The inheritance of the exstrophy-epispadias complex

Genetic analysis of two bladder exstrophy populations of South Asian and North American origin

INTRODUCTION

Bladder exstrophy-epispadias complex (BEEC) is a devastating congenital anomaly of the urinary tract and is associated with an increased risk of bladder cancer. The etiology of the BEEC is unknown, but a clear genetic component has been highlighted. Currently, all genetic studies suffer from small populations, limited to a European background.

OBJECTIVES

To identify copy number variations (CNVs) in a South Asian and North American bladder exstrophy cohorts. To identify novel non-European CNVs to expand the literature beyond its European ethnic background.

STUDY DESIGN

Patients from our South Asian and North American cohorts had DNA isolated from peripheral blood samples and biobanked at the Children Hospital of Philadelphia's (CHOP) Center for Applied Genomics (CAG). DNA Genotyping was performed with various arrays for the North American cohort and the Illumina Global Screening Array for the South Asian cohort. Controls for both cohorts were identified from CHOP's CAG and ethnicity matching by principle component analysis was performed. CNV calling and filtering were performed with PennCNV and ParseCNV, respectively.

RESULTS

The North American and South Asian cohorts included 53 and 97 patients, respectively. Fifty-five statistically significant CNVs were identified across three independent analyses, of which 53 (96.4 %) were novel to the BE literature. Thirteen of our CNVs were near (within 100 million base pairs) but not in linkage disequilibrium with 8 previously identified BEEC genome-wide association study (GWAS) loci. One of our CNVs (chr16: 28,635,133-28,636,902) was near a previously reported CNV of clinical significance (chr16:29,645,396-30,168,276). Seventeen CNVs contained 15 distinct genes associated with cancer, of which 10/15 (66.7 %) have reported associations in bladder cancer.

DISCUSSION

We present the first genetic analysis of a non-European cohort of bladder exstrophy patients. Our study identified a high number of novel CNVs containing cancer predisposition genes mostly distinct from those found in European cohorts. Limitations inherent to BEEC research include small sample sizes which required intermixing of all phenotypes of the BEEC spectrum (epispadias to cloacal exstrophy). These data highlight the importance of multi-institutional and international collaboration to create ethnically diverse cohorts and allow for severity-specific genetic analyses of the different phenotypes within the BEEC.

CONCLUSION

We identified novel CNVs with distinct cancer predisposition genes in the first study to expand the BEEC literature beyond its European ethnic background. Additional studies in other non-European cohorts are needed to expand our understanding of the genetic landscape of BEEC.

Exome Survey and Candidate Gene Re-Sequencing Identifies Novel Exstrophy Candidate Genes and Implicates LZTR1 in Disease Formation

BACKGROUND

The bladder exstrophy-epispadias complex (BEEC) is a spectrum of congenital abnormalities that involves the abdominal wall, the bony pelvis, the urinary tract, the external genitalia, and, in severe cases, the gastrointestinal tract as well.

METHODS

Herein, we performed an exome analysis of case-parent trios with cloacal exstrophy (CE), the most severe form of the BEEC. Furthermore, we surveyed the exome of a sib-pair presenting with classic bladder exstrophy (CBE) and epispadias (E) only. Moreover, we performed large-scale re-sequencing of CBE individuals for novel candidate genes that were derived from the current exome analysis, as well as for previously reported candidate genes within the CBE phenocritical region, 22q11.2.

RESULTS

The exome survey in the CE case-parent trios identified two candidate genes harboring de novo variants (NR1H2, GKAP1), four candidate genes with autosomal-recessive biallelic variants (AKR1B10, CLSTN3, NDST4, PLEKHB1) and one candidate gene with suggestive uniparental disomy (SVEP1). However, re-sequencing did not identify any additional variant carriers in these candidate genes. Analysis of the affected sib-pair revealed no candidate gene. Re-sequencing of the genes within the 22q11.2 CBE phenocritical region identified two highly conserved frameshift variants that led to early termination in two independent CBE males, in LZTR1 (c.978_985del, p.Ser327fster6) and in SLC7A4 (c.1087delC, p.Arg363fster68).

CONCLUSIONS

According to previous studies, our study further implicates LZTR1 in CBE formation. Exome analysis-derived candidate genes from CE individuals may not represent a frequent indicator for other BEEC phenotypes and warrant molecular analysis before their involvement in disease formation can be assumed.

Copy number variants suggest different molecular pathways for the pathogenesis of bladder exstrophy

Bladder exstrophy is a rare congenital malformation leaving the urinary bladder open in the midline of the abdomen at birth. There is a clear genetic background with chromosome aberrations, but so far, no consistent findings apart from 22q11-duplications detected in about 2%-3% of all patients. Some genes are implicated like the LZTR1, ISL1, CELSR3, and the WNT3 genes, but most are not explained molecularly. We have performed chromosomal microarray analysis on a cohort of 140 persons born with bladder exstrophy to look for submicroscopic chromosomal deletions and duplications. Pathogenic or possibly pathogenic microdeletions or duplications were found in 16 patients (11.4%) and further 9 with unknown significance. Two findings were in regions linked to known syndromes, two findings involved the same gene (MCC), and all other findings were unique. A closer analysis suggests a few gene networks that are involved in the pathogenesis of bladder exstrophy; the WNT-signaling pathway, the chromosome 22q11 region, the RIT2 and POU families, and involvement of the Golgi apparatus. Bladder exstrophy is a rare malformation and is reported to be associated with several chromosome aberrations. Our data suggest involvement of some specific molecular pathways.

