Hypospadias: Etiology and Current Research

Buccal versus skin graft for two-stage repair of complex hypospadias: an Egyptian center experience

Background

Urethral reconstruction in complex hypospadias poses a significant challenge. We report our 10-year experience with buccal mucosa graft (BMG) in the two-stage repair of complex hypospadias and compare its results to the skin graft.

Methods

We retrieved the data of 15 patients with complex hypospadias who underwent two-stage repair using the BMG at our institution. The data were compared to 13 patients who underwent skin graft during the same period.

Results

The median follow-up duration was 14 (12–17) months in the BMG group and 16 (13.5–22.5) months in the skin graft group. Patients in the BMG had a numerically lower incidence of the diverticulum, wound dehiscence, fistula, and infection than the skin graft group, however, without statistically significant difference (p > 0.05). On the other hand, the incidence of meatal stenosis and urethral stricture was significantly lower in the BMG group (0% each) compared to the skin graft group (30.8% each; p = 0.02). At the same time, there were no reported cases of graft contracture. The frequency of donor site morbidity was significantly higher in the skin graft group compared to the BMG group (p = 0.003). The BMG led to a lower incidence of postoperative straining than the skin graft (0% vs. 38.5%, p = 0.03). Only one patient needed revision surgery after skin graft, compared to no case in the BMG (p = 0.27).

Conclusion

The present study demonstrates the feasibility and durable outcomes of the BMG in the setting of two-stage repair of complex hypospadias.

The effect of caudal epidural block on the surgical complications of hypospadias repair in children aged 6 to 35 months: A randomized controlled trial

BACKGROUND

Caudal epidural block (CEB) in hypospadias surgery has the benefit of reducing post-operative pain and possibly intra-operative bleeding. Some studies, however, have suggested that this technique may increase the rate of post-operative complications. Considering the uncertainty about the effect of CEB on surgical complications of hypospadias repair, the current study was performed.

OBJECTIVE

The aim of this randomized clinical trial was to compare the complication rates between patients who receive CEB after hypospadias surgery and those who did not.

STUDY DESIGN

This double-blind randomized controlled trial was conducted on boys aged 6-35 months, who underwent hypospadias repair surgery in a university hospital from March 2018 to March 2019. Sixty patients were randomly divided into two groups (group A: 31 and group B: 29). In group B, CEB was performed, using 0.5 mg/kg of 0.125% bupivacaine (Marcaine). Postoperative complications including fistula, meatal stenosis, dehiscence, and occurrence of bleeding were assessed during six months after surgery.

RESULTS

The patients were assessed for possible complications at 24 h, one week, one, three and six months after surgery. No remarkable differences were observed between the patients in the two groups in terms of the frequency of dehiscence, fistula, and meatal stenosis (P > 0.05). Moreover, the difference in complication rates between the patients with proximal and distal hypospadias did not reach statistical significance (P = 0.549).

DISCUSSION

Assessment of complications showed no significant difference between the two study groups in terms of dehiscence, fistula, and meatal stenosis (Clavien type III). In addition, complication rate was not significantly different according to severity of hypospadias between the two groups. Our study had limitations such as short follow up and small sample size, which resulted in insignificant difference in complication rate between proximal and distal hypospadias. These limitations request large studies with long term follow up.

CONCLUSION

The current study showed that the use of caudal block anesthesia in comparison with general anesthesia did not increase surgical complications, which approved CEB protocol as a safe method in hypospadias repair.

Expression of mRNA vascular endothelial growth factor in hypospadias patients

Background

Hypospadias is a relatively common genital anomaly in humans, usually followed by inelastic dartos that causes penile chordee. Vascular endothelial growth factor (VEGF) is strongly linked to the viscoelasticity of tissues and their elastic phase. This study aimed to evaluate VEGF expressions in (1) fascia dartos between hypospadias and controls and (2) chordee severity.

Methods

This prospective cohort study involved 65 specimens from patients with hypospadias and ten specimens from controls. The samples were analyzed by quantitative real-time polymerase chain reaction (qPCR) for VEGF expression.

Results

The expressions of VEGF were not different between proximal and distal hypospadias patients and controls (fold change: distal − 0.25; fold change: proximal − 0.2; p = 0.664). The scaled expressions related to chordee severity were mild − 0.1; moderate 0.1; severe − 0.25 (p = 0.660).

Conclusions

VEGF expressions might not affect the severity of hypospadias and chordee, implying the pathogenesis is complex involving many growth factors. Further study with a larger sample size is necessary to clarify and confirm our findings.

Environmental Impacts on Male Reproductive Development: Lessons from Experimental Models

BACKGROUND

Male reproductive development in mammals can be divided into a gonadal formation phase followed by a hormone-driven differentiation phase. Failure of these processes may result in Differences in Sex Development (DSD), which may include abnormalities of the male reproductive tract, including cryptorchidism, hypospadias, infertility, and testicular germ cell cancer (TGCC). These disorders are also considered to be part of a testicular dysgenesis syndrome (TDS) in males. Whilst DSDs are considered to result primarily from genetic abnormalities, the development of TDS disorders is frequently associated with environmental factors.

