The genetics of congenital diaphragmatic hernia

Update on Management and Outcomes of Congenital Diaphragmatic Hernia

Infants with congenital diaphragmatic hernia (CDH) benefit from comprehensive multidisciplinary teams that have experience in caring for the unique and complex issues associated with CDH. Despite prenatal referral to specialized high-volume centers, advanced ventilation strategies and pulmonary hypertension management, and extracorporeal membrane oxygenation, mortality and morbidity remain high. These infants have unique and complex issues that begin in fetal and infant life, but persist through adulthood. Here we will review the literature and share our clinical care pathway for neonatal care and follow up. While many advances have occurred in the past few decades, our work is just beginning to continue to improve the mortality, but also importantly the morbidity of CDH.

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.

The Genomics of Congenital Diaphragmatic Hernia: A 10-Year Retrospective Review

OBJECTIVE

To evaluate genetic testing use in infants with congenital diaphragmatic hernia (CDH) over the past decade to better inform future practices and individualize prognostication and management.

STUDY DESIGN

A retrospective cohort study was performed of all infants with CDH enrolled in the Pulmonary Hypoplasia Program at Children's Hospital of Philadelphia, born between January 2011 and February 2021. For each infant, demographic information, prenatal and postnatal history, and genetic testing were reviewed.

RESULTS

The charts of 411 infants were analyzed. Overall, 22% (n = 89) were complex/syndromic and 78% (n = 322) were isolated/nonsyndromic. Mortality was significantly higher in complex/syndromic infants (P < .001) and in infants with diagnostic genetic testing (P < .001). Microarray was diagnostic in 9% (n = 34/399) and exome sequencing was diagnostic in 38% (n = 15/39). Genetic testing was diagnostic in 57% (n = 51/89) of complex/syndromic infants, but in only 2% of isolated/nonsyndromic infants (n = 8/322). Overall, genetic testing was diagnostic in 14% (n = 56).

CONCLUSIONS

The high diagnostic rate in this cohort highlights the utility of comprehensive genetic testing in infants with CDH. However, 43% of complex/syndromic and 98% of isolated/nonsyndromic infants do not have a genetic etiology identified. This finding underscores the need for additional genetic and genomic studies (eg, whole genome, RNA sequencing) to identify novel genes and mutational mechanisms (single genes, regulatory elements, complex traits) that will allow for improved diagnostic rates and ultimately individualized management of infants with CDH.

Laparoscopic repair of an incarcerated Morgagni Hernia in a COVID-19-positive patient: A video case report

Introduction

Morgagni Hernia (MH) is a type of congenital diaphragmatic hernia (CDH). CDH is a diaphragmatic discontinuity that permits abdominal viscera to herniate into the chest during development. It does not only occur in early childhood but also has been reported in adults. The most prevalent clinical sign of MH is respiratory disorder of all ages.

Case presentation

An elderly woman with a known history of diabetes, ischemic heart disease, hypertension, and constipation presented to us with increased abdominal pain. Besides, her PCR test results were positive for COVID-19. She underwent diagnostic laparoscopy surgery. The incision was closed with an intracorporeal suture, and then dual mesh was fixed to diaphragmatic wall. The postoperative progress was satisfactory two weeks after surgery. Based on a negative PCR test, the patient was discharged from the hospital.

Discussion

The foramina of Morgagni is a defect in the costosternal trigons produced by a lack of anterior pleuroperitoneal membrane muscularization. Although gastrointestinal symptoms and cardiorespiratory discomfort are typically connected with the diagnosis and treatment of MH in youngsters, there are a few middle-aged people who, like our case, develop symptoms suddenly. Albeit a paradigm change in the 21st century deems less invasive laparoscopic surgery to be the treatment of choice, open surgical procedures via a trans-thoracic or trans-abdominal route are still used.

Conclusion

MH is indeed uncommon in adults, but in patients with an acute onset of intestinal obstruction, the possibility of MH should be in mind. It can be fatal if it is misdiagnosed.

