Mutational study of the MAMLD1-gene in hypospadias

Digenic Origin of Difference of Sex Development in a Patient Harbouring DHX37 and MAMLD1 Variants

Background

The diagnostic process for identifying variations in sex development (DSD) remains challenging due to the limited availability of evidence pertaining to the association between phenotype and genotype. DSD incidence is reported as 2 in 10,000 births, and the etiology has been attributed to genetic causes. Case Presentation. The present study investigated genetic causes implicated in a case of a 15-year-old 46, XY patient, raised as a girl. Genetic analysis by clinical exome sequencing (CES) showed a digenic inheritance due to two known pathogenic mutations in the DHX37 gene and the MAMLD1 gene, while we excluded variants with pathogenic significance in 209 DSD-related genes.

Conclusions

Based on our literature review, this is the first case with the combined presence of pathogenic mutations in the MAMLD1 gene and DHX37 gene in a patient with gonadal dysgenesis.

Shared diagnostic genes and potential mechanism between PCOS and recurrent implantation failure revealed by integrated transcriptomic analysis and machine learning

Polycystic ovary syndrome (PCOS) is a complex endocrine metabolic disorder that affects 5-10% of women of reproductive age. The endometrium of women with PCOS has altered immune cells resulting in chronic low-grade inflammation, which attribute to recurrent implantation failure (RIF). In this study, we obtained three PCOS and RIF datasets respectively from the Gene Expression Omnibus (GEO) database. By analyzing differentially expressed genes (DEGs) and module genes using weighted gene co-expression networks (WGCNA), functional enrichment analysis, and three machine learning algorithms, we identified twelve diseases shared genes, and two diagnostic genes, including GLIPR1 and MAMLD1. PCOS and RIF validation datasets were assessed using the receiver operating characteristic (ROC) curve, and ideal area under the curve (AUC) values were obtained for each disease. Besides, we collected granulosa cells from healthy and PCOS infertile women, and endometrial tissues of healthy and RIF patients. RT-PCR was used to validate the reliability of GLIPR1 and MAMLD1. Furthermore, we performed gene set enrichment analysis (GSEA) and immune infiltration to explore the underlying mechanism of PCOS and RIF cooccurrence. Through the functional enrichment of twelve shared genes and two diagnostic genes, we found that both PCOS and RIF patients had disturbances in metabolites related to the TCA cycle, which eventually led to the massive activation of immune cells.

Neural network non-linear modeling to predict hypospadias genotype-phenotype correlation

INTRODUCTION

Hypospadias is an abnormal development of the urethral, ventral skin and corporeal bodies. Urethral meatus and ventral curvature have been historically the landmarks to define clinical severity. Genotyping has never been explored as a clinical predictor. Available reports have demonstrated a correlation between genetic mutations and syndromic hypospadias with poor surgical outcomes. We hypothesize that inclusion of genotyping can serve at classifying all types of hypospadias. We present the use of neural network algorithm to evaluate phenotype/genotype correlations and propose its potential clinical applicability.

METHODS

A systematic review was performed from January 1974 to June 2022. Literature was retrieved from Medline, Embase, Web of Science and Google Scholar. Included manuscripts were those that had an explicit anatomical description of hypospadias phenotype (urethral meatus location following an anatomical description) and a defined genotype (genetic mutation) description. Cases with more than one variant/mutation were excluded. A comprehensive phenotype-genotype statistical analysis using neural network non-linear data modeling SPSS™ was performed.

RESULTS

Genotype-Phenotype analysis was performed on 1731 subjects. Of those, 959 (55%) were distal and 772 (45%) proximal. 49 genes with mutations were identified. Neural network clustering predicted better for coronal (90%) and glanular (80%), and lowest for midshaft (22%) and perineal (45%). Using genes as predictor factor only, the model was able to highly and more accurately predict the phenotype for coronal and glanular hypospadias. The following genotypes showed association to a specific phenotype: AR gene n.2058G > A for glanular (p<0.0001), n.480C  >  T for coronal (p = 0.034), R840C for perineal (p = 0.002), MAMLD1 gene c.2960C > T for coronal (p< 0.0001), p. G289S for glanular (p<0.0001), gene SRD5A2 607G > A for scrotal (p<0.0001), c16C > T for penoscrotal (p<0.0001), c59 T  >  c for perineal (p = 0.042), V89L for midshaft and scrotal (p<0.0001, p = 0.041; respectively).

