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

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.

Etiology of Hypospadias: A Comparative Review of Genetic Factors and Developmental Processes Between Human and Animal Models

Hypospadias is a congenital anomaly of the penis with an occurrence of approximately 1 in 200 boys, but the etiology of the majority of hypospadias has remained unknown. Numerous genes have been reported as having variants in hypospadias patients, and many studies on genetic deletion of key genes in mouse genital development have also been published. Until now, no comparative analysis in the genes related literature has been reported. The basic knowledge of penile development and hypospadias is mainly obtained from animal model studies. Understanding of the differences and similarities between human and animal models is crucial for studies of hypospadias. In this review, mutations and polymorphisms of hypospadias-related genes have been compared between humans and mice, and differential genotype–phenotype relationships of certain genes between humans and mice have been discussed using the data available in PubMed and MGI online databases, and our analysis only revealed mutations in seven out of 43 human hypospadias related genes which have been reported to show similar phenotypes in mutant mice. The differences and similarities in the processes of penile development and hypospadias malformation among human and commonly used animal models suggest that the guinea pig may be a good model to study the mechanism of human penile development and etiology of hypospadias.

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.

Aging and the Male Reproductive System

This narrative review presents an overview of current knowledge on fertility and reproductive hormone changes in aging men, the factors driving and modulating these changes, their clinical consequences, and the benefits and risks of testosterone (T) therapy. Aging is accompanied by moderate decline of gamete quality and fertility. Population mean levels show a mild total T decline, an SHBG increase, a steeper free T decline, and a moderate LH increase with important contribution of comorbidities (e.g., obesity) to these changes. Sexual symptoms and lower hematocrit are associated with low T and are partly responsive to T therapy. The relationship of serum T with body composition and metabolic health is bidirectional; limited beneficial effects of T therapy on body composition have only marginal effects on metabolic health and physical function. Skeletal changes are associated primarily with estradiol and SHBG. Cognitive decline is not consistently linked to low T and is not improved by T therapy. Although limited evidence links moderate androgen decline with depressive symptoms, T therapy has small beneficial effects on mood, depressive symptoms, and vitality in elderly patients with low T. Suboptimal T (and/or DHT) has been associated with increased risk of stroke, but not of ischemic heart disease, whereas an association with mortality probably reflects that low T is a marker of poor health. Globally, neither severity of clinical consequences attributable to low T nor the nature and magnitude of beneficial treatment effects justify the concept of some broadly applied "T replacement therapy" in older men with low T. Moreover, long-term safety of T therapy is not established.

Polymorphisms of MAMLD1, SRD5A2, and AR Candidate Genes in Seven Dogs (78,XY; SRY-Positive) Affected by Hypospadias or Cryptorchidism

Knowledge of the molecular background of disorders of sex development (DSD) in dogs with normal sets of XY chromosomes (XY DSD) is very scarce. However, extensive studies have been carried out in humans, showing that polymorphisms and mutations of numerous genes, including SRY, MAMLD1, SRD5A2, and AR, are associated with or responsible for XY DSD. In this study, we analyzed the entire coding sequence of these genes in 7 dogs (78,XY) with ambiguous external genitalia (hypospadias, cryptorchidism, bifid scrotum, or rudimentary penis). The most common disorder was hypospadias (6 cases), followed by cryptorchidism (4 cases). The co-occurrence of both abnormalities was observed in 3 dogs. Polymorphisms were found in MAMLD1 (3 SNPs), SRD5A2 (5 SNPs), and AR (2 STRs and 1 SNP), while SRY was monomorphic. However, the distribution of the polymorphic variants in the DSD dogs and 11 control XY dogs did not differ significantly. Our study suggests that an association between the polymorphisms of the studied candidate genes and hypospadias or cryptorchidism is unlikely in dogs. We thus support the recent suggestion that hypospadias is not rare in this species, and moreover, we show that co-occurrence of hypospadias and cryptorchidism can be quite frequent.