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The possibility of Morgagni hernia should be in mind even in elderly patients

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Laparoscopic technique is one of the best approaches to the Morgagni hernia cause all abdominal organs can be evaluated with laparoscopy in a minimally invasive manner.

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The operation can be performed in a COVID-19 positive patient.

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COVID-19 may be a spark of underlying disease manifestations.

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.

Hernia of Morgagni in the Elderly: A Case Report

Congenital diaphragmatic hernias are infrequently encountered in adult patients. A rare type of this hernia is the Morgagni’s hernia. Although they remain asymptomatic in a majority of patients, we present the case of an elderly patient who presented to us with abdominal pain and upper gastrointestinal bleeding.

Complete Bilateral Agenesis of the Diaphragm

Bilateral agenesis of the diaphragm is a very rare congenital diaphragmatic defect. Bilateral congenital diaphragmatic hernia (CDH) is much more frequently associated with other anomalies compared with unilateral CDH (70% vs 30%-40%). These include cardiovascular, respiratory (other than lung hypoplasia), gastrointestinal, renal, and genital malformations. We report a case of complete bilateral agenesis of the diaphragm associated with a horseshoe kidney and an imperforate anus. These additional malformations have not previously been reported in association with complete bilateral agenesis of the diaphragm. We also present a review of previous cases of total diaphragm agenesis published in the English language and provide some insights about pathogenesis.

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.

Patterns of fetal lung growth in fetuses with isolated left-sided congenital diaphragmatic hernia

OBJECTIVE

To evaluate right lung growth pattern in fetuses with isolated left-sided congenital diaphragmatic hernia (iL-CDH) and to analyze the pattern according to postnatal outcome.

METHODS

Lung-to-head ratio (LHR) and observed-to-expected LHR (O/E LHR) were obtained in 58 cases. Correlation and regression analysis for the total number of measurements, general linear models for those cases with a least three serial measurements and linear mixed effect models were used to analyze the influence of gestational age on the right lung size. Cases expectantly managed and those with fetal endoscopic tracheal occlusion were analyzed separately.

RESULTS

LHR, but not O/E LHR, increased significantly with gestational age (GA) (r = 0.43, p = 0.003 and r = -0.13, p = 0.30, respectively). According to neonatal mortality, in those fetuses that died, LHR remained unchanged and O/E LHR decreased significantly with GA (r = 0.07, p = 0.65 and r = -0.37, p = 0.02, respectively). In those cases with at least three serial measurements, the same two patterns were found. Similarly, in cases with expectant management, surviving fetuses showed a significantly higher weekly increase in LHR (p = 0.01) and a trend to a lower weekly decrease in O/E LHR (p = 0.17) than in those that died.

CONCLUSIONS

Patterns of right lung growth in iL-CDH differ according to postnatal survival. Serial measurements, but not a single one, might increase the prediction of neonatal death.

Correlation of observed-to-expected total fetal lung volume with intrathoracic organ herniation on magnetic resonance imaging in fetuses with isolated left-sided congenital diaphragmatic hernia

OBJECTIVES

To assess using fetal magnetic resonance imaging (MRI) the relationship between the position of the stomach as well as the volume of herniation of organs into the thorax, and the observed-to-expected total fetal lung volume (o/e-TFLV), as a measure of pulmonary hypoplasia, in fetuses with isolated left-sided congenital diaphragmatic hernia (LCDH).

METHODS

This was a single-center retrospective study using archived MR images from fetuses > 20 weeks' gestation evaluated for isolated LCDH over an 11-year period between July 2002 and September 2013. We retrieved data on the gestational age at MRI, o/e-TFLV and liver position. Images were also reviewed by a single operator to determine retrospectively the position of the stomach as well as the proportion of the total thorax volume occupied by the herniated fetal liver, stomach and other viscera. Following confirmation of reproducibility, we assessed the correlation of intrathoracic organ volumes and stomach position with o/e-TFLV.