DISCUSSION

Hypospadias phenotype has always been described from a purely anatomical perspective. Our results demonstrate that current phenotyping has poor correlation to the genotype. Higher genotype/phenotype correlation for distal hypospadias proves the clinical applicability of genotyping these cases. The concept and classification of differences in sexual development needs to be reconsidered given high positive yield reported for distal hypospadias. Given the better predictive value of genotyping in correlation to the phenotype, future efforts should be directed towards using the genotype.

CONCLUSION

Hypospadias has poor phenotype/genotype correlation. Sequencing all hypospadias phenotypes may add clinical value if used in association to other predictive variables. Neural network analysis may have the ability to combine all these variables for clinical prediction.

A New MAMLD1 Variant in an Infant With Microphallus and Hypospadias With Hormonal Pattern Suggesting Partial Hypogonadotropic Hypogonadism-Case Report

MAMLD1 (X chromosome) is one of the recognized genes related to different sex development. It is expressed in testis and ovaries and seems to be involved in fetal sex development and in adult reproductive function, including testosterone biosynthesis. However, its exact role remains unclear. Over 40 genetic variants have been described, mainly in male individuals and mostly associated with hypospadias. Although MAMLD1 has been shown to regulate the expression of the steroidogenic pathway, patients with MAMLD1 variants mostly show normal gonadal function and normal testosterone levels. Here we describe a patient (46,XY) with hypospadias and microphallus, with low testosterone and dihydrotestosterone (DHT) levels, and with inappropriately low values of luteinizing hormone (LH) during minipuberty. This hormonal pattern was suggestive of partial hypogonadotropic hypogonadism. A stimulation test with hCG (4 months) showed no significant increase in both testosterone and dihydrotestosterone concentrations. At 5 months of age, he was treated with intramuscular testosterone, and the penis length increased to 3.5 cm. The treatment was stopped at 6 months of age. Our gonadal function massive-sequencing panel detected a previously unreported nonsense variant in the MAMLD1 gene (c.1738C>T:p.Gln580Ter), which was classified as pathogenic. This MAMLD1 variant, predicting a truncated protein, could explain his genital phenotype. His hormonal profile (low testosterone, dihydrotestosterone, and LH concentrations) together with no significant increase of testosterone and DHT plasma concentrations (hCG test) highlight the potential role of this gene in the biosynthesis of testosterone during the fetal stage and minipuberty of the infant. Besides this, the LH values may suggest an involvement of MAMLD1 in the LH axis or a possible oligogenesis. It is the first time that a decrease in DHT has been described in a patient with an abnormal MAMLD1.

MAMLD1 and Differences/Disorders of Sex Development: An Update

MAMLD1 (alias CXorf6) was first documented in 2006 as a causative gene of 46,XY differences/disorders of sex development (DSD). MAMLD1/Mamld1 is expressed in the fetal testis and is predicted to enhance the expression of several Leydig cell-specific genes. To date, hemizygous MAMLD1 variants have been identified in multiple 46,XY individuals with hypomasculinized external genitalia. Pathogenic MAMLD1 variants are likely to cause genital abnormalities at birth and are possibly associated with age-dependent deterioration of testicular function. In addition, some MAMLD1 variants have been identified in 46,XX individuals with ovarian dysfunction. However, recent studies have raised the possibility that MAMLD1 variants cause 46,XY DSD and ovarian dysfunction as oligogenic disorders. Unsolved issues regarding MAMLD1 include the association between MAMLD1 variants and 46,XX testicular DSD, gene-gene interactions in the development of MAMLD1-mediated DSD, and intracellular functions of MAMLD1.

Oligogenic Causes of Human Differences of Sex Development: Facing the Challenge of Genetic Complexity

BACKGROUND

Deviations of intrauterine sex determination and differentiation and postnatal sex development can result in a very heterogeneous group of differences of sex development (DSD) with a broad spectrum of phenotypes. Variants in genes involved in sexual development cause different types of DSD, but predicting the phenotype from an individual's genotype and vice versa remains challenging.

