Innervation pattern of the unclosed detrusor muscle in classic bladder exstrophy: a study of patients with urothelial overexpression of nerve growth factor.

PURPOSE: An overexpression of nerve growth factor (NGF) in the urothelium is discussed to lead to neuronal hyperinnervation of the bladder detrusor. The aim was to assess the sensory and sympathetic innervation of the detrusor in unclosed exstrophic bladders patients with known overexpression of NGF in the urothelium. METHODS: Full-thickness bladder biopsies were prospectively obtained from 34 infants at delayed primary bladder closure between 01/2015 and 04/2020. The bladder biopsies were immunohistochemically stained with antibodies against S100, calcitonin gene-related peptide (anti-CGRP), Neurofilament 200 (anti-NF200), and tyrosine-hydroxylase (anti-TH). Specimens from 6 children with congenital vesicoureterorenal reflux (VUR) served as controls. RESULTS: There was no statistically significant difference in nerve fiber density in any of the immunohistochemical assessments (anti-S100 [p = 0.210], anti-CGRP [p = 0.897], anti-NF200 [p = 0.897]), and anti-TH [p = 0.956]) between patients with BE and patients with VUR. However, we observed a trend toward lower nerve fiber densities in exstrophic detrusor. CONCLUSION: Overall our results showed an unharmed innervation pattern in this cohort but a lower density of nerve fibers in the detrusor compared to controls. Further studies in patients after successful primary closure are needed to clarify the potential impact of the urothelial overexpression of NGF modulating the innervation pattern in exstrophic bladders.

Evaluation of Undescended Testes in Newborns: It Is Really Simple, Just Not Easy.

INTRODUCTION: The evaluation of the testicular position in newborns is important to ensure timely initiation of therapy. The aim of our study was to assess the reliability of a routinely performed screening examination. PATIENTS AND METHODS: Newborns were examined by a pediatrician between 48 and 72 h after birth. Boys with suspected cryptorchidism were double-checked by a pediatric urologist within 24 h. RESULTS: 1,181/2,353 children included in the study between June 2015 and December 2017 were male. Eight hundred sixty-one boys could be included in this analysis; 5.8% (n = 50) were diagnosed with undescended testis (UDT) by the pediatrician. 30/50 boys were double-checked at the Department of Pediatric Urology. Forty percent (20/50) were lost to follow-up. In 43% (13/30), the diagnosis could be confirmed. Three former studies had shown a relevant discrepancy in the results of the diagnosis of UDT made by health care providers and urologists/pediatric surgeons. To our knowledge, this is the first study evaluating the testicular position in male newborns in such a large prospective birth cohort study by physicians with ranging expertise within 1 day. CONCLUSION: Further treatment for UDT is based on clinical examination. Ours and previous studies can clearly show the various findings in boys suspected having UDT. Therefore, it is essential that the diagnosis is confirmed by a specialist before a therapy is initiated.

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.

Standardization of pediatric uroradiological terms: a multidisciplinary European glossary.

To promote the standardization of nephro-uroradiological terms used in children, the European Society of Paediatric Radiology uroradiology taskforce wrote a detailed glossary. This work has been subsequently submitted to European experts in pediatric urology and nephrology for discussion and acceptance to improve the quality of radiological reports and communication between different clinicians involved in pediatric urology and nephrology.

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.

CNV analysis in 169 patients with bladder exstrophy-epispadias complex.