SUMMARY

In this review, we will discuss the development of the male reproductive system in relation to DSD and TDS. We will also describe the experimental systems, including studies involving animals and human tissues or cells that can be used to investigate the role of environmental factors in inducing male reproductive disorders. We will discuss recent studies investigating the impact of environmental chemicals (e.g., phthalates and bisphenols), lifestyle factors (e.g., smoking) and pharmaceuticals (e.g., analgesics) on foetal testis development. Finally, we will describe the evidence, involving experimental and epidemiologic approaches, for a role of environmental factors in the development of specific male reproductive disorders, including cryptorchidism, hypospadias, and TGCC. Key Messages: Environmental exposures can impact the development and function of the male reproductive system in humans. Epidemiology studies and experimental approaches using human tissues are important to translate findings from animal studies and account for species differences in response to environmental exposures.

Endocrine disrupting chemicals in the pathogenesis of hypospadias; developmental and toxicological perspectives

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Penis development is regulated by a tight balance of androgens and estrogens.

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EDCs that impact androgen/estrogen balance during development cause hypospadias.

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Cross-disciplinary collaborations are needed to define a mechanistic link.

Hypospadias is a defect in penile urethral closure that occurs in approximately 1/150 live male births in developed nations, making it one of the most common congenital abnormalities worldwide. Alarmingly, the frequency of hypospadias has increased rapidly over recent decades and is continuing to rise. Recent research reviewed herein suggests that the rise in hypospadias rates can be directly linked to our increasing exposure to endocrine disrupting chemicals (EDCs), especially those that affect estrogen and androgen signalling. Understanding the mechanistic links between endocrine disruptors and hypospadias requires toxicologists and developmental biologists to define exposures and biological impacts on penis development. In this review we examine recent insights from toxicological, developmental and epidemiological studies on the hormonal control of normal penis development and describe the rationale and evidence for EDC exposures that impact these pathways to cause hypospadias. Continued collaboration across these fields is imperative to understand the full impact of endocrine disrupting chemicals on the increasing rates of hypospadias.

Prenatal Diagnosis and Classification of Fetal Hypospadias: The Role and Value of Magnetic Resonance Imaging

BACKGROUND

Prenatal diagnosis and classification of hypospadias are difficult and of value for management during perinatal and neonatal periods. The conventional approach for prenatal diagnosis of hypospadias is ultrasound; however, this technique may be inconclusive in certain cases, which prompts for further exploration with magnetic resonance imaging (MRI).

PURPOSE

To investigate the role of MRI in the prenatal diagnosis and classification of fetuses with hypospadias.

STUDY TYPE

Retrospective.

POPULATION

Thirty-five fetuses (median gestational age = 37, range 24-39 weeks) with possible hypospadias.

FIELD STRENGTH/SEQUENCE

Single-shot fast spin echo T2-weighted imaging, fast imaging employing steady-state acquisition (FIESTA), and three-dimensional FIESTA acquired at 1.5 T.

ASSESSMENT

Diagnosis and classification of hypospadias using MRI were performed by three experienced radiologists based on MRI features, including a short penile shaft, abnormal penile tip, penile curvature, bifid scrotum, "tulip sign," and penoscrotal transposition. The accuracy of MRI in the diagnosis and classification of hypospadias was assessed in comparison to postnatal clinical diagnosis. The interobserver agreement between radiologists was also assessed.

STATISTICAL TESTS

Kendall's W test was applied to assess the interobserver agreement between radiologists. Taking postnatal clinical diagnosis as the reference standard, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated.

RESULTS

Of the 35 fetuses, 24 cases were confirmed as hypospadias through postnatal clinical diagnosis. The interobserver agreement between radiologists was substantial (Kendall's W = 0.781, P < 0.001). Of the 24 confirmed cases (13 cases of severe hypospadias and 11 cases of mild hypospadias), 22 cases were correctly diagnosed by MRI. The accuracy of MRI in the diagnosis of hypospadias, severe hypospadias, and mild hypospadias was 85.71%, 82.86%, and 80.00%, respectively.

DATA CONCLUSION

MRI has good performance in the diagnosis of fetal hypospadias. In addition, MRI could help evaluate the severity of fetal hypospadias.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

An unusual cause of female secondary infertility: Hypospadias

Female hypospadias is a very rare congenital anomaly and its impact on fertility has not yet been clearly defined. A 21-year-old woman with hypospadias was admitted with secondary infertility, dyspareunia, and urge symptoms. She was successfully treated with vaginal flap urethroplasty and broad spectrum antibiotics. Postoperatively, her symptoms resolved and she conceived spontaneously and aborted at her 17^th gestational week following premature rupture of membranes suggesting infection. She then conceived spontaneously again and delivered a healthy term baby 30 months after the operation. Female hypospadias may cause chronic pelvic infections, urge symptoms, sexual dysfunction, hence infertility with time. After achieving normal anatomy by vaginal flap urethroplasty, treatment of chronic infections allows restoring normal urologic and sexual functions, and fertility.

Clinical and molecular spectrum of 46,XY disorders of sex development that harbour MAMLD1 variations: case series and review of literature

Background

Mastermind-like domain-containing 1 (MAMLD1) has previously been identified as a causative gene for “46,XY Disorders of Sex Development (DSD)”. Recently, there has been some controversy regarding the causative role of MAMLD1 variations in DSDs. Here we describe a clinical series and review the reported cases to evaluate the role of MAMLD1 variants in children with 46,XY DSD. Cases of 46,XY DSD harbouring MAMLD1 variants from unrelated families were recruited from the Beijing Children’s Hospital in China (N = 10) or identified through a literature search (N = 26). The clinical manifestations and genetic variants of all the patients were evaluated.

