No evidence of WT1 gene mutations in children with congenital diaphragmatic hernia

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.

Exome sequencing identifies ZFPM2 as a cause of familial isolated congenital diaphragmatic hernia and possibly cardiovascular malformations

Using exome sequencing we identify a heterozygous nonsense mutation in ZFPM2 as a cause of familial isolated congenital diaphragmatic hernia in 2 affected siblings. This mutation displays variable phenotypic expression being present in a third sibling with a mild diaphragmatic eventration and a cardiovascular malformation. The same variant is seen in 2 additional family members, both of whom are asymptomatic, thus highlighting that ZFPM2 haploinsufficiency is associated with reduced penetrance. Our finding adds further evidence for ZFPM2 having a role in diaphragm and cardiovascular development.

Current concepts on the pathogenesis and etiology of congenital diaphragmatic hernia

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

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.

Denys-Drash syndrome and congenital diaphragmatic hernia: another case with the 1097G > A(Arg366His) mutation

Congenital diaphragmatic hernia (CDH) is a disorder of the development of the lung and diaphragm and is associated with pulmonary hypoplasia and pulmonary hypertension. Denys-Drash syndrome (DDS) is a well-known syndrome caused by several different germline mutations in the WT1-gene. CDH in DDS is rare. We present the third case of CDH with clinical features of DDS and the same, rare Arg366His mutation in the WT1-gene, as reported in the other two known cases. This report provides additional evidence that WT1 mutations can result in diaphragmatic hernia.

WT1 mutations in Meacham syndrome suggest a coelomic mesothelial origin of the cardiac and diaphragmatic malformations

Meacham syndrome is a rare sporadically occurring multiple malformation syndrome characterized by male pseudohermaphroditism with abnormal internal female genitalia comprising a uterus and double or septate vagina, complex congenital heart defect and diaphragmatic abnormalities. We report on eight new cases of this condition, two of whom were shown to have heterozygous missense mutations in the C-terminal zinc finger domains of WT1: Arg366Cys and Arg394Trp. These data represent clinical and molecular evidence that the WT1 gene plays a central role in normal development of the diaphragm and the proepicardially derived tissues. Identification of WT1 expression in the region of coelomic mesothelium which will form the proepicardium and diaphragm provides a plausible unifying patterning defect in these cases. Interestingly, the Arg366Cys mutation has been previously reported in Denys-Drash syndrome and Arg394Trp mutation has been previously reported in both isolated Wilms tumor and Denys-Drash syndrome. This phenotypic diversity with a single mutation suggests there are other factors modulating all aspects of WT1 function during human development. If genetic modifiers of WT1 can be identified in animal models these become good candidate genes for the cases with Meacham syndrome we report on here where WT1 mutations cannot be identified.

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.

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.

Hydrothorax in a patient with Denys-Drash syndrome associated with a diaphragmatic defect

The Wilms tumor suppressor gene, WT1, plays an important role in the development of the urogenital system and the gonads, and clinical syndromes associated with WT1 mutations, such as WAGR syndrome, Denys-Drash syndrome and Frasier syndrome, typically manifest as renal and genitourinary abnormalities. WT1 may also play an important role in the development of the diaphragm, and recently several papers have reported an association between WT1 mutations and diaphragmatic hernias. In addition, WT1 mutations were also detected in some patients with Meacham syndrome, a rare malformation syndrome comprising congenital diaphragmatic hernia, double vagina, sex reversal, and cardiac malformations. Here, we report a case of an infant with typical clinical features of Deny-Drash syndrome and a heterozygous missense mutation, Arg366His, in the WT1 gene, in whom a diaphragm defect was detected after starting peritoneal dialysis. Diaphragmatic defects are rare but may be considered as clinical manifestations of WT1 mutation syndromes. In addition, we suggest that WT1 abnormalities should be suspected in patients with chronic renal failure who develop hydrothorax after peritoneal dialysis, especially in those with genitourinary abnormalities.

