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

Maternal PM2.5 exposure and hypospadias risk in Chinese offspring: Insights from a nationwide surveillance-based study

Research on the association between maternal PM2.5 exposure and hypospadias risk in male offspring, particularly in highly polluted areas, has been limited and inconsistent. This study leveraged data from China's National Population-based Birth Defects Surveillance System spanning the years 2013 to 2019, and employed sophisticated machine learning models to estimate daily PM2.5 levels and other pollutants for mothers at a 1-km resolution and a 6-km buffer surrounding maternal residences. Multivariate logistic regression analyses were performed to evaluate the relationship between PM2.5 exposure and hypospadias risk. For sensitivity analyses, stratification analysis was conducted, and models for one-pollutant and two-pollutants, as well as distributed lag nonlinear models, were constructed. Of the 1194,431 boys studied, 1153 cases of hypospadias were identified. A 10 μg/m3 increase in maternal PM2.5 exposure during preconception and the first trimester was associated with an elevated risk of isolated hypospadias, with Odds Ratios (ORs) of 1.102 (95% CI: 1.023-1.188) and 1.089 (95% CI: 1.007-1.177) at the 1-km grid, and 1.122 (95% CI: 1.034-1.218) and 1.143 (95% CI: 1.048-1.246) within the 6-km buffer. Higher quartiles of PM2.5 exposure were associated with increased odds ratios compared to the lowest quartile. These findings highlight a significant association between PM2.5 exposure during the critical conception period and an elevated risk of isolated hypospadias in children, emphasizing the need for targeted interventions to reduce PM2.5 exposure among expectant mothers.

Association between CACNA1D polymorphisms and hypospadias in a southern Chinese population

BACKGROUND

Hypospadias is a congenital genitourinary malformation, with the etiology remaining complex and poorly understood. Despite several genes have been identified to be associated with the risk of hypospadias, current understanding of the susceptibility loci for hypospadias yet remained largely improved. The CACNA1D gene encodes calcium voltage-gated channel subunit alpha 1d and may be involved in androgen signaling. However, the genetic susceptibility of CACNA1D associated with hypospadias has yet been addressed.

OBJECTIVE

To evaluate the association between CACNA1D polymorphisms and the susceptibility to hypospadias.

METHODS

In this study, we accessed the association between two potential regulatory SNPs (rs3774491 and rs898415) within CACNA1D and hypospadias in a cohort of southern Chinese population which comprised of 740 cases and 948 healthy individuals. Both SNP and haplotypic associations were evaluated. Bioinformatic analysis of the regulatory abilities of the CACNA1D SNPs were carried out by utilizing public ChIP-seq and DNase-seq data. The expression of Cacna1d in mouse external genitalia and testis was evaluated by qPCR.

RESULTS

We found that the allele C in rs3774491 and allele G in rs898415 were significantly associated with an increased risk of hypospadias, especially for proximal hypospadias. Further model-based genotypic analyses showed that these association were prominent in additive model and recessive models. Bioinformatic analyses indicated that both SNPs were colocalized with DNase and multiple histone marker across multiple tissues, suggesting the regulatory potentials for these variants. Cacna1d is detectable in both testis and external genitalia of mouse, but the expression level was more prominent in testis than that in external genitalia, suggesting tissue-specific differences in its expression.

CONCLUSION

Our findings provide evidence for CACNA1D as a novel predisposing gene for hypospadias, shedding new light on the genetic basis of malformation of urinary tract. Further investigations are warranted to elucidate the functional implication of CACNA1D underlying the development of hypospadias.

LEVEL OF EVIDENCE

N/A.

Lesions of the prepuce and penis in rams: A retrospective study

In the ovine reproductive management, a thorough breeding soundness evaluation including specific inspection of the male genital tract represents a valuable tool for assessing the reproductive potential of a selected subject and for diagnosing genital disorders. During examination, accurate inspection on penis and prepuce is necessary, since conditions affecting these structures may hamper regular coitus. Records from 1270 males undergoing breeding soundness evaluation (n = 1232) or admitted for genital disorders to the Section of Obstetrics and Gynaecology (n = 38) of the Department of Veterinary Medicine, were collected, and lesions of penis and prepuce were therefore classified. The data collected revealed that 47/1270 rams examined presented lesions of the penis and prepuce. The most frequent condition was urolithiasis accounting for over 2% of the cases, followed by lack of the urethral process (0.39% incidence), lack of the glans penis and hypospadias (0.23% cases). Moreover, most of the conditions (40%) were observed in animals less than 2 years old, suggesting the importance of a careful breeding soundness evaluation in animals at young age.

Whole-exome sequencing study of hypospadias

Hypospadias results from the impaired urethral development, which is influenced by androgens, but its genetic etiology is still unknown. Through whole exome sequencing analysis, we identified NR5A1, SRD5A2, and AR as mutational hotspots in the etiology of severe hypospadias, as these genes are related to androgen signaling. Additionally, rare damaging variants in cilia-related outer dynein arm heavy chain (ODNAH) genes (DNAH5, DNAH8, DNAH9, DNAH11, and DNAH17) (p = 8.5 × 10-47) were significantly enriched in hypospadias cases. The Dnah8 KO mice exhibited significantly decreased testosterone levels, which had an impact on urethral development and disrupted steroid biosynthesis. Combined with trios data, transcriptomic, and phenotypical and proteomic characterization of a mouse model, our work links ciliary genes with hypospadias. Overall, a panel of ODNAH genes with rare damaging variants was identified in 24% of hypospadias patients, providing significant insights into the underlying pathogenesis of hypospadias as well as genetic counseling.

Hypospadias and the Use of the Ages and Stages Questionnaire to Evaluate Neurodevelopmental Status of Boys with Hypospadias

INTRODUCTION

 Placental insufficiency is one of the reasons for the reduction of hormone production. Thus, if one of the suspected causes of hypospadias is placental insufficiency, then the neurodevelopmental status of boys with hypospadias may be impaired. The aim of this study was to evaluate the neurodevelopmental status of boys with hypospadias and guide the parents of those who need support to related departments for early intervention.

MATERIALS AND METHODS

 Boys were divided into two groups, those with hypospadias (group H) and healthy children undergoing traditional circumcision (group C). The parents of the boys completed the Ages and Stages Questionnaire (ASQ) and ASQ-Social Emotional (SE), both of which are screening instruments for the early identification of developmental and social-emotional problems, respectively.

RESULTS

 Seventy-eight boys had hypospadias and 59 were admitted for traditional circumcision. The group H had statistically significant more impaired scores than group C in communication, gross motor, and personal-social skill sections. The multivariate logistic regression analysis revealed that hypospadias was the independent predictive factor for communication and personal-social skills.

CONCLUSION

 Hypospadias and neurologic impairment may share common etiologic factors. Accordingly, physicians should keep in mind that if a boy presents with hypospadias, the possibility of having neurologic impairment is higher than normal population and early intervention has crucial importance. Every boy with hypospadias should be evaluated for neurodevelopmental status.

Adult distal hypospadias repair is safe and easy

The success level of hypospadias repair in adults still needs to be established on a more extensive scaled study. Therefore, we conducted this study to document the success level of hypospadias repair in adults. This study presents the results of 620 adult distal hypospadias patients treated with TIPU operation. A retrospective study was performed for adult patients who underwent TIPU operations from February 2016 to September 2020. Patients who had distal hypospadias after the age of 16 were included in our study. The average operation time was between 35 and 65 min (50 min.). Complications developed in 79 (12.7%) patients: 37 urethral fistulas, 24 meatal stenosis, 11 anastomotic stenosis and 7 had a complete failure. In conclusion, primary adult distal hypospadias surgery is safe and easy. The complication rates are similar when compared to the paediatric group. As the surgical experience advances, the success of the operation increases in direct proportion.

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.