RESULTS

The study included 205 fetuses which underwent a total of 259 MR examinations. The reproducibility of organ volume measurements was excellent (intraclass correlation coefficient range, 0.928-0.997). The average time spent to obtain intrathoracic organ volumes ranged from 2.28 to 5.13 min. Of all herniated organ-to-thoracic volume ratios, the liver-to-thoracic volume ratio had the strongest correlation with o/e-TFLV (ρ = -0.429, P<0.0001). Stomach volume did not correlate, although, when categorized by the position and extent of stomach herniation, there was an inverse relationship to o/e-TFLV. No intrathoracic organ-to-thoracic volume ratio was related to gestational age.

CONCLUSIONS

We observed in fetuses with isolated LCDH an inverse relationship between lung volume and the amount of liver herniated as well as the position of the stomach in the chest.

The genetics of common disorders - congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high mortality and morbidity. Although numerous chromosomal aberrations and gene mutations have been associated with CDH, the etiology of the diaphragmatic defect is identified in less than 50% of patients. This review discusses the some of the more frequent, recurrent karyotypic abnormalities in which CDH is a feature, including 15q26, 8p23.1 and 4p16.3 deletions and tetrasomy 12p (Pallister-Killian syndrome), together with some of the syndromes in which CDH is a relatively common feature, including Fryns syndrome, Matthew-Wood syndrome, overgrowth syndromes and Donnai-Barrow syndrome. In the era of genomic technologies, our knowledge of the genes and chromosome regions involved in pathogenesis of CDH is likely to advance significantly.

Changes in the expression of vascular endothelial growth factor after fetal tracheal occlusion in an experimental model of congenital diaphragmatic hernia

Introduction. Vascular endothelial growth factor (VEGF), an angiogenic factor secreted by type II pneumocytes, could play a role in congenital diaphragmatic hernia (CDH) pathogenesis. Animal studies suggest that VEGF accelerates lung growth. Aim. To quantify VEGF on fetal lungs in a nitrofen rat model for CDH and to analyze the effect of tracheal occlusion (TO) in VEGF in fetal lung rats after nitrofen and in control rats not exposed to nitrofen. Methods. Pregnant rats received nitrofen on day 9.5 of gestation. Fetuses were divided into 2 groups: those that underwent TO on day 20 and those that did not. On day 21, fetuses were delivered, and the lungs were dissected for subsequent VEGF quantification. Results. CDH was detected in 43% of the fetuses that received nitrofen. Fetuses with CDH showed significantly reduced lung weight/fetal weight ratio and lower VEGF levels than the remainder. A higher VEGF value was observed after TO. Conclusions. VEGF protein was significantly lower in fetuses with CDH. TO induced a significant increase in VEGF compared to the fetuses that did not undergo TO. Although not statistically significant, we observed higher VEGF levels in fetuses with CDH and TO compared to fetuses with CDH and no further intervention.

Congenital diaphragmatic hernia

The incidence of congenital diaphragmatic hernia (CDH) may be as high as 1 in 2000. Over the past two decades, antenatal diagnosis rates have increased, the pathophysiology of CDH has become better understood, and advances in clinical care, including foetal surgery, have occurred. However, there remains a paucity of randomised controlled trials to provide evidence-based management guidelines. Reports of improved survival rates appear to be confined to a select subset of CDH infants, surviving to surgical repair, while the overall mortality, at over 60%, appears to be unchanged, largely due to the often forgotten 'hidden mortality' of CDH. The significant long-term morbidity in surviving infants has become apparent, and the need for long-term multidisciplinary follow up established. A total of 10% of cases may present later in life, and misdiagnosis on initial chest X-ray may lead to significant morbidity.