Asociación entre síndrome de WAGR y hernia diafragmática

Anomalies in WT-1 (Wilms' tumor gene), mapped to 11p13, cause Denys-Drash, Frasier and WAGR syndromes. WAGR syndrome is characterized by Wilms' tumor (W), aniridia (A), genitourinary anomalies (G) and mental retardation (R). In the early human fetus, WT-1 is expressed in the pleural and abdominal mesothelium, and consequently this gene may play a role in diaphragm development. The first report of an association between WAGR syndrome and congenital diaphragmatic hernia has recently been published. We present another infant with aniridia, left cryptorchidism with testicular dysgenesis, right-sided posterolateral diaphragmatic hernia and moderate psychomotor retardation, in whom genetic study showed a deletion of 11p13 and PAX-6, confirming the diagnosis of WAGR syndrome.

Congenital diaphragmatic hernia in WAGR syndrome

Wilms tumor, aniridia, genitourinary anomalies, and mental retardation (WAGR) syndrome is a contiguous gene deletion syndrome involving the Wilms tumor 1 gene (WT1), the paired box gene 6 (PAX6), and possibly other genes on chromosome 11p13. WT1 is required for normal formation of the genitourinary system and the high incidence of Wilms tumor and genitourinary anomalies found in patients with WAGR are attributed to haploinsufficiency of this gene. It has been hypothesized that WT1 also plays an important role in the development of the diaphragm. During mammalian embryonic development, WT1 is expressed in the pleural and abdominal mesothelium that forms part of the diaphragm. Furthermore, mice that are homozygous for a deletion in the mouse homolog of WT1 have diaphragmatic hernias. Case reports describing congenital diaphragmatic hernias in infants with Denys-Drash and Frasier syndromes, both of which can be caused by mutations in WT1, provide additional support for this hypothesis. We report an infant with aniridia, bilateral cryptorchidism, vesicoureteral reflux, and a right-sided Morgagni-type diaphragmatic hernia. G-banded chromosome analysis revealed a deletion of 11p12-p15.1. Breakpoint regions were refined by fluorescence in situ hybridization (FISH) and deletion of the WAGR critical region, including WT1, was confirmed. A review of the medical literature identified a second patient with a deletion of 11p13, a left-sided Bochdalek-type diaphragmatic hernia, and anomalies that suggest a diagnosis of WAGR including bilateral microphthalmia, a small penis, bilateral cryptorchidism, and a hypoplastic scrotum. These cases demonstrate that congenital diaphragmatic hernia can be associated with WAGR syndrome and suggest that deletions of WT1 may predispose individuals to develop congenital diaphragmatic hernia.

The genetics of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high mortality and morbidity. A clear understanding of the pathogenesis of CDH is critical for determining prognosis and planning treatment, but to date, information on the genetic etiology of both nonsyndromic and syndromic CDH is limited. This paper summarizes the current knowledge concerning the genes, syndromes, and chromosome aberrations associated with CDH in humans and in animal model systems. Mutations in several different genes have been described in syndromic CDH, but there is only one mutation that has been reported in non-syndromic CDH to date. However, animal models suggest that genes involved in cell migration, myogenesis, and connective tissue formation are critical to normal diaphragm formation, and these data provide a starting point for the search for other genes involved in the pathogenesis of CDH.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a lethal human birth defect. Hypoplastic lung development is the leading contributor to its 30-50% mortality rate. Efforts to improve survival have focused on fetal surgery, advances in intensive care and elective delivery at specialist centres following in utero diagnosis. The impact of abnormal lung development on affected infants has stimulated research into the developmental biology of CDH. Traditionally lung hypoplasia has been viewed as a secondary consequence of in utero compression of the fetal lung. Experimental evidence is emerging for a primary defect in lung development in CDH. Culture systems are providing research tools for the study of lung hypoplasia and the investigation of the role of growth factors and signalling pathways. Similarities between the lungs of premature newborns and infants with CDH may indicate a role for antenatal corticosteroids. Further advances in postnatal therapy including permissive hypercapnia and liquid ventilation hold promise. Improvements in our basic scientific understanding of lung development may hold the key to future developments in CDH care.