Genetic Counseling for Bladder Exstrophy-Epispadias Complex

Bladder exstrophy-epispadias complex (BEEC) represents the severe end of the uro-rectal malformation spectrum and has profound impact on continence, sexual, and renal function. Treatment of BEEC is primarily surgical, and the main goals are safe closure of the abdominal wall, urinary continence while preserving renal function, and adequate cosmetic and functional genital reconstruction. Psychosocial and psychosexual outcomes and adequate health-related quality of life depend on long-term multidisciplinary care. The overall outcome is now considered very positive and affected individuals usually lead self-determined and independent lives with the desire to start their own families later in life. Certainty about the risk of recurrence and the provision of information about the current state of knowledge about the identified genetic causes with high penetrance will have an impact on family planning for healthy parents with an affected child and for affected individuals themselves. This review addresses this information and presents the current state of knowledge.

Exome sequencing of child-parent trios with bladder exstrophy: Findings in 26 children

Bladder exstrophy (BE) is a rare, lower ventral midline defect with the bladder and part of the urethra exposed. The etiology of BE is unknown but thought to be influenced by genetic variation with more recent studies suggesting a role for rare variants. As such, we conducted paired-end exome sequencing in 26 child/mother/father trios. Three children had rare (allele frequency ≤ 0.0001 in several public databases) inherited variants in TSPAN4, one with a loss-of-function variant and two with missense variants. Two children had loss-of-function variants in TUBE1. Four children had rare missense or nonsense variants (one per child) in WNT3, CRKL, MYH9, or LZTR1, genes previously associated with BE. We detected 17 de novo missense variants in 13 children and three de novo loss-of-function variants (AKR1C2, PRRX1, PPM1D) in three children (one per child). We also detected rare compound heterozygous loss-of-function variants in PLCH2 and CLEC4M and rare inherited missense or loss-of-function variants in additional genes applying autosomal recessive (three genes) and X-linked recessive inheritance models (13 genes). Variants in two genes identified may implicate disruption in cell migration (TUBE1) and adhesion (TSPAN4) processes, mechanisms proposed for BE, and provide additional evidence for rare variants in the development of this defect.

The Genomic Architecture of Bladder Exstrophy Epispadias Complex

The bladder exstrophy-epispadias complex (BEEC) is an abdominal midline malformation comprising a spectrum of congenital genitourinary abnormalities of the abdominal wall, pelvis, urinary tract, genitalia, anus, and spine. The vast majority of BEEC cases are classified as non-syndromic and the etiology of this malformation is still unknown. This review presents the current knowledge on this multifactorial disorder, including phenotypic and anatomical characterization, epidemiology, proposed developmental mechanisms, existing animal models, and implicated genetic and environmental components.

Further support linking the 22q11.2 microduplication to an increased risk of bladder exstrophy and highlighting LZTR1 as a candidate gene

Background

The bladder exstrophy‐epispadias complex (BEEC) is a congenital malformation of the bladder and urethra. The underlying causes of this malformation are still largely unknown; however, aside from environment, genetics is thought to play an essential role. The recurrent 22q11.2 microduplication is the most persistently detected genetic aberration found in BEEC cases.

Methods

We performed array comparative genomic hybridization (array‐CGH) analysis of 76 Swedish BEEC patients. Statistical analysis was performed on current dataset pooled with previously published data on the 22q11.2 microduplication in BEEC patients. We performed massive parallel sequencing (MPS) of the 22q11.2 region in 20 BEEC patients without the 22q11.2 microduplication followed by functional studies.

Results

We identified three additional cases with the 22q11.2 microduplication. Pooling data from this study with previously published reports showed a statistically significant enrichment of the 22q11.2 microduplication in BEEC patients (2.61% in cases vs. 0.08% in controls; OR = 32.6; p = 8.7 × 10⁻⁴). MPS of the 22q11.2 region in 20 BEEC patients without the 22q11.2 microduplication identified a novel variant in LZTR1 (p.Ser698Phe) in one patient. Functional evaluation of the LZTR1 p.Ser698Phe variant in live NIH 3T3 cells showed that the concentration and cytoplasmic mobility differ between the Lztr1_wt and Lztr1_mut, indicating a potential functional effect of the LZTR1_mut.

Conclusion

Our study further emphasizes the involvement of the 22q11.2 region in BEEC development and highlights LZTR1 as a candidate gene underlying the urogenital malformation.

Evaluation of the ISL1 gene in the pathogenesis of bladder exstrophy in a Swedish cohort

Bladder exstrophy is a congenital closure defect of the urinary bladder with a profound effect on morbidity. Although the malformation is usually sporadic, a genetic background is supported by an increased recurrence risk in relatives, higher concordance rates in monozygotic twins and several associated chromosomal aberrations. Recently, the ISL1 gene was presented as a candidate gene for bladder exstrophy and epispadias complex (BEEC) development in two different studies. In our study, we screened for genetic variants in the ISL1 gene in DNA from 125 Swedish patients using Sanger sequencing and array-CGH analysis. In addition, we evaluated ISL1 expression in RNA of human bladder during embryonic and fetal weeks 5–10 relative to that in lung tissue (week 9). In total, 21 single-nucleotide variants were identified, including a potentially novel missense variant, c.137C>G p.(Ala46Gly), substituting a conserved amino acid. This variant was inherited from an unaffected mother. No structural variants were identified. RNA sequencing revealed ISL1 mRNA expression during the critical time frame of human bladder development. In conclusion, we did not detect any known or likely pathogenic variants in the ISL1 gene in 125 Swedish BEEC patients, indicating that variation in the ISL1 gene is not a common genetic mechanism of BEEC development in the Swedish population.