Associated malformations in Morgagni hernia

Morgagni hernia (MH) is a congenital herniation of the abdominal organs through the subcostosternal portion of the diaphragm. It is a rare type of diaphragmatic hernia that has been associated with other congenital anomalies. The purpose of this clinical review was to determine the incidence of associated anomalies in patients with MH at a major pediatric referral center. The medical records of all patients with the diagnosis of MH were reviewed retrospectively between 1983 and 2006. The age, sex, side of herniation, presenting symptoms and signs, associated anomalies, radiologic features, intraoperative findings, postoperative course, complications, and mortality were recorded. There were 11 males and 5 females. The average age of the patients was 34.5 months (range 2 months-14 years). Twelve patients (75%) had at least one associated congenital malformation and eight (66.6%) of them had multiple anomalies. Six (37.5%) patients had a chromosomal anomaly, Down's syndrome in five and Turner syndrome in one. MH has a high incidence of associated congenital malformations.

Single gene disorders associated with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high pre- and postnatal mortality. Although the majority of diaphragmatic hernias occur as isolated malformations, additional major and minor anomalies are common and are present in more than 40% of patients. There are compelling data for the importance of genetic factors in the etiology of CDH, but the pathogenesis and the causative genes for CDH in humans remain elusive. There are more than 70 syndromes in which diaphragmatic hernias have been described, and several of these syndromes are single gene disorders for which the gene is known. One method for identifying the causative genes in isolated CDH is to study syndromes with known genes in which CDH is a recognized feature, with the rationale that those genes have a role in diaphragm development. This review discusses the syndromes that are most commonly associated with CDH, with greater attention towards syndromes in which the causative genes have been identified, including Simpson-Golabi-Behmel syndrome, Denys-Drash syndrome, spondylocostal dysostosis, craniofrontonasal syndrome, Cornelia de Lange syndrome and Marfan syndrome.

Candidate genes for congenital diaphragmatic hernia from animal models: sequencing of FOG2 and PDGFRα reveals rare variants in diaphragmatic hernia patients

Congenital diaphragmatic hernia (CDH) is a common, life threatening birth defect. Although there is strong evidence implicating genetic factors in its pathogenesis, few causative genes have been identified, and in isolated CDH, only one de novo, nonsense mutation has been reported in FOG2 in a female with posterior diaphragmatic eventration. We report here that the homozygous null mouse for the Pdgfralpha gene has posterolateral diaphragmatic defects and thus is a model for human CDH. We hypothesized that mutations in this gene could cause human CDH. We sequenced PDGFRalpha and FOG2 in 96 patients with CDH, of which 53 had isolated CDH (55.2%), 36 had CDH and additional anomalies (37.5%), and 7 had CDH and known chromosome aberrations (7.3%). For FOG2, we identified novel sequence alterations predicting p.M703L and p.T843A in two patients with isolated CDH that were absent in 526 and 564 control chromosomes respectively. These altered amino acids were highly conserved. However, due to the lack of available parental DNA samples we were not able to determine if the sequence alterations were de novo. For PDGFRalpha, we found a single variant predicting p.L967V in a patient with CDH and multiple anomalies that was absent in 768 control chromosomes. This patient also had one cell with trisomy 15 on skin fibroblast culture, a finding of uncertain significance. Although our study identified sequence variants in FOG2 and PDGFRalpha, we have not definitively established the variants as mutations and we found no evidence that CDH commonly results from mutations in these genes.

Stephen L. Gans Distinguished Overseas Lecture. The neural crest in pediatric surgery

AIM

This review highlights the relevance of the neural crest (NC) as a developmental control mechanism involved in several pediatric surgical conditions and the investigative interest of following some of its known signaling pathways.

METHODS

The participation of the NC in facial clefts, ear defects, branchial fistulae and cysts, heart outflow tract and aortic arch anomalies, pigmentary disorders, abnormal enteric innervation, neural tumors, hemangiomas, and vascular anomalies is briefly reviewed. Then, the literature on clinical and experimental esophageal atresia-tracheoesophageal fistula (EA-TEF) and congenital diaphragmatic hernia (CDH) is reviewed for the presence of associated NC defects. Finally, some of the molecular signaling pathways involved in both conditions (sonic hedgehog, Hox genes, and retinoids) are summarized.

