Genetic aspects of human congenital diaphragmatic hernia

Congenital diaphragmatic hernia and cleft lip and palate: looking for a common genetic etiology

PURPOSE

Congenital diaphragmatic hernia (CDH) and cleft lip and/or palate (CL/P) are inborn closure defects. Genetic factors in and outcomes for patients with both anomalies (CDH+CL/P) remain unclear. We aimed to investigate associated genetic aberrations, prevalence of, and outcomes for, CDH+CL/P.

METHODS

Data from Congenital Diaphragmatic Hernia Study Group (CDHSG) registry were collected. CL/P prevalence in CDH patients was determined. Genetic abnormalities and additional malformations in CDH+CL/P were explored. Patient characteristics and outcomes were compared between CDH+CL/P and isolated CDH (CDH-) using Fisher's Exact Test for categorical, and t-test or Mann-Whitney U-test for continuous, data. p < 0.05 was considered statistically significant.

RESULTS

Genetic anomalies in CDH+CL/P included trisomy 13, 8p23.1 deletion, and Wolf-Hirschhorn syndrome (4p16.3 deletion). CL/P prevalence in CDH was 0.7%. CDH+CL/P had lower survival rates than CDH-, a nearly fourfold risk of death within 7 days, were less supported with extracorporeal life support (ECLS), had higher non-repair rates, and survivors had longer length of hospital stay.

CONCLUSION

Genetic anomalies, e.g. trisomy 13, 8p23.1 deletion, and Wolf-Hirschhorn syndrome, are seen in patients with the combination of CDH and orofacial clefts. CL/P in CDH patients is rare and associated with poorer outcomes compared to CDH-, influenced by goals of care decision-making.

The etiology of congenital diaphragmatic hernia: the retinoid hypothesis 20 years later

Congenital diaphragmatic hernia (CDH) is a severe birth defect and a major cause of neonatal respiratory distress. Impacting ~2-3 in 10,000 births, CDH is associated with a high mortality rate, and long-term morbidity in survivors. Despite the significant impact of CDH, its etiology remains incompletely understood. In 2003, Greer et al. proposed the Retinoid Hypothesis, stating that the underlying cause of abnormal diaphragm development in CDH was related to altered retinoid signaling. In this review, we provide a comprehensive update to the Retinoid Hypothesis, discussing work published in support of this hypothesis from the past 20 years. This includes reviewing teratogenic and genetic models of CDH, lessons from the human genetics of CDH and epidemiological studies, as well as current gaps in the literature and important areas for future research. The Retinoid Hypothesis is one of the leading hypotheses to explain the etiology of CDH, as we continue to better understand the role of retinoid signaling in diaphragm development, we hope that this information can be used to improve CDH outcomes. IMPACT: This review provides a comprehensive update on the Retinoid Hypothesis, which links abnormal retinoic acid signaling to the etiology of congenital diaphragmatic hernia. The Retinoid Hypothesis was formulated in 2003. Twenty years later, we extensively review the literature in support of this hypothesis from both animal models and humans.

Radiomics-Assisted Computed Tomography-Based Analysis to Evaluate Lung Morphology Characteristics after Congenital Diaphragmatic Hernia

Purpose: Children with congenital diaphragmatic hernia suffer from long-term morbidity, including lung function impairment. Our study aims to analyze lung morphology characteristics via radiomic-assisted extraction of lung features in patients after congenital diaphragmatic hernia repair. Materials and Methods: 72 patients were retrospectively analyzed after approval by the local research ethics committee. All the image data were acquired using a third-generation dual-source CT (SOMATOM Force, Siemens Healthineers, Erlangen, Germany). Dedicated software was used for image analysis, segmentation, and processing. Results: Radiomics analysis of pediatric chest CTs of patients with status after CDH was possible. Between the ipsilateral (side of the defect) and contralateral lung, three shape features and two higher-order texture features were considered statistically significant. Contralateral lungs in patients with and without ECMO treatment showed significant differences in two shape features. Between the ipsilateral lungs in patients with and without the need for ECMO 1, a higher-order texture feature was depicted as statistically significant. Conclusions: By adding quantitative information to the visual assessment of the radiologist, radiomics-assisted feature analysis could become an additional tool in the future to assess the degree of lung hypoplasia in order to further improve the therapy and outcome of CDH patients.

Congenital diaphragmatic hernia in Coffin Siris syndrome: Further evidence from two cases

Coffin-Siris Syndrome (CSS) is a rare multi-system dominant condition with a variable clinical presentation mainly characterized by hypoplasia/aplasia of the nail and/or distal phalanx of the fifth digit, coarse facies, hirsutism/hypertrichosis, developmental delay and intellectual disability of variable degree and growth impairment. Congenital anomalies may include cardiac, genitourinary and central nervous system malformations whereas congenital diaphragmatic hernia (CDH) is rarely reported. The genes usually involved in CSS pathogenesis are ARID1B (most frequently), SMARCA4, SMARCB1, ARID1A, SMARCE1, DPF2, and PHF6. Here, we present two cases of CSS presenting with CDH, for whom Whole Exome Sequencing (WES) identified two distinct de novo heterozygous causative variants, one in ARID1B (case 1) and one in SMARCA4 (case 2). Due to the rarity of CDH in CSS, in both cases the occurrence of CDH did not represent a predictive sign of CSS but, on the other hand, prompted genetic testing before (case 1) or independently (case 2) from the clinical hypothesis of CSS. We provide further evidence of the association between CSS and CDH, reviewed previous cases from literature and discuss possible functional links to related conditions.