SUMMARY

Next Generation Sequencing (NGS) studies suggested that oligogenic inheritance contributes to the broad manifestation of DSD phenotypes. This review will focus on possible oligogenic inheritance in DSD identified by NGS studies with a special emphasis on NR5A1variants as an example of oligogenic origin associated with a broad range of DSD phenotypes. We thoroughly searched the literature for evidence regarding oligogenic inheritance in DSD diagnosis with NGS technology and describe the challenges to interpret contribution of these genes to DSD phenotypic variability and pathogenicity. Key Messages: Variants in common DSD genes like androgen receptor (AR), mitogen-activated protein kinase kinase kinase 1 (MAP3K1), Hydroxy-Delta-5-Steroid Dehydrogenase 3 Beta- And Steroid Delta-Isomerase 2 (HSD3B2), GATA Binding Protein 4 (GATA4), zinc finger protein friend of GATA family member 2 (ZFPM2), 17b-hydroxysteroid dehydrogenase type 3 (HSD17B3), mastermind-like domain-containing protein 1 (MAMLD1), and nuclear receptor subfamily 5 group A member 1 (NR5A1) have been detected in combination with additional variants in related genes in DSD patients with a broad range of phenotypes, implying a role of oligogenic inheritance in DSD, while still awaiting proof. Use of NGS approach for genetic diagnosis of DSD patients can reveal more complex genetic traits supporting the concept of oligogenic cause of DSD. However, assessing the pathomechanistic contribution of multiple gene variants on a DSD phenotype remains an unsolved conundrum.

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.

Hybrid schwannoma-perineurioma frequently harbors VGLL3 rearrangement

Benign peripheral nerve tumors include schwannoma, neurofibroma, and perineurioma, as well as a recently recognized group of tumors with dual patterns of differentiation. The molecular pathogenesis of these so-called "hybrid" tumors remains poorly understood. Following identification of a novel CHD7-VGLL3 fusion gene in a hybrid schwannoma-perineurioma, we evaluated an expanded cohort of this tumor-type-as well as tumors with VGLL3 rearrangement identified from a curated molecular database-to characterize the prevalence of fusion genes among these tumors. Eighteen tumors met the inclusion criteria for this study. RNA sequencing identified VGLL3 rearrangement in 14 of these cases; the partner genes included CHD7 (ten cases), CHD9 (two cases), and MAMLD1 (two cases). Two cases possessed altogether unrelated fusions, including: DST-BRAF and SQSTM1-CDX1 fusion genes. Finally, two cases lacked identifiable fusion products. These findings highlight the molecular diversity of these neoplasms, with frequent rearrangement of VGLL3. More importantly, despite their dual pattern of differentiation, our results reveal the pathogenesis of hybrid schwannoma-perineurioma is unrelated to conventional schwannoma and perineurioma, thereby implying this tumor represents an altogether pathologically distinct entity.

A Proteomics Signature of Mild Hypospadias: A Pilot Study

Background and Objective: Mild hypospadias is a birth congenital condition characterized by the relocation of the male urethral meatus from its typical anatomical position near the tip of the glans penis, to a lower ventral position up to the brim of the glans corona, which can also be accompanied by foreskin ventral deficiency. For the most part, a limited number of cases have known etiology. We have followed a high-throughput proteomics approach to study the proteome in mild hypospadias patients. Methods: Foreskin samples from patients with mild hypospadias were collected during urethroplasty, while control samples were collected during elective circumcision (n = 5/group). A high-throughput, quantitative proteomics approach based on multiplexed peptide stable isotope labeling (SIL) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was used to ascertain protein abundance changes in hypospadias patients when compared to control samples. Results: A total of 4,815 proteins were quantitated (2,522 with at least two unique peptides). One hundred and thirty-three proteins from patients with mild hypospadias showed significant abundance changes with respect to control samples, where 38 proteins were increased, and 95 proteins were decreased. Unbiased functional biological analysis revealed that both mitochondrial energy production and apoptotic signaling pathways were enriched in mild hypospadias. Conclusions: This first comprehensive proteomics characterization of mild hypospadias shows molecular changes associated with essential cellular processes related to energy production and apoptosis. Further evaluation of the proteome may expand the search of novel candidates in the etiology of mild hypospadias and could also lead to the identification of biomarkers for this congenital urogenital condition.

