Increased gene copy number of VAMP7 disrupts human male urogenital development through altered estrogen action

Genomic and transcriptomic evaluations of infertile or subfertile Arunachali yak sperm

Sperm infertility or subfertility is detrimental to the precious highland germplasm like yak whose population has been gradually declining in India. Understanding the 'omic' landscape of infertile or subfertile yak sperm can reveal some interesting insights. In an attempt to do the same, this study considered the semen of infertile or subfertile yak bulls for whole-genome and transcriptome evaluations. DNA sequencing revealed that the yak sperm genome contains the necessary genes to carry out all the important biological processes related to the growth, development, survival and multiplication of an organism. Interestingly, RNA Seq results highlighted that genes like VAMP7, MYLK, ARAP2 and MARCH6 showed increased expression, while biological processes related to immune response (GO:0043308, GO:0002447, GO:0002278, GO:0043307, GO:0043312, GO:0002283, GO:0043299 and GO:0002446) were significantly overrepresented. These findings hint at a possible role played by immune system in regulating infertility or subfertility in yaks. Further, in-depth studies can validate these findings and help in improving our biological understanding in this area.

Streamlined identification of clinically and functionally relevant genetic regulators of lower-tract urogenital development

Congenital anomalies of the lower genitourinary (LGU) tract are frequently comorbid due to genetically linked developmental pathways, and are among the most common yet most socially stigmatized congenital phenotypes. Genes involved in sexual differentiation are prime candidates for developmental anomalies of multiple LGU organs, but insufficient prospective screening tools have prevented the rapid identification of causative genes. Androgen signaling is among the most influential modulators of LGU development. The present study uses SpDamID technology in vivo to generate a comprehensive map of the pathways actively regulated by the androgen receptor (AR) in the genitalia in the presence of the p300 coactivator, identifying wingless/integrated (WNT) signaling as a highly enriched AR-regulated pathway in the genitalia. Transcription factor (TF) hits were then assayed for sexually dimorphic expression at two critical time points and also cross-referenced to a database of clinically relevant copy number variations to identify 252 TFs exhibiting copy variation in patients with LGU phenotypes. A subset of 54 TFs was identified for which LGU phenotypes are statistically overrepresented as a proportion of total observed phenotypes. The 252 TF hitlist was then subjected to a functional screen to identify hits whose silencing affects genital mesenchymal growth rates. Overlap of these datasets results in a refined list of 133 TFs of both functional and clinical relevance to LGU development, 31 of which are top priority candidates, including the well-documented renal progenitor regulator, Sall1. Loss of Sall1 was examined in vivo and confirmed to be a powerful regulator of LGU development.

VAMP7j: A Splice Variant of Human VAMP7 That Modulates Neurite Outgrowth by Regulating L1CAM Transport to the Plasma Membrane

The vesicle-associated membrane protein 7 (VAMP7) is a SNARE protein of the longin family involved in a wide range of subcellular trafficking events, including neurite sprouting and elongation. The expression of the human gene SYBL1, encoding VAMP7, is finely regulated by alternative splicing. Among the minor isoforms identified so far, VAMP7j is the one most expressed and modulated in the human brain. Therefore, we focused on gaining functional evidence on VAMP7j, which lacks a functional SNARE motif but retains both the longin and transmembrane domains. In human SH-SY5Y cells, we found VAMP7j to modulate neuritogenesis by mediating transport of L1CAM toward the plasma membrane, in a fashion regulated by phosphorylation of the longin domain. VAMP7-mediated regulation of L1CAM trafficking seems at least to differentiate humans from rats, with VAMP7j CNS expression being restricted to primates, including humans. Since L1CAM is a central player in neuritogenesis and axon guidance, these findings suggest the species-specific splicing of SYBL1 is among the fine tuners of human neurodevelopmental complexity.

Hormone receptor expression in hypospadias

INTRODUCTION

Sex hormone imbalance in utero is hypothesized to play an important role in the pathogenesis of hypospadias. Due to its easy accessibility, foreskin samples have been used to describe hormone receptor expression in rodents, and both adult and pediatric patients. In this study we conducted a systematic approach to assess hormone receptor expression in pediatric patients with hypospadias compared to healthy controls with a focus on age-matching and differences in severity and degree of hypospadias.

METHODS

Foreskin samples were collected from 35 children during hypospadias operations (18 distal and 17 proximal hypospadias) and compared with ventral foreskin samples of a control group of 32 children during circumcision (15 age-matched and 17 older boys). The samples were stained with H/E, androgen (AR), estrogen (ER) and progesterone receptors (PR). The receptor stainings were blindly evaluated. An Allred score was used to evaluate receptor expression in both the epithelium as well as stroma.

RESULTS

AR was detected in all cases. AR expression in the stroma was more evident than in the epithelium. AR expression in the hypospadias groups was significantly less than the age matched controls (p < 0.05). There was no significant difference between the two hypospadias groups nor between the two control groups. Older control group showed significantly elevated levels of AR expression compared to the hypospadias group (p < 0.05). ER was also detected in all cases. The stroma showed more ER than in epithelium. PR was minimal or negative in all samples.

CONCLUSION

Boys with hypospadias showed significantly weaker expression of androgen receptors than age matched controls. The severity of hypospadias did not influence hormone receptor distribution. AR expression is better observed in the stroma than in the epithelium. There was no difference in ER expression between the hypospadias group (distal or proximal) and age matched normal controls. ER was expressed in larger numbers in normal older preputial tissue. The foreskin of prepubertal boys shows little to no expression of PR.

A Rare 46,X,t(Y;10)(q12;p14) Balanced Translocation in Non-Obstructive Azoospermic Patient with Elevated FSH and LH Levels

Structural chromosomal aberrations like translocations have been shown to cause spermatogenic failure. We report a rare 46,X,t(Y;10)(q12;p14) balanced translocation in an otherwise healthy non-obstructive azoospermic male with high follicle-stimulating hormone (26.65 IU/L) and high luteinizing hormone (13.58 IU/L). The patient was referred to us after clinical, hormonal, and histopathological investigations to identify chromosomal abnormalities by karyotyping and fluorescence in situ hybridization (FISH). Analysis of the banding pattern by karyotyping followed by FISH confirmed reciprocal translocation and identified the breakpoints at Yq heterochromatin (Yq12) and 10p14. Further molecular tests including AZF microdeletion assay were done, and the results, which showed no mutations in the analyzed genes, were provided by the referring doctor. Thus, our study points to the importance of conventional cytogenetic techniques in the preliminary evaluation of a genetic abnormality in cases of infertility and would help the patient make an informed decision before pursuing assisted reproductive technology.