Bladder Exstrophy from Childhood into Adult Life

Exstrophy of the bladder is rare and the incidence of bladder exstrophy is calculated to be from 1 per 30 000 to 50 000 live births with male to female ratio ranging from 1.5-5 to 1 1-4 It was found that persistence or overgrowth of the cloacal membrane on the lower anterior abdominal area, prevents normal mesenchymal ingrowth. This causes divergence of the lower abdominal muscular structures and forces the genital ridges to fuse caudal to the cloacal membrane. The stage of ingrowth of the urorectal septum at the time of rupture determines whether one will produce an exstrophic urinary tract alone (classic bladder exstrophy or epispadias) or cloacal exstrophy with the hindgut interposed between the hemibladders5,6.

Pelvic Organ Prolapse and Pregnancy in the Female Bladder Exstrophy Patient

PURPOSE OF REVIEW

Classic bladder exstrophy (BE) remains one of the most demanding reconstructive challenges encountered in urology. In female BE patients, the long-term sequela of both primary and revision genitoplasty, as well as intrinsic pelvic floor deficits, predispose adult women to significant issues with sexual function, pelvic organ prolapse (POP), and complexities with reproductive health.

RECENT FINDINGS

Contemporary data suggest 30-50% of women with BE develop prolapse at a mean age of 16 years. Most women will require revision genitoplasty for successful sexual function, although in some series over 40% report dyspareunia. Current management for pregnancy includes elective cesarean section with involvement of high-risk obstetrics and urologic surgery. This review encapsulates contemporary concepts of etiology, prevalence, and management of POP and pregnancy in the adult female BE patient.

Genetics of Bladder-Exstrophy-Epispadias Complex (BEEC): Systematic Elucidation of Mendelian and Multifactorial Phenotypes

The Bladder-Exstrophy-Epispadias Complex (BEEC) represents the severe end of the uro-rectal malformation spectrum, and has a profound impact on continence, and on sexual and renal function. While previous reports of familial occurrence, in-creased recurrence among first-degree relatives, high concordance rates among monozygotic twins, and chromosomal aberra-tions were suggestive of causative genetic factors, the recent identification of copy number variations (CNVs), susceptibility regions and genes through the systematic application of array based analysis, candidate gene and genome-wide association studies (GWAS) provide strong evidence. These findings in human BEEC cohorts are underscored by the recent description of BEEC(-like) murine knock-out models. Here, we discuss the current knowledge of the potential molecular mechanisms, mediating abnormal uro-rectal development leading to the BEEC, demonstrating the importance of ISL1-pathway in human and mouse and propose SLC20A1 and CELSR3 as the first BEEC candidate genes, identified through systematic whole-exome sequencing (WES) in BEEC patients.

Bladder exstrophy-epispadias complex and the role of methylenetetrahydrofolate reductase C677T polymorphism: A case control study

Purpose:

The Bladder Exstrophy-Epispadias Complex (BEEC) is the most serious form of midline abdominal malformation. The etiology of BEEC is unknown and is thought to be multifactorial. Methylenetetrahydrofolate reductase (MTHFR) polymorphism C677T is strongly associated with other midline abnormalities such as neural tube defects. No proper case-control study existed comparing MTHFR polymorphism with BEEC. We sought to find an association with MTHFR polymorphism and patients with bladder exstrophy (BE).

Materials and Methods:

The design of the study was a case-control study, involving 50 children with BEEC and 50 normal healthy school children. Genetic analysis for MTHFR 677 polymorphism was carried out after DNA extraction and polymerase chain reaction amplification. Epidemiological analysis was done by using the birth defect questionnaire on parents of BEEC.

Results:

Forty-two classical BE, two cloacal exstrophies (CE), four epispadias, and two exstrophy variant patients were a part of this study. Severe variety of BE had a significant association with C667T MTHFR polymorphism as compared to the normal control population (P = 0.01).

Conclusion:

C677T MTHFR polymorphism has a strong association with severe variety (CE) of BEEC occurrence.

Prospective study on the incidence of bladder/cloacal exstrophy and epispadias in Europe

OBJECTIVE

On behalf of the European Society of Paediatric Urology (ESPU), a prospective study was designed with the aim of defining the actual number of babies born with bladder exstrophy, cloacal exstrophy, and epispadias in Europe over a 12-month period, and verifying the distribution of the exstrophy patients born during the study period among the different paediatric urology centres in Europe.

STUDY DESIGN

The study was structured with a chief investigator and one national investigator for each country enrolled in the study. The national investigators nominated one local investigator for each European centre of paediatric surgery/paediatric urology and urology where the exstrophy complex could potentially be treated. The local investigators were responsible for reporting babies treated in their institutions for bladder/cloacal exstrophy and/or epispadias. During 2010, every 3 months, an electronic survey (Figure) was e-mailed to the local investigators asking them to report babies treated or referred for treatment during the previous 3 months.

RESULTS

One-hundred and sixteen centres in 27 European counties were enrolled in the study. The overall response rate for the four online surveys was 79%. Two-hundred and thirty-eight babies were reported to be born with a condition within the bladder exstrophy epispadias complex (BEEC): 71 primary epispadias (66 males), 146 classic bladder exstrophy (97 males) of which two were female bladder exstrophy variant, and 21 cloacal exstrophy (17 males). Two of 67 (3%) male epispadias, 24/146 (16.4%) bladder exstrophy, and 6/21 (28%) cloacal exstrophy were antenatally diagnosed. Associated anomalies were reported in 2/71 (2.8%) epispadias patients, 8/146 (5.5%) bladder exstrophy patients, and 15/21 (71.4%) cloacal exstrophy patients. One-hundred and forty-seven (62%) of the 238 babies born in Europe with a condition within the exstrophy spectrum during 2010 were transferred from other institutions for treatment (36 male epispadias, 97 bladder exstrophy, and 14 cloacal exstrophy). Only 12 centres treated six or more exstrophy and or epispadias patients during the study period; 52 treated between one and five patients, of which 22 treated only one case in 12 months.