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

Background

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

Results

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

Conclusion

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

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.

Disorders of Sex Development in Individuals Harbouring MAMLD1 Variants: WES and Interactome Evidence of Oligogenic Inheritance

Mastermind-like domain-containing 1 (MAMLD1) has been shown to play an important role in the process of sexual development and is associated with 46,XY disorders of sex development (DSDs). However, the causative role of MAMLD1 variations in DSDs remains disputable. In this study, we have described a clinical series on children from unrelated families with 46,XY DSD harbouring MAMLD1 variants. Whole exome sequencing (WES) was performed for each patient. WES data were filtered using common tools and disease customisation algorithms, including comparison against lists of known and candidate MAMLD1-related and DSD-related genes. Lastly, we investigated the hypothesis that MAMLD1-related DSD may follow an oligogenic mode of inheritance. Forty-three potentially deleterious/candidate variants of 18 genes (RET, CDH23, MYO7A, NOTCH2, MAML1, MAML2, CYP1A1, WNT9B, GLI2, GLI3, MAML3, WNT9A, FRAS1, PIK3R3, FREM2, PTPN11, EVC, and FLNA) were identified, which may have contributed to the patient phenotypes. MYO7A was the most commonly identified gene. Specific gene combinations were also identified. In the interactome analysis, MAMLD1 exhibited direct connection with MAML1/2/3 and NOTCH1/2. Through NOTCH1/2, the following eight genes were shown to be associated with MAMLD1:WNT9A/9B, GLI2/3, RET, FLNA, PTPN11, and EYA1. Our findings provide further evidence that individuals with MAMLD1-related 46,XY DSD could carry two or more variants of known DSD-related genes, and the phenotypic outcome of affected individuals might be determined by multiple genes.

Broad Phenotypes of Disorders/Differences of Sex Development in MAMLD1 Patients Through Oligogenic Disease

Disorders/differences of sex development (DSD) are the result of a discordance between chromosomal, gonadal, and genital sex. DSD may be due to mutations in any of the genes involved in sex determination and development in general, as well as gonadal and/or genital development specifically. MAMLD1 is one of the recognized DSD genes. However, its role is controversial as some MAMLD1 variants are present in normal individuals, several MAMLD1 mutations have wild-type activity in functional studies, and the Mamld1-knockout male mouse presents with normal genitalia and reproduction. We previously tested nine MAMLD1 variants detected in nine 46,XY DSD patients with broad phenotypes for their functional activity, but none of the mutants, except truncated L210X, had diminished transcriptional activity on known target promoters CYP17A1 and HES3. In addition, protein expression of MAMLD1 variants was similar to wild-type, except for the truncated L210X. We hypothesized that MAMLD1 variants may not be sufficient to explain the phenotype in 46,XY DSD individuals, and that further genetic studies should be performed to search for additional hits explaining the broad phenotypes. We therefore performed whole exome sequencing (WES) in seven of these 46,XY patients with DSD and in one 46,XX patient with ovarian insufficiency, who all carried MAMLD1 variants. WES data were filtered by an algorithm including disease-tailored lists of MAMLD1-related and DSD-related genes. Fifty-five potentially deleterious variants in 41 genes were identified; 16/55 variants were reported in genes in association with hypospadias, 8/55 with cryptorchidism, 5/55 with micropenis, and 13/55 were described in relation with female sex development. Patients carried 1-16 variants in 1-16 genes together with their MAMLD1 variation. Network analysis of the identified genes revealed that 23 genes presented gene/protein interactions with MAMLD1. Thus, our study shows that the broad phenotypes of individual DSD might involve multiple genetic variations contributing towards the complex network of sexual development.