Male infertility

Clinical infertility is the inability of a couple to conceive after 12 months of trying. Male factors are estimated to contribute to 30-50% of cases of infertility. Infertility or reduced fertility can result from testicular dysfunction, endocrinopathies, lifestyle factors (such as tobacco and obesity), congenital anatomical factors, gonadotoxic exposures and ageing, among others. The evaluation of male infertility includes detailed history taking, focused physical examination and selective laboratory testing, including semen analysis. Treatments include lifestyle optimization, empirical or targeted medical therapy as well as surgical therapies that lead to measurable improvement in fertility. Although male infertility is recognized as a disease with effects on quality of life for both members of the infertile couple, fewer data exist on specific quantification and impact compared with other health-related conditions.

Modeling development of genitourinary birth defects to understand disruption due to changes in gene dosage

Genitourinary development is a delicately orchestrated process that begins in the embryo. Once complete, the genitourinary system is a collection of functionally disparate organs spread throughout the abdominal and pelvic regions. These distinct organs are interconnected through an elaborate duct system which aggregates the organs' products to a common exit point. The complicated nature of the genitourinary system makes it highly susceptible to developmental disruptions that produce anomalies. In fact, genitourinary anomalies are among the most common class of human birth defects. Aside from congenital anomalies of the kidney and urinary tract (CAKUT), for males, these birth defects can also occur in the penis (hypospadias) and testis (cryptorchism), which impact male fertility and male mental health. As genetic technology has advanced, it has become clear that a subset of cases of genitourinary birth defects are due to gene variation causing dosage changes in critical regulatory genes. Here we first review the parallels between human and mouse genitourinary development. We then demonstrate how translational research leverages mouse models of human gene variation cases to advance mechanistic understanding of causation in genitourinary birth defects. We close with a view to the future highlighting upcoming technologies that will provide a deeper understanding of gene variation affecting regulation of genitourinary development, which should ultimately advance treatment options for patients.

Gene dosage changes in KCTD13 result in penile and testicular anomalies via diminished androgen receptor function

Despite the high prevalence of hypospadias and cryptorchidism, the genetic basis for these conditions is only beginning to be understood. Using array-comparative-genomic-hybridization (aCGH), potassium-channel-tetramerization-domain-containing-13 (KCTD13) encoded at 16p11.2 was identified as a candidate gene involved in hypospadias, cryptorchidism and other genitourinary (GU) tract anomalies. Copy number variants (CNVs) at 16p11.2 are among the most common syndromic genomic variants identified to date. Many patients with CNVs at this locus exhibit GU and/or neurodevelopmental phenotypes. KCTD13 encodes a substrate-specific adapter of a BCR (BTB-CUL3-RBX1) E3-ubiquitin-protein-ligase complex (BCR (BTB-CUL3-RBX1) E3-ubiquitin-protein-ligase complex (B-cell receptor (BCR) [BTB (the BTB domain is a conserved motif involved in protein-protein interactions) Cullin3 complex RING protein Rbx1] E3-ubiqutin-protein-ligase complex), which has essential roles in the regulation of cellular cytoskeleton, migration, proliferation, and neurodevelopment; yet its role in GU development is unknown. The prevalence of KCTD13 CNVs in patients with GU anomalies (2.58%) is significantly elevated when compared with patients without GU anomalies or in the general population (0.10%). KCTD13 is robustly expressed in the developing GU tract. Loss of KCTD13 in cell lines results in significantly decreased levels of nuclear androgen receptor (AR), suggesting that loss of KCTD13 affects AR sub-cellular localization. Kctd13 haploinsufficiency and homozygous deletion in mice cause a significant increase in the incidence of cryptorchidism and micropenis. KCTD13-deficient mice exhibit testicular and penile abnormalities together with significantly reduced levels of nuclear AR and SOX9. In conclusion, gene-dosage changes of murine Kctd13 diminish nuclear AR sub-cellular localization, as well as decrease SOX9 expression levels which likely contribute in part to the abnormal GU tract development in Kctd13 mouse models and in patients with CNVs in KCTD13.

Associations of benzotriazoles and benzothiazoles with estrogens and androgens among pregnant women: A cohort study with repeated measurements

People are extensively exposed to benzotriazoles (BTRs) and benzothiazoles (BTHs) derivatives, which are environmental pollutants that may possess endocrine-disrupting potential; however, no epidemiological evidence is available on the associations of BTRs and BTHs with estrogens and androgens. This study aimed at investigating the associations of BTRs and BTHs with estrogens and androgens among pregnant women. Based on a prospective cohort study, we included 459 pregnant women who donated a complete serial of urine samples at each trimester and had repeated measurements of four BTRs, four BTHs, three estrogens (estrone, 17β-estradiol, and estrio), and two androgens (dehydroepiandrosterone and testosterone) in the urine samples. Associations of repeatedly measured BTRs and BTHs with maternal urinary estrogens and androgens were analyzed, and the cross-sectional associations were also analyzed. Tolyltriazole (TTR) (≥59.3%) and benzothiazole (BTH) (≥93.5%) had the highest detection rate among the BTRs and BTHs, respectively. Repeated measurement analysis and cross-sectional analysis consistently found the target BTRs and BTHs were positively associated with 17β-estradiol, estriol, and testosterone, while the trend of the associations with estrone and dehydroepiandrosterone was inconsistent. Among the positive associations with 17β-estradiol, estriol, and testosterone, the percent of change in estriol associated with TTR was the most prominent [28.5% (95% confidential interval: 24.2%, 32.9%) for each doubling in TTR]. The significant associations with estrone, estriol, testosterone, and dehydroepiandrosterone were stronger among pregnant women who gave birth to a boy than those who gave birth to a girl. These findings add epidemiological evidence on the endocrine-disrupting potential of BTRs and BTHs and highlight the importance of focusing on the health outcomes of BTRs and BTHs related to disturbed estrogens and androgens. Future studies are needed to validate these findings and explore the underlying mechanisms.