Results

Hypospadias was the most prevalent phenotype among our 10 cases (8 out of 10 cases) and in all the previously reported ones. Central precocious puberty and isolated micropenis were observed for the first time. Among the 10 cases, nine variants were identified, including three nonsense (p.R356X, p.Q152X, and p.Q124X) and six missense (p.P334S, p.S662R, p.A421P,p.T992I, p.P542S, and p.R927L) variants. In silico analysis showed that the variants p.P334S, p.P542S, p.S662R, and p.R927Lmight lead to drastic changes in the interaction force of the amino acid chain and the flexibility of the spatial structure, and such changes may affect protein function.

Conclusion

Patients with 46,XY DSD harbouring MAMLD1variants manifest a broad spectrum of phenotypes and mostly present with hypospadias. The six novel variants reported here enrich the mutation database and contribute to our understanding of the pathogenesis of 46,XY DSD.

Effectiveness of caudal epidural block on interaoperative blood loss during hypospadias repair: A randomized clinical trial

BACKGROUND

Intraoperative blood loss is considered to be an important issue in hypospadias surgery. Some studies have demonstrated the utility of caudal epidural block (CEB) in this regard among pediatric patients with hypospadias. Though there is evidence in favor of the use of CEB as the only anesthetic method for pediatric surgeries, it is usually used in combination with general anesthesia. In this form of use, it could have more favorable outcomes for both intra- and postoperative periods. There are few studies regarding the effectiveness of CEB on intraoperative blood loss.

OBJECTIVE

We aimed to evaluate the utility of CEB on blood loss, operation time, and analgesic use during hypospadias repairs of pediatric population referred to our university hospitals.

STUDY DESIGN

In this randomized clinical trial, consecutive patients with hypospadias who were candidate for surgery were enrolled and randomly allocated to one of the two groups: group A received caudal epidural block (CEB) plus general anesthesia (GA) before surgery and group B received only GA. Intraoperative blood loss, operation time, and dose of fentanyl used during the procedure were recorded and compared. All surgeries were performed by a single pediatric urologist in two different university hospitals that was not blinded to the study groups.

RESULTS

In this study, 57 pediatric patients with hypospadias who underwent surgical repair were studied, from which 29 and 28 patients were allocated to receive or not to receive preoperative CEB, respectively. The patients' age, weight, ASA, score and severity of hypospadias were not significantly different between the two groups. The operation time was significantly lower in the CEB before surgery group (p < 0.05). The mean dose of fentanyl and volume of blood loss during procedure were lower in the CEB group, although for fentanyl it approached but did not reach statistical significance.

CONCLUSION

The findings of current study indicated that caudal epidural anesthesia in addition to general anesthesia has a favorable effect on reducing blood loss during operation, operation time, and analgesic use. Our data confirm the findings of previous studies in this field. Further studies are recommended to evaluate the effect of this type of analgesia in other outcomes of hypospadias repair surgery. Our results could be used for revising existing surgical guidelines for better management of hypospadias.

Management of failed hypospadias: choosing the right method and achieving optimal results

OBJECTIVE

Because of the complexity of the abnormalities and limited options for reconstruction of failed hypospadias, creating a neourethra presents a challenge to surgeons. We reviewed our experiences with staged urethroplasty strategies to repair the penis of failed hypospadias.

MATERIALS AND METHODS

We retrospectively reviewed 56 consecutives patients following multiple unsuccessful hypospadias repairs from 2010 to 2016. Patients were divided into the following two groups based on their penile conditions and urethroplasty procedures: staged buccal mucosa graft Bracka urethroplasty (group1) and two-stage urethroplasty with additional buccal mucosa graft augmentation of the dorsal urethral plate (group2).

RESULT

Median follow-ups were 26.5 months (12-59 months) and 28.6 months (14-59 months) in the group 1 and group 2. After the second stage, three patients (11.1%) in group 1 and two patients (6.89%) in group 2 did not have a meatal opening at the top of the glans. Three patients (11.1%) in group 1 and 4 patients (13.79%) in group 2 had urethrocutaneous fistulas. One patient (3.70%) in group 1 and no patients in group 2 had meatal stenosis. Two patients (6.89%) in group 2 and no patients in group 1 had urethral strictures; all patients with strictures were cured using dilations, so follow-up surgeries were not required. No patients in either group had signs of diverticulum or residual chordee. Three patients (11.1%) in group 1 and 4 patients (13.79%) in group 2 needed reoperations.

CONCLUSION

Failed hypospadias repairs were often due to the underestimation of the penile conditions at the prior surgery. The results indicated that two-staged strategies were preferred for treating complex situations during the intermediate period of our study. Staged buccal mucosa graft Bracka urethroplasty and two-stage urethroplasty with additional buccal mucosa graft augmentation of the dorsal urethral plate severed as reliable approaches in complex hypospadias cases and could improve the overall success rate.

Description of a novel variant in the MAMLD1 gene in isolated hypospadias

Introduction Hypospadias is a multifactorial malformation. Among previously described genes, the MAMLD1 has recently been identified in association with the development of hypospadias. So far, there are no studies in Latin America addressing this gene. The aim of this paper is to describe the presence of variants in exon 3 of the MAMLD1 in our population.