BACKGROUND: The bladder exstrophy-epispadias complex (BEEC) represents the severe end of the congenital uro-rectal malformation spectrum. Initial studies have implicated rare copy number variations (CNVs), including recurrent duplications of chromosomal region 22q11.21, in BEEC etiology. METHODS: To detect further CNVs, array analysis was performed in 169 BEEC patients. Prior to inclusion, 22q11.21 duplications were excluded using multiplex ligation-dependent probe amplification. RESULTS: Following the application of stringent filter criteria, seven rare CNVs were identified: n = 4, not present in 1307 in-house controls; n = 3, frequency of <0.002 in controls. These CNVs ranged from 1 to 6.08 Mb in size. To identify smaller CNVs, relaxed filter criteria used in the detection of previously reported BEEC associated chromosomal regions were applied. This resulted in the identification of six additional rare CNVs: n = 4, not present in 1307 in-house controls; n = 2, frequency <0.0008 in controls. These CNVs ranged from 0.03-0.08 Mb in size. For 10 of these 13 CNVs, confirmation and segregation analyses were performed (5 of maternal origin; 5 of paternal origin). Interestingly, one female with classic bladder extrophy carried a 1.18 Mb duplication of 22q11.1, a chromosomal region that is associated with cat eye syndrome. CONCLUSIONS: A number of rare CNVs were identified in BEEC patients, and these represent candidates for further evaluation. Rare inherited CNVs may constitute modifiers of, or contributors to, multifactorial BEEC phenotypes.

Classic bladder exstrophy: Frequent 22q11.21 duplications and definition of a 414 kb phenocritical region.

BACKGROUND: Classic bladder exstrophy (CBE) is the most common form of the bladder exstrophy and epispadias complex. Previously, we and others have identified four patients with a duplication of 22q11.21 among a total of 96 unrelated CBE patients. METHODS: Here, we investigated whether this chromosomal aberration was commonly associated with CBE/bladder exstrophy and epispadias complex in an extended case-control sample. Multiplex ligation-dependent probe amplification and microarray-based analysis were used to identify 22q11.21 duplications in 244 unrelated bladder exstrophy and epispadias complex patients (including 217 CBE patients) and 665 healthy controls. RESULTS: New duplications of variable size were identified in four CBE patients and one control. Pooling of our previous and present data (eight duplications in 313 CBE patients) yielded a combined odds ratio of 31.86 (95% confidence interval, 4.24-1407.97). Array-based sequence capture and high-throughput targeted re-sequencing established that all breakpoints resided within the low-copy repeats 22A to 22D. Comparison of the eight duplications revealed a 414 kb phenocritical region harboring 12 validated RefSeq genes. Characterization of these 12 candidate genes through whole-mount in situ hybridization of mouse embryos at embryonic day 9.5 suggested that CRKL, THAP7, and LZTR1 are CBE candidate genes. CONCLUSION: Our data suggest that duplication of 22q11.21 increases CBE risk and implicate a phenocritical region in disease formation.

Assisted reproductive techniques and risk of exstrophy-epispadias complex: a German case-control study.

PURPOSE: We assessed the risk of exstrophy-epispadias complex in children conceived by in vitro fertilization or intracytoplasmic sperm injection. MATERIALS AND METHODS: Data from the German Network for Congenital Uro-REctal malformations were compared to nationwide data from the German In Vitro Fertilization Register and the German Federal Statistical Office. Odds ratios (95% CI) were determined to quantify associations using logistic regression. RESULTS: A total of 123 patients with exstrophy-epispadias complex born in Germany between 1997 and 2011 were recruited through participating departments of pediatric urology and pediatric surgery throughout the country as well as the German self-help organizations Blasenekstrophie/Epispadie e.V. and Kloakenekstrophie. All German live births (10,069,986) between 1997 and 2010 comprised the controls. Overall, 12 subjects (10%) and 129,982 controls (1%) were conceived by in vitro fertilization or intracytoplasmic sperm injection. Conception by assisted reproductive technique was associated with a more than eightfold increased risk of exstrophy-epispadias complex compared to spontaneous conception (OR 8.3, 95% CI 4.6-15.0, p <0.001). Separate analyses showed a significantly increased risk of exstrophy-epispadias complex in children conceived by in vitro fertilization (OR 14.0, 95% CI 6.5-30.0, p <0.0001) or intracytoplasmic sperm injection (OR 5.3, 95% CI 2.2-12.9, p <0.0001). CONCLUSIONS: This study provides evidence that assisted reproductive techniques such as in vitro fertilization and intracytoplasmic sperm injection are associated with a markedly increased risk of having a child born with exstrophy-epispadias complex. However, it remains unclear whether this finding may be due to assisted reproduction per se and/or underlying infertility/subfertility etiology or parent characteristics.