HAAO rs3816183 Polymorphisms [T] Increase Anterior/Middle Hypospadias Risk in Southern Han Chinese Population

Hypospadias is one of the most common congenital external genital malformations, which is characterized by abnormal urethral meatus. However, the etiology remains to be incompletely understood. HAAO is a gene that encodes a protein, which catalyzes the synthesis of quinolinic acid, and has been identified as a risk gene for hypospadias. Thus, this study was conducted to elaborate the association between HAAO gene polymorphism rs3816183 T>C and hypospadias in the largest hypospadias cohort from Asia, including 577 patients and 654 healthy controls in China. The strength of interrelation was evaluated using 95% confidence intervals (CIs) and odds ratios (ORs). Based on the stratified analysis of hypospadias subtypes, it was found that the HAAO risk allele rs386183[T] enhances the susceptibility for hypospadias among patients with anterior/middle hypospadias subtypes (adjusted OR = 1.31, 95% CI = 1.05-1.64, p = 0.017). Enhanced risk of hypospadias in the entirety could not be demonstrated (OR = 1.20, 95% CI = 1.00-1.47, p = 0.054). In summary, our study found that the rs3816183[T] polymorphism is associated with increased risk of anterior/middle hypospadias among Southern Han Chinese children. The mechanisms by which the variations in the HAAO gene require further research.

A mixture of 15 phthalates and pesticides below individual chemical no observed adverse effect levels (NOAELs) produces reproductive tract malformations in the male rat

Humans carry residues of multiple synthetic chemicals at any given point in time. Research has demonstrated that compounds with varying molecular initiating events (MIE) that disrupt common key events can act in concert to produce cumulative adverse effects. Congenital defects of the male reproductive tract are some of the most frequently diagnosed malformations in humans and chemical exposures in utero can produce these effects in laboratory animals and humans. Here, we hypothesized that in utero exposure to a mixture of pesticides and phthalates, each of which produce male reproductive tract defects individually, would produce cumulative effects even when each chemical is present at a no observed adverse effect level (NOAEL) specific for male reproductive effects. Pregnant Sprague-Dawley rats were exposed via oral gavage to a fixed-ratio dilution mixture of 5 pesticides (vinclozolin, linuron, procymidone, prochloraz, pyrifluquinazon), 1 pesticide metabolite (dichlorodiphenyldichloroethylene (DDE)), and 9 phthalates (dipentyl, dicyclohexyl, di-2-ethylhexyl, dibutyl, benzyl butyl, diisobutyl, diisoheptyl, dihexyl, and diheptyl) during the critical window of rat fetal masculinization (gestation day 14-18). The top dose (100% dose) contained each compound at a concentration 2-fold greater than the individual chemical NOAEL followed by a dilution series that represented each chemical at NOAEL, NOAEL/2, NOAEL/4, NOAEL/8, NOAEL/15, NOAEL/100, NOAEL/1000. Reduced fetal testis gene expression occurred at NOAEL/15, reduced fetal testis testosterone production occurred at NOAEL/8, reduced anogenital distance, increased nipple retention, and delayed puberty occurred at NOAEL/4, and severe effects including genital malformations and weight reductions in numerous reproductive tissues occurred at NOAEL/2. This study demonstrates that these phthalates and pesticides acted cumulatively to produce adverse effects at doses below which any individual chemical had been shown to produce an effect alone and even though they have different MIEs.

The role of sonic hedgehog homologue signal pathway in hypospadias aetiology

INTRODUCTION

Hypospadias is one of the most common congenital anomalies of the male genitalia. Sonic hedgehog homologue (SHH) signalling pathway is believed to be involved in the development of the male genital system.

OBJECTIVE

In this clinical prospective study, the role of the SHH pathway in hypospadias aetiology was investigated.

STUDY DESIGN

In this study, 200 healthy children (boys without hypospadias, control group), 118 patients (boys with distal hypospadias) and 82 patients (boys with proximal hypospadias) of age 0-16 years were included. The expression of the genes suppressor of fused protein (SUFU), SHH, protein patched homologue (PTCH; PTCH1 and PTCH2), glioma-associated oncogene homologue (GLI; GLI1, GLI2, GLI3 and GLI4), smoothened, frizzled-class receptor (SMO) and serine/threonine-protein kinase 36 (STK36) that are involved in SHH pathway were investigated. Furthermore, polymorphism analyses of GLI2, SHH and PTCH1 genes were performed. The history of hypospadias in the first and second-degree relatives of the patients in boys with distal hypospadias and boys with proximal hypospadias was inquired.

RESULTS

Ten patients in the boys with distal hypospadias and twenty patients in the boys with proximal hypospadias had a history of hypospadias in first or second-degree relatives (p < 0.05). There was a significant decrease in mRNA expressions of SHH and PTCH1 genes in boys with proximal hypospadias compared to boys without hypospadias (p < 0.05). Besides, a significant decrease in mRNA fold-change of GLI2 gene was detected in boys with both distal hypospadias and proximal hypospadias compared to boys without hypospadias (p < 0.05). In contrast, there was no significant difference in the mRNA fold-changes of PTCH2, SUFU, GLI1, GLI3, GLI4, SMO and STK36 genes among the groups. Moreover, there were no significant differences in the frequencies of variant genotypes and alleles rs735557, rs12711538 and rs4848632 (GLI2 gene), rs104894049 (SHH gene) and rs41313327 (PTCH1 gene) (p > 0.05).

DISCUSSION

SHH expression is required for the growth and differentiation of the genital bulge. Developmental defects in the external genital organs were demonstrated in mice with SHH deletion. It has been demonstrated that SHH mainly plays a role in the formation of sinusoid morphology of the penis. In the present study, although SHH and PTCH gene expressions were found to be decreased only in the penile tissues of proximal hypospadias, GLI2 gene expression was decreased in penile tissues of boys with both distal hypospadias and boys with proximal hypospadias.

CONCLUSION

Genes involved in the SHH pathway might play a role in the aetiology of hypospadias. Furthermore, there is a correlation between molecular defects in this pathway and severity of hypospadias.

Characterization With Gene Mutations in Han Chinese Patients With Hypospadias and Function Analysis of a Novel AR Genevariant

It is estimated that around 10-20% of hypospadias are caused by genetic abnormalities worldwide although the spectrum of associated genes does vary across different ethnicities. The prevalence of hypospadias among the Chinese population has been increasing the last couple of decades. However, the pathogenesis underlying the disease and its associated genetic abnormality remains unclear. Here we performed a genetic analysis of 81 children with karyotype 46, XY and the hypospadias phenotype in order to characterize the genetic components that contribute to the development of hypospadias in Chinese patients. 15 candidate genes, including sex determination genes-SOX9, SRY, NR0B1 (DAX1), NR5A1 (SF1), DHH, sex differentiation genes-AR, SRD5A2, MAMLD1, INSL3, and hypospadias-associated genes-FGF8, FGF10, BMP4, BMP7, ATF3, and MID1 were screened by using next generation sequencing. A total of 18 patients were found to have mutations identified by PCR and sequencing, including 11 cases of SRD5A2 genes, 6 cases of AR genes, and 1 case of MID1 gene, respectively. One novel missense mutation p.I817N was discovered in AR gene. Further molecular analysis found that subcellular localization of the AR_{I 81 7N} was the same as that of wild type AR_WT in the absence or presence of hormone. But it led to 50% reduction in AR-induced transcriptional activity in the presence of either the synthetic androgen R1881 or the natural ligand dihydrotestosterone. Our results indicate that SRD5A2 and AR genes are two top candidate genes associated with 46, XY hypospadias in Chinese patients. Further epidemiological and genetic analysis are still needed to further clarify the pathogenesis of hypospadias in Han Chinese patients.

Increased hypospadias risk by GREM1 rs3743104[G] in the southern Han Chinese population

Hypospadias is a common congenital genitourinary malformation characterized by ventral opening of the urethral meatus. As a member of the bone morphogenic protein antagonist family, GREM1 has been identified as associated with susceptibility to hypospadias in the European population. The present study was designed to elaborate on the mutual relationship between replicated single-nucleotide polymorphisms (SNPs) and hypospadias in Asia's largest case-control study in the Southern Han Chinese population involving 577 patients and 654 controls. Our results demonstrate that the GREM1 risk allele rs3743104[G] markedly increases the risk of mild/moderate and severe hypospadias (P<0.01, 0.28≤OR≤0.66). GTEx expression quantitative trait locus data revealed that the eQTL SNP rs3743104 has more associations of eQTL SNP rs3743104 and GREM1 targets in pituitary tissues. Additionally, Bioinformatics and Luciferase Assays show that miR-182 is identified as a suppressor for GREM1 expression, likely through regulation of its binding affinity to rs3743104 locus. In conclusion, the GREM1 risk allele rs3743104[G] increases hypospadias susceptibility in mild/moderate and severe cases among the southern Han population. rs3743104 regulates GREM1 expression by altering the binding affinity of miR-182 to their locus. Collectively, this study provides new evidence that GREM1 rs3743104 is associated with an increased risk of hypospadias. These findings provide a promising biomarker and merit further exploration.