DISCUSSION

This study provides a contemporary incidence of the BEEC in Europe. It demonstrates also that only a minority (19%) of the European centres involved in the treatment of exstrophy can be considered "high volume" exstrophy centres.

CONCLUSION

There is a case for proposing a rationalisation of the treatment of this group of conditions in a small number of exstrophy units around Europe.

Genome-wide association study and meta-analysis identify ISL1 as genome-wide significant susceptibility gene for bladder exstrophy

The bladder exstrophy-epispadias complex (BEEC) represents the severe end of the uro-rectal malformation spectrum, and is thought to result from aberrant embryonic morphogenesis of the cloacal membrane and the urorectal septum. The most common form of BEEC is isolated classic bladder exstrophy (CBE). To identify susceptibility loci for CBE, we performed a genome-wide association study (GWAS) of 110 CBE patients and 1,177 controls of European origin. Here, an association was found with a region of approximately 220kb on chromosome 5q11.1. This region harbors the ISL1 (ISL LIM homeobox 1) gene. Multiple markers in this region showed evidence for association with CBE, including 84 markers with genome-wide significance. We then performed a meta-analysis using data from a previous GWAS by our group of 98 CBE patients and 526 controls of European origin. This meta-analysis also implicated the 5q11.1 locus in CBE risk. A total of 138 markers at this locus reached genome-wide significance in the meta-analysis, and the most significant marker (rs9291768) achieved a P value of 2.13 × 10-12. No other locus in the meta-analysis achieved genome-wide significance. We then performed murine expression analyses to follow up this finding. Here, Isl1 expression was detected in the genital region within the critical time frame for human CBE development. Genital regions with Isl1 expression included the peri-cloacal mesenchyme and the urorectal septum. The present study identified the first genome-wide significant locus for CBE at chromosomal region 5q11.1, and provides strong evidence for the hypothesis that ISL1 is the responsible candidate gene in this region.

Genome-wide association study and mouse expression data identify a highly conserved 32 kb intergenic region between WNT3 and WNT9b as possible susceptibility locus for isolated classic exstrophy of the bladder

Bladder exstrophy-epispadias complex (BEEC), the severe end of the urorectal malformation spectrum, has a profound impact on continence as well as sexual and renal functions. It is widely accepted that for the majority of cases the genetic basis appears to be multifactorial. Here, we report the first study which utilizes genome-wide association methods to analyze a cohort comprising patients presenting the most common BEEC form, classic bladder exstrophy (CBE), to identify common variation associated with risk for isolated CBE. We employed discovery and follow-up samples comprising 218 cases/865 controls and 78 trios in total, all of European descent. Our discovery sample identified a marker near SALL1, showing genome-wide significant association with CBE. However, analyses performed on follow-up samples did not add further support to these findings. We were also able to identify an association with CBE across our study samples (discovery: P = 8.88 × 10(-5); follow-up: P = 0.0025; combined: 1.09 × 10(-6)) in a highly conserved 32 kb intergenic region containing regulatory elements between WNT3 and WNT9B. Subsequent analyses in mice revealed expression for both genes in the genital region during stages relevant to the development of CBE in humans. Unfortunately, we were not able to replicate the suggestive signal for WNT3 and WNT9B in a sample that was enriched for non-CBE BEEC cases (P = 0.51). Our suggestive findings support the hypothesis that larger samples are warranted to identify association of common variation with CBE.

New insights into the pathogenesis of bladder exstrophy-epispadias complex

Bladder exstrophy-epispadias complex (BEEC) is a complex and debilitating congenital disease. Familial and twin studies suggest a possible genetic component in BEEC pathogenesis. Bladder mesenchyme (detrusor) development requires induction by a signal from bladder urothelium, and we and others have shown the Shh-Gli-Bmp4 signalling pathway is likely to be involved. P63 is a master regulator in epithelial stratification and is expressed in urothelium. We have shown that p63 knock-out mice undergo excessive urothelial apoptosis. Failure of mesenchymal induction by epithelium leads to BEEC. We further demonstrated that insertion/deletion (in/del) polymorphisms (1 base pair (bp) ins and 4 bp ins., and 12 bp del) in the ΔNP63 promoter reduce transcriptional efficiency, and are associated with a statistically significant increase in the risk of BEEC in humans. Furthermore, a Genome-Wide Expression Profiling (GWEP) study suggests possible involvement of PERP in human BEEC. Intriguingly, PERP is a direct target of p63 during development, and is also involved in epithelial stratification. PERP co-localizes with desmosome, and both PERP and desmosome are essential for maintaining tissue integrity by cellular adhesion and epithelial stratification. A recent study showed that PERP and desmosome expression levels are abnormal in human BEEC patients. This review describes the role of the P63 > PERP > desmosome pathway in the development of human bladder during embryogenesis. We hypothesize that disruption of this pathway may increase the risk of BEEC.

No TAP63 promoter mutation is detected in bladder exstrophy-epispadias complex patients

BACKGROUND/PURPOSE

Bladder exstrophy-epispadias complex (BEEC) is thought to have a genetic component in its pathogenesis. Previously we found that p63(-/-) mice show increased ventral apoptosis and develop a BEEC phenotype. Down-regulation of the anti-apoptotic ΔNP63 and an up-regulation of pro-apoptotic TAP63 isoforms have been demonstrated in BEEC patient bladder tissues. We have previously shown that insertion/deletion polymorphisms of the ΔNp63 promoter are associated with an increased risk of BEEC. In this study, we specifically examined the TAP63 promoter to see if any sequence changes might lead to up-regulation of TAP63 and exaggerated apoptosis in BEEC patients.