Congenital Hepatopulmonary Fusion

Congenital hepatopulmonary fusion (HPF) is a rare anomaly characterized by a fusion between the liver and lung parenchyma. HPF cases have been scarcely reported in the literature. An extensive search of publications was performed in the PubMed and Google Scholar databases without a time limit. In total, 34 clinical case reports were found in the literature, and a study by the Congenital Diaphragmatic Hernia (CDH) Study Group reported data on 10 patients with HPF. Of these 44 infants, 20 were male, 20 were female, and four were reported without gender specification. Nineteen (43.2%) patients required intubation on the first day of life. Six (13.6%) patients had their clinical presentation during the first year of life, and four (9%) clinically presented with HPF between 2.5 and 11 years of age. In these patients, cough, asthma-like symptoms, dyspnea, hemoptysis, right-side chest pain, respiratory infections, and pneumonia were the relevant clinical signs. Right-lung vascular anomalies were present in 18 (40.9%) patients. A complete liver and lung separation was successful in 17 (38.6%) patients. The overall survival was 56.8%. Congenital HPF has no gender predominance. In most cases, it behaves similar to a right CDH in need of resuscitation and intubation after birth. The majority of the cases are discovered during the surgical procedure for CDH. The best surgical approach has not been established and depends on the degree of fusion and vascular anomalies. An advanced imaging assessment is necessary before a surgical approach is attempted. The prognosis is ominous.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a rare birth defect characterized by incomplete closure of the diaphragm and herniation of fetal abdominal organs into the chest that results in pulmonary hypoplasia, postnatal pulmonary hypertension owing to vascular remodelling and cardiac dysfunction. The high mortality and morbidity rates associated with CDH are directly related to the severity of cardiopulmonary pathophysiology. Although the aetiology remains unknown, CDH has a polygenic origin in approximately one-third of cases. CDH is typically diagnosed with antenatal ultrasonography, which also aids in risk stratification, alongside fetal MRI and echocardiography. At specialized centres, prenatal management includes fetal endoscopic tracheal occlusion, which is a surgical intervention aimed at promoting lung growth in utero. Postnatal management focuses on cardiopulmonary stabilization and, in severe cases, can involve extracorporeal life support. Clinical practice guidelines continue to evolve owing to the rapidly changing landscape of therapeutic options, which include pulmonary hypertension management, ventilation strategies and surgical approaches. Survivors often have long-term, multisystem morbidities, including pulmonary dysfunction, gastroesophageal reflux, musculoskeletal deformities and neurodevelopmental impairment. Emerging research focuses on small RNA species as biomarkers of severity and regenerative medicine approaches to improve fetal lung development.

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.

Clinical exome sequencing data reveal high diagnostic yields for congenital diaphragmatic hernia plus (CDH+) and new phenotypic expansions involving CDH

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a life-threatening birth defect that often co-occurs with non-hernia-related anomalies (CDH+). While copy number variant (CNV) analysis is often employed as a diagnostic test for CDH+, clinical exome sequencing (ES) has not been universally adopted.

METHODS

We analysed a clinical database of ~12 000 test results to determine the diagnostic yields of ES in CDH+ and to identify new phenotypic expansions.

RESULTS

Among the 76 cases with an indication of CDH+, a molecular diagnosis was made in 28 cases for a diagnostic yield of 37% (28/76). A provisional diagnosis was made in seven other cases (9%; 7/76). Four individuals had a diagnosis of Kabuki syndrome caused by frameshift variants in KMT2D. Putatively deleterious variants in ALG12 and EP300 were each found in two individuals, supporting their role in CDH development. We also identified individuals with de novo pathogenic variants in FOXP1 and SMARCA4, and compound heterozygous pathogenic variants in BRCA2. The role of these genes in CDH development is supported by the expression of their mouse homologs in the developing diaphragm, their high CDH-specific pathogenicity scores generated using a previously validated algorithm for genome-scale knowledge synthesis and previously published case reports.

CONCLUSION

We conclude that ES should be ordered in cases of CDH+ when a specific diagnosis is not suspected and CNV analyses are negative. Our results also provide evidence in favour of phenotypic expansions involving CDH for genes associated with ALG12-congenital disorder of glycosylation, Rubinstein-Taybi syndrome, Fanconi anaemia, Coffin-Siris syndrome and FOXP1-related disorders.

Antenatal management and outcomes of pregnancies with congenital diaphragmatic hernia

BACKGROUND

The objective of this study is to evaluate the obstetric outcomes of pregnancies with congenital diaphragmatic hernia (CDH).

METHODS

Fifty one pregnancies prenatally diagnosed with CDH at our institution between January 1, 2002 and August 31, 2018 were retrospectively evaluated. The pregnancies were divided into two groups according to neonatal survival. Demographic features, clinical characteristics and prognostic factors were compared between the neonatal survival (n = 16) and non-survival (n = 28) groups. Cut-off values of fetal lung area to head circumference ratio (LHR), observed/expected LHR (o/e LHR) and observed/expected total fetal lung volume (o/e TFLV) for neonatal survival were calculated.

RESULTS

Thirty six (70.6%) and fifteen (29.4%) fetuses had left and right sided CDH respectively. Seven patients chose termination of their pregnancies (13.7%). Statistically significant differences were found between survival and non-survival groups in terms of parity, median gestational week at diagnosis, polyhydroamniosis rate, CDH type, stomach position, liver position, median LHR, o/e LHR, o/e TFLV, median 5th minute Apgar score and neonatal operation rate values (p values were 0.03,<0.001, 0.02, 0.006,<0.001, 0.006,<0.001,<0.001,<0.001, 0.04 and <0.001 respectively). According to ROC curve analysis, 1.05 (82% sensitivity, 74% specificity) for LHR, 22.5 (78.6% sensitivity, 73.9% specifity) for o/e LHR and 23.5 (85.7% sensitivity,74.2% specificity) for o/e TFLV were determined to be cut-offs for neonatal survival, respectively, with highest sensitivity and specificity.

CONCLUSION

Earlier gestational week at diagnosis, right sided CDH, presence of liver herniation, supradiaphragmatic stomach position, lower LHR, o/e LHR and o/e TFLV were associated with decreased rates of neonatal survival.

Parental risk factors for congenital diaphragmatic hernia - a large German case-control study

Background

Evidence for periconceptional or prenatal environmental risk factors for the development of congenital diaphragmatic hernia (CDH) is still scarce. Here, in a case-control study we investigated potential environmental risk factors in 199 CDH patients compared to 597 healthy control newborns.

Methods

The following data was collected: time of conception and birth, maternal BMI, parental risk factors such as smoking, alcohol or drug intake, use of hairspray, contact to animals and parental chronic diseases. CDH patients were born between 2001 and 2019, all healthy control newborns were born in 2011. Patients and control newborns were matched in the ratio of three to one.

Results

Presence of CDH was significantly associated with maternal periconceptional alcohol intake (odds ratio = 1.639, 95% confidence interval 1.101–2.440, p = 0.015) and maternal periconceptional use of hairspray (odds ratio = 2.072, 95% confidence interval 1.330–3.229, p = 0.001).

Conclusion

Our study suggests an association between CDH and periconceptional maternal alcohol intake and periconceptional maternal use of hairspray. Besides the identification of novel and confirmation of previously described parental risk factors, our study underlines the multifactorial background of isolated CDH.