Association between prenatal air pollution exposure and risk of hypospadias in offspring: a systematic review and meta-analysis of observational studies

Background: The findings of associations between prenatal air pollution exposure and hypospadias risk in offspring are inconsistent. No systematic review or meta-analysis has yet summarized the present knowledge on the aforementioned topic.

Methods: Relevant manuscripts were identified by searching PubMed and Web of Science databases through January 31, 2020. Summary odds ratios (ORs) with 95% confidence intervals (CIs) in meta-analyses were estimated based on a random effects model. Publication bias was evaluated by funnel plots, Begg’s test, and Egger’s test.

Results: The search identified 3,032 relevant studies. Sixteen studies cumulatively involving 21,701 hypospadias cases and 1,465,364 participants were included. All of these studies were classified as having a low risk of bias. We classified pollutants as nitrogen oxides, particulate matter (PM), ozone, and other exposures. The exposure window to pollutants varied from three months before conception to seven days after delivery. In the meta-analyses, only PM_2.5 exposure in the first trimester was related to increased risk of hypospadias (per 10 μg/m³ OR = 1.34; 95% CI: 1.06–1.68).

Conclusion: We found evidence for an effect of PM_2.5 exposure on hypospadias risk. Improvements in the areas of study design, exposure assessment, and specific exposure window are needed to advance this field.

A Microphysiological Approach to Evaluate Effectors of Intercellular Hedgehog Signaling in Development

Paracrine signaling in the tissue microenvironment is a central mediator of morphogenesis, and modeling this dynamic intercellular activity in vitro is critical to understanding normal and abnormal development. For example, Sonic Hedgehog (Shh) signaling is a conserved mechanism involved in multiple developmental processes and strongly linked to human birth defects including orofacial clefts of the lip and palate. SHH ligand produced, processed, and secreted from the epithelial ectoderm is shuttled through the extracellular matrix where it binds mesenchymal receptors, establishing a gradient of transcriptional response that drives orofacial morphogenesis. In humans, complex interactions of genetic predispositions and environmental insults acting on diverse molecular targets are thought to underlie orofacial cleft etiology. Consequently, there is a need for tractable in vitro approaches that model this complex cellular and environmental interplay and are sensitive to disruption across the multistep signaling cascade. We developed a microplate-based device that supports an epithelium directly overlaid onto an extracellular matrix-embedded mesenchyme, mimicking the basic tissue architecture of developing orofacial tissues. SHH ligand produced from the epithelium generated a gradient of SHH-driven transcription in the adjacent mesenchyme, recapitulating the gradient of pathway activity observed in vivo. Shh pathway activation was antagonized by small molecule inhibitors of epithelial secretory, extracellular matrix transport, and mesenchymal sensing targets, supporting the use of this approach in high-content chemical screening of the complete Shh pathway. Together, these findings demonstrate a novel and practical microphysiological model with broad utility for investigating epithelial-mesenchymal interactions and environmental signaling disruptions in development.

Expression of Mafb is down-regulated in the foreskin of children with hypospadias

BACKGROUND

Hypospadias is the second most common congenital malformation in males. Although the aetiology of hypospadias is not clear, it is generally thought to be affected by both genetic and environmental endocrine-disrupting factors that affect the development of the urethra, leading to deformity.

OBJECTIVE

To investigate the difference in expression of the transcription factor Mafb in hypospadias and normal penile tissues and to assess whether it is related to the occurrence of hypospadias.

STUDY DESIGN

Penile tissue was obtained from children with hypospadias who underwent surgical repair at the Children's Hospital of Chongqing Medical University. Patients diagnosed with undescended testicles, intersex status or endocrine abnormalities were excluded from the study. Twenty-five cases with hypospadias (average 3.5 years old) and 15 cases with circumcisions (as control) (average 5 years old) were included in this study. Real-time quantitative polymerase chain reaction, Immunochemistry and Western blot were used to detect the expression of Mafb.

RESULTS

Mafb mRNA expressions in the prepuce of cases with hypospadias was significantly reduced compared with that in the controls [(1.179 ± 0.1275), (0.6652 ± 0.07506), p < 0.05)]. Hypospadias cases also showed decreased Mafb protein expression in the preputial subcutaneous mesenchymal cell layer. Mafb protein levels were significantly decreased in those with hypospadias compared with controls [(1.932 ± 0.1139), (1.006 ± 0.03312), p < 0.05]. However, no such differences were found in Mafb expression between subjects with mild and severe hypospadias.

DISCUSSION

Compared to the normal foreskin, expression of the Mafb gene was down-regulated at both mRNA and protein levels, which was consistent with our RNA-seq sequencing results in Diethylhexyl phthalate (DEHP)-induced hypospadias rats. This study is the first to report abnormal expression of Mafb in the preputial tissue of hypospadias cases. An in-depth study of the relationship between Mafb and cell proliferation, apoptosis, and urethra development may reveal the pathogenesis of hypospadias.

CONCLUSION

Expression of the Mafb gene and protein in the foreskin of children with hypospadias is lower than that in normal foreskin. We postulate that such abnormal expression of the Mafb gene may be related to the occurrence of hypospadias and that this abnormal expression may affect the development of the urethra during the embryonic period.

WITHDRAWN: Hypospadias induced by medications and environmental exposures- A scoping review

This article has been withdrawn as the request of the author(s) and/or Editors. The Publisher apologizes for any inconvenience this may cause.

Association between prenatal exposure to ambient particulate matter and risk of hypospadias in offspring: A systematic review and meta-analysis

BACKGROUND

Epidemiological studies on whether prenatal exposure to PM_2.5, PM_2.5-10, and PM₁₀ increases the risk of hypospadias are limited and the results are inconsistent.

OBJECTIVES

We conducted this systematic review and meta-analysis to evaluate these associations.

METHODS

Relevant studies were identified by searching the PubMed and Embase databases up to the end of February 2020. Observational studies that investigated the relationships between prenatal exposure to PM₁₀, PM_2.5, and PM_2.5-10 and the risk of hypospadias in offspring were eligible for the review. The risk of bias was evaluated using the Newcastle-Ottawa scale. Random-effects models were used to estimate pooled relative risks (RRs) and 95% confidence intervals (CIs) for the associations.

RESULTS

Nine studies (two cohort and seven case-control studies) with a total of 2806 hypospadias cases were included. Eight studies were at low risk of bias and only one study was at high risk of bias. Five studies reported the association between per interquartile range increase in PM_2.5 exposure within the first trimester and the risk of hypospadias. The pooled RR was 1.17 (95% CI: 1.00, 1.36). Two studies reported the per interquartile range increase in PM_2.5 exposure during 1 month before pregnancy associated with the risk of hypospadias, with a pooled RR of 1.25 (95% CI: 1.03, 1.51). No association was observed between PM_2.5-10 and PM₁₀ exposure during pregnancy and the risk of hypospadias in offspring.

CONCLUSION

This study suggested a modest association between prenatal PM_2.5 exposure during 1 month before pregnancy or within the first trimester and the risk of hypospadias in offspring. Further large-scale cohort studies are required to verify this association.

Endocrine disrupting chemicals and reproductive disorders in women, men, and animal models

This chapter covers the known effects of endocrine disrupting chemicals (EDCs) on reproductive disorders. The EDCs represented are highly studied, including plasticizers (bisphenols and phthalates), chemicals in personal care products (parabens), persistent environmental contaminants (polychlorinated biphenyls), and chemicals in pesticides or herbicides. Both female and male reproductive disorders are reviewed in the chapter. Female disorders include infertility/subfertility, irregular reproductive cycles, early menopause, premature ovarian insufficiency, polycystic ovarian syndrome, endometriosis, and uterine fibroids. Male disorders include infertility/subfertility, cryptorchidism, and hypospadias. Findings from both human and animal studies are represented.