CNV analysis of VAMP7 gene reveals variation associated with growth traits in Chinese cattle

Copy number variant (CNV), a common genetic polymorphism, is closely related to the phenotypic variation traits of organisms. Vesicle-associated membrane protein 7 gene (VAMP7) codes a protein, which is a member of the SNARE proteins family and plays an important role in the process of intracellular vesicle transport. In this study, a total of four cattle breeds (Yunling cattle, Xianan cattle, Pinan cattle, Jiaxian red cattle) were used to investigate the copy numbers, and we found an association relationship between CNV of VAMP7 gene and growth traits of cattle by SPSS 20.0 software. The results showed that the CNV type of VAMP7 gene in four cattle breeds had the same distribution, Duplication type occupies a dominant position among the four varieties. In Yunling cattle, the Duplication type of VAMP7 is significantly related to the height at the hip cross (p < 0.05), Individuals with Duplication type commonly have less performance on growth and development, which indicates that the Duplication type of the VAMP7 gene may have a negative effect on cattle growth. Individuals with the other two CNV types may become the breeding direction of the VAMP7 gene. This study provided a new perspective and basic material for the molecular genetics of the CNV of the VAMP7 gene, and also promoted the breeding progress of Chinese local cattle.

What advances may the future bring to the diagnosis, treatment, and care of male sexual and reproductive health?

Over the past 40 years, since the publication of the original WHO Laboratory Manual for the Examination and Processing of Human Semen, the laboratory methods used to evaluate semen markedly changed and benefited from improved precision and accuracy, as well as the development of new tests and improved, standardized methodologies. Herein, we present the impact of the changes put forth in the sixth edition together with our views of evolving technologies that may change the methods used for the routine semen analysis, up-and-coming areas for the development of new procedures, and diagnostic approaches that will help to extend the often-descriptive interpretations of several commonly performed semen tests that promise to provide etiologies for the abnormal semen parameters observed. As we look toward the publication of the seventh edition of the manual in approximately 10 years, we describe potential advances that could markedly impact the field of andrology in the future.

Canary in the Coal Mine? Male Infertility as a Marker of Overall Health

Male factor infertility is a common problem. Evidence is emerging regarding the spectrum of systemic disease and illness harbored by infertile men who otherwise appear healthy. In this review, we present evidence that infertile men have poor overall health and increased morbidity and mortality, increased rates of both genitourinary and non-genitourinary malignancy, and greater risks of systemic disease. The review also highlights numerous genetic conditions associated with male infertility as well as emerging translational evidence of genitourinary birth defects and their impact on male infertility. Finally, parallels to the overall health of infertile women are presented. This review highlights the importance of a comprehensive health evaluation of men who present for an infertility assessment.

Differences of sex development in the newborn: from clinical scenario to molecular diagnosis

Differences/disorders of sex development (DSD) are defined as a group of congenital conditions in which the development of chromosomal, gonadal or anatomical sex is atypical. The incidence of DSD is 1:4500 births. The current classification divides DSDs into 3 categories according to chromosomal sex: 46,XX DSD, 46,XY DSD and sex chromosome DSD. DSD phenotypes can be concordant with the genotype (apparently normal external genitalia associated with gonadal dysgenesis), or can range from simply hypospadias to completely masculinised or feminised genitalia with a discordant karyotype. Numerous genes implicated in genital development have been reported. The search of genetic variants represents a central element of the extended investigation, as an improved knowledge of the genetic aetiology helps the immediate and long-term management of children with DSDs, in term of sex of rearing, hormone therapy, surgery, fertility and cancer risk. This review aims to assess the current role of molecular diagnosis in DSD management.

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.

Global 3'UTR shortening and down-regulation of repeated element related piRNA play crucial roles in boys with cryptorchidism

BACKGROUND

Cryptorchidism is the most common congenital defect in children's genitourinary system. Decades of research have identified both environmental and genetic factors contribute to the etiology.

METHODS

Small-RNA/mRNA-seq were performed on testicular tissues from cryptorchidism patients. Downstream analysis included mRNA expression, piRNA expression and miRNA expression.

RESULTS

We find a global downregulation of repeated element related piRNA expression as well as a global 3'UTR shortening of mRNAs in patients with cryptorchidism. We also find that genes with shortened 3'UTR which are highly enriched in vascular endothelial growth and protein ubiquitination, tend to be up-regulated in cryptorchidism. These results indicate that boys with cryptorchidism may not have normal piRNA functions to protect developmental tissues from transposon invasion. Dysregulated shortened 3'UTR genes may affect normal testicular tissue development.

CONCLUSION

In summary, our findings also provided the first landscape of gene regulation in cryptorchidism, especially in terms of post-transcriptional regulations.

E2F1 regulates testicular descent and controls spermatogenesis by influencing WNT4 signaling

Cryptorchidism is the most common urologic birth defect in men and is a predisposing factor of male infertility and testicular cancer, yet the etiology remains largely unknown. E2F1 microdeletions and microduplications contribute to cryptorchidism, infertility and testicular tumors. Although E2f1 deletion or overexpression in mice causes spermatogenic failure, the mechanism by which E2f1 influences testicular function is unknown. This investigation revealed that E2f1-null mice develop cryptorchidism with severe gubernacular defects and progressive loss of germ cells resulting in infertility and, in rare cases, testicular tumors. It was hypothesized that germ cell depletion resulted from an increase in WNT4 levels. To test this hypothesis, the phenotype of a double-null mouse model lacking both Wnt4 and E2f1 in germ cells was analyzed. Double-null mice are fertile. This finding indicates that germ cell maintenance is dependent on E2f1 repression of Wnt4, supporting a role for Wnt4 in germ cell survival. In the future, modulation of WNT4 expression in men with cryptorchidism and spermatogenic failure due to E2F1 copy number variations may provide a novel approach to improve their spermatogenesis and perhaps their fertility potential after orchidopexy.

Steroidogenesis during prenatal testicular development in Spix's cavy Galea spixii

Spix's cavy is a potentially good experimental model for research on reproductive biology and sexual development. The aim of the present study was to evaluate the ontogeny of the steroidogenic enzymes involved in testicular androgen synthesis during prenatal development. Testes were investigated on Days 25, 30, 40 and >50 of gestation. Immunohistochemistry and immunoblotting were used to establish the site and relative amount of androgenic enzymes, including 5α-reductase, cytosolic 17β-hydroxysteroid dehydrogenase (17β-HSDI) and mitochondrial microsomal 3β-hydroxysteroid dehydrogenase (3β-HSDII), throughout prenatal development. The testicular parenchyma began to organise on Day 25 of gestation, with the development of recognisable testicular cords. The mesonephros was established after Day 25 of gestation and the ducts differentiated to form the epididymis, as testicular cords were beginning to proliferate and the interstitium to organise by Day 30 of gestation, continuing thereafter. The androgen-synthesising enzymes 5α-reductase, 17β-HSDI and 3β-HSDII were evident in Leydig cells as they differentiated at all subsequent gestational ages studied. In addition, immunoblotting showed an increase in immunoreactivity for the enzymes at Days 30 and 40 of gestation (P<0.05) and a decrease at Day 50 of gestation (P<0.05). It is concluded that the increase in androgenic enzymes in Leydig cells coincides with the functional differentiation of the testes, and with the stabilisation and differentiation of mesonephric ducts forming the epididymis.