RESULTS

The association of facial, cardiovascular, thymic, parathyroid, and C-cell defects together with anomalies of extrinsic and intrinsic esophageal innervation in babies and/or animals with both EA-TEF and CDH strongly supports the hypothesis that NC is involved in the pathogenesis of these malformative clusters. On the other hand, both EA-TEF and CDH are observed in mice mutant for genes involved in the previously mentioned signaling pathways.

CONCLUSIONS

The investigation of NC-related molecular pathogenic pathways involved in malformative associations like EA-TEF and CDH that are induced by chromosomal anomalies, chemical teratogens, and engineered mutations is a promising way of clarifying why and how some pediatric surgical conditions occur. Pediatric surgeons should be actively involved in these investigations.

Diaphragm development and congenital diaphragmatic hernia

Advances in the understanding of normal diaphragm embryogenesis have provided the necessary foundation for novel insights into the pathogenesis of congenital diaphragmatic hernia (CDH). Although diaphragm formation is still not completely understood, we have identified key structures and periods of development that are clearly abnormal in animal models of CDH. The pleuroperitoneal fold (PPF) is a transient structure which is the target for the neuromuscular component of the diaphragm. The PPF has been shown to be abnormal in multiple animal models of Bochdalek CDH; specifically, a malformation of the nonmuscular component of this tissue is thought to underlie the later defect in the complete diaphragm. Based on data from animal models and the examination of human postmortem tissue, we hypothesize that abnormal PPF development underlies Bochdalek CDH. Further, the understanding of the pathogenesis of rarer subtypes of CDH will be advanced by the study of various new animal models discussed in this review.

Molecular genetics of congenital diaphragmatic defects

Congenital diaphragmatic hernia (CDH) is a severe birth defect that is accompanied by malformations of the lung, heart, testis, and other organs. Patients with CDH may have any combination of these extradiaphragmatic defects, suggesting that CDH is often a manifestation of a global embryopathy. This review highlights recent advances in human and mouse genetics that have led to the identification of genes involved in CDH. These include genes for transcription factors, molecules involved in cell migration, and extracellular matrix components. The expression patterns of these genes in the developing embryo suggest that mesenchymal cell function is compromised in the diaphragm and other affected organs in patients with CDH. We discuss potential mechanisms underlying the seemingly random combination of diaphragmatic, pulmonary, cardiovascular, and gonadal defects in these patients.

Gata4 is necessary for normal pulmonary lobar development

Mutations of Fog2 in mice result in a phenotype that includes pulmonary lobar defects. To determine whether formation of the accessory lobe bronchus is mediated by a Gata family cofactor, we evaluated embryonic lungs from mice carrying missense mutations that cause loss of FOG-GATA protein interaction. Lungs from embryos carrying a missense mutation in Gata6 were structurally normal, while lungs from embryos carrying mutations of either Gata4 or of both Gata4 and Gata6 had a structural phenotype that matched the Fog2 mutant phenotype. Expression analysis showed that Gata4 and Fog2 are expressed in the ventral and medial pulmonary mesenchyme during secondary budding. Although Gata4 has not previously been suspected as playing a role in lung development, we have found that a Fog2-Gata4 interaction is critical for the development of normal pulmonary lobar structure, and this phenotype is not influenced by the additional loss of Gata6 interaction. Fog2 and Gata4 in the early pulmonary mesenchyme participate in patterning the secondary bronchus of the accessory lobe.

Prenatal intervention for isolated congenital diaphragmatic hernia

PURPOSE OF REVIEW

We aim to review the recent literature regarding early prenatal prediction of outcome in babies diagnosed with isolated congenital diaphragmatic hernia, as well as results of fetal therapy for this condition.