Materials and Methods Using the Bio-Repository's database of the Human Genetics Institute, we identified 51 patients between 2008 and 2012 with varying degrees of isolated hypospadias. Exon 3 was sequenced looking for polymorphisms. These were assessed with in silico prediction algorithms to describe the effect of these changes on the function and structure of the protein.

Results Four patients with 3 variants were identified. The p.S364P variant has not been previously described and has a deleterious effect. The other two, rs41313406 and rs61740566, have been previously described and are not considered variations with harmful effect on the protein function. The genotype-phenotype correlation varies in severity between the variables described.

Conclusions For the first time a Latin American population is molecularly analyzed. The p.S364P variation has never been described before. Variations with different degrees of hypospadias are described.

Current Status of Tissue Engineering in the Management of Severe Hypospadias

Hypospadias, characterized by misplacement of the urinary meatus in the lower side of the penis, is a frequent birth defect in male children. Because of the huge variation in the anatomic presentation of hypospadias, no single urethroplasty procedure is suitable for all situations. Hence, many surgical techniques have emerged to address the shortage of tissues required to bridge the gap in the urethra particularly in the severe forms of hypospadias. However, the rate of postoperative complications of currently available surgical procedures reaches up to one-fourth of the patients having severe hypospadias. Moreover, these urethroplasty techniques are technically demanding and require considerable surgical experience. These limitations have fueled the development of novel tissue engineering techniques that aim to simplify the surgical procedures and to reduce the rate of complications. Several types of biomaterials have been considered for urethral repair, including synthetic and natural polymers, which in some cases have been seeded with cells prior to implantation. These methods have been tested in preclinical and clinical studies, with variable degrees of success. This review describes the different urethral tissue engineering methodologies, with focus on the approaches used for the treatment of hypospadias. At present, despite many significant advances, the search for a suitable tissue engineering approach for use in routine clinical applications continues.

Associations of TGFBR1 and TGFBR2 gene polymorphisms with the risk of hypospadias: a case-control study in a Chinese population

This case-control study investigated the association of transforming growth factor-β (TGF-β) receptor type I and II (TGFBR1 and TGFBR2) gene polymorphisms with the risk of hypospadias in a Chinese population. One hundred and sixty two patients suffering from hypospadias were enrolled as case group and 165 children who underwent circumcision were recruited as control group. Single nucleotide polymorphisms (SNPs) in TGFBR1 and TGFBR2 genes were selected on the basis of genetic data obtained from HapMap. PCR-restriction fragment length polymorphism (PCR-RFLP) was performed to identify TGFBR1 and TGFBR2 gene polymorphisms and analyze genotype distribution and allele frequency. Logistic regression analysis was conducted to estimate the risk factors for hypospadias. No significant difference was found concerning the genotype and allele frequencies of TGFBR1 rs4743325 polymorphism between the case and control groups. However, genotype and allele frequencies of TGFBR2 rs6785358 in the case group were significantly different in contrast with those in the control group. Patients carrying the G allele of TGFBR2 rs6785358 polymorphism exhibited a higher risk of hypospadias compared with the patients carrying the A allele (P<0.05). The TGFBR2 rs6785358 genotype was found to be significantly related to abnormal pregnancy and preterm birth (both P<0.05). The frequency of TGFBR2 rs6785358 GG genotype exhibited significant differences amongst patients suffering from four different pathological types of hypospadias. Logistic regression analysis revealed that preterm birth, abnormal pregnancy, and TGFBR2 rs6785358 were the independent risk factors for hypospadias. Our study provides evidence that TGFBR2 rs6785358 polymorphism might be associated with the risk of hypospadias.

Can a graft be placed over a flap in complex hypospadias surgery? An experimental study in rabbits

Purpose:

To develop a rabbit experimental study to test the hypothesis that surgical repair of hypospadias with severe ventral curvatures might be completed in one stage, if a graft, such as buccal mucosa, could be placed over the tunica vaginalis flap used in corporoplasty for ventral lengthening, with the addition of an onlay preputial island flap to complete the urethroplasty.

Materials and methods:

The experimental procedure with rabbits included a tunica vaginalis flap for reconstruction of the corpora after corporotomy, simulating a ventral lengthening operation. A buccal mucosa graft was placed directly on top of the flap, and the urethroplasty was completed with an onlay preputial island flap. Eight rabbits were divided into 4 groups, sacrificed at 2, 4, 8 and 12 weeks postoperatively, and submitted to histological evaluation.

Results:

We observed a large number of complications, such as fistula (75%), urinary retention (50%) and stenosis (50%). There were two deaths related to the procedure. Histological evaluation demonstrated a severe and persistent inflammatory reaction. No viable tunica vaginalis or buccal mucosa was identified.

Conclusions:

In this animal model, the association of a buccal mucosa graft over the tunica vaginalis flap was not successful, and resulted in complete loss of both tissues.

ECLAMC Study: Prevalence patterns of hypospadias in South America: Multi-national analysis over a 24-year period

OBJECTIVE

To evaluate prevalence trends of hypospadias in South-America it is essential to perform multicenter and multinational studies with the same methodology. Herein we present systematic data as part of an international multicenter initiative evaluating congenital malformations in South America over a 24-year period.