METHODS

i) Bioinformatic analysis of the TAP63 promoter was performed to identify putative regulatory regions. ii) High-resolution Melt and Sanger sequencing was used to screen targeted regions in 112 BEEC patient DNA samples for potential sequence variants. iii) Sequence variation was analysed for significance against normal population frequency data.

RESULTS

i) We identified multiple epigenetic markers of transcriptional regulation within highly conserved areas of the TAP63 promoter sequence. ii) Of the 112 buccal swab DNA samples, adequate and successful screening ranged between 48 and 67 for each region. iii) No novel sequence variation or mutation was uncovered. iv) Two known SNPs were identified. However, allele frequency analysis was not statistically significant.

CONCLUSION

Our data do not associate genetic variation within the TAP63 promoter region with an increased risk of BEEC. Our data so far suggests that only ΔNP63 promoter aberration is involved in BEEC pathogenesis.

CNV analysis in monozygotic twin pairs discordant for urorectal malformations

Early post-twinning mutational events can account for discordant phenotypes in monozygotic (MZ) twin pairs. Such mutational events may comprise genomic alterations of different sizes, ranging from single nucleotides to large copy-number variations (CNVs). Anorectal malformations (ARM) and the bladder exstrophy-epispadias complex (BEEC) represent the most severe end of the urorectal malformation spectrum. Recently, CNV studies in patients with sporadic ARM and the BEEC have identified de novo events that occur in specific chromosomal regions. We hypothesized that early arising, post-twinning CNVs might contribute to discordance in MZ twin pairs with ARM or the BEEC; knowledge of such CNVs might help to identify additional chromosomal regions involved in the development of these malformations. We investigated four discordant MZ twin pairs (three ARM and one BEEC) using molecular karyotyping arrays comprising 1,140,419 markers with a median marker spacing of 1.5 kb. Filtering the coding regions for possible disease-causing post-twinning de novo CNVs present only in the affected twin, but not in the unaffected twin or the parents, identified a total of 136 CNVs. These 136 CNVs were then filtered against publicly available databases and finally re-evaluated visually. No potentially causative CNV remained after applying these filter criteria. Our results suggest that post-twinning CNV events that affect coding regions of the genome did not contribute to the discordant phenotypes in MZ twin pairs that we investigated. Possible causes for the discordant phenotypes include changes in regulatory elements or smaller genetic changes within coding regions which may be detectable by whole-exome sequencing.

Isolated bladder exstrophy associated with a de novo 0.9 Mb microduplication on chromosome 19p13.12

BACKGROUND

The exstrophy-epispadias complex (BEEC) is a urogenital birth defect of varying severity. The causes of the BEEC are likely to be heterogeneous, with individual environmental or genetic risk factors still being largely unknown. In this study, we aimed to identify de novo causative copy number variations (CNVs) that contribute to the BEEC.

METHODS

Array-based molecular karyotyping was performed to screen 110 individuals with BEEC. Promising CNVs were tested for de novo occurrence by investigating parental DNAs. Genes located in regions of rearrangements were prioritized through expression analysis in mice to be sequenced in the complete cohort, to identify high-penetrance mutations involving small sequence changes.

RESULTS

A de novo 0.9 Mb microduplication involving chromosomal region 19p13.12 was identified in a single patient. This region harbors 20 validated RefSeq genes, and in situ hybridization data showed specific expression of the Wiz gene in regions surrounding the cloaca and the rectum between GD 9.5 and 13.5. Sanger sequencing of the complete cohort did not reveal any pathogenic alterations affecting the coding region of WIZ.

CONCLUSIONS

The present study suggests chromosomal region 19p13.12 as possibly involved in the development of CBE, but further studies are needed to prove a causal relation. The spatiotemporal expression patterns determined for the genes encompassed suggest a role for Wiz in the development of the phenotype. Our mutation screening, however, could not confirm that WIZ mutations are a frequent cause of CBE, although rare mutations might be detectable in larger patient samples. 19p13.12, microduplication, bladder exstrophy-epispadias complex, array-based molecular karyotyping, in situ hybridization analysis, copy number variations, WIZ gene.

Insertion/deletion polymorphisms in the ΔNp63 promoter are a risk factor for bladder exstrophy epispadias complex

Bladder exstrophy epispadias complex (BEEC) is a severe congenital anomaly; however, the genetic and molecular mechanisms underlying the formation of BEEC remain unclear. TP63, a member of TP53 tumor suppressor gene family, is expressed in bladder urothelium and skin over the external genitalia during mammalian development. It plays a role in bladder development. We have previously shown that p63^−/− mouse embryos developed a bladder exstrophy phenotype identical to human BEEC. We hypothesised that TP63 is involved in human BEEC pathogenesis. RNA was extracted from BEEC foreskin specimens and, as in mice, ΔNp63 was the predominant p63 isoform. ΔNp63 expression in the foreskin and bladder epithelium of BEEC patients was reduced. DNA was sequenced from 163 BEEC patients and 285 ethnicity-matched controls. No exon mutations were detected. Sequencing of the ΔNp63 promoter showed 7 single nucleotide polymorphisms and 4 insertion/deletion (indel) polymorphisms. Indel polymorphisms were associated with an increased risk of BEEC. Significantly the sites of indel polymorphisms differed between Caucasian and non-Caucasian populations. A 12-base-pair deletion was associated with an increased risk with only Caucasian patients (p = 0.0052 Odds Ratio (OR) = 18.33), whereas a 4-base-pair insertion was only associated with non-Caucasian patients (p = 0.0259 OR = 4.583). We found a consistent and statistically significant reduction in transcriptional efficiencies of the promoter sequences containing indel polymorphisms in luciferase assays. These findings suggest that indel polymorphisms of the ΔNp63 promoter lead to a reduction in p63 expression, which could lead to BEEC.