Management of Congenital Diaphragmatic Hernia (CDH): Role of Molecular Genetics

Congenital diaphragmatic hernia (CDH) is a relatively common major life-threatening birth defect that results in significant mortality and morbidity depending primarily on lung hypoplasia, persistent pulmonary hypertension, and cardiac dysfunction. Despite its clinical relevance, CDH multifactorial etiology is still not completely understood. We reviewed current knowledge on normal diaphragm development and summarized genetic mutations and related pathways as well as cellular mechanisms involved in CDH. Our literature analysis showed that the discovery of harmful de novo variants in the fetus could constitute an important tool for the medical team during pregnancy, counselling, and childbirth. A better insight into the mechanisms regulating diaphragm development and genetic causes leading to CDH appeared essential to the development of new therapeutic strategies and evidence-based genetic counselling to parents. Integrated sequencing, development, and bioinformatics strategies could direct future functional studies on CDH; could be applied to cohorts and consortia for CDH and other birth defects; and could pave the way for potential therapies by providing molecular targets for drug discovery.

Diaphragmatic Hernia as a Prenatal Feature of Glycosylphosphatidylinositol Biosynthesis Defects and the Overlap With Fryns Syndrome - Literature Review

Fryns syndrome is an autosomal recessive multiple congenital anomaly syndrome, with diaphragmatic defects and secondary lung hypoplasia as cardinal features. Despite it was reported first in 1979, its exact etiology has not been established to date. With this review, we would like to draw attention to the prenatal presentation of multiple congenital anomalies syndromes, resulting from defects in the synthesis of glycosylphosphatidylinositol anchors, to be considered in a prenatal assessment of fetuses with DH and Fryns-like phenotype.

miR-200 family expression during normal and abnormal lung development due to congenital diaphragmatic hernia at the later embryonic stage in the nitrofen rat model

INTRODUCTION

Congenital diaphragmatic hernia (CDH) is a life-threatening disease associated with pulmonary hypoplasia. CDH occurs approximately 1 in every 2000-3000 live births, and the pathophysiology is unknown. MicroRNAs are short, non-coding RNAs that control gene expression through post-transcriptional regulation. Based on our previous work, we hypothesized that the miR-200 family is differentially expressed in normal and abnormal lung development. We aimed to examine the expression of the miR-200 family during normal and hypoplastic lung development due to CDH.

METHODS

We performed reverse transcriptase polymerase chain reaction (RT-qPCR) and fluorescent in situ hybridization (FISH) to study the expression levels and distribution of the miR-200 family members on embryonic day 21 (E21) rat control and nitrofen-induced hypoplastic CDH lungs.

RESULTS

RT-qPCR showed up-regulation of miR-200a in hypoplastic CDH lungs. FISH showed contrasting expression patterns for miR- 200a, miR-200c, and miR-429 between control and hypoplastic CDH lungs, while we could not detect miR-141 in control and hypoplastic CDH lungs.

CONCLUSION

We demonstrate a specific expression pattern of miR-200 family members in hypoplastic CDH lungs different from control lungs. This study suggests that disruption of miR-200 family expression plays a role in the pathogenesis of pulmonary hypoplasia associated with CDH.

Laparoscopic Repair of Bilateral Congenital Diaphragmatic Hernia Without Pulmonary Hypoplasia

We report the case of a 14-month-old female who had a right-sided congenital diaphragmatic hernia (CDH) without pulmonary hypoplasia. The patient was preoperatively diagnosed with a Morgagni hernia due to the size and location of the hernia seen on imaging. However, the patient was found to have bilateral diaphragmatic defects intraoperatively, and her right diaphragm was almost completely absent. Our patient did not have pulmonary hypoplasia or any of the respiratory comorbidities that CDH patients typically present with, though she did have repeated respiratory infections and cough. This case demonstrates that CDH is not always diagnosed in an accurate or timely manner radiographically and that the surgeon should be prepared to potentially repair more of the diaphragm than expected. Additionally, there is a need to study the pathophysiology and genetics of CDHs further.

Accuracy of estimated fetal weight assessment in fetuses with congenital diaphragmatic hernia

BACKGROUND

Congenital diaphragmatic hernia is a congenital anomaly in which fetal abdominal organs herniate into the thoracic cavity through a diaphragmatic defect, which can impede fetal lung development. Standard formulas for estimated fetal weight include measurement of fetal abdominal circumference, which may be inaccurate in fetuses with congenital diaphragmatic hernia because of displacement of abdominal contents into the thorax.

OBJECTIVES

This study aimed to assess the accuracy of standard estimated fetal weight assessment in fetuses with congenital diaphragmatic hernia by comparing prenatal assessment of fetal weight with actual birthweight.

STUDY DESIGN

A retrospective cohort study of fetuses diagnosed with congenital diaphragmatic hernia was performed at a single center from 2012 to 2018. Fetuses with multiple anomalies or confirmed chromosome abnormalities were excluded. Estimated fetal weight was calculated using the Hadlock formula. Published estimates of fetal growth rate were used to establish a projected estimated fetal weight at birth from the final growth ultrasound, and the percentage difference between projected estimated fetal weight at birth and actual birthweight was calculated. A Wilcoxan rank-sum test was used to examine the difference between projected estimated fetal weight and birthweight.

RESULTS

We had complete data for 77 fetuses with congenital diaphragmatic hernia. The majority (76.6%, 55 of 77) had left-sided congenital diaphragmatic hernia. The median [interquartile range] projected estimated fetal weight was similar to median birthweight, at 3177 g [2691-3568] and 3180 g [2630-3500], respectively, which did not represent a statistically significant difference between projected estimated fetal weight and birthweight (P = .66). The median absolute percentage difference between projected birthweight and actual birthweight was 6.3% [3.2-7.0]. Estimated fetal weight was overall underestimated in a minority of cases (44.2%, 34 of 77).

CONCLUSION

In fetuses with a congenital diaphragmatic hernia, standard measurements of fetal estimated fetal weight show accuracy that is at least comparable with previously established margins of error for ultrasound assessment of fetal weight. Standard estimated fetal weight assessment remains an appropriate method of estimating fetal weight in fetuses with congenital diaphragmatic hernia.

Maternal Risk Factors and Perinatal Characteristics in Congenital Diaphragmatic Hernia: A Nationwide Population-Based Study

BACKGROUND

The etiology of congenital diaphragmatic hernia (CDH) remains poorly understood. We hypothesize that environmental factors play an important role in the development of CDH.

AIM

The objective of this study was to investigate associated maternal risk factors in pregnancies with CDH.

MATERIAL AND METHODS

The study was a nationwide, population-based prospective case-control study consisting of a cohort of newborn children entered into the records of pregnant women receiving antenatal care in Sweden, registered in the Medical Birth Registry during the period from January 1, 1982 to December 31, 2015. The study outcome CDH and the different exposures were assessed through linkage to the Swedish National Patient Registry for both cases and mothers.