MATERIALS AND METHODS

A nested case-control study was conducted using the Latin American Collaborative Study of Congenital Malformations (ECLAMC), between January 1989 and December 2012. Cases were stratified as isolated (IH) and non-isolated hypospadias (NIH). Global prevalence was calculated and discriminated by country. Associations between birth weight and gestational age, and NIH distribution by associated abnormality and severity of hypospadias, were analyzed.

RESULTS

A total of 159 hospitals from six countries participated, reporting surveillance on 4.020.384 newborns. A total of 4.537 hypospadias cases were detected, with a global prevalence of 11.3/10.000 newborns. Trend analyses showed in Chile, Brazil and Uruguay a statistically significant increase in prevalence. Analysis of severity and associated anomalies did not to find an association for distal cases, but did for proximal (RR=1.64 [95% CI=1.33-2.03]).

CONCLUSION

This is one of only a few Latin American multicenter studies reporting on the epidemiology of hypospadias in South America in the last two decades. Our data adds to evidence suggesting an increase in some countries in the region at different times. There were also variations in prevalence according to severity. This study adds to literature describing associated anomalies at a hospital-based level.

Molecular Mechanism of MicroRNA-200c Regulating Transforming Growth Factor-β (TGF-β)/SMAD Family Member 3 (SMAD3) Pathway by Targeting Zinc Finger E-Box Binding Homeobox 1 (ZEB1) in Hypospadias in Rats

Background

The aim of this study was to explore effects of microRNA-200c regulating TGF-β/Smad3 pathway by targeting Zeb1 on the occurrence and development of hypospadias and to evaluate the relationship between microRNA-200c and occurrence of hypospadias.

Material/Methods

Pregnant rats with a gestational age of 12 days were allocated into 2 groups; one received gavage of DEHP-contained soybean oil (1 ml/day, 8 days; Group A) and the other had gavage of normal soybean oil (1 ml/day, 8 days; Group B). Baby rats with hypospadias from Group A were assigned to the model group (n=20) and healthy baby rats from Group B were assigned to the control group (n=20). Real-time quantitative polymerase chain reaction (qRT-PCR), immunohistochemistry and Western blot analysis were performed to detect microRNA-200c, Zeb1, TGF-β, and Smad3 mRNA and protein expressions in the model group (n=20) and the control group (n=20). The relationship between microRNA-200c and Zeb1 was detected using a dual-luciferase reporter gene experiment. After the in vitro intervention experiment in fetal rat penises, Western blot was used to detect the expression of Zeb1, TGF-β, and Smad3.

Results

In the model group, microRNA-200c was expressed at a low level, and microRNA-200c expression in control group was 2.1 times higher than in the model group (P<0.05). When compared with the control group, mRNA expressions, protein expressions, and positive rates of Zeb1, TGF-β, and Smad3 were higher in the model group (all P<0.01). Luciferase gene report determined that Zeb1 is a target gene of microRNA-200c. The in vitro intervention experiment in fetal rat penises found that a high concentration of microRNA-200c inhibited hypospadias occurrence by suppressing the expression of Zeb1, TGF-β, and Smad3.

Conclusions

MicroRNA-200c was expressed in hypospadias penis tissues at low levels and was negatively correlated with Zeb1 expression. MicroRNA-200c up-regulated Zeb1 expression to regulate the TGF-β/Smad3 pathway, which led to the occurrence of hypospadias.

Association between SNP12 in estrogen receptor α gene and hypospadias: a systematic review and meta-analysis

To investigate the association between single nucleotide polymorphism 12 in estrogen receptor α gene and hypospadias, four databases (PubMed, Web of Science, Embase and Cochrane Library) were electronically searched by 2nd November 2015. Finally, four studies were included for our meta-analysis, involving 1379 cases and 1648 controls. A quality assessment was performed using the Newcastle–Ottawa Scale of case–control study. Meta-analysis and publication bias measuring were all done by Stata 12.0. No significant publication bias (P_Begg = 0.296, P_Egger = 0.161) was found. Overall, there was statistically significant association for recessive genetic model (AA vs. GA + GG: OR 3.45, 95 % CI [1.89, 6.30], P = 0.038). Moreover, the positive result was confirmed using trial sequential analysis even only three original studies. For allele model, there was also statistically significant association (allele A vs. G: OR 1.43, 95 % CI [1.23, 1.67], P = 0.034). Meanwhile, A allele as a risk factor turned out to be true positive by trial sequential analysis. In a word, this meta-analysis suggested that the single nucleotide polymorphism 12 definitely increase the risk of hypospadias.

Male infants with hypospadias and/or cryptorchidism show a lower 2D/4D digit ratio than normal boys

BACKGROUND

In humans the ratio of the index finger to the ring finger is sexually dimorphic, with the mean ratio being larger in women than in men. It has been suggested that this difference is related to prenatal androgen exposure. This has been further demonstrated in children with congenital adrenal hyperplasia. Normal development of the male external genitalia is linked to androgen-mediated events during gestation. We therefore wanted to determine if the 2D:4D digit ratio was normal in boys with cryptorchidism or hypospadias.

METHODS

We prospectively enrolled all prepubertal patients seen in the outpatient clinic for cryptorchidism or hypospadias between September and December 2012. We then compared their 2D:4D digit ratio with two control groups made up of normal boys and normal girls. Interobserver and intraobserver variability was evaluated.