Xp;Yq Unbalanced Translocation with Pseudoautosomal Region Aberrations in a Natural Two-Generation Transmission

Translocations involving X and Y chromosomes rarely occur in humans and may affect reproductive function. We investigated an Xp:Yq unbalanced translocation with pseudoautosomal region (PAR) aberrations in a natural two-generation transmission. We report the case of an azoospermic male and his fertile mother without any other abnormal clinical phenotypes, except for short stature. Cytogenetic methods, including karyotyping and fluorescence in situ hybridization (FISH), revealed the translocation. Chromosomal microarray comparative genomic hybridization (array-CGH) was used to investigate the regions of Xp partial deletion and Yq partial duplication. Final chromosome karyotypes in the peripheral blood of the infertile male and his mother were 46,Y,der(X)t(X;Y)(p22.33;q11.22) and 46,X,der(X)t(X;Y)(p22.33;q11.22), respectively. Short-stature-homeobox gene deletion was responsible for the short stature in both subjects. PAR aberrations and AZFc duplication may be a direct genetic risk factor for spermatogenesis. This report further supports the use of routine karyotype analysis, FISH-based technology, and array-CGH analysis to identify derivative chromosomes in a complex rearrangement.

Clinical implications of Y chromosome microdeletions among infertile men

Male factor infertility contributes significantly to couples facing difficulty achieving a pregnancy. Genetic factors, and specifically those related to the Y chromosome, may occur in up to 15% of men with oligozoospermia or azoospermia. A subset of loci within the Y chromosome, known as the azoospermia factors (AZFa, AZFb, and AZFc), have been associated with male infertility. Emerging evidence has demonstrated that microdeletions of at least a subset of these regions may also have impacts on systemic conditions. This review provides a brief review of male infertility and the structure of the Y chromosome, and further highlights the role of Y chromosome microdeletions in male infertility and other systemic disease.

Male infertility and genitourinary birth defects: there is more than meets the eye

Male factor infertility is a significant problem present in up to 50% of infertile couples. The relationship between male infertility and systemic disease is of significant interest, and emerging evidence suggests a relationship between male infertility and male genitourinary (GU) birth defects (cryptorchidism, hypospadias, ambiguous genitalia, and congenital anomalies of the kidney and urinary tract). Many of these birth defects are treated in isolation by busy urologists without acknowledgment that these may be related to more global syndromic conditions. Conversely, geneticists and nonurologists who treat variable systemic phenotypes may overlook GU defects, which are indeed related conditions. Many of these defects are attributed to copy number variants dosage-sensitive genes due to chromosome microdeletions or microduplications. These variants are responsible for disease phenotypes seen in the general population. The copy number variants described in this review are syndromic in some cases and responsible for both GU birth defects as well as other systemic phenotypes. This review highlights the emerging evidence between these birth defects, male infertility, and other systemic conditions.

A case series of infants with increased VAMP7 gene dosage at birth and virilization defects

BACKGROUND

Genitourinary disorders are the most frequent congenital defects in newborns; however, little is known about their etiology. Several studies have been carried out to find genetic risk factors in the development of these malformations. The expression of VAMP7 is found in testes, epididymis, seminal vesicles, prostatic tissues, penis, and urethra. Alterations in gene dose of VAMP7 were recently reported in a subset of male patients initially identified clinically by the presence of congenital genitourinary disorders. In 2016, the authors developed a diagnostic algorithm for early detection of sex chromosome aneuploidies by quantifying the SHOX, VAMP7, and SRY gene dose in newborns by qPCR using dried blood spot (DBS) samples.

OBJECTIVE

Correlate the increased gene dose of VAMP7, obtained by qPCR using DBS, with genitourinary congenital defects attributable to disorders in virilization and verify the increased gene dose by microarrays.

STUDY DESIGN

Samples that only presented increased VAMP7 gene dosage were selected from a previously analyzed group of 5088 males in which the early detection of sex chromosomes aneuploidies was performed. Eight males were found with an increased gene dose of VAMP7 (relative quantitation > 1.3) and were called in for a complete clinical evaluation aimed at the identification of genitourinary anomalies, qPCR and microarrays.

RESULTS

Eight males from 5088 samples were identified with increased VAMP7 gene dosage of which six patients were clinically evaluated, of which 50% were identified with alterations in genital development (bilateral cryptorchidism, unilateral cryptorchidism, and glandular hypospadias) and speech delay, while the rest presented different types of atopy.

DISCUSSION

Tannour-Louet et al. postulated on 2014 that the duplication of the Xq28 region, specifically of VAMP7, plays a role in the human masculinization disorders of the urogenital tract. The study was based on array comparative genomic hybridization (aCGH) results performed to 116 males with disorders of sexual differentiation. In the present study, the patients were initially selected due to an increased gene dose of VAMP7 detected by qPCR, then the clinical evaluation and the aCGH were performed, inverse to what was reported previously but with similar percentages between both studies.

CONCLUSION

In this work, the authors report cases of cryptorchidism, hypospadias, language delay and atopy in male preschoolers initially identified because they have an increased gene dose of VAMP7.

[Aphallia - report of two cases]

Aphallia is an extremely rare congenital malformation of unknown cause. The incidence is reported in the literature to be 1 in 10-30 million live births. Almost 100 cases have been described to date. Aphallia is associated with other congenital malformations (in particular urogenital and gastrointestinal anomalies) in >50% of cases. The diagnosis is made clinically and shows the complete absence of the corpora cavernosa and the corpus spongiosum with a urethral opening along the perineal midline (most frequently ventral to the anus and in the ventral rectal wall). Two case reports from the authors' department: The first child was a male newborn (46,XY) with penis agenesis and additional bilateral intraabdominal testis, an anorectal malformation (ARM) with a rectovesical fistula, as well as left renal duplication and grade III vesico-ureteral reflux on the right side. The second child was a male newborn (46,XY) with aphallia without further urological or anorectal malformation. Only right inguinal hernia was present. In the first patient, several corrective surgeries were performed in the further course in view of the additional malformations. With regard to the aphallia, the various temporary treatment options (scrotal or parascrotal phalloplasty or penis prosthesis) were discussed with the parents. Masculinizing surgery by means of definitive phalloplasty was planned once the patient has reached puberty. Due to the technical demands of phallus reconstruction, feminization is still favored in some countries in the literature, which nowadays, however, cannot be justified medically or legally.