Candidate gene association study implicates p63 in the etiology of nonsyndromic bladder-exstrophy-epispadias complex.

BACKGROUND: Bladder-exstrophy-epispadias complex (BEEC) is a severe congenital anomaly that represents a spectrum of urological abnormalities where parts or all of the distal urinary tract fail to close during development. Multiple lines of evidence strongly suggested p63 as a plausible candidate gene. We conducted a candidate gene association study to further investigate the role of p63 in human BEEC. METHODS: We conducted a family-based association study of p63 using 154 Caucasian patients with nonsyndromic BEEC and their unaffected parents. High throughput single nucleotide polymorphism (SNP) genotyping was carried out using Illumina's Golden Gate Assay for 109 selected tagging SNPs localized within p63 with a minor allele frequency > 0.01. Individual and haplotype SNP transmission disequilibrium tests were conducted using Plink and Haploview, respectively. We also examined parent-of-origin effects using paternal asymmetry tests implemented in FAMHAP (http://famhap.meb.uni-bonn.de/index.html). RESULTS: Nominally significant associations were identified between BEEC and six SNPs (rs17447782, rs1913720, rs6790167, rs9865857, rs1543969, rs4687100), and four haplotype blocks including or near these significant SNPs. Analysis of parent-of-origin effects showed significant results for seven SNPs (rs4118375, rs12696596, rs6779677, rs13091309, rs7642420, rs1913721, and rs1399774). None of these results remained significant after multiple testing correction. CONCLUSION: The altered transmission of p63 variants in nonsyndromic BEEC patients may be suggestive of its involvement in the disease etiology. Further and large multi-institutional collaborative studies are required to elucidate the role of p63 in nonsyndromic BEEC.

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.

[Between wish and reality: more efficiency through increased outpatient procedures in paediatric urology]. / Zwischen Wunsch und Wirklichkeit: Mehr Effizienz durch Ambulantisierung von Eingriffen in der Kinderurologie.

The "outpatientisation" of procedures is gaining more and more interest. According to a report published by the German research institute IGES, more than 2000 procedures will be included in the catalogue for outpatient surgery in the future. This also means a significant increase in the number of procedures that can be performed on an outpatient basis in the field of (paediatric) urology. However, the feasibility, especially in paediatric urology, depends on many specific personnel, organisational and structural conditions.

Open Pyeloplasty in Infants under 1 Year-Proven or Meaningless?

The use of minimally invasive surgery (MIS) to treat ureteropelvic junction obstruction (UPJO) in children has significantly increased. Nowadays, open pyeloplasty (OP) seems to lose importance. The aim of this study is to evaluate the safety and efficacy of OP in infants < 1 year. Medical records of patients < 1 year with UPJO who had undergone retroperitoneal OP (January 2008-February 2022) at our institution were retrospectively analyzed. Included patients were operated on according to a modified Anderson-Hynes technique. All clinical, operative, and postoperative (1 month-5 years' follow-up) data were collected. Additionally, a nonvalidated questionnaire was sent to the patients/parents. A total of 162 infants (124 boys) met the inclusion criteria. The median age at surgery was 3 months (range: 0-11 months). The median operation time was 106 min (range: 63-198 min). None of the patients had severe surgical complication (Clavien-Dindo > 3). The nonvalidated questionnaire showed a high impact of quality of life. Follow-up was in median 30.5 months (0-162 months). OP is still a reliable procedure with good long-term results especially in infants < 1 year of age, which can be performed in a variety of centers.

Ureterocystoplasty in Boys with Valve Bladder Syndrome-Is This Method Still up to Date?