RESULTS

A total of 972 cases of CDH were registered into one of the national registries in Sweden between 1982 and 2015. The incidence of neonates with CDH in Sweden from 1982 to 2015 was 3/10,000 live births. The mortality rate during the study period was 31%. Maternal age, ethnicity, parity, exposure to tobacco, BMI, IVF, previous history of spontaneous abortion or intrauterine fetal demise, and coexisting chronic diseases (urinary tract infection, chronic renal disease, pregestational diabetes, epilepsy, asthma, ulcerative colitis, inflammatory bowel disease, or systemic lupus erythematous) were not associated with an increased risk of CDH in the fetus. There was a significant association between maternal hypertension and the risk of the child being affected by CDH (OR 3.32, 95% CI 1.41-7.79, p = 0.01). No association was found between preeclampsia and CDH.

CONCLUSIONS

Pregestational hypertension is associated with an increased risk of giving birth to a baby with CDH, but no association was observed in pregnancies developing preeclampsia and the occurrence of CDH.

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.

Congenital diaphragmatic hernia in a case of Cat eye syndrome

Our findings extend the phenotypic spectrum of Cat eye syndrome, a disorder with wide clinical variability. The potentially life-threatening complications of congenital diaphragmatic hernia should be considered in genetic counseling and prenatal diagnostic.

Systematic analysis of copy number variation associated with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH), characterized by malformation of the diaphragm and hypoplasia of the lungs, is one of the most common and severe birth defects, and is associated with high morbidity and mortality rates. There is growing evidence demonstrating that genetic factors contribute to CDH, although the pathogenesis remains largely elusive. Single-nucleotide polymorphisms have been studied in recent whole-exome sequencing efforts, but larger copy number variants (CNVs) have not yet been studied on a large scale in a case control study. To capture CNVs within CDH candidate regions, we developed and tested a targeted array comparative genomic hybridization platform to identify CNVs within 140 regions in 196 patients and 987 healthy controls, and identified six significant CNVs that were either unique to patients or enriched in patients compared with controls. These CDH-associated CNVs reveal high-priority candidate genes including HLX, LHX1, and HNF1B We also discuss CNVs that are present in only one patient in the cohort but have additional evidence of pathogenicity, including extremely rare large and/or de novo CNVs. The candidate genes within these predicted disease-causing CNVs form functional networks with other known CDH genes and play putative roles in DNA binding/transcription regulation and embryonic development. These data substantiate the importance of CNVs in the etiology of CDH, identify CDH candidate genes and pathways, and highlight the importance of ongoing analysis of CNVs in the study of CDH and other structural birth defects.

Early development of pleuroperitoneal fold of the diaphragm in the rat fetus

The embryonic diaphragm comprises four major structural components derived from the transverse septum, the dorsal foregut mesentery, the pleuroperitoneal folds (PPFs), and the body wall. In this study, the appearance of PPFs and related factors were investigated using light microscopy of horizontal sections of rat fetuses from embryonic day 12 to 13. In rat fetuses, the sign of PPF projection was noted in the sidewall of the pericardioperitoneal canal at embryonic day 12, and was confirmed as folds at embryonic day 12.25. Expressions of GATA4, COUP-TF2, and FOG2 were detected in PPF at the early stage of formation. Localizations of these factors suggested that COUP-TF2 and FOG2 are the main factors in PPF appearance and that GATA4 is unlikely to be a main factor, although it is necessary for PPF formation.

HLX is a candidate gene for a pattern of anomalies associated with congenital diaphragmatic hernia, short bowel, and asplenia

Isolated congenital diaphragmatic hernia is often a sporadic event with a low recurrence risk. However, underlying genetic etiologies, such as chromosome anomalies or single gene disorders, are identified in a small number of individuals. We describe two fetuses with a unique pattern of multiple congenital anomalies, including diaphragmatic hernia, short bowel and asplenia, born to first-cousin parents. Whole exome sequencing showed that both were homozygous for a missense variant, c.950A>C, predicting p.Asp317Ala, in the H.20-Like Homeobox 1 (HLX1) gene. HLX is a homeobox transcription factor gene which is relatively conserved across species. Hlx homozygous null mice have a short bowel and reduced muscle cells in the diaphragm, closely resembling the anomalies in the two fetuses and we therefore suggest that the HLX mutation in this family could explain the fetal findings.

Genetic specification of left-right asymmetry in the diaphragm muscles and their motor innervation

The diaphragm muscle is essential for breathing in mammals. Its asymmetric elevation during contraction correlates with morphological features suggestive of inherent left–right (L/R) asymmetry. Whether this asymmetry is due to L versus R differences in the muscle or in the phrenic nerve activity is unknown. Here, we have combined the analysis of genetically modified mouse models with transcriptomic analysis to show that both the diaphragm muscle and phrenic nerves have asymmetries, which can be established independently of each other during early embryogenesis in pathway instructed by Nodal, a morphogen that also conveys asymmetry in other organs. We further found that phrenic motoneurons receive an early L/R genetic imprint, with L versus R differences both in Slit/Robo signaling and MMP2 activity and in the contribution of both pathways to establish phrenic nerve asymmetry. Our study therefore demonstrates L–R imprinting of spinal motoneurons and describes how L/R modulation of axon guidance signaling helps to match neural circuit formation to organ asymmetry.

DOI:http://dx.doi.org/10.7554/eLife.18481.001

The diaphragm is a dome-shaped muscle that forms the floor of the rib cage, separating the lungs from the abdomen. As we breathe in, the diaphragm contracts. This causes the chest cavity to expand, drawing air into the lungs. A pair of nerves called the phrenic nerves carry signals from the spinal cord to the diaphragm to tell it when to contract. These nerves project from the left and right sides of the spinal cord to the left and right sides of the diaphragm respectively.

The left and right sides of the diaphragm are not entirely level, but it was not known why. To investigate, Charoy et al. studied how the diaphragm develops in mouse embryos. This revealed that the left and right phrenic nerves are not symmetrical. Neither are the muscles on each side of the diaphragm. Further investigation revealed that a genetic program that establishes other differences between the left and right sides of the embryo also gives rise to the differences between the left and right sides of the diaphragm. This program switches on different genes in the left and right phrenic nerves, which activate different molecular pathways in the left and right sides of the diaphragm muscle.

The differences between the nerves and muscles on the left and right sides of the diaphragm could explain why some muscle disorders affect only one side of the diaphragm. Similarly, they could explain why congenital hernias caused by abdominal organs pushing through the diaphragm into the chest cavity mostly affect the left side of the diaphragm. Further studies are now needed to investigate these possibilities. The techniques used by Charoy et al. to map the molecular diversity of spinal cord neurons could also lead to new strategies for repairing damage to the spinal cord following injury or disease.