Bioinformatic identification of key genes and molecular pathways in the spermatogenic process of cryptorchidism

This study aims to determine key genes and pathways that could play important roles in the spermatogenic process of patients with cryptorchidism. The gene expression profile data of GSE25518 was obtained from the Gene Expression Omnibus (GEO) database. Microarray data were analyzed using BRB-Array Tools to identify differentially expressed genes (DEGs) between high azoospermia risk (HAZR) patients and controls. In addition, other analytical methods were deployed, including hierarchical clustering analysis, class comparison between patients with HAZR and the normal control group, gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and the construction of a protein–protein interaction (PPI) network. In total, 1015 upregulated genes and 1650 downregulated genes were identified. GO and KEGG analysis revealed enrichment in terms of changes in the endoplasmic reticulum cellular component and the endoplasmic reticulum protein synthetic process in the HAZR group. Furthermore, the arachidonic acid pathway and mTOR pathway were also identified as important pathways, while RICTOR and GPX8 were indentified as key genes involved in the spermatogenic process of patients with cryptorchidism. In present study, we found that changes in the synthesis of endoplasmic reticulum proteins, arachidonic acid and the mTOR pathway are important in the incidence and spermatogenic process of cryptorchidism. GPX8 and RICTOR were also identified as key genes associated with cryptorchidism. Collectively, these data may provide novel clues with which to explore the precise etiology and mechanism underlying cryptorchidism and cryptorchidism-induced human infertility.

Molecular Characterization of Mosaicism for a Small Supernumerary Marker Chromosome Derived from Chromosome Y in an Infertile Male with Apparently Normal Phenotype: A Case Report and Literature Review

Small supernumerary marker chromosomes (sSMCs), equal in size or smaller than chromosome 20 of the same metaphase, can hardly be identified through traditional banding technique. They are usually associated with intelligent disability, growth retardation, and infertility, but the genotype-phenotype correlations are still complicated for their complex origins and constitutions. Herein, we identified a 26-year-old Chinese infertile male who carried a mosaic sSMC and was diagnosed as severe oligospermia. The G-banding analysis initially described his karyotype as mos 47, XY, +mar[32]/46, XY[18]. The chromosomal microarray analysis results showed a 25.5 Mb gain in Yp11.31q11.23 and a 0.15 Mb loss in Yq12. Two SRY signals were discovered in the “seemingly” normal chromosome Y in both cell lines using SRY probe: one normal SRY was located on the distal tip of the short arm of chromosome Y while the other SRY was located on the terminal of long arm in the same chromosome Y. The sSMC(Y) was finally identified as der(Y) (pter ⟶ q11.23) (SRY-). To our knowledge, the chromosomal Y anomalies, SRY gene translocated from der(Y) (pter ⟶ q11.23) to qter of normal chromosome Y, were not reported before. Our findings indicated that the mosaic presence of sSMC(Y) may be the main cause of severe oligospermia although no other apparent abnormalities were observed in the proband. Further research on association between sSMC(Y) and spermatogenesis impairment should be investigated. It is recommended measures of traditional and molecular cytogenetic analysis should be taken to determine the origins and constitutions of sSMC so as to offer more appropriate genetic counseling for the infertile sSMC carriers.

Regulatory roles of epithelial-mesenchymal interaction (EMI) during early and androgen dependent external genitalia development

Development of external genitalia (ExG) has been a topic of long mystery in the field of organogenesis research. Early stage male and female of mouse embryos develop a common genital tubercle (GT) in the perineum whose outgrowth extends distally from the posterior cloacal regions. Concomitant with GT outgrowth, the cloaca is divided into urogenital sinus and anorectum by urorectal septum (URS) internally. The outgrowth of the GT is associated with the formation of endodermal epithelial urethral plate (UP) attached to the ventral epidermis of the GT. Such a common developmental phase is observed until around embryonic day 15.5 (E15.5) morphologically in mouse embryogenesis. Various growth factor genes, such as Fibroblast growth factor (Fgf) and Wnt genes are expressed and function during GT formation. Since the discovery of key growth factor signals and several regulatory molecules, elucidation of their functions has been achieved utilizing mouse developmental models, conditional gene knockout mouse and in vitro culture. Analyses on the phenotypes of such mouse models have revealed that several growth factor families play fundamental roles in ExG organogenesis based on the epithelial-mesenchymal interaction (EMI). More recently, EMI between developing urethral epithelia and its bilateral mesenchyme of later stages is also reported during subsequent stage of androgen-dependent male-type urethral formation in the mouse embryo. Mafb, belonging to AP-1 family and a key androgen-responsive mesenchymal gene, is identified and starts to be expressed around E14.5 when masculinization of the urethra is initiated. Mesenchymal cell condensation and migration, which are regulated by nonmuscle myosin, are shown to be essential process for masculinization. Hence, studies on EMI at various embryonic stages are important not only for early but also for subsequent masculinization of the urethra. In this review, a dynamic mode of EMI for both early and late phases of ExG development is discussed.

Temporal, spatial, and genetic regulation of external genitalia development

Fertilization requires the physical combination of gametes, and terrestrial mammals necessitated the evolution of genitalia capable of successfully completing the fertilization process in a non-aqueous environment. Thus, the male mammalian external genitalia evolved as an outgrowth from the body, an appendage sufficient to fertilize eggs housed deep inside the female. In this way, sexual dimorphism of mammalian genitalia became highly pronounced. This highly complex evolutionary divergence both from aqueous fertilization, as well as divergence between the sexes of terrestrial mammals, required exquisitely coordinated, novel patterns of gene expression to regulate the spatial and temporal events governing external genitalia development. Recent studies delineating the genetic regulation of external genitalia development, largely focusing on development of the murine genital tubercle, have vastly enlightened the field of reproductive developmental biology. Murine homologs of human genes have been selectively deleted in the mouse, either in the whole body or using tissue-specific and temporally-specific genetic drivers. The defects in outgrowth and urethral tubularization subsequent to the deletion of specific genes in the developing murine external genitalia delineates which genes are required in which compartments and at what times. This review details how these murine genetic models have created a somewhat modest but rapidly growing library of knowledge detailing the spatial-temporal genetic regulation of external genitalia development.

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.