Attenuation of MAMLD1 Expression Suppresses the Growth and Migratory Properties of Gonadotroph Pituitary Adenomas

Gonadotroph pituitary adenomas (GPAs) constitute approximately 15-40% of pituitary tumors. Some GPAs can be highly infiltrative, making full surgical resection challenging and increasing the risk of recurrence. The transcriptional co-activator Mastermind-Like Domain Containing 1 (MAMLD1, CXorf6, F18) is involved in regulating signaling pathways important in pituitary tumorigenesis, including the Notch signaling pathway. However, MAMLD1's role in GPA remains unknown. GPA biopsies were collected from 96 patients following surgery, who were monitored until tumor recurrence. GPA tissue was used for immunohistochemistry. The murine GPA cell lines αT3 and LβT2 were used for in vitro experiments. Lentiviral constructs were employed for MAMLD1 knockdown (KD) and dominant negative (DN) mutant experiments. Quantitative real-time PCR (qPCR) and Western blotting of MAMLD1 and Notch2 were performed. MTT and Transwell assays were used to quantify proliferation and migration, respectively. An αT3 xenograft model was established in athymic nude mice followed by fluorescent IHC of xenograft tumors. MAMLD1 and Notch2 levels correlated positively with aggressive GPAs. Increased MAMLD1 levels correlated with shortened recurrence-free survival (RFS) in aggressive GPA patients. Moreover, MAMLD1 expression independently affected patient RFS according to multivariate Cox regression. In vitro, MAMLD1 KD in the murine GPA cell lines attenuated their proliferation and migration and Notch2 expression. Additionally, DN MAMLD1^L210X lowered their proliferative and migratory capacity. MAMLD1 KD suppressed tumor growth and Notch2 expression in murine xenografts. MAMLD1 may serve as a predictor of GPA patient outcome and may also be leveraged as a possible therapeutic target for aggressive GPA tumors.

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

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

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

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

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

Polymorphism of 3' UTR of MAMLD1 gene is also associated with increased risk of isolated hypospadias in Indian children: a preliminary report

OBJECTIVE

To study MAMLD1 gene polymorphisms, serum LH and testosterone levels amongst Indian children with isolated hypospadias (IH) and controls.

MATERIALS AND METHODS

Screening of the MAMLD1 gene was performed by PCR sequencing method in 100 Indian children aged 0-12 years presenting with IH and 100 controls. LH and testosterone hormone levels were also assessed (categorized in four age-wise groups).

RESULTS

IH subjects had significantly higher incidence of MAMLD1 polymorphism as compared to controls (33 vs 15 %, p = 0.01). Of various genomic variants identified in this study, the noteworthy novel ones were missense mutation P299A and single nucleotide polymorphism c.2960C>T in 3' UTR of Exon 7. While p 299A was found to cause protein structural instability consequent to amino acid change, eighty percent subjects with c.2960C>T in 3' UTR of Exon 7 (corresponding to newly discovered currently non-validated exon 11) were found to have lower testosterone levels when compared with their age group mean. IH showed statistically higher incidence of c.2960C>T in comparison to controls (22 vs 10 %, p value 0.046) and about 2.5-folds higher risk of this anomaly.

CONCLUSION

Occurrence of MAMDL1 gene polymorphisms, specially of c.2960C>T in 3' UTR of its exon 7 is associated with a higher risk of IH in Indian children, probably by lowering androgenic levels.

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.

Human MAMLD1 Gene Variations Seem Not Sufficient to Explain a 46,XY DSD Phenotype

MAMLD1 is thought to cause disordered sex development in 46,XY patients. But its role is controversial because some MAMLD1 variants are also detected in normal individuals, several MAMLD1 mutations have wild-type activity in functional tests, and the male Mamld1-knockout mouse has normal genitalia and reproduction. Our aim was to search for MAMLD1 variations in 108 46,XY patients with disordered sex development, and to test them functionally. We detected MAMDL1 variations and compared SNP frequencies in controls and patients. We tested MAMLD1 transcriptional activity on promoters involved in sex development and assessed the effect of MAMLD1 on androgen production. MAMLD1 expression in normal steroid-producing tissues and mutant MAMLD1 protein expression were also assessed. Nine MAMLD1 mutations (7 novel) were characterized. In vitro, most MAMLD1 variants acted similarly to wild type. Only the L210X mutation showed loss of function in all tests. We detected no effect of wild-type or MAMLD1 variants on CYP17A1 enzyme activity in our cell experiments, and Western blots revealed no significant differences for MAMLD1 protein expression. MAMLD1 was expressed in human adult testes and adrenals. In conclusion, our data support the notion that MAMLD1 sequence variations may not suffice to explain the phenotype in carriers and that MAMLD1 may also have a role in adult life.

