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.

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.

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.

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.