Translating genomics to the clinical diagnosis of disorders/differences of sex development

The medical and psychosocial challenges faced by patients living with Disorders/Differences of Sex Development (DSD) and their families can be alleviated by a rapid and accurate diagnostic process. Clinical diagnosis of DSD is limited by a lack of standardization of anatomical and endocrine phenotyping and genetic testing, as well as poor genotype/phenotype correlation. Historically, DSD genes have been identified through positional cloning of disease-associated variants segregating in families and validation of candidates in animal and in vitro modeling of variant pathogenicity. Owing to the complexity of conditions grouped under DSD, genome-wide scanning methods are better suited for identifying disease causing gene variant(s) and providing a clinical diagnosis. Here, we review a number of established genomic tools (karyotyping, chromosomal microarrays and exome sequencing) used in clinic for DSD diagnosis, as well as emerging genomic technologies such as whole-genome (short-read) sequencing, long-read sequencing, and optical mapping used for novel DSD gene discovery. These, together with gene expression and epigenetic studies can potentiate the clinical diagnosis of DSD diagnostic rates and enhance the outcomes for patients and families.

Molecular signaling pathways elicited by 17α-ethinylestradiol in Japanese medaka male larvae undergoing gonadal differentiation

Estrogenic contaminants released into water bodies are potentially affecting the reproduction of aquatic organisms. Exposure to 17α-ethinylestradiol (EE2), a synthetic estrogen agonist commonly found in sewage effluents, has been shown to cause gonadal changes in male gonochoristic fish ranging from gonadal intersex to complete sex reversal. Although these gonadal changes have been well studied in Japanese medaka Oryzias latipes, the molecular mechanisms behind them are poorly understood. Our objective was to study the signaling pathways elicited by exposure to different concentrations of EE2 in this species. Embryos and larvae were sexed by the presence of leucophores and dmy expression (only in males). Male medaka were exposed to two EE2 concentrations (30 and 300 ng/L) during their gonadal differentiation period (7-22 dpf). The transcriptome of larvae was analyzed using RNA sequencing followed by pathway analysis. Genes involved in sex differentiation and gonadal development (e.g., cldn19, ctbp1, hsd17b4) showed a female-like expression pattern in EE2-exposed males with some genes changing in expression in an EE2 concentration-dependent manner. However, not all genes known to be involved in sex differentiation and gonadal development (e.g., wnt4b) were altered by EE2. Several of the prominently affected signaling pathways involved genes associated with steroidogenesis, steroid receptor signaling and steroid metabolism, such as cyp2b3, cyp3b40, cyp1a, hsd17b4. We also report on novel genes and pathways affected that might play a role in gonadal changes, including several genes associated with FXR/RXR and LXR/RXR activation networks. This study is the first to examine the transcriptomic changes in male fish resulting from exposure to EE2 during the gonadal differentiation period, providing new insights on the signaling pathways involved in the development of gonadal changes in gonochoristic fish.

Increased gene copy number of DEFA1/DEFA3 worsens sepsis by inducing endothelial pyroptosis

Sepsis claims an estimated 30 million episodes and 6 million deaths per year, and treatment options are rather limited. Human neutrophil peptides 1-3 (HNP1-3) are the most abundant neutrophil granule proteins but their neutrophil content varies because of unusually extensive gene copy number polymorphism. A genetic association study found that increased copy number of the HNP-encoding gene DEFA1/DEFA3 is a risk factor for organ dysfunction during sepsis development. However, direct experimental evidence demonstrating that these risk alleles are pathogenic for sepsis is lacking because the genes are present only in some primates and humans. Here, we generate DEFA1/DEFA3 transgenic mice with neutrophil-specific expression of the peptides. We show that mice with high copy number of DEFA1/DEFA3 genes have more severe sepsis-related vital organ damage and mortality than mice with low copy number of DEFA1/DEFA3 or wild-type mice, resulting from more severe endothelial barrier dysfunction and endothelial cell pyroptosis after sepsis challenge. Mechanistically, HNP-1 induces endothelial cell pyroptosis via P2X7 receptor-mediating canonical caspase-1 activation in a NLRP3 inflammasome-dependent manner. Based on these findings, we engineered a monoclonal antibody against HNP-1 to block the interaction with P2X7 and found that the blocking antibody protected mice carrying high copy number of DEFA1/DEFA3 from lethal sepsis. We thus demonstrate that DEFA1/DEFA3 copy number variation strongly modulates sepsis development in vivo and explore a paradigm for the precision treatment of sepsis tailored by individual genetic information.

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.

Expression of androgen, estrogen, and progesterone hormone receptors in the penile tissues of children with different types of hypospadias

OBJECTIVE:

Androgen (AR), Estrogen (ER) and Progesterone (PR) hormones play an important role in the prenatal and postnatal development of urogenital tract and especially the penis. The expressions of AR, ER and PR receptors in penile tissues in children with hypospadiases had also been shown previously. In this leading study, to demonstrate of the sex hormone receptor expression in cases with different types of hypospadias were aimed.

METHODS:

This study was designed in children operated due to hypospadiases without DSD. Biopsy samples of 3 mm’s were obtained from three different sytes as the lateral parameatal tissue and the anterior corner of the prepuce, and inner layer of posterior prepuce. The presence of AR, ER and PR receptors was investigated immunehistochemically.

RESULTS:

Mean age was 5.4 years in 18 children with hypospadiases; in totally 33 specimens were taken in 5 subcoronal as 5 specimens, and 7 penile as 15 specimens, and 6 penoscrotal as 13 specimens. According to sytes of samples; 13 samples were from lateral para-meatal tissues, and 13 were from anterior corners of prepuces, and 7 were from inner layers of posterior prepuces. In regard to receptor expression; ER and AR receptors were positive in 29 (87.8%) and 12 (36.4%) respectively; PR receptors were negative.

CONCLUSION:

This study emphasized the dominant expression of estrogen receptors in penile tissues of children with hypospadias. Although there was not a manifest correlation of androgen receptors absence in regard to the severity of hypospadias patients, there was a marked estrogen receptors presence in penile tissues. These findings suggest that the disrupted androgen and estrogen receptor interaction and/or balance could play a role during the development of external genitalia in hypospadias patients. Progesterone receptor was not present and therefore the active role in the postnatal development of hypospadias is still debatable.

