Clinical and molecular characterization of the bladder exstrophy-epispadias complex: analysis of 232 families

Epidemiological survey of 214 families with bladder exstrophy-epispadias complex

PURPOSE

We sought to identify causative nongenetic and genetic risk factors for the bladder exstrophy-epispadias complex.

MATERIALS AND METHODS

A total of 237 families with the bladder exstrophy-epispadias complex were invited to participate in the study, and information was obtained from 214 families, mainly from European countries.

RESULTS

Two families showed familial occurrence. Male predominance was found among all subgroups comprising epispadias, classic bladder exstrophy and cloacal exstrophy, with male-to-female ratios of 1.4:1, 2.8:1 and 2.0:1, respectively (p = 0.001). No association with parental age, maternal reproductive history or periconceptional maternal exposure to alcohol, drugs, chemical noxae, radiation or infections was found. However, periconceptional maternal exposure to smoking was significantly more common in patients with cloacal exstrophy than in the combined group of patients with epispadias/classic bladder exstrophy (p = 0.009). Only 16.8% of mothers followed the current recommendations of periconceptional folic acid supplementation, and 17.6% had started supplementation before 10 weeks of gestation. Interestingly, in the latter group mothers of patients with cloacal exstrophy were more compliant with folic acid supplementation than were mothers of the combined group of patients with epispadias/classic bladder exstrophy (p = 0.037). Furthermore, mothers of children with cloacal exstrophy knew significantly more often prenatally that their child would have a congenital malformation than did mothers of children with epispadias/classic bladder exstrophy (p <0.0001).

CONCLUSIONS

Our study corroborates the hypothesis that epispadias, classic bladder exstrophy and cloacal exstrophy are causally related, representing a spectrum of the same developmental defect, with a small risk of recurrence within families. Embryonic exposure to maternal smoking appears to enforce the severity, whereas periconceptional folic acid supplementation does not seem to alleviate it. There is a disproportional prenatal ultrasound detection rate between severe and mild phenotypes, possibly due to the neglect of imaging of full bladders with a focus on neural tube defects.

Microarray analysis of exstrophic human bladder smooth muscle

OBJECTIVE

To compare the genetic profiles of 'healthy' bladder smooth muscle cells (SMCs) and exstrophic SMCs (ESMCs) to identify genes that are over- and under-expressed in ESMCs, thus providing a molecular evaluation of the quality and therapeutic potential of ESMC tissue.

PATIENTS, MATERIAL AND METHODS

Classical bladder exstrophy is a rare disorder, occurring in 1 in 30,000 live births. Studies have shown that exstrophic bladders are developmentally immature at birth. After surgical closure, the bladder typically undergoes abnormal remodelling (such as over-expression of collagen III) throughout early development. We hypothesized that the predominant genetic differences between normal SMCs and ESMCs are in the developmental genes. This hypothesis was tested by the use of microarray analysis. Bladder SM biopsies were taken from 'healthy' subjects undergoing bladder surgeries for other conditions (for example, urinary reflux) and patients with bladder exstrophy. Cells were expanded in vitro, and total RNA was isolated and hybridized to the Affymetrix U133A GeneChip (Affymetrix Inc., Santa Clara, CA, USA) by the Wake Forest University School of Medicine Affymetrix core facility, using standard protocols.

RESULTS

We created a genetic signature consisting of 961 genes that are over-expressed and 432 genes that are under-expressed in ESMCs. Analysis of these signatures identified an over-expression of inflammatory genes and an under-expression of developmental genes.

CONCLUSION

Our data is in concordance with previous studies and histological data showing that ESMCs are developmentally immature relative to healthy bladder SM. The clinical implication of the ESMC genetic signature is that it provides a list of targets that can be (i) manipulated ex vivo and/or in vivo to induce differentiation (the completion of development) and (ii) used as biomarkers to explain the variability of the clinical symptoms after surgical closure.

Genome-wide analysis for micro-aberrations in familial exstrophy of the bladder using array-based comparative genomic hybridization

OBJECTIVE

Exstrophy of the bladder (EB) is part of the bladder-exstrophy-epispadias complex (BEEC). Because familial occurrence of BEEC is rare, exogenous factors are thought to play a major role in the etiology of most BEEC cases. We aimed to investigate a possible genetic basis of BEEC in a consanguineous kindred of Moroccan origin with three members showing the same phenotypic expression of BEEC.

PATIENTS AND METHODS

The three affected males (two cousins and their maternal uncle) all presenting with nonsyndromic classic EB, were born in Morocco or The Netherlands. One Moroccan patient had an open bladder surface for 22 years due to late surgical reconstruction, avoided upright posture and developed severe lumbar scoliosis. Because three maternally related males from a consanguineous family living in different environments are affected, a genetic basis for EB is likely in this family. To screen for chromosomal aberrations and micro-aberrations in the two patients who were still alive, conventional karyotyping and array-based comparative genomic hybridization (array-CGH) were used on DNA-microarrays with a genome-wide average resolution of <0.5 Mb.

RESULTS

Chromosome banding revealed normal karyotypes. By array-CGH, one of 8000 clones was aberrant in both affected cousins. This clone from 1p21.1 contained the AMY1B, AMY2B, AMY2A genes coding for salivary and pancreatic amylases.

CONCLUSION

The aberration detected by array-CGH in both affected cousins is a known copy-number variant and most likely unrelated to the EB-phenotype. Nevertheless, in this family the nonsyndromic EB could be a monogenic disorder inherited in an autosomal-recessive or X-linked fashion.