Molecular diagnostics of disorders of sexual development: an Indian survey and systems biology perspective

We aimed to survey the monogenic causes of disorders of sex development (DSD) and thereby its prevalence in India. This study revealed mutations resulting in androgen insensitivity syndrome, 5α-reductase type 2 deficiency, and gonadal dysgenesis were commonly reported. Intriguingly, AR deficits were the most prevalent (32 mutations) and of 11/26 missense mutations were in exons 4-8 (encoding ligand binding domain). The unique features of SRD5A2 defects were p.R246Q (most prevalent) and p.G196S could be mutational hotspots, dual gene defects (p.A596T in AR and p.G196S in SRD5A2) in a patient with hypospadias and novel 8 nucleotide deletion (exon 1) found in a patient with perineal hypospadias. Deficits in SRY, WT1, DHH, NR5A1, and DMRT1 caused 46,XY gonadal dysgenesis. Notably, mutations in AR, SRD5A2, MAMLD1, WT1, and MAP3K1 have led to hypospadias and only one CYP19A1 mutation caused aromatase deficiency was reported to date. Data mining from various databases has not only reinforced the role of well-established genes (e.g., SRY, WT1, DHH, NR5A1, DMRT1, AR, SRD5A2, MAMLD1) involved in DSD but also provided us 12 more potential candidate genes (ACVR1, AMHR2, CTNNB1, CYP11A1, CYP19A1, FGFR2, FGF9, PRKACA, PRKACG, SMAD9, TERT, ZFPM2), which benefit from a close association with the well-established genes involved in DSD and might be useful to screen owing to their direct gene-phenotype relationship or through direct functional interaction. As more genes have been revealed in relation to DSD, we believe ultimately it holds a better scenario for therapeutic regimen. Despite the advances in translational medicine, hospitals are yet to adopt genetic testing and counseling facilities in India that shall have potential impact on clinical diagnosis. Abbreviations: 5α-RD2: 5α-Reductase type 2; AIS: androgen insensitivity syndrome; AMH: antimullerian hormone; AMHR: antimullerian hormone receptor; AR: androgen receptor gene; CAH: congenital adrenal hyperplasia; CAIS: complete AIS; CAH: congenital adrenal hyperplasia; CHH: congenital hypogonadotropic hypogonadism; CXORF6: chromosome X open reading frame 6 gene; CYP19A1: cytochrome P450 family 19 subfamily A member 1 gene; DHT: dihydrotestosterone; DMRT1: double sex and mab-3 related transcription factor 1 gene; DSD: disorders of sexual development; GD: gonadal dysgenesis; HGMD: human gene mutation database; IH: isolated hypospadias; MAMLD1: mastermind like domain containing 1 gene; MIS: mullerian inhibiting substance; NTD: N-terminal domain; OT DSD: ovotesticular DSD; PAIS: partial AIS; SOX9: SRY-related HMG-box 9 gene; SRY: sex-determining region Y gene; STAR: steroidogenic acute regulatory protein gene; SRD5A2: steroid 5 alpha-reductase 2 gene; T DSD: testicular DSD; T: testosterone; WNT4: Wnt family member 4 gene; WT1: Wilms tumor 1 gene; Δ₄: androstenedione.

Single-nucleotide and copy-number variance related to severity of hypospadias

BACKGROUND

The genetic association of hypospadias-risk studies has been conducted in Caucasians, Chinese-Han populations and few in Indian populations. However, no comprehensive approach has been followed to assess genetic involvement in the severity of the disorder.

METHODS

The study evaluated to establish the correlation between genotyped single nucleotide and copy number variants (SNPs/CNVs) and severity of hypospadias by an association in a total 30 SNPs in genes related to sex hormone-biosynthesis and metabolism; embryonic-development and phospholipase-D-signalling pathways on 138 surgery-confirmed hypospadias-cases from North India (84 penile and 28 cases of penoscrotal-hypospadias as compared with 31 cases of glanular + coronal), and analyzed and identified CNVs in four familial cases (18 members) and three paired-sporadic cases (6 members) using array-based comparative-genomic-hybridization and validated in 32 hypospadias samples by TaqMan assay.

RESULTS

Based on odds ratio at 95% CI, Z Statistic and Significance Levels, STS gene-rs17268974 was associated with Penile-Hypospadias and 9-SNPs [seven-SNPs (rs5934740; rs5934842; rs5934913; rs6639811; rs3923341; rs17268974; rs5934937)] of STS gene; rs7562326-SRD5A2 and rs1877031-STARD3 were associated with penoscrotal-hypospadias. On aggregate analysis with p < 0.001, we identified homozygous-loss of Ch7:q34 (PRSS3P2, PRSS2). On validation in previously CNV-characterized and new (32 hypospadias cases), we identified PRSS3P2-loss in most of the grade 3 and 4 hypospadias. Hence, Grade 1 and 2 (coronal and granular) show no-PRSS3P2-loss and no-association with SNPs in STS; SRD5A2; STARD3-gene but Grade 3 and 4 (Penile and Penoscrotal) show PRSS3P2-loss accompanied with the association of SNPs in STS; SRD5A2; STARD3.

CONCLUSIONS

Hence, homozygous-loss of PRSS3P2 accompanied with the association of STS; SRD5A2; STARD3 may link to the severity of the disease.