Development of urogenital system in the Spix cavy: A model for studies on sexual differentiation

This study documented, for the first time, the morphological patterns of differentiation of male and female genital organs of Spix cavy (Galea spixii) using histological and ultrastructural analyses, with immuno-localization of steroidogenic enzymes, cytochromes P450 aromatase (P450arom) and 17α-hydroxylase/17, 20-lyase (P450c17), involved in the synthesis of estrogens and androgens respectively throughout fetal sexual development. Undifferentiated gonads of Spix cavy develop into ovaries in females after 25 days of gestation (DG), exhibiting P450arom immunoreactivity. After 25 DG, paramesonephric ducts develop and form oviducts, uterine horns and cranial portion of the vagina. The caudal portion of the vagina originates from the urogenital sinus, and a vaginal closure membrane is present at the end of gestation. Partial channeling of the urethra into the clitoris occurs after 40 DG, but complete channeling never occurs. A preputial meatus emerges near the tip of organ. In males, undifferentiated gonads develop into testes at 25 DG and develop immunoreactivity for P450c17, which is required for androgens synthesis and likely maintenance of mesonephric ducts. Mesonephric ducts develop subsequently, forming the epididymis and ductus deferens. The pelvic urethra develops after 25 DG with channeling into the penis occurring around 30 DG. This is the first morphological study describing the process of sexual differentiation during gestation in a hystricomorph rodent and one of the most comprehensive analyses conducted in any mammal. Male genital organ development follows the general pattern described in other domestic mammals, but does not include formation of the baculum as occurs in mice and rats. In females, clitoral development includes partial canalization by the urethra and development of a preputial meatus. Further studies are required to clarify the mechanisms involved in the differentiative processes described.

Genome-wide screening for smallest regions of overlaps in cryptorchidism

Cryptorchidism is a urogenital abnormality associated with increased rates of testicular neoplasia and impaired spermatogenesis. The field is facing expansion of genomics data; however, it lacks protocols for biomarker prioritization. Identification of smallest regions of overlap (SRO) presents an approach for candidate gene identification but has not yet been systematically conducted in cryptorchidism. The aim of this study was to conduct a genome-wide screening for SRO (GW-SRO) associated with cryptorchidism development. We updated the Cryptorchidism Gene Database to version 3, remapped genomic coordinates of loci from older assemblies to the GRCh38 and performed genome-wide screening for overlapping regions associated with cryptorchidism risk. A total of 73 chromosomal loci (68 involved in chromosomal mutations and five copy number variations) described in 37 studies associated with cryptorchidism risk in humans were used for SRO identification. Analysis resulted in 18 SRO, based on deletions, duplications, inversions, derivations and copy number variations. Screening for SRO was challenging owing to heterogeneous reporting of genomic locations. To our knowledge, this is the first GW-SRO study for cryptorchidism and it presents the basis for further narrowing of critical regions for cryptorchidism and planning functional experiments. The developed protocol could also be applied to other multifactorial diseases.

Genomic copy number variation association study in Caucasian patients with nonsyndromic cryptorchidism

Background

Copy number variation (CNV) is a potential contributing factor to many genetic diseases. Here we investigated the potential association of CNV with nonsyndromic cryptorchidism, the most common male congenital genitourinary defect, in a Caucasian population.

Methods

Genome wide genotyping were performed in 559 cases and 1772 controls (Group 1) using Illumina HumanHap550 v1, HumanHap550 v3 or Human610-Quad platforms and in 353 cases and 1149 controls (Group 2) using the Illumina Human OmniExpress 12v1 or Human OmniExpress 12v1-1. Signal intensity data including log R ratio (LRR) and B allele frequency (BAF) for each single nucleotide polymorphism (SNP) were used for CNV detection using PennCNV software. After sample quality control, gene- and CNV-based association tests were performed using cleaned data from Group 1 (493 cases and 1586 controls) and Group 2 (307 cases and 1102 controls) using ParseCNV software. Meta-analysis was performed using gene-based test results as input to identify significant genes, and CNVs in or around significant genes were identified in CNV-based association test results. Called CNVs passing quality control and signal intensity visualization examination were considered for validation using TaqMan CNV assays and QuantStudio® 3D Digital PCR System.

Results

The meta-analysis identified 373 genome wide significant (p < 5X10⁻⁴) genes/loci including 49 genes/loci with deletions and 324 with duplications. Among them, 17 genes with deletion and 1 gene with duplication were identified in CNV-based association results in both Group 1 and Group 2. Only 2 genes (NUCB2 and UPF2) containing deletions passed CNV quality control in both groups and signal intensity visualization examination, but laboratory validation failed to verify these deletions.

Conclusions

Our data do not support that structural variation is a major cause of nonsyndromic cryptorchidism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12894-016-0180-4) contains supplementary material, which is available to authorized users.

The Genetic and Environmental Factors Underlying Hypospadias

Hypospadias results from a failure of urethral closure in the male phallus and affects 1 in 200-300 boys. It is thought to be due to a combination of genetic and environmental factors. The development of the penis progresses in 2 stages: an initial hormone-independent phase and a secondary hormone-dependent phase. Here, we review the molecular pathways that contribute to each of these stages, drawing on studies from both human and mouse models. Hypospadias can occur when normal development of the phallus is disrupted, and we provide evidence that mutations in genes underlying this developmental process are causative. Finally, we discuss the environmental factors that may contribute to hypospadias and their potential immediate and transgenerational epigenetic impacts.

Timing of androgen receptor disruption and estrogen exposure underlies a spectrum of congenital penile anomalies

Congenital penile anomalies (CPAs) are among the most common human birth defects. Reports of CPAs, which include hypospadias, chordee, micropenis, and ambiguous genitalia, have risen sharply in recent decades, but the causes of these malformations are rarely identified. Both genetic anomalies and environmental factors, such as antiandrogenic and estrogenic endocrine disrupting chemicals (EDCs), are suspected to cause CPAs; however, little is known about the temporal window(s) of sensitivity to EDCs, or the tissue-specific roles and downstream targets of the androgen receptor (AR) in external genitalia. Here, we show that the full spectrum of CPAs can be produced by disrupting AR at different developmental stages and in specific cell types in the mouse genital tubercle. Inactivation of AR during a narrow window of prenatal development results in hypospadias and chordee, whereas earlier disruptions cause ambiguous genitalia and later disruptions cause micropenis. The neonatal phase of penile development is controlled by the balance of AR to estrogen receptor α (ERα) activity; either inhibition of androgen or augmentation of estrogen signaling can induce micropenis. AR and ERα have opposite effects on cell division, apoptosis, and regulation of Hedgehog, fibroblast growth factor, bone morphogenetic protein, and Wnt signaling in the genital tubercle. We identify Indian hedgehog (Ihh) as a novel downstream target of AR in external genitalia and show that conditional deletion of Ihh inhibits penile masculinization. These studies reveal previously unidentified cellular and molecular mechanisms by which antiandrogenic and estrogenic signals induce penile malformations and demonstrate that the timing of endocrine disruption can determine the type of CPA.