Maternal Exposure to Disinfection By-Products and Risk of Hypospadias in the National Birth Defects Prevention Study (2000-2005)

The purpose of this study was to estimate the association between 2nd and 3rd degree hypospadias and maternal exposure to disinfection by-products (DBPs) using data from a large case-control study in the United States. Concentration estimates for total trihalomethanes (TTHMs), the sum of the five most prevalent haloacetic acids (HAA5), and individual species of each were integrated with data on maternal behaviors related to water-use from the National Birth Defects Prevention Study (NBDPS) to create three different exposure metrics: (1) household DBP concentrations; (2) estimates of DBP ingestion; (3) predicted uptake (i.e., internal dose) of trihalomethanes (THMs) via ingestion, showering, and bathing. The distribution of DBP exposure was categorized as follows: (Q1/referent) < 50%; (Q2) ≥ 50% to < 75%; and (Q3) ≥ 75%. Logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Generally, null associations were observed with increasing TTHM or HAA5 exposure. An increased risk was observed among women with household bromodichloromethane levels in the second quantile (aOR: 1.8; 95% CI: 1.2, 2.7); however, this association did not persist after the inclusion of individual-level water-use data. Findings from the present study do not support the hypothesis that maternal DBP exposures are related to the occurrence of hypospadias.

Ontogeny of estrogen receptors in human male and female fetal reproductive tracts

This paper reviews and provides new observations on the ontogeny of estrogen receptor alpha (ESR1) and estrogen receptor beta (ESR2) in developing human male and female internal and external genitalia. Included in this study are observations on the human fetal uterine tube, the uterotubal junction, uterus, cervix, vagina, penis and clitoris. We also summarize and report on the ontogeny of estrogen receptors in the human fetal prostate, prostatic urethra and epididymis. The ontogeny of ESR1 and ESR2, which spans from 8 to 21 weeks correlates well with the known "window of susceptibility" (7-15 weeks) for diethylstilbestrol (DES)-induced malformations of the human female reproductive tract as determined through examination of DES daughters exposed in utero to this potent estrogen. Our fairly complete mapping of the ontogeny of ESR1 and ESR2 in developing human male and female internal and external genitalia provides a mechanistic framework for further investigation of the role of estrogen in normal development and of abnormalities elicited by exogenous estrogens.

Prevalence rates study of selected isolated non-Mendelian congenital anomalies in the Hutterite population of Alberta, 1980-2016

A study of the prevalence rates for selected isolated non-Mendelian congenital anomalies in the Hutterite Brethren of Alberta, Canada was undertaken to further examine longitudinal data in this isolated community that was last reported in 1985 (Lowry et al., 1985), although there are numerous publications on recessive disorders (Boycott et al., 2008; Triggs-Raine et al., 2016). Cases were ascertained from the Alberta Congenital Anomaly Surveillance System for the years 1997-2016. Since our initial results showed some surprising findings in the Hutterite Brethren, such as zero cases of spina bifida, cleft lip and palate, gastroschisis, and omphalocele, and a significant excess of cases with hypospadias, we extended the study to prior years (1980-1996) for selected anomalies. For the extended study period (1980-2016), there was a significant increased prevalence of hypospadias, tetralogy of Fallot and tricuspid atresia in the Hutterite population, and although not statistically significant, zero cases of cleft lip with cleft palate, gastroschisis and omphalocele were confirmed. Further research is needed to determine the precise effects of rural environmental exposures, lifestyle factors, and genetic associations for selected multifactorial congenital anomalies.

Altered mechanisms of genital development identified through integration of DNA methylation and genomic measures in hypospadias

Hypospadias is a common birth defect where the urethral opening forms on the ventral side of the penis. We performed integrative methylomic, genomic, and transcriptomic analyses to characterize sites of DNA methylation that influence genital development. In case–control and case-only epigenome-wide association studies (EWAS) of preputial tissue we identified 25 CpGs associated with hypospadias characteristics and used one-sample two stage least squares Mendelian randomization (2SLS MR) to show a causal relationship for 21 of the CpGs. The largest difference was 15.7% lower beta-value at cg14436889 among hypospadias cases than controls (EWAS P = 5.4e−7) and is likely causal (2SLS MR P = 9.8e−15). Integrative annotation using two-sample Mendelian randomization of these methylation regions highlight potentially causal roles of genes involved in germ layer differentiation (WDHD1, DNM1L, TULP3), beta-catenin signaling (PKP2, UBE2R2, TNKS), androgens (CYP4A11, CYP4A22, CYP4B1, CYP4X1, CYP4Z2P, EPHX1, CD33/SIGLEC3, SIGLEC5, SIGLEC7, KLK5, KLK7, KLK10, KLK13, KLK14), and reproductive traits (ACAA1, PLCD1, EFCAB4B, GMCL1, MKRN2, DNM1L, TEAD4, TSPAN9, KLK family). This study identified CpGs that remained differentially methylated after urogenital development and used the most relevant tissue sample available to study hypospadias. We identified multiple methylation sites and candidate genes that can be further evaluated for their roles in regulating urogenital development.

The Success Level of Hypospadias Repair in Adults

Introduction

Hypospadias is the abnormal opening of the urethra at the undersurface of the penis. Hypospadias repair is performed in such patients to treat the condition. The success level of hypospadias repair in adults still needs to be established on a larger scale. Therefore, we conducted this study to document the success level of hypospadias repair in adults in our setting to add to the literature.

Materials and methods

This prospective study was conducted at a major metropolitan hospital in Karachi over a period of six months. A total of 75 male patients aged between 20-50 years and diagnosed with hypospadias of any level with or without mild to moderate chordee were included. Demographic features such as age and the duration of hypospadias were noted. Hypospadias repair using a tubularized incised plate (TIP) urethroplasty technique was performed, and the patients were observed for three days in the ward and for three months in the outpatient department for any complications. The procedure was considered a success if there were no complications and no need for a second surgery; we also took into account patient satisfaction with the procedure to determine the success level. The mean and standard deviation were calculated for patient age and the duration of hypospadias. Frequency and percentages were calculated for distribution of patient age, distribution of the duration of hypospadias, and the success of hypospadias repair. The correlation of patient age and the duration of hypospadias with the success of hypospadias repair was also determined by applying the Chi-square test, and a p-value of ≤0.05 was considered to be statistically significant.

Results

The mean age and the duration of hypospadias for the study population were the same at 31.43 ± 8.47 years. Distribution of patient age and the duration of hypospadias was also the same with 51 (68%) patients of ≤35 years of age and 24 (32%) patients of >35 years of age. Hypospadias repair was successful in 52 (69.33%) patients but unsuccessful in 23 (30.66%). The stratification of patient age and the duration of hypospadias with the success of hypospadias repair showed a significant inverse relationship (p = 0.017). The data relating to patient age and the duration of hypospadias showed the same values as hypospadias is a birth defect.

Conclusion

Adult patients undergoing primary hypospadias repair generally show good outcomes. However, the chances of favorable outcomes gradually decrease with age. Hence, patients should be encouraged to undergo the procedure as early in their lives as possible. Patients who are middle-to-old aged should especially be counseled about the relatively higher risk of unsuccessful procedures. Further analysis is needed to confirm the validity of these findings.

New frontiers on the molecular underpinnings of hypospadias according to severity

Hypospadias, which is characterised by the displacement of the urethral meatus from its typical anatomical location in males, shows various degrees of severity. In this systematic review, we surveyed our current understanding of the genetics of isolated hypospadias in humans according to the severity of the condition. We found that sequencing and genotyping approaches were the preferred methods of study and that single nucleotide polymorphisms were the most common finding associated with hypospadias. Most genes fell into four gene-pathway categories related to androgens, oestrogens, growth factors, or transcription factors. Few hypospadias studies classify their findings by severity. Taken together, we argue that it is advantageous to take into consideration the severity of the condition in search of novel candidates in the aetiology of hypospadias. Abbreviations: AR: androgen receptor; ATF3: activating transcription factor 3; BMP4: bone morphogenetic protein 4; BMP7: bone morphogenetic protein 7; CYP17: steroid 17-alpha-hydroxylase/17,20 lyase; CYP1A1: cytochrome P450 1A1; CYP3A4: cytochrome P450 3A4; CNVs: copy number variants; DGKK: diacylglycerol kinase kappa; ESR1: oestrogen receptor 1; ESR2: oestrogen receptor 2; FGF8: fibroblast growth factor 8; FGF10: fibroblast growth factor 10; FGFR2: fibroblast growth factor receptor 2; HOXA4: homeobox protein Hox-A4; HOXB6: homeobox protein Hox-B6; HSD17B3: hydroxysteroid 17-beta dehydrogenase 3; MAMLD1: mastermind-like domain-containing protein 1; SF-1: splicing factor 1; SHH: sonic hedgehog; SNPs: single nucleotide polymorphisms; SOX9: SRY-box 9; SRD5A2: steroid 5 alpha-reductase 2; SRY: sex-determining region Y protein; STAR: steroidogenic acute regulatory protein; STARD3: StAR-related lipid transfer protein 3; STS: steryl-sulfatase; WT1: Wilms tumour protein; ZEB1: zinc finger oestrogen-box binding homeobox 1.