DOI:http://dx.doi.org/10.7554/eLife.18481.002

Abnormal lung development in congenital diaphragmatic hernia

The outcomes of patients diagnosed with congenital diaphragmatic hernia (CDH) have recently improved. However, mortality and morbidity remain high, and this is primarily caused by the abnormal lung development resulting in pulmonary hypoplasia and persistent pulmonary hypertension. The pathogenesis of CDH is poorly understood, despite the identification of certain candidate genes disrupting normal diaphragm and lung morphogenesis in animal models of CDH. Defects within the lung mesenchyme and interstitium contribute to disturbed distal lung development. Frequently, a disturbance in the development of the pleuroperitoneal folds (PPFs) leads to the incomplete formation of the diaphragm and subsequent herniation. Most candidate genes identified in animal models have so far revealed relatively few strong associations in human CDH cases. CDH is likely a highly polygenic disease, and future studies will need to reconcile how disturbances in the expression of multiple genes cause the disease. Herein, we summarize the available literature on abnormal lung development associated with CDH.

Genome-wide enrichment of damaging de novo variants in patients with isolated and complex congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is a common and often lethal birth defect characterized by diaphragmatic structural defects and pulmonary hypoplasia. CDH is isolated in 60% of newborns, but may also be part of a complex phenotype with additional anomalies. We performed whole exome sequencing (WES) on 87 individuals with isolated or complex CDH and on their unaffected parents, to assess the contribution of de novo mutations in the etiology of diaphragmatic and pulmonary defects and to identify new candidate genes. A combined analysis with 39 additional trios with complex CDH, previously published, revealed a significant genome-wide burden of de novo variants compared to background mutation rate and 900 control trios. We identified an increased burden of likely gene-disrupting (LGD, i.e. nonsense, frameshift, and canonical splice site) and predicted deleterious missense (D-mis) variants in complex and isolated CDH patients. Overall, an excess of predicted damaging de novo LGD and D-mis variants relative to the expected frequency contributed to 21% of complex cases and 12% of isolated CDH cases. The burden of de novo variants was higher in genes expressed in the developing mouse diaphragm and heart. Some overlap with genes responsible for congenital heart defects and neurodevelopmental disorders was observed in CDH patients within our cohorts. We propose that de novo variants contribute significantly to the development of CDH.

Congenital diaphragmatic hernia - a Belgrade single center experience

OBJECTIVE

Though the outcome for children with congenital diaphragmal hernia (CDH) is improving, management of seriously compromised respiratory and cardiovascular function remains a great challenge. The aim of this study was to review a tertiary center experience in treating children with CDH.

DESIGN

Retrospective observational study from January 2005 to December 2014.

SETTING

Neonatal Intensive Care Unit (NICU) of University Children Hospital (UCH), Belgrade, Serbia.

PATIENTS

Children with CDH.

RESULTS

The CDH was diagnosed prenatally in 23% patients. An overall survival rate was 62%. Among those patients who underwent surgical repair 29 (90%) survived. There was statistically significant difference in survival rate between operated patients and total examined population (P=0.020). Prenatally diagnosed neonates with CDH had significantly lower survival rate comparing to those who were postnatally diagnosed (20% vs. 75%; P=0.002). Fatal outcome was more frequent in patients with small birth weight comparing to those with normal birth weight (67% vs. 30%; P=0.046).

CONCLUSIONS

Our center survival rate for CDH is in accordance with other reported studies. Based on our experience there are potential points for further improvement. First, further increase of prenatal detection, planning for delivery, and coordinated transfer to tertiary institution, in order to avoid transfer of near death patients. Second, preoperative management in the NICU. This could be done by more uniform implementation of current consensual guidelines in monitoring, mechanical ventilation and circulatory support of these delicate patients, together with rationale use of newer therapeutic resources.

Polygenic Causes of Congenital Diaphragmatic Hernia Produce Common Lung Pathologies

Congenital diaphragmatic hernia (CDH) is one of the most common and lethal congenital anomalies, and significant evidence is available in support of a genetic contribution to its etiology, including single-gene knockout mice associated with diaphragmatic defects, rare monogenetic disorders in humans, familial aggregation, and association of CDH with chromosomal abnormalities. Structural lung defects in the form of lung hypoplasia are almost invariably seen in patients with CDH and frequently in animal models of this condition. Better understanding of the mechanisms of pulmonary defects in CDH has the potential for creating targeted therapies, particularly in postnatal stages, when therapeutics can have maximum clinical impact on the surviving cohorts. Successful treatment of CDH is dependent on the integration of human genomic and genetic data with developmental expression profiling, mouse knockouts, and gene network and pathway modeling, which have generated a large number of candidate genes and pathways for follow-up studies. In particular, defective alveolarization appears to be a common and potentially actionable phenotype in both patients and animal models.

Congenital retrosternal hernias of Morgagni: Manifestation and treatment in children

BACKGROUND

Due to scarcity of congenital diaphragmatic hearnias of Morgagni (CDHM), non-specific clinical presentation in the pediatric age group, we aimed to investigate the incidence, clinical manifestations, anatomical characteristics, and develop diagnostic algorithm and treatment of CDHM in children.

MATERIALS AND METHODS

The patients' records of children with CDHM treated in our hospital during past 20 years were retrospectively reviewed for the age at diagnosis, gender, clinical findings, anatomical features, operative details and outcome.

RESULTS

Since 1995 to 2014 we observed 6 (3 boys, 3 girls) patients with CDHM, that comprise 3.2% of all congenital diaphragmatic hernia cases (n = 185). Age at diagnosis varied from 3 mo. to 10y.o. Failure to thrive was main symptom in 4 patients, followed by recurrent respiratory infections (n = 3), dyspnea (n = 3), and gastrointestinal manifestations: constipation (n = 2), abdominal pain (n = 1). Work-up consisted of plain X-ray for all (n = 6), upper GI (n = 3), barium enema (n = 2), sonography (n = 6) and CT (n = 2). Abdominal approach used in 5 patients, and thoracotomy in one. Herniated contents were: liver lobes (n = 4), transverse colon (n = 3) and greater omentum (n = 1). 5 had right-sided lesion, 1- left-sided. Defect repaired using local tissues. Post-operative course was uneventful; all patients appeared well during follow-up.

CONCLUSION

CDHM is very uncommon anomaly, very occasionally diagnosed at the early age. Failure to thrive and recurrent respiratory infections are most frequent clinical manifestations. In suspected CDHM we advocate the following work-up: plain chest and abdominal X-ray, contrast study (upper GI series or barium enema), ultrasonographic screen and CT scan. Surgical repair via abdominal approach, using local tissues and hernia sac removal is preferred.