Pathway analysis supports association of nonsyndromic cryptorchidism with genetic loci linked to cytoskeleton-dependent functions

STUDY QUESTION

What are the genetic loci that increase susceptibility to nonsyndromic cryptorchidism, or undescended testis?

SUMMARY ANSWER

A genome-wide association study (GWAS) suggests that susceptibility to cryptorchidism is heterogeneous, with a subset of suggestive signals linked to cytoskeleton-dependent functions and syndromic forms of the disease.

WHAT IS KNOWN ALREADY

Population studies suggest moderate genetic risk of cryptorchidism and possible maternal and environmental contributions to risk. Previous candidate gene analyses have failed to identify a major associated locus, although variants in insulin-like 3 (INSL3), relaxin/insulin-like family peptide receptor 2 (RXFP2) and other hormonal pathway genes may increase risk in a small percentage of patients.

STUDY DESIGN, SIZE, DURATION

This is a case-control GWAS of 844 boys with nonsyndromic cryptorchidism and 2718 control subjects without syndromes or genital anomalies, all of European ancestry.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All boys with cryptorchidism were diagnosed and treated by a pediatric specialist. In the discovery phase, DNA was extracted from tissue or blood samples and genotyping performed using the Illumina HumanHap550 and Human610-Quad (Group 1) or OmniExpress (Group 2) platform. We imputed genotypes genome-wide, and combined single marker association results in meta-analyses for all cases and for secondary subphenotype analyses based on testis position, laterality and age, and defined genome-wide significance as P = 7 × 10(-9) to correct for multiple testing. Selected markers were genotyped in an independent replication group of European cases (n = 298) and controls (n = 324). We used several bioinformatics tools to analyze top (P < 10(-5)) and suggestive (P < 10(-3)) signals for significant enrichment of signaling pathways, cellular functions and custom gene lists after multiple testing correction.

MAIN RESULTS AND THE ROLE OF CHANCE

In the full analysis, we identified 20 top loci, none reaching genome-wide significance, but one passing this threshold in a subphenotype analysis of proximal testis position (rs55867206, near SH3PXD2B, odds ratio = 2.2 (95% confidence interval 1.7, 2.9), P = 2 × 10(-9)). An additional 127 top loci emerged in at least one secondary analysis, particularly of more severe phenotypes. Cytoskeleton-dependent molecular and cellular functions were prevalent in pathway analysis of suggestive signals, and may implicate loci encoding cytoskeletal proteins that participate in androgen receptor signaling. Genes linked to human syndromic cryptorchidism, including hypogonadotropic hypogonadism, and to hormone-responsive and/or differentially expressed genes in normal and cryptorchid rat gubernaculum, were also significantly overrepresented. No tested marker showed significant replication in an independent population. The results suggest heterogeneous, multilocus and potentially multifactorial susceptibility to nonsyndromic cryptorchidism.

LIMITATIONS, REASONS FOR CAUTION

The present study failed to identify genome-wide significant markers associated with cryptorchidism that could be replicated in an independent population, so further studies are required to define true positive signals among suggestive loci.

WIDER IMPLICATIONS OF THE FINDINGS

As the only GWAS to date of nonsyndromic cryptorchidism, these data will provide a basis for future efforts to understand genetic susceptibility to this common reproductive anomaly and the potential for additive risk from environmental exposures.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by R01HD060769 (the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD)), P20RR20173 (the National Center for Research Resources (NCRR), currently P20GM103464 from the National Institute of General Medical Sciences (NIGMS)), an Institute Development Fund to the Center for Applied Genomics at The Children's Hospital of Philadelphia, and Nemours Biomedical Research. The authors have no competing interests to declare.

Oestrogen action and male fertility: experimental and clinical findings

A proper balance between androgen and oestrogen is fundamental for normal male reproductive development and function in both animals and humans. This balance is governed by the cytochrome P450 aromatase, which is expressed also under spatio-temporal control. Oestrogen receptors ERα and/or ERβ, together with the membrane-associated G-protein-coupled functional ER (GPER), mediate the effects of oestrogen in the testis. Oestrogen action in male reproduction is more complex than previously predicted. The androgen/oestrogen balance and its regulation in the masculinisation programming window (MPW) during foetal life is the most critical period for the development of the male reproductive system. If this balance is impaired during the MPW, the male reproductive system may be negatively affected. Recent data from genetically modified mice and human infertile patients have shown that oestrogens may promote the engulfment of live Leydig cells by macrophages leading to male infertility. We also discuss recent data on environmental oestrogen exposure in men and rodents, where a rodent-human distinction is crucial and analyse some aspects of male fertility potentially related to impaired oestrogen/androgen balance.

Tissue-specific roles of Fgfr2 in development of the external genitalia

Congenital anomalies frequently occur in organs that undergo tubulogenesis. Hypospadias is a urethral tube defect defined by mislocalized, oversized, or multiple openings of the penile urethra. Deletion of Fgfr2 or its ligand Fgf10 results in severe hypospadias in mice, in which the entire urethral plate is open along the ventral side of the penis. In the genital tubercle, the embryonic precursor of the penis and clitoris, Fgfr2 is expressed in two epithelial populations: the endodermally derived urethral epithelium and the ectodermally derived surface epithelium. Here, we investigate the tissue-specific roles of Fgfr2 in external genital development by generating conditional deletions of Fgfr2 in each of these cell types. Conditional deletion of Fgfr2 results in two distinct phenotypes: endodermal Fgfr2 deletion causes mild hypospadias and inhibits maturation of a complex urethral epithelium, whereas loss of ectodermal Fgfr2 results in severe hypospadias and absence of the ventral prepuce. Although these cell type-specific mutants exhibit distinctive genital anomalies, cellular analysis reveals that Fgfr2 regulates epithelial maturation and cell cycle progression in the urethral endoderm and in the surface ectoderm. The unexpected finding that ectodermal deletion of Fgfr2 results in the most severe hypospadias highlights a major role for Fgfr2 in the developing genital surface epithelium, where epithelial maturation is required for maintenance of a closed urethral tube. These results demonstrate that urethral tubulogenesis, prepuce morphogenesis, and sexually dimorphic patterning of the lower urethra are controlled by discrete regions of Fgfr2 activity.