Periconceptional exposure to air pollution and congenital hypospadias among full-term infants

BACKGROUND

Evidence regarding whether prenatal exposure to air pollution increases the risk of hypospadias remains limited. The aim of the study is to evaluate the association between exposure to ambient air pollution during early pregnancy and the incidence of hypospadias.

METHODS

We conducted a 1:10 case-control study using the Taiwanese Birth Registry database. Male full-term infants reported to have hypospadias were defined as cases, and controls were randomly selected from male full-term infants without any congenital anomaly. The monthly average of ambient air pollutants, including PM₁₀, PM_2.5, PM_2.5-10, NO₂, NOx, O₃, and O₃ 8-h maximum, from 3 months before conception to 6 months post conception was retrieved from air quality monitoring stations and interpolated to the level of township using the kriging method. Multivariable logistic regression models were utilized to evaluate the associations.

RESULTS

A total of 200 hypospadias cases, with 2000 healthy controls sampled, were reported during 2007-2014. The results revealed that PM_2.5 exposure during the first 3 months after conception (odds ratio [OR] = 1.29, 95% confidence interval [CI]: 1.01-1.65, per interquartile range [IQR] = 15.6 μg/m³) and O₃ exposure during the first month after conception (OR = 1.40, 95% CI: 1.08-1.82, per IQR = 8.0 ppb) were associated with a higher incidence of hypospadias.

CONCLUSIONS

The results of the study suggest that early gestational exposure to ambient air pollution increases the risk of hypospadias among full-term infants.

TGF-β1 relieves epithelial-mesenchymal transition reduction in hypospadias induced by DEHP in rats

BACKGROUNDS

To investigate the potential mechanism of hypospadias induced by DEHP in rats to reveal the preventative effect of TGF-β1 in hypospadias induced by DEHP via the reduction of EMT.

METHODS

Time-mated Sprague-Dawley rats underwent cesarean section, and the penises of male pups were collected after exposure to corn oil or DEHP to establish a rat model of hypospadias and to further study the molecular mechanisms of hypospadias in vivo. In addition, the penises were cultured and treated with MEHP or MEHP+TGF-β1 in vitro. Subsequently, histomorphology and elements in TGF-β/Smad signaling pathway changes were evaluated using scanning electron microscopy, immunofluorescence, polymerase chain reaction, and western blot.

RESULTS

The development of rat penis and urethral seam fusion were delayed after the treatment with DEHP in vivo or MEHP in vitro compared with the Control group. Moreover, TGF-β1, Smad2/Smad3, and the mesenchymal biomarkers, including α-SMA, N-cadherin, and Vimentin, were decreased. However, the epithelial biomarkers, including E-cadherin, ZO-1, β-catenin, and occludin, were increased. In addition, TGF-β1 could relieve all of the above changes.

CONCLUSION

Gestational DEHP exposure could lead to hypospadias by reducing urethral EMT. Moreover, TGF-β1 could prevent it by regenerating EMT through activating the TGF-β/Smad signal pathway.

FGF8, FGF10 and FGF receptor 2 in foreskin of children with hypospadias: an analysis of immunohistochemical expression patterns and gene transcription

INTRODUCTION

Fibroblast growth factors (FGFs) play a crucial role in early embryogenesis of the genital tubercle and are involved in the development of hypospadias, affecting both endo- and ectodermally derived tissues. It was hypothesized that expression of FGFs could be qualitatively or quantitatively altered in skin of children with hypospadias.

OBJECTIVE

The objective of the study was to investigate expression patterns and transcription levels of FGF8, FGF10, and FGF Receptor 2 (FGFR2) in patients with hypospadias compared to normal controls.

PATIENTS AND METHODS

Skin samples from the ventro-lateral aspect of the foreskin of 32 patients with hypospadias (17 distal and 15 proximal, mean age 25 months) and 10 normal foreskin samples (mean age 77 months) were analyzed by immunohistochemistry. Staining, localization, and distribution of positive cells in epidermis and dermis were categorized independently by two researchers. Complementary DNA (cDNA) samples prepared from messenger RNA (mRNA) isolates of the same samples were analyzed by quantitative polymerase chain reaction (qPCR), comparing expressions of FGF8, FGF10, and FGFR2 with loading controls.

RESULTS

Patients with hypospadias consistently showed aberrant immunohistochemical staining patterns for FGF8/FGF10/FGFR2 in epidermis and dermis compared to patients without penile malformation (p < 0.01 for all markers). qPCR displayed no difference in expression levels on mRNA level (FGFR2 p = 0.44, FGF8 p = 0.77, and FGF10 p = 0.17) comparing normal foreskin with foreskin from patients with hypospadias. Figure.

DISCUSSION

The results point at an impact of FGF signaling during embryological development of hypospadias on skin, as an ectodermally derived tissue. Similar to the urethral development, this might be a result of mesothelial-epithelial interactions. The differing expression patterns in immunohistochemistry are not matched by a quantitative difference in marker expression on the mRNA level, putatively caused by post-translational modifications or alterations of the downstream pathway. FGFs, particularly FGF10 and FGFR2, are critically involved in wound healing.

CONCLUSIONS

There are significant differences in localization and distribution of FGF8, FGF10, and FGFR2 in comparisons of normal foreskin to foreskin of patients with hypospadias, whereas there is no difference in the quantitative expression of these markers on the mRNA level. This confirms the notion that penile skin is affected as well by the embryological aberrations during the embryogenesis of hypospadias.

Severity-Dependent Profile of the Metabolome in Hypospadias

Background & Objective: Hypospadias, characterized by the displacement of the opening of the urethra at any point in the medial-ventral side of the penis, is classified upon severity as mild (Type I) and severe (Type II and Type III) hypospadias. Hypospadias' etiology is idiopathic in the majority of cases, and underlying causes seem of multifactorial origin. Studies regarding genetic variants support this notion. It is unknown whether downstream gene products fit this profile. This study evaluated the metabolome of hypospadias by using the emerging technology of metabolomics in the search for distinct cellular processes associated with hypospadias' etiology according to the severity of this congenital urogenital condition. Methods: Foreskin samples were collected during urethroplasty from boys with Type I, II, and III hypospadias or undergoing elective circumcision (N = 28) between 5 and 28 months of age. Samples were processed and submitted to gas chromatography-mass spectrometry (GC/MS). MetaboloAnalyst (http://www.metaboanalyst.ca/) online platform was used for bioinformatic analyses. Results: Thirty-five metabolites across experimental groups were identified by GC/MS. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) showed that the metabolome of Type II and Type III hypospadias patients differs from the metabolome of Type I hypospadias and control patients. Of those 35, 10 amino acids were found in significantly low concentrations in severe hypospadias: aspartate, glutamate, glycine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, and tyrosine. A high concentration of the amino acid lysine was detected in mild hypospadias. Conclusions: The observed downregulation of specific amino acids in severe hypospadias provides alternative routes for future research aiming to identify disrupted networks and pathways while considering the severity of hypospadias.

Genome-wide association study in Chinese cohort identifies one novel hypospadias risk associated locus at 12q13.13

Background

Hypospadias risk–associated gene variants have been reported in populations of European descent using genome-wide association studies (GWASs). There is little known at present about any possible hypospadias risk associations in Han Chinese populations.

Methods

To systematically investigate hypospadias risk–associated gene variants in Chinese patients, we performed the first GWAS in a Han Chinese cohort consisting of 197 moderate-severe hypospadias cases and 933 unaffected controls. Suggestive loci (p < 1 × 10^− 4) were replicated in 118 cases and 383 controls, as well as in a second independent validation population of 137 cases and 190 controls. Regulatory and protein-protein interactions (PPIs) were then conducted for the functional analyses of candidate variants.