Familial tetrasomy 4q35.2 associated with congenital diaphragmatic hernia and unilateral renal agenesis: a case report

Background

Previous reports of chromosomal aberrations in different forms of congenital diaphragmatic hernia have been described as comprising aneuploidies (for example, trisomy 21), microdeletions, and duplications (for example, monosomy 15q24, 22q11.2).

Case presentation

We describe the first association of a de novo partial tetrasomy 4q35.2 in a father with left-sided, isolated renal agenesis and left-sided, isolated congenital diaphragmatic hernia in his son, who inherited the chromosomal aberration from his father.

Conclusions

Given that the aberration occurred de novo in the father and was transmitted to his son, with both presenting with unilateral left-sided developmental field defects, we suggest a gene dosage effect of the tetrasomic region to be involved in the phenotype of our two patients. Furthermore, we suggest performing a genetic workup in multiplex families with congenital malformations.

Pre- and Postnatal Analysis of Chromosome 15q26.1 and 8p23.1 Deletions in Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) is defined as a protrusion of abdominal content into the thoracic cavity through an abnormal opening in the diaphragm present at birth. It is a common birth defect with high mortality and morbidity. Submicroscopic deletions of 15q26.1 and 8p23.1 have been reported in several cases of CDH. We studied a total of 17 cases with CDH in pre- and postnatal samples using FISH probes. Deletion 15q26.1 was seen in 1/17 prenatal samples. There was no deletion for 8p23.1 in all the samples analyzed. CDH has a genetic etiology, and deletion 15q26.1 increases the risk of CDH. Deletion 15q26.1 in a fetus with CDH is a predictor of poor prognosis. This deletion is also seen in a phenotype similar to Fryns syndrome. CDH identified pre- or postnatally should be investigated further to exclude a 15q26.1 deletion and enable appropriate parental counseling.

Risk factors for congenital diaphragmatic hernia in the Bogota birth defects surveillance and follow-up program, Colombia

PURPOSE

The mortality rate for congenital diaphragmatic hernia (CDH) remains high and prevention efforts are limited by the lack of known risk factors. The aim of this study was to determine prevalence, risk factors, and neonatal results associated with CDH on a surveillance system hospital-based in Bogotá, Colombia.

METHODS

The data used in this study were obtained from The Bogota Birth Defects Surveillance and Follow-up Program (BBDSFP), between January 2001 and December 2013. With 386,419 births, there were 81 cases of CDH. A case-control methodology was conducted with 48 of the total cases of CDH and 192 controls for association analysis.

RESULTS

The prevalence of CDH was 2.1 per 10,000 births. In the case-control analysis, risk factors found were maternal age ≥35 years (OR, 33.53; 95 % CI, 7.02-160.11), infants with CDH were more likely to be born before 37 weeks of gestation (OR, 5.57; 95 % CI, 2.05-15.14), to weigh less than 2500 g at birth (OR, 9.05; 95 % CI, 3.51-23.32), and be small for gestational age (OR, 5.72; 95 % CI, 2.18-14.99) with a high rate of death before hospital discharge in the CDH population (CDH: 38 % vs BBDSFP: <1 %; p < 0.001).

CONCLUSIONS

The prevalence of CDH calculated was similar to the one reported in the literature. CDH is strongly associated with a high rate of death before hospital discharge and the risk factors found were maternal age ≥35 years, preterm birth, be small for gestational age, and have low weight at birth. These neonatal characteristics in developing countries would help to identify early CDH. Prevention efforts have been limited by the lack of known risk factors and established epidemiological profiles, especially in developing countries.

Trends in treatment and in-hospital mortality for neonates with congenital diaphragmatic hernia

OBJECTIVE

We performed a retrospective cohort study in order to examine recent trends in use of post-partum treatments and in-hospital mortality for congenital diaphragmatic hernia (CDH).

STUDY DESIGN

Included were infants with CDH, born in 2003 to 2012 and hospitalized at ⩽7 days of age at one of 33 United States tertiary referral children's hospitals with extracorporeal membrane oxygenation (ECMO) programs. In-hospital mortality as well as use of ECMO, surfactant and a variety of vasodilators were examined for trends during the study period.

RESULT

Inclusion criteria were met by 3123 infants with CDH. Among 2423 term or near-term infants, odds of death decreased annually for those with isolated or complex CDH. For 700 premature or low-birth weight infants with CDH, in-hospital mortality did not change. Among treatments for CDH, increasing with time in the study cohort were use of milrinone and sildenafil individually, and use of multiple vasodilators during the hospitalization.

CONCLUSION

Survival improved in large subgroups of term or near-term infants with CDH in this 10-year multicenter cohort, temporally associated with increasing use of multiple vasodilators. Use of vasodilators for infants with CDH is increasing despite a lack of evidence supporting efficacy or safety. Prospective research is needed to clarify specific causal effects contributing to improving survival in these infants.

Wt1 and β-catenin cooperatively regulate diaphragm development in the mouse

The developing diaphragm consists of various differentiating cell types, many of which are not well characterized during organogenesis. One important but incompletely understood tissue, the diaphragmatic mesothelium, is distinctively present from early stages of development. Congenital Diaphragmatic Hernia (CDH) occurs in humans when diaphragm tissue is lost during development, resulting in high morbidity and mortality postnatally. We utilized a Wilms Tumor 1 (Wt1) mutant mouse model to investigate the involvement of the mesothelium in normal diaphragm signaling and development. Additionally, we developed and characterized a Wt1(CreERT2)-driven β-catenin loss-of-function model of CDH after finding that canonical Wnt signaling and β-catenin are reduced in Wt1 mutant mesothelium. Mice with β-catenin loss or constitutive activation induced in the Wt1 lineage are only affected when tamoxifen injection occurs between E10.5 and E11.5, revealing a critical time-frame for Wt1/ β-catenin activity. Conditional β-catenin loss phenocopies the Wt1 mutant diaphragm defect, while constitutive activation of β-catenin on the Wt1 mutant background is sufficient to close the diaphragm defect. Proliferation and apoptosis are affected, but primarily these genetic manipulations appear to lead to a change in normal diaphragm differentiation. Our data suggest a fundamental role for mesothelial signaling in proper formation of the diaphragm.

Congenital diaphragmatic hernia in a case of patau syndrome: a rare association

Congenital diaphragmatic hernia (CDH) occurs in 5-10% associated with chromosomal abnormalities like, Pallister Killian syndrome, Trisomy 18, and certain deletions.. Association of CDH with trisomy 13 (Patau syndromes) is very rare. Here, we report such an unusual association, where surgical repair was done, but eventually the case succumbed as a result of multiple fatal co-morbidities.