Novel Splice Site Mutation in MAMLD1 in a Patient with Hypospadias

MAMLD1 is a causative gene for disorders of sex development. Several MAMLD1 mutations have been shown to cause hypospadias by generating dysfunctional proteins and/or unstable mRNAs. Here, we identified an intronic mutation of MAMLD1 (g.IVS4-2A>G) in 1 of 180 hypospadias patients. RT-PCR of the patient's skin sample showed normal expression of full-length MAMLD1 and markedly reduced expression of a known splice variant lacking exon 4. A hitherto unreported splice variant that lacks exon 5 was similarly identified in samples of the patient and control individuals. The full-length transcript of the patient contained mutant mRNA lacking the first 10 nucleotides of exon 5 (c.1822_1831delACTCATGTAG, p.K609fsX1070). In vitro assays using cells expressing the full-length wild-type and mutant proteins revealed reduced expression of the mutant. The expression of the wild-type and mutant MAMLD1 showed parallel changes upon treatment with a proteasome inhibitor and a translation inhibitor. The mutant-expressing cells exerted low transactivation activity for the Hes3 promoter, which reflected limited expression of the mutant protein. These results imply that the pathogenic events resulting from MAMLD1 mutations include splice errors. Furthermore, this study raises the possibility of translation failure of MAMLD1 mutants, which deserves further investigation.

[Perineal hypospadia in a red Holstein-calf. A case report]

Hypospadia is a congenital deformation of the urethra. Several surgical correction methods have been described, but there are also cases when an operation is not necessarily required. In this report, the case of a bull calf which did not need an invasive therapy will be presented.

Review of genetic and environmental factors leading to hypospadias

Hypospadias is one of the most common congenital malformations, affecting about 4-6 males per 1000 male births, and ranging in severity from a urethral meatus that is slightly off-center to a meatus in the perineal area. Over the past three decades its prevalence may have increased due to changes in reporting of mild cases and/or increased survival of low birth weight infants due to improved neonatal care. However, despite the increasing numbers of males with hypospadias, the overall etiology remains unclear and likely multifactorial in nature. The purpose of this review article is to provide a comprehensive overview of the various factors implicated in hypospadias etiology, including genetic and environmental factors. In addition, we list syndromes in which hypospadias is a relatively common association and delineate the areas that require further investigation in an effort to understand this condition.

Understanding the genetic aetiology in patients with XY DSD

BACKGROUND

Disorders of sex development (DSD) consist of a wide range of disorders and are commoner in those with an XY karyotype. In over half of these cases who have a 46,XY karyotype and who are raised as boys, the underlying aetiology remains unclear.

AREAS OF AGREEMENT

Identification of the underlying genetic abnormality may predict long-term outcome. However, genetic abnormalities that are associated with XY DSD manifest themselves with a wide range of phenotype. To understand the aetiology as well as the phenotypic variation, there is a need to harness the advanced genetic technology that is now available.

AREAS OF CONTROVERSY

The point at which genetic analysis should be undertaken in the course of investigations is unclear. In addition, there is little agreement on the most effective approach for genetic analysis that will be of clinical benefit to the patient.

AREAS TIMELY FOR DEVELOPING RESEARCH

There is a need to understand and improve the clinical utility of genetic analysis in the clinical setting of the patient with a suspected DSD. This will be even more important when parallel gene sequencing identifies variations in multiple genes.