DeltaNp63 plays an anti-apoptotic role in ventral bladder development

The bladder, the largest smooth-muscle organ in the human body, is responsible for urine storage and micturition. P63, a homolog of the p53 tumor-suppressor gene, is essential for the development of all stratified epithelia, including the bladder urothelium. The N-terminal truncated isoform of p63, DeltaNp63, is known to have anti-apoptotic characteristics. We have established that DeltaNp63 is not only the predominant isoform expressed throughout the bladder, but is also preferentially expressed in the ventral bladder urothelium during early development. We observed a host of ventral defects in p63-/- embryos, including the absence of the abdominal and ventral bladder walls. This number of ventral defects is identical to bladder exstrophy, a congenital anomaly exhibited in human neonates. In the absence of p63, the ventral urothelium was neither committed nor differentiated, whereas the dorsal urothelium was both committed and differentiated. Furthermore, in p63-/- bladders, apoptosis in the ventral urothelium was significantly increased. This was accompanied by the upregulation of mitochondrial apoptotic mediators Bax and Apaf1, and concurrent upregulation of p53. Overexpression of DeltaNp63gamma and DeltaNp63beta in p63-/- bladder primary cell cultures resulted in a rescue, evidenced by significantly reduced expressions of Bax and Apaf1. We conclude that DeltaNp63 plays a crucial anti-apoptotic role in normal bladder development.

Bladder exstrophy and epispadias complex in sibling: case report and review of literature

The bladder exstrophy and classic epispadias represent a spectrum of congenital anomalies with different degrees of anterior midline defect. Although the anomaly usually occurs sporadically there are some cases indicative of a strong genetic component. We present the clinical data of two siblings with bladder exstrophy and epispadias complex (BEEC), who were the product of consanguineous union. All previous reports of familial BEEC in the literature have been reviewed.

Recent advances in external genitalia

In the last decade, significant progress in the knowledge and management of external genital anomalies has been achieved, including an improved understanding of epidemiology and pathophysiology of these anomalies, the identification of etiologic genetic defects, and significant improvements in surgical approaches that have decreased complications and improved cosmetic outcomes. We highlight the most clinically important advances of the commonly encountered external genital anomalies.

A reciprocal translocation 46,XY,t(8;9)(p11.2;q13) in a bladder exstrophy patient disrupts CNTNAP3 and presents evidence of a pericentromeric duplication on chromosome 9

A patient with sporadic bladder exstrophy and de novo apparently balanced chromosomal translocation 46,XY,t(8;9)(p11.2;q13) was analyzed by fluorescence in situ hybridization (FISH) and molecular methods. We were able to map both translocation breakpoints to single genomic clones. The chromosome 8p11.2 breakpoint was mapped to BAC clone RP4-547J18, predicted to contain several hypothetical genes. Characterization of the chromosome 9q13 breakpoint indicated a disruption in the 5' region of CNTNAP3 within BAC RP11-292B8. This observation suggests possible involvement of CNTNAP3 in the etiology of bladder exstrophy. Additionally, FISH analysis identified several genomic copies of CNTNAP3 on both sides of the chromosome 9 centromere flanking the polymorphic heterochromatin. Northern blot analysis of lymphoblast and bladder RNA confirmed CNTNAP3 transcripts in these tissues and did not show abnormal CNTNAP3 expression in the proband and two unrelated patients with bladder exstrophy. The identification of multiple copies of three BAC clones in the proband, his parents, and unrelated controls suggests that duplications of CNTNAP3 and the surrounding genomic region have occurred as a result of repeated events of unequal crossing over and pericentric inversions during chromosome 9 evolution.

The morphogenesis of the exstrophy-epispadias complex: a new concept based on observations made in early embryonic cases of cloacal exstrophy

BACKGROUND

The term exstrophy-epispadias complex (EEC) has been coined for a group of congenital malformations that includes epispadias, bladder exstrophy and cloacal exstrophy. It is usually thought that these malformations develop against a similar embryological background. This background, however, is still obscure. This is mainly due to the lack of availability of abnormal human or non-human embryos showing the crucial developmental steps in the morphogenesis of EEC malformations. In this paper, we present chick embryos that show cloacal exstrophy at early developmental stages. To the best of our knowledge, this is the first documentation of this rare malformation in young embryos.

MATERIALS AND METHODS

Embryos with cloacal exstrophy (n=4) were found among embryos from two experimental series (n=50) that were primarily performed to document the early morphogenesis of facial and cardiovascular malformations. The malformations were induced by the administration of suramin according to established protocols. Suramin can induce a spectrum of malformations including facial clefts, heart defects, and cloacal exstrophy.

RESULTS AND CONCLUSIONS

Besides the presence of an abnormal opening into the cloaca, all embryos were characterised by an abnormal broadening of the caudal trunk at the level of the leg buds, which, in the youngest embryos, was associated with the abnormal presence of large aneurysmatic swellings of the dorsal aortae at this side. We postulate that these aneurysmatic swellings might be the primary defects leading to the development of EEC malformations. These space-occupying anomalies seem to cause abnormal distensions of the developing pelvis and of the infra-umbilical portion of the developing body wall. In consequence, the mid-portion of the developing ventral body wall between the origin of the umbilical cord and the cloacal plate becomes stretched and thinned out. Tension and thinning of the ventral body wall might ultimately lead to its rupture with exposure of the lumen of the embryonic cloaca and allantois. This new concept on the morphogenesis of the EEC is the first not to be inferred from the conditions seen in fetal or postnatal human cases but is based entirely on data from malformed embryos.