Variable expression pattern in Donnai-Barrow syndrome: Report of two novel LRP2 mutations and review of the literature

Donnai-Barrow syndrome (DBS; MIM 222448) is characterized by typical craniofacial anomalies (major hypertelorism with bulging eyes), high grade myopia, deafness and low molecular weight proteinuria. The disorder results from mutations in the low density lipoprotein receptor-related protein 2 gene LRP2 that maps to chromosome 2q31.1. LRP2 encodes megalin, a multi-ligand endocytic receptor. Herein, we describe the clinical presentation of 4 patients from 2 unrelated Saudi families. Two novel LRP2 mutations, a homozygous nonsense mutation (c.4968C>G; p.Tyr1656*) and a missense mutation (c.12062G>A; p.Cys4021Tyr), were detected in the first and second family respectively. Interestingly, intrafamilial phenotypic variability was observed in one family, while DBS features were atypical in the second family. Differential diagnosis of DBS includes several syndromes associating hypertelorism with high grade myopia, and several syndromal forms of CDH, which are briefly summarized in this study.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia is an uncommon congenital anomaly of the diaphragm with pulmonary hypoplasia and persistent pulmonary hypertension as serious consequences. Despite recent advances in therapy, congenital diaphragmatic hernia remains a challenging condition. Best treatment strategies are still largely unknown, and practice strategies vary widely among different centres. Additionally, as congenital diaphragmatic hernia is a relatively uncommon condition, it is difficult to recruit sufficient numbers of patients for clinical trials. In recent years, survival rates of congenital diaphragmatic hernia patients appear to have increased. With the progressively improved survival rates, the long-term prognosis and quality of life of patients have become an increasingly important issue. Survivors have been shown to be at risk for many long-term morbidities, which highlights the importance of long-term follow-up of these children. The aim of this review is to give an overview of the current knowledge regarding congenital diaphragmatic hernia.

Molecular pathogenesis of congenital diaphragmatic hernia revealed by exome sequencing, developmental data, and bioinformatics

Congenital diaphragmatic hernia (CDH) is a common and severe birth defect. Despite its clinical significance, the genetic and developmental pathways underlying this disorder are incompletely understood. In this study, we report a catalog of variants detected by a whole exome sequencing study on 275 individuals with CDH. Predicted pathogenic variants in genes previously identified in either humans or mice with diaphragm defects are enriched in our CDH cohort compared with 120 size-matched random gene sets. This enrichment was absent in control populations. Variants in these critical genes can be found in up to 30.9% of individuals with CDH. In addition, we filtered variants by using genes derived from regions of recurrent copy number variations in CDH, expression profiles of the developing diaphragm, protein interaction networks expanded from the known CDH-causing genes, and prioritized genes with ultrarare and highly disruptive variants, in 11.3% of CDH patients. These strategies have identified several high priority genes and developmental pathways that likely contribute to the CDH phenotype. These data are valuable for comparison of candidate genes generated from whole exome sequencing of other CDH cohorts or multiplex kindreds and provide ideal candidates for further functional studies. Furthermore, we propose that these genes and pathways will enhance our understanding of the heterogeneous molecular etiology of CDH.

Whole exome sequencing identifies de novo mutations in GATA6 associated with congenital diaphragmatic hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a common birth defect affecting 1 in 3000 births. It is characterised by herniation of abdominal viscera through an incompletely formed diaphragm. Although chromosomal anomalies and mutations in several genes have been implicated, the cause for most patients is unknown.

METHODS

We used whole exome sequencing in two families with CDH and congenital heart disease, and identified mutations in GATA6 in both.

RESULTS

In the first family, we identified a de novo missense mutation (c.1366C>T, p.R456C) in a sporadic CDH patient with tetralogy of Fallot. In the second, a nonsense mutation (c.712G>T, p.G238*) was identified in two siblings with CDH and a large ventricular septal defect. The G238* mutation was inherited from their mother, who was clinically affected with congenital absence of the pericardium, patent ductus arteriosus and intestinal malrotation. Deep sequencing of blood and saliva-derived DNA from the mother suggested somatic mosaicism as an explanation for her milder phenotype, with only approximately 15% mutant alleles. To determine the frequency of GATA6 mutations in CDH, we sequenced the gene in 378 patients with CDH. We identified one additional de novo mutation (c.1071delG, p.V358Cfs34*).

CONCLUSIONS

Mutations in GATA6 have been previously associated with pancreatic agenesis and congenital heart disease. We conclude that, in addition to the heart and the pancreas, GATA6 is involved in development of two additional organs, the diaphragm and the pericardium. In addition, we have shown that de novo mutations can contribute to the development of CDH, a common birth defect.

Family-based studies to identify genetic variants that cause congenital heart defects

Congenital heart defects (CHDs) are the most common congenital abnormalities. Analysis of large multigenerational families has led to the identification of a number of genes for CHDs. However, identifiable variations in these genes are the cause of a small proportion of cases of CHDs, suggesting significant genetic heterogeneity. In addition, large families with CHDs are rare, making the identification of additional genes difficult. Next-generation sequencing technologies will provide an opportunity to identify more genes in the future. However, the significant genetic variation between individuals will present a challenge to distinguish between 'pathogenic' and 'benign' variants. We have demonstrated that the analysis of multiple individuals in small families using combinations of algorithms can reduce the number of candidate variants to a small, manageable number. Thus, the analysis of small nuclear families or even distantly related 'sporadic' cases may begin to uncover the 'dark matter' of CHD genetics.

Roundabout receptors are critical for foregut separation from the body wall

In mammals, precise placement of organs is essential for survival. We show here that inactivation of Roundabout (Robo) receptors 1 and 2 in mice leads to mispositioning of the stomach in the thoracic instead of the abdominal cavity, which likely contributes to poor lung inflation and lethality at birth, reminiscent of congenital diaphragmatic hernia (CDH) cases in humans. Unexpectedly, in Robo mutant mice, the primary defect preceding organ misplacement and diaphragm malformation is a delayed separation of foregut from the dorsal body wall. Foregut separation is a rarely considered morphogenetic event, and our data indicate that it occurs via repulsion of Robo-expressing foregut cells away from the Slit ligand source. In humans, genomic lesions containing Robo genes have been documented in CDH. Our findings suggest that separation of the foregut from the body wall is genetically controlled and that defects in this event may contribute to CDH.