Mamld1 deficiency significantly reduces mRNA expression levels of multiple genes expressed in mouse fetal Leydig cells but permits normal genital and reproductive development

Although mastermind-like domain containing 1 (MAMLD1) (CXORF6) on human chromosome Xq28 has been shown to be a causative gene for 46,XY disorders of sex development with hypospadias, the biological function of MAMLD1/Mamld1 remains to be elucidated. In this study, we first showed gradual and steady increase of testicular Mamld1 mRNA expression levels in wild-type male mice from 12.5 to 18.5 d postcoitum. We then generated Mamld1 knockout (KO) male mice and revealed mildly but significantly reduced testicular mRNA levels (65-80%) of genes exclusively expressed in Leydig cells (Star, Cyp11a1, Cyp17a1, Hsd3b1, and Insl3) as well as grossly normal testicular mRNA levels of genes expressed in other cell types or in Leydig and other cell types. However, no demonstrable abnormality was identified for cytochrome P450 17A1 and 3β-hydroxysteroid dehydrogenase (HSD3B) protein expression levels, appearance of external and internal genitalia, anogenital distance, testis weight, Leydig cell number, intratesticular testosterone and other steroid metabolite concentrations, histological findings, in situ hybridization findings for sonic hedgehog (the key molecule for genital tubercle development), and immunohistochemical findings for anti-Müllerian hormone (Sertoli cell marker), HSD3B (Leydig cell marker), and DEAD (Asp-Glu-Ala-Asp) box polypeptide 4 (germ cell marker) in the KO male mice. Fertility was also normal. These findings imply that Mamld1 deficiency significantly reduces mRNA expression levels of multiple genes expressed in mouse fetal Leydig cells but permits normal genital and reproductive development. The contrastive phenotypic findings between Mamld1 KO male mice and MAMLD1 mutation positive patients would primarily be ascribed to species difference in the fetal sex development.

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

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

Screening of MAMLD1 mutations in 70 children with 46,XY DSD: identification and functional analysis of two new mutations

More than 50% of children with severe 46,XY disorders of sex development (DSD) do not have a definitive etiological diagnosis. Besides gonadal dysgenesis, defects in androgen biosynthesis, and abnormalities in androgen sensitivity, the Mastermind-like domain containing 1 (MAMLD1) gene, which was identified as critical for the development of male genitalia, may be implicated. The present study investigated whether MAMLD1 is implicated in cases of severe 46,XY DSD and whether routine sequencing of MAMLD1 should be performed in these patients.

Seventy children with severe non-syndromic 46,XY DSD of unknown etiology were studied. One hundred and fifty healthy individuals were included as controls. Direct sequencing of the MAMLD1, AR, SRD5A2 and NR5A1 genes was performed. The transactivation function of the variant MAMLD1 proteins was quantified by the luciferase method.

Two new mutations were identified: p.S143X (c.428C>A) in a patient with scrotal hypospadias with microphallus and p.P384L (c.1151C>T) in a patient with penile hypospadias with microphallus. The in vitro functional study confirmed no residual transactivating function of the p.S143X mutant and a significantly reduced transactivation function of the p.P384L protein (p = 0.0032). The p.P359S, p.N662S and p.H347Q variants are also reported with particularly high frequency of the p.359T- p.662G haplotype in the DSD patients.

Severe undervirilization in XY newborns can reveal mutations of MAMLD1. MAMLD1 should be routinely sequenced in these patients with otherwise normal AR, SRD5A2 and NR5A1genes.

Aetiology of hypospadias: a systematic review of genes and environment

BACKGROUND

Hypospadias is a common congenital malformation of the male external genitalia. Most cases have an unknown aetiology, which is probably a mix of monogenic and multifactorial forms, implicating both genes and environmental factors. This review summarizes current knowledge about the aetiology of hypospadias.

METHODS

Pubmed was used to identify studies on hypospadias aetiology published between January 1995 and February 2011. Reference lists of the selected manuscripts were also searched to identify additional studies, including those published before 1995.

RESULTS

The search provided 922 articles and 169 articles were selected for this review. Studies screening groups of patients with hypospadias for single gene defects found mutations in WT1, SF1, BMP4, BMP7, HOXA4, HOXB6, FGF8, FGFR2, AR, HSD3B2, SRD5A2, ATF3, MAMLD1, MID1 and BNC2. However, most investigators are convinced that single mutations do not cause the majority of isolated hypospadias cases. Indeed, associations were found with polymorphisms in FGF8, FGFR2, AR, HSD17B3, SRD5A2, ESR1, ESR2, ATF3, MAMLD1, DGKK, MID1, CYP1A1, GSTM1 and GSTT1. In addition, gene expression studies indentified CTGF, CYR61 and EGF as candidate genes. Environmental factors consistently implicated in hypospadias are low birthweight, maternal hypertension and pre-eclampsia, suggesting that placental insufficiency may play an important role in hypospadias aetiology. Exogenous endocrine-disrupting chemicals have the potential to induce hypospadias but it is unclear whether human exposure is high enough to exert this effect. Other environmental factors have also been associated with hypospadias but, for most, the results are inconsistent.