Boys with valve bladder syndrome (PUV) require adequate treatment of the lower urinary tract to preserve renal function and improve long-term outcomes. In some patients, further surgery may be necessary to improve bladder capacity and function. Ureterocytoplasty (UCP) is usually carried out with a small segment of intestine or, alternatively, with a dilated ureter. Our aim was to evaluate the long-term outcomes after UCP in boys with PUV. UCP had been performed in 10 boys with PUV at our hospital (2004-2019). Pre- and postoperative data were evaluated in relation to kidney and bladder function, the SWRD score, additional surgery, complications, and long-term follow-up. The mean time between primary valve ablation and UCP was 3.5 years (SD ± 2.0). The median follow-up time was 64.5 months (IQR 36.0-97.25). The mean increase in age-adjusted bladder capacity was 25% (from 77% (SD ± 0.28) to 102% (SD ± 0.46)). Eight boys micturated spontaneously. Ultrasounds showed no severe hydronephrosis (grade 3-4). The SWRD score showed a median decrease from 4.5 (range 2-7) to 3.0 (range 1-5). No conversion of augmentation was required. UCP is a safe and effective approach to improve bladder capacity in boys with PUV. In addition, the possibility of micturating naturally is still maintained.

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.

Testicular tumors in patients with exstrophy-epispadias complex.

PURPOSE: Due to separated pubic bone and patent processus vaginalis, males with exstrophy-epispadias complex often present with inguinal hernia during infancy. Since most of these testicles are operatively repositioned, testicular development is assumed to be normal. However, there is a paucity of knowledge about long-term testicular development in males with exstrophy-epispadias complex. We identified males with sonographic intratesticular abnormalities or testicular tumor in exstrophy-epispadias complex. MATERIALS AND METHODS: Since 2003, a Germany wide cross-sectional followup study has been permanently offered to men with exstrophy-epispadias complex, focusing on andrological issues. A total of 22 men with exstrophy-epispadias complex presented to our clinical service for andrological evaluation, including testicular ultrasound. RESULTS: Sonography showed testicular and epididymal pathology in more than 50% of patients, with intratesticular abnormality in 23%, most commonly testicular microlithiasis (9%). Three patients underwent testicular biopsy. Histopathological evaluation revealed 1 case of testicular intraepithelial neoplasia and 2 benign testicular stromal tumors (1 Sertoli cell tumor and 1 Leydig cell tumor). Followup visits at 10, 28 and 68 months were uneventful. CONCLUSIONS: The observation of comorbid testicular tumor in males with exstrophy-epispadias complex should prompt a preventive health examination after puberty, which gives these patients the opportunity for further appropriate diagnostics and treatment if necessary. Biopsy is recommended for sonographically detected intratesticular lesions. Organ sparing procedures are worth considering, especially when stromal tumors with favorable outcome are discovered. However, current oncologic principles must be strictly followed. Although the etiology and true incidence of testicular tumors in exstrophy-epispadias complex are still unclear, our findings highlight the importance of long-term followup in patients with exstrophy-epispadias complex.

Is Vesicostomy Still a Contemporary Method of Managing Posterior Urethral Valves?

In boys with posterior urethral valves (PUVs) the main treatment aim is to preserve long-term bladder and renal function. To determine the effectiveness of secondary vesicostomy in boys with PUVs, the medical records of 21 patients with PUV (2010-2019), divided into two groups (group I: valve ablation; group II: secondary vesicostomy), were reviewed regarding the course of serum creatinine, renal ultrasound, voiding cystourethrogram, urodynamics, postoperative complications, need of further surgery, and long-term solution. The median age of all patients at first follow-up was 11 (9-13) months and at last follow-up 64.5 (39.5-102.5) months. Despite a significant difference of the SWDR score (shape, wall, reflux, and diverticula) (p = 0.014), both groups showed no significant differences preoperatively. Postoperatively, serum creatinine (p = 0.024), grade of vesicoureteral reflux (p = 0.003), side of upper tract dilatation (p = 0.006), side of megaureter (p = 0.004), and SWDR score (p = 0.002) were significantly decreased in group II. Postoperative urodynamic measurements showed comparable results in both groups. Stoma complications were found in three (20%) patients (group II). Eight (53.3%) patients already received a closure of the vesicostomy. Seven out of eight (87.5%) patients were able to micturate spontaneously. Vesicostomy remains a reliable treatment option for boys with PUV to improve bladder function and avoid further damage to the urinary tract.

Congenital Heart Defects in Patients with Classic Bladder Exstrophy: A Hitherto Neglected Association?