A family-based paradigm to identify candidate chromosomal regions for isolated congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a developmental defect of the diaphragm that causes high newborn mortality. Isolated or non-syndromic CDH is considered a multifactorial disease, with strong evidence implicating genetic factors. As low heritability has been reported in isolated CDH, family-based genetic methods have yet to identify the genetic factors associated with the defect. Using the Utah Population Database, we identified distantly related patients from several extended families with a high incidence of isolated CDH. Using high-density genotyping, seven patients were analyzed by homozygosity exclusion rare allele mapping (HERAM) and phased haplotype sharing (HapShare), two methods we developed to map shared chromosome regions. Our patient cohort shared three regions not previously associated with CDH, that is, 2q11.2-q12.1, 4p13 and 7q11.2, and two regions previously involved in CDH, that is, 8p23.1 and 15q26.2. The latter regions contain GATA4 and NR2F2, two genes implicated in diaphragm formation in mice. Interestingly, three patients shared the 8p23.1 locus and one of them also harbored the 15q26.2 segment. No coding variants were identified in GATA4 or NR2F2, but a rare shared variant was found in intron 1 of GATA4. This work shows the role of heritability in isolated CDH. Our family-based strategy uncovers new chromosomal regions possibly associated with disease, and suggests that non-coding variants of GATA4 and NR2F2 may contribute to the development of isolated CDH. This approach could speed up the discovery of the genes and regulatory elements causing multifactorial diseases, such as isolated CDH.

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.

Congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is defined by the presence of an orifice in the diaphragm, more often left and posterolateral that permits the herniation of abdominal contents into the thorax. The lungs are hypoplastic and have abnormal vessels that cause respiratory insufficiency and persistent pulmonary hypertension with high mortality. About one third of cases have cardiovascular malformations and lesser proportions have skeletal, neural, genitourinary, gastrointestinal or other defects. CDH can be a component of Pallister-Killian, Fryns, Ghersoni-Baruch, WAGR, Denys-Drash, Brachman-De Lange, Donnai-Barrow or Wolf-Hirschhorn syndromes. Some chromosomal anomalies involve CDH as well. The incidence is < 5 in 10,000 live-births. The etiology is unknown although clinical, genetic and experimental evidence points to disturbances in the retinoid-signaling pathway during organogenesis. Antenatal diagnosis is often made and this allows prenatal management (open correction of the hernia in the past and reversible fetoscopic tracheal obstruction nowadays) that may be indicated in cases with severe lung hypoplasia and grim prognosis. Treatment after birth requires all the refinements of critical care including extracorporeal membrane oxygenation prior to surgical correction. The best hospital series report 80% survival but it remains around 50% in population-based studies. Chronic respiratory tract disease, neurodevelopmental problems, neurosensorial hearing loss and gastroesophageal reflux are common problems in survivors. Much more research on several aspects of this severe condition is warranted.

Current advances in prenatal imaging of congenital diaphragmatic [corrected] hernia

Congenital diaphragmatic hernia, despite advances in therapy, remains a complex condition with significant morbidity and mortality. The etiology of the disorder is still incompletely understood, though the pulmonary hypoplasia and pulmonary hypertension that develop secondarily must be overcome to improve survival. Prenatal US and fetal MRI have helped in the development of a greater understanding of this disease. Also with these modalities, measurement techniques have been developed in an attempt to provide prognosticators for the development of pulmonary hypoplasia and pulmonary hypertension. There is a broad range of approaches for performing these measurements, and variability among imaging centers is noted. Despite inconsistent approaches, these techniques have become the foundation for counseling and prenatal and postnatal therapy. It is hoped that with further research with prenatal US and fetal MRI and the development of innovative medical and surgical therapies that the morbidity and mortality of children with congenital diaphragmatic hernias can be significantly reduced.

Current technology in the diagnosis of developmentally related lung disorders

Respiratory disorders that present in the newborn period may result from structural, functional, or acquired mechanisms that limit gas exchange between the airspace and vascular bed. Exciting new imaging, gene sequencing, mass spectrometry, and molecular and cell-based techniques are enhancing our understanding of mechanisms of disease; highlighting the complexity of interactions between genes, development, and environment in the manifestation of health and disease; and becoming part of the clinical armamentarium for the care of patients. Some of these technologies and their clinical potential are briefly reviewed in this paper.

Prenatally diagnosed 17q12 microdeletion syndrome with a novel association with congenital diaphragmatic hernia

We describe the first reported case of a prenatally diagnosed and recently described 17q12 microdeletion syndrome. The fetus was noted to have a congenital diaphragmatic hernia (CDH), echogenic kidneys and cystic left lung on prenatal ultrasound. The patient underwent amniocentesis which resulted in a normal fluorescence in-situ hybridization and karyotype. An oligonucleotide microarray was then performed which demonstrated a 1.4-Mb deletion within the 17q12 region. The deletion caused haploinsufficiency for 17 genes, including AATF, ACACA, DDX52, DUSP14, GGNBP2, HNF-1B, LHX1, PIGW, SYNRG, TADA2A, and ZNHIT3. The deleted region on 17q12 is similar in size and gene content to previously reported 17q12 microdeletion syndromes, which have a minimal critical region of 1.52 Mb. The newly described 17q12 microdeletion syndrome has been associated with MODY5 (maturity-onset of diabetes of the young type 5), cystic renal disease, pancreatic atrophy, liver abnormalities, cognitive impairment and structural brain abnormalities. CDH has not been previously described with the 17q12 microdeletion syndrome. We hypothesize that CDH is part of the spectrum of this syndrome and likely not detected postnatally due to high prenatal mortality.

[Congenital diaphragmatic hernia - mechanisms of pulmonary hypoplasia]

Congenital diaphragmatic hernia (CDH) is a common cause of severe neonatal respiratory distress. Mortality and morbidity are determined by the amount of pulmonary hypoplasia (PH) that occurs and by the development of therapy-resistant pulmonary hypertension. The pathogenesis and aetiology of CDH and its associated anomalies are still largely unknown despite all research efforts. The pathogenesis of CDH is based on an assumption linking herniation of abdominal viscera into the thorax with compression of the developing lung. PH, however, can also result from reduced distension of the developing lung secondary to impaired fetal breathing movements. Our understanding of CDH has also been aided by basic research with the use of dietary, teratogen-induced, and knockout models of CDH. These studies indicate that lung hypoplasia may involve disturbances of mitogenic signalling pathways fundamental to embryonic lung development. Recent data reveal the role of disruption of a retinoid-signalling pathway in the pathogenesis of CDH. Although multifactorial inheritance may best explain most cases of CDH in humans, much has been learned about the genetic factors that play a role in the development of CDH by studies of patients with CDH caused by specific genetic syndromes and chromosome anomalies. More research is warranted to improve our understanding of normal and abnormal lung development in relation to CDH. Such investigations will help in the design of new treatment strategies to improve the natural course or even to prevent this anomaly.