CONCLUSIONS

Although a number of contributors to the aetiology of hypospadias have been identified, the majority of risk factors remain unknown.

Polymorphisms of MAMLD1 gene in hypospadias

PURPOSE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

Mutation analysis of NR5A1 encoding steroidogenic factor 1 in 77 patients with 46, XY disorders of sex development (DSD) including hypospadias

Background

Mutations of the NR5A1 gene encoding steroidogenic factor-1 have been reported in association with a wide spectrum of 46,XY DSD (Disorder of Sex Development) phenotypes including severe forms of hypospadias.

Methodology/Principal Findings

We evaluated the frequency of NR5A1 gene mutations in a large series of patients presenting with 46,XY DSD and hypospadias. Based on their clinical presentation 77 patients were classified either as complete or partial gonadal dysgenesis (uterus seen at genitography and/or surgery, n = 11), ambiguous external genitalia without uterus (n = 33) or hypospadias (n = 33). We identified heterozygous NR5A1 mutations in 4 cases of ambiguous external genitalia without uterus (12.1%; p.Trp279Arg, pArg39Pro, c.390delG, c140_141insCACG) and a de novo missense mutation in one case with distal hypospadias (3%; p.Arg313Cys). Mutant proteins showed reduced transactivation activity and mutants p.Arg39Pro and p.Arg313Cys did not synergize with the GATA4 cofactor to stimulate reporter gene activity, although they retained their ability to physically interact with the GATA4 protein.

Conclusions/Significance

Mutations in NR5A1 were observed in 5/77 (6.5%) cases of 46,XY DSD including hypospadias. Excluding the cases of 46,XY gonadal dysgenesis the incidence of NR5A1 mutations was 5/66 (7.6%). An individual with isolated distal hypopadias carried a de novo heterozygous missense mutation, thus extending the range of phenotypes associated with NR5A1 mutations and suggesting that this group of patients should be screened for NR5A1 mutations.

Mamld1 knockdown reduces testosterone production and Cyp17a1 expression in mouse Leydig tumor cells

BACKGROUND

MAMLD1 is known to be a causative gene for hypospadias. Although previous studies have indicated that MAMLD1 mutations result in hypospadias primarily because of compromised testosterone production around the critical period for fetal sex development, the underlying mechanism(s) remains to be clarified. Furthermore, although functional studies have indicated a transactivation function of MAMLD1 for the non-canonical Notch target Hes3, its relevance to testosterone production remains unknown. To examine these matters, we performed Mamld1 knockdown experiments.

METHODOLOGY/PRINCIPAL FINDINGS

Mamld1 knockdown was performed with two siRNAs, using mouse Leydig tumor cells (MLTCs). Mamld1 knockdown did not influence the concentrations of pregnenolone and progesterone but significantly reduced those of 17-OH pregnenolone, 17-OH progesterone, dehydroepiandrosterone, androstenedione, and testosterone in the culture media. Furthermore, Mamld1 knockdown significantly decreased Cyp17a1 expression, but did not affect expressions of other genes involved in testosterone biosynthesis as well as in insulin-like 3 production. Hes3 expression was not significantly altered. In addition, while 47 genes were significantly up-regulated (fold change >2.0×) and 38 genes were significantly down-regulated (fold change <0.5×), none of them was known to be involved in testosterone production. Cell proliferation analysis revealed no evidence for compromised proliferation of siRNA-transfected MLTCs.

CONCLUSIONS/SIGNIFICANCE

The results, in conjunction with the previous data, imply that Mamld1 enhances Cyp17a1 expression primarily in Leydig cells and permit to produce a sufficient amount of testosterone for male sex development, independently of the Hes3-related non-canonical Notch signaling.

Hypospadias: interactions between environment and genetics

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