Results

We identified rs11170516 with the risk allele G within the SP1/SP7 region that was independently associated with moderate-severe hypospadias [SP1/SP7, rs11170516, P_combine = 3.5 × 10^− 9, odds ratio (OR) = 1.96 (1.59–2.44)]. Results also suggested that rs11170516 is associated with the expression of SP1 as a cis-expression quantitative trait locus (cis-eQTL). Protein SP1 could affect the risk of hypospadias via PPIs.

Conclusions

We performed the first GWAS of moderate-severe hypospadias in a Han Chinese cohort, and identified one novel susceptibility cis-acting regulatory locus at 12q13.13, which may regulate a variety of hypospadias-related pathways by affecting proximal SP1 gene expression and subsequent PPIs. This study complements known common hypospadias risk-associated variants and provides the possible role of cis-acting regulatory variant in causing hypospadias.

Genome-wide association studies of structural birth defects: A review and commentary

BACKGROUND

While there is strong evidence that genetic risk factors play an important role in the etiologies of structural birth defects, compared to other diseases, there have been relatively few genome-wide association studies (GWAS) of these conditions. We reviewed the current landscape of GWAS conducted for birth defects, noting novel insights, and future directions.

METHODS

This article reviews the literature with regard to GWAS of structural birth defects. Key defects included in this review include oral clefts, congenital heart defects (CHDs), biliary atresia, pyloric stenosis, hypospadias, craniosynostosis, and clubfoot. Additionally, other issues related to GWAS are considered, including the assessment of polygenic risk scores and issues related to genetic ancestry, as well as utilizing genome-wide single nucleotide polymorphism array data to evaluate gene-environment interactions and Mendelian randomization.

RESULTS

For some birth defects, including oral clefts and CHDs, several novel susceptibility loci have been identified and replicated through GWAS, including 8q24 for oral clefts, DGKK for hypospadias, and 4p16 for CHDs. Relatively common birth defects for which there are currently no published GWAS include neural tube defects, anotia/microtia, anophthalmia/microphthalmia, gastroschisis, and omphalocele.

CONCLUSIONS

Overall, GWAS have been successful in identifying several novel susceptibility genes and genomic regions for structural birth defects. These findings have provided new insights into the etiologies of these phenotypes. However, GWAS have been underutilized for understanding the genetic etiologies of several birth defects.

A loss of estrogen signaling in the aromatase deficient mouse penis results in mild hypospadias

Hypospadias is the abnormal opening of the urethra on the underside of the penis and occurs in approximately 1/125 live male births worldwide. The incidence rate of hypospadias has dramatically increased over the past few decades. This is now attributed, at least in part, to our exposure to endocrine-disrupting chemicals (EDCs) which alter the hormonal signals required for development of the penis. In humans androgens are the main drivers of fusion of the urethral folds to form the urethra within the shaft of the penis, a process required for termination of the urethra in its normal location at the tip of the penis. However, recent research has suggested that estrogen also plays a role in this process. To better understand how EDCs impact urethral development it is essential that we understand the normal function of hormones during development of the penis. To define the role of estrogen in urethral development we examined development of the penis in the aromatase (Cyp19a1) Knockout (ArKO) mouse strain in which endogenous estrogen production is completely ablated. We found that the ArKO penis had a mild hypospadias phenotype. The developing ArKO postnatal penis displayed an early disruption in preputial development, which likely causes the mild hypospadias observed in adults. Using qPCR, we found altered expression of keratin genes and key urethral patterning genes in response to the disrupted estrogen signaling. The hypospadias phenotype was almost identical to that reported for the estrogen receptor α (ERα) knockout confirming that ERα is the predominant receptor for mediating estrogen action during development of the mouse penis. Our results show that estrogen is required for normal prepucial development and placement of the mature urethral opening at the distal aspect of the penis. We also identified several genes which are potential downstream targets of estrogen during normal urethral closure. With this knowledge, we can now better understand how anti-estrogenic as well as estrogenic EDCs disrupt urethral closure to cause mild hypospadias in both mice and humans.

A critical role for estrogen signaling in penis development

Hypospadias, a developmental defect of the penis, is one of the most common congenital malformations in humans. Its incidence has rapidly increased over recent decades, and this has been largely attributed to our increased exposure to endocrine-disrupting chemicals. Penis development is primarily an androgen-driven process; however, estrogen and xenoestrogens are known to affect penis development in both humans and mice. Here, we investigated the role of estrogen in the developing penis. Using a novel penis culture system, we showed that exogenous estrogen directly targets the developing penis in utero to cause hypospadias. In addition, we also uncovered an unexpected endogenous role for estrogen in normal postnatal penis development and showed that a loss of estrogen signaling results in a mild hypospadias phenotype, the most common manifestation of this disease in humans. Our findings demonstrated that both androgen and estrogen signaling are intrinsically required for normal urethral closure. These findings confirmed that penis development is not an entirely androgen-driven process but one in which endogenous estrogen signaling also plays a critical role.-Govers, L. C., Phillips, T. R., Mattiske, D. M., Rashoo, N., Black, J. R., Sinclair, A., Baskin, L. S., Risbridger, G. P., Pask, A. J. A critical role for estrogen signaling in penis development.

Psychiatric symptoms in men with hypospadias - preliminary results of a cross-sectional cohort study

AIM

Population studies have shown an increased risk of neurodevelopmental disorders in males born with the congenital condition hypospadias, where the opening of the urethra is on the underside of the penis. We investigated overall psychiatric morbidity in cases and matched controls.

METHODS

This study compared 167 men born with hypospadias from 1959 to 1994 in Stockholm or Gothenburg in Sweden using hospital registers. They were compared with controls from the Swedish population registry, who were contacted by regular mail and students who were recruited by local advertisements. The total sample had a mean age of 33.5 years (range: 19-54). They completed self-rating scales for depressive, anxiety and obsessive-compulsive symptoms and symptoms of attention deficit hyperactivity disorder. In addition, 33 cases and 47 controls underwent psychiatric morbidity interviews that covered the 17 most common psychiatric diagnoses.

RESULTS

A fifth (21%) of both the cases and controls reported current or previous psychiatric symptoms. There were no significant differences in self-rated depression, anxiety or obsessive-compulsive disorder symptoms between the patients and controls or between the different phenotype groups. The distribution was not significantly affected by the severity of hypospadias.

CONCLUSION

Psychiatric morbidity was no higher in men with hypospadias than population-based controls.

Mixed "Antiandrogenic" Chemicals at Low Individual Doses Produce Reproductive Tract Malformations in the Male Rat

Biomonitoring efforts have clearly shown that all humans are exposed to chemical mixtures. Of concern is whether or not exposure to mixtures during pregnancy contributes to congenital abnormalities in children even when each chemical is at an individual dose that does not affect the fetus. Here, we hypothesized that in utero exposure to a mixture of chemicals covering multiple "antiandrogenic" mechanisms of action at doses that individually have no adverse effect would result in permanent reproductive tract alterations in the male rat after birth. Pregnant dams were exposed to a range of dilutions (100%, 50%, 25%, 12.5%, 6.25%, or vehicle control) of a mixture containing pesticides, phthalates, and drugs (p, p'-DDE, linuron, prochloraz, procymidone, pyrifluquinazon, vinclozolin, finasteride, flutamide, simvastatin, and 9 phthalates [dipentyl, dicyclohexyl, di-2-ethylhexyl, dibutyl, benzyl butyl, diisobutyl, diisoheptyl, dihexyl, and diheptyl]). The top dose contained each chemical at 20% of its lowest observed adverse effect level (LOAEL) for the most sensitive male reproductive alteration following in utero exposure. We found that male rat offspring displayed a variety of neonatal, pubertal, and permanent adult effects across all dose levels. Even at the lowest dose (each chemical approximately 80-fold below lowest observed adverse effect level) there were permanent reductions in several reproductive tract tissue weights. In the top dose group, 100% of male offspring displayed permanent severe birth defects including genital malformations. Despite acting via 5 different molecular initiating events, a mixture of 18 chemicals can combine to produce additive effects even when each compound is at is at a relatively low dose.

The role of genetic variation in DGKK on moderate and severe hypospadias

BACKGROUND

Recent genome-wide association studies of hypospadias have implicated the role of genetic variants in or near the diacylglycerol kinase kappa (DGKK) gene. However, these variants are largely identified among samples of mild and moderate hypospadias cases. Therefore, we evaluated previously identified DGKK variants among second- and third-degree hypospadias cases and controls recruited in Arkansas, a state characterized by a high birth prevalence of hypospadias.

