatic hernias which are covered by a membranous sac. We confirmed that Frem1 is expressed in the anterior portion of the developing diaphragm and found that Frem1(eyes2) embryos had decreased levels of cell proliferation in their developing diaphragms when compared to wild-type embryos. We conclude that FREM1 plays a critical role in the development of the diaphragm and that FREM1 deficiency can cause CDH in both humans and mice.

Developmental and genetic aspects of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a frequent occurring cause of neonatal respiratory distress and occurs 1 in every 3,000 liveborns. Ventilatory support and pharmaceutical treatment of the co-occurring lung hypoplasia and pulmonary hypertension are insufficient in, respectively, 20% of isolated cases and 60% of complex ones leading to early perinatal death. The exact cause of CDH remains to be identified in the majority of human CDH patients and prognostic factors predicting treatment refraction are largely unknown. Their identification is hampered by the multifactorial and heterogenic nature of this congenital anomaly. However, application of high-resolution molecular cytogenetic techniques to patients' DNA now enables detection of chromosomal aberrations in 30% of the patients. Furthermore, recent insights in rodent embryogenesis pointed to a specific disruption of the early mesenchymal structures in the primordial diaphragm of CDH-induced offspring. Together, these data allowed for the introduction of new hypotheses on CDH pathogenesis, although many issues remain to be resolved. In this review, we have combined these new insights and remaining questions on diaphragm pathogenesis with a concise overview of the clinical, embryological, and genetic data available.

Genomic alterations that contribute to the development of isolated and non-isolated congenital diaphragmatic hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a life threatening birth defect. Most of the genetic factors that contribute to the development of CDH remain unidentified.

OBJECTIVE

To identify genomic alterations that contribute to the development of diaphragmatic defects.

METHODS

A cohort of 45 unrelated patients with CDH or diaphragmatic eventrations was screened for genomic alterations by array comparative genomic hybridisation or single nucleotide polymorphism based copy number analysis.

RESULTS

Genomic alterations that were likely to have contributed to the development of CDH were identified in 8 patients. Inherited deletions of ZFPM2 were identified in 2 patients with isolated diaphragmatic defects and a large de novo 8q deletion overlapping the same gene was found in a patient with non-isolated CDH. A de novo microdeletion of chromosome 1q41q42 and two de novo microdeletions on chromosome 16p11.2 were identified in patients with non-isolated CDH. Duplications of distal 11q and proximal 13q were found in a patient with non-isolated CDH and a de novo single gene deletion of FZD2 was identified in a patient with a partial pentalogy of Cantrell phenotype.

CONCLUSIONS

Haploinsufficiency of ZFPM2 can cause dominantly inherited isolated diaphragmatic defects with incomplete penetrance. These data define a new minimal deleted region for CDH on 1q41q42, provide evidence for the existence of CDH related genes on chromosomes 16p11.2, 11q23-24 and 13q12, and suggest a possible role for FZD2 and Wnt signalling in pentalogy of Cantrell phenotypes. These results demonstrate the clinical utility of screening for genomic alterations in individuals with both isolated and non-isolated diaphragmatic defects.

Management of congenital diaphragmatic hernia

PURPOSE OF REVIEW

To evaluate the impact of recent research on the management of congenital diaphragmatic hernia in the light of new theories on embryological development, earlier antenatal diagnosis, fetal and postnatal interventions together with advances in perinatal intensive care.

RECENT FINDINGS

The year 2007 provided in excess of 200 publications that address various aspects of congenital diaphragmatic hernia. The genetic basis and the causes of pulmonary hypoplasia at the molecular level are slowly being unravelled. Fetal MRI of lung volume, lung-head ratio, liver position and size of diaphragmatic defect have all been evaluated as early predictors of outcome and with a view to prenatal counselling. The impact of fetal interventions such as fetal endoluminal tracheal occlusion, the mode of delivery, the surgical techniques and agents for treating pulmonary hypertension were evaluated. The influence of associated anomalies and therapeutic interventions on the outcome and quality of life of survivors continue to be appraised.

SUMMARY

Deferred surgery after stabilization with gentle ventilation and reversal of pulmonary hypertension remain the cornerstones of management. Optimal presurgery and postsurgery ventilatory settings remain unproven. Continued improvement in neonatal intensive care raises the bar against which any intervention such as fetal endoluminal tracheal occlusion and extracorporeal membrane oxygenation will be judged.