RESULTS

We included 57 boys with hypospadias and/or cryptorchidism, 79 boys without genital abnormalities and 25 girls without genital abnormalities. The mean 2D:4D ratio for both hands was significantly different between the three groups, with the digit ratio for boys with genital anomalies being lower than for normal boys and normal girls (p<0.0001).

CONCLUSIONS

It appears that boys with genital abnormalities (cryptorchidism and/or hypospadias) have a lower 2D:4D digit ratio than boys without genital anomalies.

Sexually dimorphic expression of Mafb regulates masculinization of the embryonic urethral formation

Masculinization of external genitalia is an essential process in the formation of the male reproductive system. Prominent characteristics of this masculinization are the organ size and the sexual differentiation of the urethra. Although androgen is a pivotal inducer of the masculinization, the regulatory mechanism under the control of androgen is still unknown. Here, we address this longstanding question about how androgen induces masculinization of the embryonic external genitalia through the identification of the v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog B (Mafb) gene. Mafb is expressed prominently in the mesenchyme of male genital tubercle (GT), the anlage of external genitalia. MAFB expression is rarely detected in the mesenchyme of female GTs. However, exposure to exogenous androgen induces its mesenchymal expression in female GTs. Furthermore, MAFB expression is prominently down-regulated in male GTs of androgen receptor (Ar) KO mice, indicating that AR signaling is necessary for its expression. It is revealed that Mafb KO male GTs exhibit defective embryonic urethral formation, giving insight into the common human congenital anomaly hypospadias. However, the size of Mafb KO male GTs is similar with that of wild-type males. Moreover, androgen treatment fails to induce urethral masculinization of the GTs in Mafb KO mice. The current results provide evidence that Mafb is an androgen-inducible, sexually dimorphic regulator of embryonic urethral masculinization.

Intrauterine growth restriction and hypospadias: is there a connection?

Hypospadias is one of the most common congenital malformations of the genitourinary tract in males. It is an incomplete fusion of urethral folds early in fetal development and may be associated with other malformations of the genital tract. The etiology is poorly understood and may be hormonal, genetic, or environmental, but most often is idiopathic or multifactorial. Among many possible risk factors identified, of particular importance is low birth weight, which is defined in various ways in the literature. No mechanism has been identified for the association of low birth weight and hypospadias, but some authors propose placental insufficiency as a common inciting factor. Currently, there is no standardized approach for evaluating children with hypospadias in the setting of intrauterine growth restriction. We reviewed the available published literature on the association of hypospadias and growth restriction to determine whether it should be considered a separate entity within the category of disorders of sexual differentiation.

Association between maternal age and birth defects of unknown etiology: United States, 1997-2007

BACKGROUND

Birth defects affect 3% of babies born, and are one of the leading causes of infant mortality. Both younger and older maternal age may pose increased risks for certain birth defects. This study assessed the relationship between maternal age at the estimated delivery date and the risk for birth defects.

METHODS

Data were obtained from the National Birth Defects Prevention Study, a population-based case-control study including mothers across 10 states. Maternal age was stratified into six categories: <20, 20 to 24, 25 to 29, 30 to 34, 35 to 39, and ≥40 years, and also analyzed as a continuous variable. Logistic regression models adjusted formaternal race/ethnicity, education, body mass index (BMI), folic acid use, smoking, gravidity, and parental age difference were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

For maternal age <20 years, associations with total anomalous pulmonary venous return (aOR, 2.3; 95% CI, 1.3-4.0), amniotic band sequence (aOR, 2.4; 95% CI, 1.5-3.8), and gastroschisis (aOR, 6.1; 95% CI, 4.8-8.0) were observed. For the ≥40 year age group, associations with several cardiac defects, esophageal atresia (aOR, 2.9; 95% CI, 1.7-4.9), hypospadias (aOR, 2.0; 95% CI, 1.4-3.0), and craniosynostosis (aOR, 1.6; 95% CI, 1.1-2.4) were observed. Results using maternal age as a continuous variable were consistent with those that used categorized maternal age.

CONCLUSION

Elucidating risk factors specific to women ateither extreme of maternal age may offer prevention opportunities. All women should be made aware of prevention opportunities, such as folic acid supplementation, to reduce the occurrence of birth defects.

Diacylglycerol kinase K variants impact hypospadias in a California study population

PURPOSE

A recent genome wide association study demonstrated the novel finding that variants in DGKK are associated with hypospadias. Our objectives were to determine whether this finding could be replicated in a more racially/ethnically diverse study population of California births and to provide a more comprehensive investigation of variants.

MATERIALS AND METHODS

We examined the association of 27 DGKK single nucleotide polymorphisms with hypospadias relative to population based nonmalformed controls born in selected California counties from 1990 to 2003. Analyses included a maximum of 928 controls and 665 cases (mild in 91, moderate in 336, severe in 221 and undetermined in 17). Results for mild and moderate cases were similar, so they were grouped together.

RESULTS

For mild and moderate cases OR for 15 of the 27 single nucleotide polymorphisms had p values less than 0.05, with 2 less than 1 and the others ranging from 1.3 to 1.8. Among severe cases ORs tended to be closer to 1, and none of the p values were less than 0.05. Due to high linkage disequilibrium across the single nucleotide polymorphisms, haplotype analyses were conducted and 2 blocks were generated. These analyses identified a set of 8 variants associated with a threefold to fourfold increased risk relative to the most common haplotype, regardless of severity of the phenotype (OR 4.1, p <10(-4) for mild to moderate cases and 3.3, p = 0.001 for severe cases).