Bladder exstrophy epispadias complex is a severe congenital abnormality. The affected babies' bladders are born open, leaking urine constantly. Treatment involves multiple major reconstructive surgeries and the need for lifelong care for the complications of the disease. Although a number of studies have suggested a genetic cause of the disease, the genetic and molecular mechanism underlying the formation of BEEC remains unknown. One gene, TP63, plays a crucial role in the early bladder development. Two different genetic promoters of TP63 produce different forms of the protein with opposing properties. We have shown mice lacking p63 displayed a deformity complex identical to human BEEC. There are no genetic mutations in the p63 protein in BEEC, so genetic variants in the promoter could alter protein expression. Our hypothesis was that loss of p63 expression due to sequence polymorphisms in a promoter is a risk factor for BEEC. We found promoter sequence variants that were statistically associated with the disease and the sequence variant location varied between Caucasian and non-Caucasian patients. This is particularly important as Caucasian populations have a higher risk of BEEC. These findings provide an explanation of BECC and a base for further study of TP63 related genes in this disease.

Successful pregnancy and delivery in a patient with bladder exstrophy

Bladder exstrophy (BE) is a rare congenital anomaly. Owing to the advanced reconstructive surgical techniques and effective antibiotics, the incidence of urinary and systemic complications in patients with BE has decreased and the life expectancy has increased. However, this brings along social, sexual, and psychological problems; particularly, successful pregnancy and delivery is extremely rare in females with BE. We present a pregnancy of an 18-year-old female with BE, who has been followed at our university hospital since birth.

Congenital renal anomalies in patients with classic bladder exstrophy

OBJECTIVE

To determine the proportion and type of renal anomalies that occur in children born with classic bladder exstrophy.

MATERIAL AND METHODS

All patients in a database of 1044 patients with the bladder exstrophy-epispadias-cloacal exstrophy complex were reviewed. Those with classic bladder exstrophy had their complete medical records reviewed and children with radiographic evidence of congenital renal anomalies were identified and characterized.

RESULTS

A total of 674 patients were identified with classic bladder exstrophy, of whom 462 had renal ultrasounds at the authors' institution. In this population, 13/462 (2.8%) had concomitant renal anomalies. The most common malformation was a duplicated collecting system in 6 patients. Hypoplastic or absent kidneys were present in 3 patients, pelvic kidney in 2, ureteropelvic junction obstruction in 1, and multicystic dysplastic kidney in 1 patient.

CONCLUSION

Isolated renal anomalies occur at a rate of 2.8% in children born with classic bladder exstrophy. Although uncommon in this rare birth defect, anatomic understanding of the entire genitourinary system is critical for operative planning and long-term follow-up of patients with bladder exstrophy.

Bladder exstrophy: an epidemiologic study from the International Clearinghouse for Birth Defects Surveillance and Research, and an overview of the literature

Bladder exstrophy (BE) is a complex congenital anomaly characterized by a defect in the closure of the lower abdominal wall and bladder. We aimed to provide an overview of the literature and conduct an epidemiologic study to describe the prevalence, and maternal and case characteristics of BE. We used data from 22 participating member programs of the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR). All cases were reviewed and classified as isolated, syndrome, and multiple congenital anomalies. We estimated the total prevalence of BE and calculated the frequency and odds ratios for various maternal and case characteristics. A total of 546 cases with BE were identified among 26,355,094 births. The total prevalence of BE was 2.07 per 100,000 births (95% CI: 1.90-2.25) and varied between 0.52 and 4.63 among surveillance programs participating in the study. BE was nearly twice as common among male as among female cases. The proportion of isolated cases was 71%. Prevalence appeared to increase with increasing categories of maternal age, particularly among isolated cases. The total prevalence of BE showed some variations by geographical region, which is most likely attributable to differences in registration of cases. The higher total prevalence among male cases and older mothers, especially among isolated cases, warrants further attention.

Sexual function and fertility issues in cases of exstrophy epispadias complex

In patients with EEC, the issues such as sexuality, sexual function and fertility gain more importance once theses patients advance from puberty to adulthood. The aim of this review is to critically examine the available evidence on these issues. A systemic literature search was performed in Medline over the last 25 years using the key words: Exstrophy, sexual function and pregnancy. Search results were limited to studies of patients with exstrophy published in English literature. A total of 1500 publications were found and subsequently screened by title and when appropriate by abstracts. Of these, 40 publications pertinent to the subject were included for the analysis. The publications were supplemented by an additional 15 publications obtained from their bibliographies. The studies were rated according to the guidelines published by the US department of health and human services. Heterosexuality is usually expressed in both the sexes and most of them have adequate sexual function. Urinary diversion in some series seems to result in better ejaculatory hence fertility outcome in male patients. Recent series have shown equally good results with primary reconstruction. Most of the female patients have normal fertility while male patients have significantly low fertility. Most of the male and female patients with EEC have adequate sexual function. Most of the female patients have normal fertility while most of the male patients have significantly low fertility.

Prenatal diagnosis of 45,X/46,XY mosaicism with cleft lip and epispadias

INTRODUCTION

45,X/46,XY mosaicism is an uncommon chromosomal anomaly with a range of phenotypes from normal males to cases of multiple congenital anomalies.