METHODS

Second- and third-degree hypospadias non-Hispanic white cases (n = 36 and n = 9, respectively) and controls (n = 45) were recruited at Arkansas Children's Hospital. Preputial tissue was collected on cases and controls between 2013 and 2017. Cases and controls were genotyped using the Illumina Infinium Global Screening Array. We used logistic regression models to assess the association of genotyped and imputed genetic variants mapped to the DGKK region with second- and third-degree hypospadias.

RESULTS

All families self-reported as non-Hispanic white and genetic principal component analyses did not demonstrate evidence of population stratification. Five DGKK variants previously reported as associated with hypospadias were identified in the genotype data. None of the variants were associated with second- or third-degree hypospadias (range of odds ratios = 0.7-0.9, all p > .05).

CONCLUSIONS

In our analyses, genetic variation in DGKK does not play a role in the development of moderate and severe hypospadias. Our findings provide support to the etiologic heterogeneity of hypospadias by all classifications of severity.

Risk Factors for hypospadias in Northwest Russia: A Murmansk County Birth Registry Study

Background

Hypospadias is the most common congenital anomaly of the penis, but its causes are mainly unknown. Of the risk factors identified, the most plausible are hormonal and genetic. The aim of this study was to identify risk factors for hypospadias in Northwest Russia based on registry data.

Methods

The study population included male infants registered in the Murmansk County Birth Registry between 1 January 2006 and 31 December 2011 (n = 25 475). These infants were followed-up for 2 years using the Murmansk Regional Congenital Defects Registry to identify cases of hypospadias not diagnosed at birth. We used logistic regression analysis to examine the contributions of hypospadias risk factors.

Results

Out of 25 475 male infants born during the study period, 148 had isolated hypospadias. The overall prevalence rate was 54.2 (95% CI 53.6–54.8) per 10 000 male infants. Those born to mothers with preeclampsia (OR = 1.65; 95% CI 1.03–2.66) or infant birthweight < 2500 g (OR = 2.06; 95% CI 1.18–3.60) exhibited increased risk for hypospadias. Maternal age, smoking during pregnancy, folic acid intake during pregnancy or hepatitis B surface antigen positivity did not associate with increased risk of hypospadias.

Conclusions

Combining data from a birth registry with those from a congenital defects registry provided optimal information about the prevalence of hypospadias and its association with low infant birthweight and preeclampsia. These factors have in common changes in hormone levels during pregnancy, which in turn may have contributed to hypospadias development.

Hypospadias Risk from Maternal Residential Exposure to Heavy Metal Hazardous Air Pollutants

Objective: Investigate whether residential prenatal exposure to heavy metal hazardous air pollutants (HMHAPs) is associated with an increased risk of hypospadias. Methods: Data on non-syndromic hypospadias cases (n = 8981) and control patients delivered in Texas were obtained from the Texas Birth Defects Registry and matched 1:10 by birth year. Average exposure concentrations of HMHAPs were obtained from the 2005 U.S. Environmental Protection Agency National-Scale Air Toxics Assessment and categorized into quintiles. Odds ratios and 95% confidence intervals were estimated. STROBE reporting guidelines were followed. Results: We observed associations between hypospadias and prenatal HMHAP exposure. Manganese demonstrated significant increased risk of hypospadias at the medium, medium-high and high exposure quintiles; lead in the medium-high and high exposure quintiles. Cadmium, mercury and nickel demonstrated a significant inverted "U-shaped" association for exposures with significant associations in the medium and medium-high quintiles but not in the medium-low and high quintiles. Arsenic and chromium demonstrated a significant bivalent association for risk of hypospadias in a lower quintile as well as a higher quintile with non-significant intermediate quintiles. Conclusions: Using data from one of the world's largest active surveillance birth defects registries, we identified significant associations between hypospadias and HMHAP exposures. These results should be used in counseling for maternal demographic risk factors as well as avoidance of heavy metals and their sources.

A retrospective population-based cohort study to evaluate the impact of an older sibling with undescended testis and hypospadias on the known maternal and fetal risk factors for undescended testis and hypospadias in Ontario, Canada, 1997-2007

INTRODUCTION

There are several reported risk factors for undescended testis (UDT) and hypospadias (HYP). Also, a family history of UDT or HYP has not been accounted for in prior studies, and doing so may influence these independent risk estimates.

STUDY DESIGN

A population-based retrospective cohort study was conducted using linked administrative databases in Ontario, Canada, to identify all live male newborns born between 1997 and 2007, and it was determined whether they underwent an orchidopexy or HYP repair within 5 years of birth. Baseline maternal and fetal risk factors were obtained using appropriate ICD codes. A statistical analysis using a generalized estimating equation with a logit link was performed, adjusting for clustering in mothers with a previous child born in the 5 years before the proband with UDT or HYP, to evaluate the adjusted risk factors of UDT and HYP.

RESULTS

A total of 709,968 male infants were followed up from birth for 5 years, of which 5830 underwent an orchidopexy and 2722 had an HYP repair. On multivariable analysis, factors associated with a higher risk of UDT included prematurity, small for gestational age (SGA), associated HYP, gestational hypertension, use of assisted fertility techniques, increased maternal age, Cesarean section, previous sibling with UDT, and disorders of sexual differentiation (DSDs). After adjusting for clustering in mothers with a previous baby with UDT, DSD, associated HYP (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.0-4.1), and a previous sibling with UDT (OR, 3.6; 95% CI, 2.5-5.2) remained significant risk factors. The risk factors on multivariable analysis predicting the risk of HYP included SGA, prematurity, higher income families, and associated anomalies such as UDT. After adjusting for clustering in mothers with a previous sibling with HYP, SGA (OR, 1.8; 95% CI, 1.0-3.1), higher income families (OR, 1.5-1.6), associated UDT (OR, 7.1; 95% CI, 4.9-10.0), and a previous sibling with HYP (OR, 12.8; 95% CI, 9.1-18.1) remained significant risk factors.

DISCUSSION

Studies estimating risk factors for UDT and HYP have used variable methodologies to identify index cases and perform statistical analysis. This study suggests that having an older sibling with UDT or HYP is a significant independent risk factor. Performing an analysis adjusting for clustering in mothers with a previous child with UDT or HYP leads to loss of statistical significance for other described risk factors.

CONCLUSION

Underlying genetic or similar environmental exposures may be a key risk factor for UDT and HYP, which confounds known maternal and fetal risk factors for these anomalies.

Hypospadias risk is increased with maternal residential exposure to hormonally active hazardous air pollutants

BACKGROUND

With the increasing birth prevalence of hypospadias, there is growing concern for pollutant exposure interfering with normal penile development. We assess the association between hypospadias and hormonally active hazardous air pollutants (HAHAPs) through a nationwide database of hazardous air pollutants and the Texas Birth Defects Registry (TBDR).

METHODS

Using the TBDR, we identified 8,981 nonsyndromic isolated hypospadias cases from 1999 to 2008. Birth certificate controls were matched for birth year at a 10:1 ratio to cases. Estimated HAHAP concentrations from the 2005 U.S. EPA National-Scale Air Toxics Assessment were used to assign exposure based on maternal residence at birth. Exposure levels were categorized as quintiles based on the distribution in controls. Logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (CI) for each increasing exposure category of selected HAHAPs.

RESULTS

Of the 10 HAHAPs studied, seven were significantly associated with hypospadias risk. The HAHAP that was most strongly associated with hypospadias was phenol, which was associated with risk in all groups except the high exposure group. Cumulative HAHAP exposure demonstrated a modest increase in hypospadias risk (OR 1.15, 95% CI: 1.07-1.24, p < 0.001) in the medium and medium-high quintiles.

CONCLUSIONS

While maternal exposure to some HAHAPs was significantly associated with the risk of hypospadias in male offspring, the effects were modest, and no dose-response effects were observed. Future work should employ biomarkers of exposure to better delineate the relationship.

Maternal hypertension and hypospadias in offspring: A systematic review and meta-analysis

BACKGROUND

Several studies have reported an association between maternal hypertensive disorders and hypospadias in offspring; however there is still debate on the role of maternal hypertension and preeclampsia on this relatively common congenital malformation. Therefore, we conducted a systematic review and meta-analysis to comprehensively evaluate the relationship between these frequent maternal conditions and hypospadias in offspring.