CONCLUSIONS

This study confirms that DGKK variants are associated with hypospadias. Additional studies are needed to allow a more thorough investigation of DGKK variability and to delineate the mechanism by which DGKK contributes to urethral development.

Nutritional factors and hypospadias risks

BACKGROUND

We examined whether hypospadias was associated with several aspects of the diet, including intake of animal products, intake of several nutrients and food groups related to a vegetarian diet and oestrogen metabolism, and diet quality.

METHODS

The study included deliveries from 1997 to 2005 that were part of the National Birth Defects Prevention Study. Diet was assessed by food frequency questionnaire during maternal telephone interviews, and two diet quality indices were developed based on existing indices. Analyses included 1250 cases with second- or third-degree hypospadias (urethra opened at the penile shaft, scrotum or perineum) and 3118 male, liveborn, non-malformed controls. All odds ratios (OR) and 95% confidence intervals [CI] were estimated from logistic regression models that included several potential confounders, including energy intake.

RESULTS

Intake of animal products was not associated with hypospadias; for example, the adjusted OR for any vs. no intake of meat was 1.0 [95% CI 0.6, 1.6]. Frequency of intake of meat or other animal products was also not associated with hypospadias, nor was intake of iron or several nutrients that are potentially related to oestrogen metabolism. Diet quality was also not associated with hypospadias; the OR for diet quality in the highest vs. lowest quartile for the two diet quality indices were 1.0 [95% CI 0.6, 1.6] and 0.9 [95% CI 0.7, 1.1].

CONCLUSION

This large study does not support an association of a vegetarian diet or worse diet quality with hypospadias.

Environmental and genetic contributors to hypospadias: a review of the epidemiologic evidence

This review evaluates current knowledge related to trends in the prevalence of hypospadias, the association of hypospadias with endocrine-disrupting exposures, and the potential contribution of genetic susceptibility to its etiology. The review focuses on epidemiologic evidence. Increasing prevalence of hypospadias has been observed, but such increases tend to be localized to specific regions or time periods. Thus, generalized statements that hypospadias is increasing are unsupported. Owing to the limitations of study designs and inconsistent results, firm conclusions cannot be made regarding the association of endocrine-disrupting exposures with hypospadias. Studies with more rigorous study designs (e.g., larger and more detailed phenotypes) and exposure assessment that encompasses more breadth and depth (e.g., specific endocrine-related chemicals) will be critical to make better inferences about these important environmental exposures. Many candidate genes for hypospadias have been identified, but few of them have been examined to an extent that enables solid conclusions. Further study is needed that includes larger sample sizes, comparison groups that are more representative of the populations from which the cases were derived, phenotype-specific analyses, and more extensive exploration of variants. In conclusion, examining the associations of environmental and genetic factors with hypospadias remain important areas of inquiry, although our actual understanding of their contribution to hypospadias risk in humans is currently limited.

Polymorphisms of MAMLD1 gene in hypospadias

PURPOSE

Mastermind-like domain containing 1 (MAMLD1) is a causative gene for the fetal development of male external genitalia. Almost 10% of patients with both severe and non-severe hypospadias exhibit mutations of MAMLD1. The aim of this work was to determine whether polymorphisms of MAMLD1 are a genetic risk factor for hypospadias.

MATERIAL AND METHODS

This study included 150 hypospadias with a range of severities and 150 controls. Direct sequencing of the MAMLD1 coding exons and their flanking splice sites was performed. In silico secondary and tertiary structure prediction and accessibility of changed amino acids were evaluated using JPred, Netsurf and PHYRE software. Functional studies of the transactivation of haplotypes on Hes3 promoter were performed in vitro using cDNAs of missense variants of MAMLD1.

RESULTS

The p.P286S polymorphism was identified in 17/150 patients and 12/150 controls (11.3% vs. 8.0%, p = 0.32). The p.N589S polymorphism was identified in 22/150 patients and 12/150 controls (14.6% vs. 8.0%, p = 0.068). The double polymorphism (S-S haplotype) was present in 16/150 patients and 6/150 controls (10.6% vs. 4.0%, p = 0.044, OR = 2.87, CI from 1.09 to 7.55). The association of polymorphisms consistently revealed a modification in the structure prediction or amino acid accessibility in all three in silico models. The P286S, N589S and P286S + N589S proteins did not exhibit reduced transactivating activity on Hes3 promoter.

CONCLUSION

Polymorphisms of MAMLD1 gene are frequent in patients with hypospadias. Although no change in transactivation was noted on Hes3 promoter, the in silico studies and the significantly increased incidence of the S-S haplotype in hypospadiac patients raise the hypothesis of a particular susceptibility conferred by these variants.

Abnormalities of the penis in utero--hypospadias on fetal MRI

OBJECTIVE

To demonstrate the visualization of penile abnormalities on fetal magnetic resonance imaging (MRI).

METHODS

This retrospective study included five fetuses (25+0 to 31+6 gestational weeks) with penile abnormalities, positively depicted on fetal MRI, using prenatal ultrasonography (US) as a standard of reference. On MRI, the penis, as well as the scrotum and testicles, were evaluated. All fetal organs were reviewed to define penile abnormalities as isolated or in association with other anomalies. Furthermore, US and MRI findings were compared.