MATERIALS AND METHODS

We report a case with associated cleft lip and epispadias prenatally diagnosed with autopsy evidences.

CONCLUSION

Our case, with an uncommon association of congenital anomalies, stresses the difficulty of prenatal counselling regarding 45,X/46,XY mosaicism and discuss the possible role of sex chromosome genes that may be involved in the pathogenesis of both types of midline defect.

Embryology and bony and pelvic floor anatomy in the bladder exstrophy-epispadias complex

The exstrophy-epispadias complex is a complex congenital anomaly that, although rare, remains the largest genitourinary birth defect that is surgically correctable. The primary defect in exstrophy is a derangement in midline developmental that presents with a spectrum of severity. In its mildest form, epispadias, the dorsal urethral unit is not fused and has failed to form into a tube. Next, patients with classic bladder exstrophy present with a bladder and urethra open and continuous with the abdominal wall; also associated is a failure of the abdominal muscles, pelvic ring, and pelvic floor musculature to fuse in the midline. Cloacal exstrophy, the most severe variant, includes exstrophied hindgut tube and a more severe degree of concomitant congenital derangements of musculoskeletal, genitourinary, gastrointestinal, and neurological systems. The embryology of the exstrophy-epispadias complex has been long studied, yet debate still exists over the specific origins of the anomaly. This article covers the embryologic theories of this congenital defect and the subsequent bony pelvic and pelvic floor muscular defects characteristic of exstrophy. Primarily, the anatomic focus will be on classic bladder exstrophy because it is the most common and well studied to date.

Prenatal diagnosis of OEIS (omphalocele, bladder exstrophy, imperforate anus, clubfeet) variant associated with increased nuchal translucency and OEIS complex with ambiguous genitalia associated with corrected transposition of the great arteries: case series and review of the literature

INTRODUCTION

The OEIS complex refers to a combination of defects consisting in omphalocele, bladder exstrophy, imperforate anus and spinal defects and represents a rare nosologic entity (from 1:200,000 to 1:400,000 pregnancies). The defect probably occurs in early blastogenesis or in mesodermal migration during the primitive streak period.

MATERIALS AND METHODS

Two cases of OEIS complex diagnosed prenatally by ultrasound are reported. The medical record regarding differential diagnosis, associated anomalies, treatment and prognosis has also been sought and reported.

CONCLUSION

Differential diagnosis with exstrophy-epispadias complex and/or cloacalexstrophy complex may be difficult antenatally by means of ultrasound. However, color Doppler has been proved to aid the diagnosis of bladder exstrophy by depicting the urine flow in direct communication with the abdominal cavity and has been useful in showing the course of the perivesical umbilical arteries. Prenatal 3D ultrasound with tomographic ultrasound imaging (TUI) and antenatal MR imaging might be useful adjuncts to conventional 2D scan in aiding the prenatal diagnosis of such malformation.

Evidence for linkage of the bladder exstrophy-epispadias complex on chromosome 4q31.21-22 and 19q13.31-41 from a consanguineous Iranian family

BACKGROUND

The bladder exstrophy-epispadias complex (BEEC) is a spectrum of anomalies involving the abdominal wall, pelvis, urinary tract, genitalia, and, occasionally, the spine and anus. Although BEEC typically occurs sporadically, families with two or more affected members have been reported. The present authors previously conducted a genome-wide linkage analysis in two multiply affected (multiplex) families (one of German and one of Spanish origin), which revealed several chromosomal regions compatible with linkage. In the present study, genome-wide linkage analysis was performed in a recently reported consanguineous Iranian multiplex family with an affected sibling pair: a female with epispadias and a male with classic exstrophy of the bladder.

METHODS

The Affymetrix 250K Sty chip (238,304 single nucleotide polymorphisms) was used to genotype the parents and four children, including the two affected siblings. Parametric and nonparametric linkage analyses were performed.

RESULTS

Parametric linkage analysis under a recessive model with complete penetrance identified seven loci with LOD scores >1.6 (1p33, 4q31.21-22, 9q22.33, 12q13.13-2, 13q12.12-13, 18q23, and 19q13.31-41). These results were supported by nonparametric linkage analysis. Haplotype analysis showed that the affected individuals were homozygous identical by descent for all seven regions. Two of these regions overlapped with regions observed previously in the Spanish family -one on chromosome 4q31.21-22, and the other on chromosome 19q13.31-41.

CONCLUSION

These results suggest that chromosomal regions 4q31.21-22 and 19q13.31-41 are likely to harbor genes for an autosomal recessive form of BEEC.

BILATERAL ANTERIOR PELVIC OSTEOTOMY FOR OLOSURE OF BLADDER EXSTROPHY: DESCRIPTION OF TECHNIQUE

Bladder and cloacal exstrophy are rare malformations associated with abnormalities in the pelvis. The objectives in reconstruction are to obtain a closed and continent bladder, with an acceptable cosmetic appearance. Treatment for the abnormalities of pelvic anatomy is an important part of achieving successful treatment for these urological conditions. This article aims to describe the technique of bilateral anterior pelvic osteotomy for treating bladder and cloacal exstrophy, and presents two cases to demonstrate the difficulties and applications of the technique.

Embryonic expression of the cysteine rich protein 61 (CYR61) gene: A candidate for the development of human epispadias

BACKGROUND

Isolated epispadias is the mildest phenotype of the exstrophy-epispadias complex, a urogenital birth defect of variable severity. The androgen receptor antagonist flutamide (FLU) is known to cause malformations in the rat genital and reproductive tract, and single-dose prenatal FLU exposure can induce epispadias in rat offspring. The Cyr61 gene exhibited the highest response to FLU in rat fetal testis, and we suggested it a promising candidate gene for epispadias in humans, because its protein product promotes proliferation, migration, and adhesion of endothelial cells and fibroblasts.