METHODS

Fifteen articles meeting the eligibility criteria were identified in our search and included in the analysis. A meta-analysis was conducted and pooled odds ratio (OR) estimates were calculated separately for hypertension and preeclampsia using meta-analysis. We also conducted several secondary analyses, including (a) studies conducted before versus after January 1, 1998; (b) studies in United States versus other countries; and (c) studies that accounted for ≥3 versus fewer or no potential confounders, among others.

RESULTS

Significant positive associations were observed between hypertension and hypospadias (OR 1.68; 95% CI 1.46-1.93), as well as preeclampsia and hypospadias (OR 2.18; 95% CI 1.63-2.91). The direction and magnitude of effect was comparable for the majority of secondary analyses conducted.

CONCLUSIONS

Our results indicate that maternal hypertensive disorders are positively associated with hypospadias in offspring. Further research is needed to better understand the mechanisms involved, and to ultimately develop public health strategies geared toward prevention of hypospadias.

Molecular genetics of hypospadias and cryptorchidism recent developments

During the last decade, a tremendous amount of work has been devoted to the study of the molecular genetics of isolated hypospadias and cryptorchidism, two minor forms of disorders of sex development (DSD). Beyond the genes involved in gonadal determination and sex differentiation, including those underlying androgen biosynthesis and signaling, new genes have been identified through genome-wide association study and familial clustering. Even if no single genetic defect can explain the whole spectrum of DSD, these recent studies reinforce the strong role of the genetic background in the occurrence of these defects. The timing of signaling disruption may explain the different phenotypes.

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.

Association between diacylglycerol kinase kappa variants and hypospadias susceptibility in a Han Chinese population

Previous genome-wide association studies have identified variants in the diacylglycerol kinase kappa (DGKK) gene associated with hypospadias in populations of European descent. However, no variants of DGKK were confirmed to be associated with hypospadias in a recent Han Chinese study population, likely due to the limited number of single-nucleotide polymorphisms (SNPs) included in the analysis. In this study, we aimed to address the inconsistent results and evaluate the association between DGKK and hypospadias in the Han Chinese population through a more comprehensive analysis of DGKK variants. We conducted association analyses for 17 SNPs in or downstream of DGKK with hypospadias among 322 cases (58 mild, 113 moderate, 128 severe, and 23 unknown) and 1008 controls. Five SNPs (rs2211122, rs4554617, rs7058226, rs7063116, and rs5915254) in DGKK were significantly associated with hypospadias (P < 0.05), with odds ratios (ORs) of 1.64-1.76. When only mild and moderate cases were compared to controls, 10 SNPs in DGKK were significant (P < 0.05), with ORs of 1.56-2.13. No significant SNP was observed when only severe cases were compared to controls. This study successfully implicated DGKK variants in hypospadias risk among a Han Chinese population, especially for mild/moderate cases. Severe forms of hypospadias are likely due to other genetic factors.

Epithelial-mesenchymal transformation and apoptosis in rat urethra development

BackgroundTo examine the mechanism of urethral seam formation during embryonal development of rat urethra.MethodsTime-mated Sprague-Dawley rats were killed and the genital tubercles of male pups harvested on embryonic day (ED) 15, 16, 18, and 19. External morphology was observed under scanning electron microscope. Serial transverse sections were prepared to examine dynamic changes in the urethral seam morphology with hematoxylin-eosin staining, immunohistochemistry, transmission electron microscopy, and double immunofluorescence.ResultsBilateral outgrowth of urethral swelling followed by urethral plate fusion in the midline to form urethral seam was observed from ED 16 onwards. Coexpression of epithelial and mesenchymal markers was observed in several cells at the urethral seam; a few cells with coexpression of epithelial and apoptotic markers were also observed. Mesenchymal transformation of epithelial cells and apoptotic epithelial cells was observed under transmission electron microscope.ConclusionUrethral formation occurs by tubulogenesis, which initiates proximally and progresses distally. This is the first study to demonstrate epithelial-mesenchymal transformation and epithelial cell apoptosis in the urethral seam cells of fetal rats. These findings provide new insights into the mechanisms involved in embryonal development of the urethra.

Maternal Smoking, Alcohol, and Caffeine Exposures and Risk of Hypospadias

BACKGROUND

We examined the association of hypospadias risk with maternal smoking and consumption of alcohol and caffeine.

METHODS

We analyzed data from mothers of 2437 moderate/severe cases and 5472 nonmalformed controls born from 1997 to 2011 who participated in the National Birth Defects Prevention Study (NBDPS). Exposures were assessed by maternal telephone interviews. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) adjusted for mother's age, parity, race-ethnicity, education, vitamin/mineral supplement intake, obesity, and study center.

RESULTS

Active smoking during the first month of pregnancy was associated with reduced risk, with smaller ORs for increasing quantity smoked; the OR for smoking >1/2 pack/day was 0.7 (95% CI, 0.5-0.9). Among nonsmokers, the OR for any secondhand smoke exposure was 0.8 (95% CI, 0.7-0.9). ORs for alcohol and caffeine consumption were near one and CIs included 1.0. In an analysis of joint exposures to smoking and alcohol and caffeine consumption, the only OR for which the 95% CI excluded 1.0 was for women who smoked, drank, and had low caffeine consumption (OR, 0.6; 95% CI, 0.4-0.8).

CONCLUSION

Maternal exposure to cigarette smoke was associated with reduced risk, and women who smoked, drank, and had low caffeine intake were at lowest risk. We do not interpret these results to suggest that these exposures have overall benefit to a pregnant woman or developing fetus. They may, however, offer clues to help us understand mechanisms that lead to hypospadias. Birth Defects Research 109:1127-1133, 2017. © 2017 Wiley Periodicals, Inc.

A population-based study of prevalence trends and geospatial analysis of hypospadias and cryptorchidism compared with non-endocrine mediated congenital anomalies

INTRODUCTION

Several reports have suggested an increase in the prevalence of hypospadias and cryptorchidism over the last few decades. Endocrine disruption caused by exposure to environmental chemicals has been postulated as a possible cause.

OBJECTIVES

The objectives of our study were: 1) to determine whether the prevalence of hypospadias and cryptorchidism is increasing compared with other congenital anomalies not known to be mediated by endocrine factors; and 2) to perform a geospatial analysis of these congenital malformations looking for clustering that could offer insight into environmental risk factors.

MATERIAL AND METHODS

Data were obtained from the Nova Scotia ATLEE Perinatal Database containing the perinatal records of all live births in Nova Scotia, Canada since 1988. Records from 1988 to 2013 defined the study cohort. Overall prevalence rates and prevalence trends by year were calculated for hypospadias, cryptorchidism, gastroschisis, and clubfoot. County of residence was collected and spatial autocorrelation testing for clustering was performed for each of the congenital anomalies.

RESULTS

There were 258,147 live births during the study period. Overall prevalence rates for the four malformations over the study period were: hypospadias 78 per 10,000 male births, cryptorchidism 75 per 10,000 male births, clubfoot 24 per 10,000 total births, and gastroschisis 4 per 10,000 total births. Incidence rate ratios per year for hypospadias, cryptorchidism, clubfoot, and gastroschisis were 1.00 (0.99-1.01), 0.99 (0.98-1.00), 0.98 (0.97-0.99), and 1.04 (1.04-1.07), respectively. During the study period, the prevalence rates in the region were unchanged for hypospadias, slightly reduced for cryptorchidism and clubfoot, and rising for gastroschisis (Figure). Spatial autocorrelation testing revealed statistically significant clustering for hypospadias (p = 0.03) and cryptorchidism (p = 0.03), while no spatial autocorrelation was observed for the other malformations.

DISCUSSION

Contrary to previous studies we show that hypospadias and cryptorchidism prevalence rates are not increasing over time in our region. Nonetheless, rates for these conditions in our area are high compared with other regions of the world. Local clustering of these congenital anomalies without clustering of the control, non-endocrine mediated congenital malformations supports a possible unique spatial distribution associated with environmental exposure. The hotspots identified for hypospadias and cryptorchidism are associated with intense agricultural activity.

CONCLUSIONS

Our study found no increase in hypospadias and cryptorchidism prevalence over a 26-year period compared with other congenital anomalies not known to be associated with endocrine factors. Geospatial analysis supports high clustering for hypospadias and cryptorchidism in areas of intense agricultural activity.