RESULTS

Posterior hypospadias were demonstrated in all five fetuses, and abnormal testicular descent in two. Associated anomalies were present in all five fetuses on MRI, including abdominal/urogenital pathologies in four; brain pathologies in three; and craniofacial, cardiac, musculoskeletal, pathologies each in one fetus, and intrauterine growth retardation in one fetus. Compared to US, additional MRI findings were shown in four of five fetuses.

CONCLUSIONS

Our MRI results demonstrate the visualization of fetal penile abnormalities and associated pathologies, which may provide information for perinatal management. MRI may show additional findings compared to prenatal US in certain cases.

Analysis of the Wilms' tumor suppressor gene (WT1) in patients 46,XY disorders of sex development

CONTEXT

The Wilms' tumor suppressor gene (WT1) is one of the major regulators of early gonadal and kidney development. WT1 mutations have been identified in 46,XY disorders of sex development (DSD) with associated kidney disease and in few isolated forms of 46,XY DSD.

OBJECTIVE

The objective of the study was the evaluation of WT1 mutations in different phenotypes of isolated 46,XY DSD and clinical consequences.

DESIGN

The design of the study was: 1) sequencing of the WT1 gene in 210 patients with 46,XY DSD from the German DSD network, consisting of 150 males with severe hypospadias (70 without cryptorchidism, 80 with at least one cryptorchid testis), 10 males with vanishing testes syndrome, and 50 raised females with partial to complete 46,XY gonadal dysgenesis; and 2) genotype-phenotype correlation of our and all published patients with 46,XY DSD and WT1 mutations.

RESULTS

We have detected WT1 mutations in six of 80 patients with severe hypospadias (7.5%) and at least one cryptorchid testis and in one of 10 patients with vanishing testes syndrome (10%). All patients except one developed Wilms' tumor and/or nephropathy in childhood or adolescence.

CONCLUSION

WT1 analysis should be performed in newborns with complex hypospadias with at least one cryptorchid testis and in isolated 46,XY partial to complete gonadal dysgenesis. Kidney disease might not develop until later life in these cases. WT1 analysis is mandatory in all 46,XY DSD with associated kidney disease. WT1 analysis is not indicated in newborns with isolated hypospadias without cryptorchidism. Patients with WT1 mutations should be followed up closely because the risk of developing a Wilms' tumor, nephropathy, and/or gonadal tumor is very high.

Hypospadias: interactions between environment and genetics

Hypospadias is one of the most common congenital malformations. It is considered to be a mild form of the 46,XY disorders of sex development (DSD), but its precise etiology remains to be elucidated. Compromised androgen synthesis or effects can cause this frequent malformation, although the mutational analyses of the genes involved in androgen actions have identified abnormalities in only a very small portion of patients. The overwhelming majority of cases remain unexplained and hypospadias may be a highly heterogeneous condition subject to multiple genetic and environmental factors. We here review the recent advances in this field and discuss the potential interactions between the environment and genetics.

Congenital anomalies in the baboon (Papio spp.)

BACKGROUND

A comprehensive survey of the prevalence of congenital anomalies in baboons has not been previously reported. We report the congenital anomalies observed over a 26-year period in a large captive baboon colony.

METHODS

A computer search was performed for all baboon congenital anomalies identified at necropsy and recorded on necropsy submissions.

RESULTS

We identified 198 congenital anomalies in 166 baboons from 9972 necropsies (1.66% of total necropsies). The nervous, urogenital, musculoskeletal, and cardiovascular systems were most commonly affected. The most common organs affected were the brain, bone, heart, testicle, kidney, penis, aorta, and skeletal muscle. The most frequent congenital anomalies were blindness, seizures, and hydrocephalus.

CONCLUSIONS

The baboon has an overall frequency of congenital anomalies similar to humans and other non-human primates. Although the most frequently affected systems are similar, congenital anomalies involving the digestive system appear to be less common in the baboon.

Human balanced translocation and mouse gene inactivation implicate Basonuclin 2 in distal urethral development

We studied a man with distal hypospadias, partial anomalous pulmonary venous return, mild limb-length inequality and a balanced translocation involving chromosomes 9 and 13. To gain insight into the etiology of his birth defects, we mapped the translocation breakpoints by high-resolution comparative genomic hybridization (CGH), using chromosome 9- and 13-specific tiling arrays to analyze genetic material from a spontaneously aborted fetus with unbalanced segregation of the translocation. The chromosome 13 breakpoint was ∼400  kb away from the nearest gene, but the chromosome 9 breakpoint fell within an intron of Basonuclin 2 (BNC2), a gene that encodes an evolutionarily conserved nuclear zinc-finger protein. The BNC2/Bnc2 gene is abundantly expressed in developing mouse and human periurethral tissues. In all, 6 of 48 unrelated subjects with distal hypospadias had nine novel nonsynonymous substitutions in BNC2, five of which were computationally predicted to be deleterious. In comparison, two of 23 controls with normal penile urethra morphology, each had a novel nonsynonymous substitution in BNC2, one of which was predicted to be deleterious. Bnc2(-/-) mice of both sexes displayed a high frequency of distal urethral defects; heterozygotes showed similar defects with reduced penetrance. The association of BNC2 disruption with distal urethral defects and the gene's expression pattern indicate that it functions in urethral development.