METHODS

We used whole mount in situ analysis in mice to investigate ventrocaudal expression of the Cyr61 transcript at gestational days 9.5 to 11.5, which is the equivalent of human gestational weeks 4 to 6 (postulated time of epispadias organogenesis in humans). We also performed mutational analysis of the CYR61 gene in 11 patients with isolated epispadias and in additional eight patients with the related classic bladder exstrophy phenotype.

RESULTS

Expression of Cyr61 was detected in endothelial cells of vessels surrounding the cloaca and the umbilical cord on gestational days 10 and 11.5. The mutation screening, however, revealed no alterations in the coding region of human CYR61.

CONCLUSIONS

The spatiotemporal expression pattern observed suggests a role for Cyr61 in the development of the external genitalia. Our mutation screening study, however, could not confirm that mutations affecting the CYR61 gene are a frequent cause of epispadias or classic bladder exstrophy, although rare mutations might be detectable in larger patient samples.

The exstrophy-epispadias complex

Exstrophy-epispadias complex (EEC) represents a spectrum of genitourinary malformations ranging in severity from epispadias (E) to classical bladder exstrophy (CEB) and exstrophy of the cloaca (EC). Depending on severity, EEC may involve the urinary system, musculoskeletal system, pelvis, pelvic floor, abdominal wall, genitalia, and sometimes the spine and anus. Prevalence at birth for the whole spectrum is reported at 1/10,000, ranging from 1/30,000 for CEB to 1/200,000 for EC, with an overall greater proportion of affected males. EEC is characterized by a visible defect of the lower abdominal wall, either with an evaginated bladder plate (CEB), or with an open urethral plate in males or a cleft in females (E). In CE, two exstrophied hemibladders, as well as omphalocele, an imperforate anus and spinal defects, can be seen after birth. EEC results from mechanical disruption or enlargement of the cloacal membrane; the timing of the rupture determines the severity of the malformation. The underlying cause remains unknown: both genetic and environmental factors are likely to play a role in the etiology of EEC. Diagnosis at birth is made on the basis of the clinical presentation but EEC may be detected prenatally by ultrasound from repeated non-visualization of a normally filled fetal bladder. Counseling should be provided to parents but, due to a favorable outcome, termination of the pregnancy is no longer recommended. Management is primarily surgical, with the main aims of obtaining secure abdominal wall closure, achieving urinary continence with preservation of renal function, and, finally, adequate cosmetic and functional genital reconstruction. Several methods for bladder reconstruction with creation of an outlet resistance during the newborn period are favored worldwide. Removal of the bladder template with complete urinary diversion to a rectal reservoir can be an alternative. After reconstructive surgery of the bladder, continence rates of about 80% are expected during childhood. Additional surgery might be needed to optimize bladder storage and emptying function. In cases of final reconstruction failure, urinary diversion should be undertaken. In puberty, genital and reproductive function are important issues. Psychosocial and psychosexual outcome depend on long-term multidisciplinary care to facilitate an adequate quality of life.

Overview of bladder exstrophy: a third world perspective

INTRODUCTION

Bladder exstrophy is an uncommon condition, and the ramifications for patients living in a Third World environment are extensive.

PATIENTS AND METHODS

This was a retrospective study of 57 patients, managed between 1983 and 2006. The review looked at the home environment, clinical findings, treatment provided, and short-term outcome.

RESULTS

Of the 57 patients, 19 were born in metropolitan and 38 in rural hospitals. Twenty-four patients (42%) were referred on the first day of life, 21 (37%) within the first week, and 12 patients (21%) were older than 1 week of life. Associated congenital anomalies were seen in 18 patients (32%). Twelve patients died in hospital, the remaining 45 were discharged. Thirty three patients returned for review; their ages ranged from 2 to 17 years (median, 3 years). The overall mortality was 42%. On follow-up, urinary incontinence was the main complaint, which greatly affected the child's schooling and social life.

CONCLUSION

Bladder exstrophy is an uncommon condition. The associated congenital abnormalities together with the impoverished environment result in a poor prognosis. Antenatal screening, early referral, and establishing urinary continence are factors that will improve the outcome in children with this condition in a Third World environment.

Investigation of FGF10 as a candidate gene in patients with anorectal malformations and exstrophy of the cloaca

The spectrum of anorectal malformations (ARM) comprises anal stenosis, ectopic anus, recto-urogenital fistula, persistent cloaca, multisystem VACTERL (VATER associations including cardiac and limb anomalies) associations, and exstrophy of the cloaca (CE). The latter also constitutes the most severe form of the bladder exstrophy epispadias complex. Since recent data revealed that fibroblast growth factor 10 (fgf-10) invalidation in mice resulted in a genetically reproducible urorectal defect, we considered FGF10 a suitable candidate gene for ARM and CE, as the protein seems to be involved in the development of this primary developmental field. A total of 20 patients (ten with ARM and VACTERL association, respectively, and ten with CE) were analysed for genomic mutations in the coding regions and exon-intron boundaries of FGF10. Aside from a common FGF10 variant no deviation from the wild-type sequence could be detected and data obtained is not supportive of FGF10 as a genetic cause of ARMs or CE in the patients investigated. Nonetheless, mutations in possibly further upstream located promoter regions and/or unknown regulatory sequences or non-coding regions cannot be excluded. Furthermore, it cannot be ruled out that other genes involved in the signalling pathway of FGF10 may contribute to the formation of these congenital malformations.

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.