RECENT FINDINGS

Current survival rates in population-based studies are around 55-70%. Highly specialized centers report 80% and more, but discount the hidden mortality, mainly in the antenatal period. Fetuses presenting with liver herniation and a lung-to-head ratio of less than 1.0 measured in midgestation have a poor prognosis. Other volumetric techniques are being evaluated for use in midtrimester. Recently, a randomized trial failed to show benefit from prenatal therapy, but lacked power to document the potential advantage of prenatal therapy in severe cases. We proposed percutaneous fetal endoluminal tracheal occlusion with a balloon at 26-28 weeks through a 3.3 mm incision. In severe cases, fetal endoluminal tracheal occlusion increased lung size as well as survival, with an early (7 day) survival, late neonatal (28 day) survival and survival at discharge of 75, 58 and 50%, respectively, comparing favorably with 9% in contemporary controls. Airways can be restored prior to birth improving neonatal survival (83.3% compared with 33.3%). The procedure carries a risk for preterm prelabour rupture of the fetal membranes, although that may decrease with experience.

SUMMARY

Fetuses with severe congenital diaphragmatic hernia can be identified in the second trimester. Fetal endoluminal tracheal occlusion can be considered as a minimally invasive fetal therapy, improving outcome in such highly selected cases.

Array comparative genomic hybridization in patients with congenital diaphragmatic hernia: mapping of four CDH-critical regions and sequencing of candidate genes at 15q26.1–15q26.2

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high mortality and morbidity. There have been few studies that have assessed copy number changes in CDH. We present array comparative genomic hybridization data for 29 CDH patients to identify and map chromosome aberrations in this disease. Three patients with 15q26.1-15q26.2 deletions had heterogeneous breakpoints that overlapped with the critical 4 Mb region previously delineated for CDH, confirming 15q26.1-15q26.2 as a critical region for CDH. The three other most compelling CDH-critical regions for genomic deletions based on these data and a literature review are located at chromosomes 8p23.1, 4p16.3-4pter, and 1q41-1q42.1. Based on these recurrent deletions at 15q26.1-15q26.2, we hypothesized that loss-of-function mutations in a gene or genes from this region could cause CDH and sequenced six candidate genes from this region in more than 100 patients with CDH. For three of these genes (CHD2, ARRDC4, and RGMA), we identified missense changes and that were not identified in normal controls; however, none of these alterations appeared unambiguously causal with CDH. These data suggest that CDH caused by chromosome deletions at 15q26.2 may arise because of a contiguous gene deletion syndrome or may have a multifactorial etiology. In addition, there is evidence for substantial genetic heterogeneity in CDH and diaphragmatic hernias can be non-penetrant in patients who have deletions involving CDH-critical regions.

Expanding the phenotype of craniofrontonasal syndrome: two unrelated boys with EFNB1 mutations and congenital diaphragmatic hernia

Craniofrontonasal syndrome (CFNS, MIM 304110) is an X-linked craniofacial disorder that shows paradoxically greater severity in heterozygous females than in hemizygous males. Mutations have been identified in the EFNB1 gene that encodes a member of the ephrin-B family of transmembrane ligands for Eph receptor tyrosine kinases. Here, we describe two unrelated families, in both of which a mother and her son have proven mutations in EFNB1. The mothers have classical features of CFNS; although the sons have no major craniofacial features other than telecanthus, both had a congenital diaphragmatic hernia (CDH). Our cases represent the first in which CDH has been confirmed in males with mutations in EFNB1, highlighting an important role for signalling by ephrin-B1 in the development of the diaphragm.

Findings from aCGH in patients with congenital diaphragmatic hernia (CDH): a possible locus for Fryns syndrome

Congenital diaphragmatic hernia (CDH) is a common and often devastating birth defect that can occur in isolation or as part of a malformation complex. Considerable progress is being made in the identification of genetic causes of CDH. We applied array-based comparative genomic hybridization (aCGH) of approximately 1Mb resolution to 29 CDH patients with prior normal karyotypes who had been recruited into our multi-site study. One patient, clinically diagnosed with Fryns syndrome, demonstrated a de novo 5Mb deletion at chromosome region 1q41-q42.12 that was confirmed by FISH. Given prior reports of CDH in association with cytogenetic abnormalities in this region, we propose that this represents a locus for Fryns syndrome, a Fryns syndrome phenocopy, or CDH.