INTRODUCTION: Classic bladder exstrophy (BE) is regarded as an isolated malformation without any further anomalies, but some studies have indicated a higher incidence of cardiac anomalies. This cross-sectional study is planned to evaluate the prevalence of congenital heart defects (CHDs) and the clinical relevance for patients with BE admitted for primary closure. MATERIALS AND METHODS: Patients were prospectively recruited between March 2012 and January 2019. Patients' profiles including demographic data, results of transthoracic echocardiography (TTE), as well as essential peri- and postoperative data were assessed. RESULTS: Thirty-nine (25 boys and 14 girls) patients with BE (median age 61 days) underwent delayed primary bladder closure. Thirty-seven (24 boys and 13 girls) patients had received TTE 1 day before surgery. CHD was detected in 7 (18.9%) out of the 39 patients, but no clinical differences between patients with and without CHD were observed peri- or postoperatively. DISCUSSION AND CONCLUSION: This prospective systematic evaluation shows an even higher rate of CHD in patients with BE than assumed previously. Although peri- and postoperative outcome did not differ between patients with and without CHD, we consider TTE an important additional method for ensuring a safe peri- and postoperative courses and a short- and long-term care for patients with CHD.

Delayed primary closure of bladder exstrophy without osteotomy: 12 year experience in a safe and gentle alternative to neonatal surgery.

BACKGROUND: Successful primary closure of bladder exstrophy is of utmost importance for bladder capacity and urinary continence. We evaluated our concept of delayed primary closure that challenges the role of neonatal surgery, pelvic osteotomy, and perioperative pain management. MATERIAL AND METHODS: We reviewed the medical records of patients with classic bladder exstrophy (CBE) who had undergone delayed primary closure without osteotomy at our institution between January 2008 and May 2020. Data to be analyzed included patient demographics, intraoperative pelvic laxity, blood transfusion, postoperative ventilation time, requirement of pain medication, time to full feeds, length of ICU stay, postoperative complications, and total hospital stay. RESULTS: 66 patients (44 boys) met the inclusion criteria. Mean age at surgery was 64.8 days (SD±24.7). Pelvic approximation < 5 mm was possible in 66 (100%) patients. Blood transfusion was required by 31 (47%) patients. 14 (21.2%) patients needed postoperative ventilation for a mean time of 2.7 h. 45 (68.2%) children required intravenous opioids in addition to an epidural catheter. Oral feeding started on average 17.6 h after surgery. Mean ICU stay was 1.3 day. The initial success rate of delayed closure was 93.9%. None of the patients had bladder dehiscence. Girls developed more often minor postoperative complications than boys (m/f: 12 [27.3%] vs. 8 [36.4%]. Mean overall time of hospitalization was 19 days (13-34 d). CONCLUSION: Delayed primary closure of CBE without osteotomy but with continuous epidural blockage is a safe and promising procedure that has crucial advantages in the pre- and postoperative management of CBE. LEVEL OF EVIDENCE: Level III.

A genome-wide association study with tissue transcriptomics identifies genetic drivers for classic bladder exstrophy.

Classic bladder exstrophy represents the most severe end of all human congenital anomalies of the kidney and urinary tract and is associated with bladder cancer susceptibility. Previous genetic studies identified one locus to be involved in classic bladder exstrophy, but were limited to a restrict number of cohort. Here we show the largest classic bladder exstrophy genome-wide association analysis to date where we identify eight genome-wide significant loci, seven of which are novel. In these regions reside ten coding and four non-coding genes. Among the coding genes is EFNA1, strongly expressed in mouse embryonic genital tubercle, urethra, and primitive bladder. Re-sequence of EFNA1 in the investigated classic bladder exstrophy cohort of our study displays an enrichment of rare protein altering variants. We show that all coding genes are expressed and/or significantly regulated in both mouse and human embryonic developmental bladder stages. Furthermore, nine of the coding genes residing in the regions of genome-wide significance are differentially expressed in bladder cancers. Our data suggest genetic drivers for classic bladder exstrophy, as well as a possible role for these drivers to relevant bladder cancer susceptibility.