The role of endothelial nitric oxide synthase (eNOS) T-786C, G894T, and 4a/b gene polymorphisms in the risk of idiopathic male infertility

Antioxidant Genes Variants and Their Association with Sperm DNA Fragmentation

Semen possesses a variety of antioxidant defense mechanisms which protect sperm DNA from the damaging effects of oxidative stress. Correlation between antioxidant genes variants and sperm DNA fragmentation (SDF) level is not sufficiently studied. Therefore, we investigated the association between several single nucleotide polymorphisms (SNPs): CYP1A1 (rs1048943A > G), CYP4F2 (rs2108622G > A), NRF2 (rs6721961C > A), PON1 (rs662A > G), NOS3 (rs1799983G > T), GSTM1 (null), CAT (rs1001179C > T), SOD2 (rs4880A > G), GSTP1 (rs1695A > G), PON2 (rs7493G > C), EPHX2 (rs1042064T > C), and AHR (rs2066853G > A) and elevated SDF. The study employed a case-control design where, the allele and genotype frequencies of the selected SNPs were compared between 75 semen samples with abnormal SDF (the cases) and 75 samples with normal SDF (the controls). DNA was extracted from the semen samples and allele-specific PCR (AS-PCR) was used for genotyping the SNPs. Relevant data were collected from the patients' records et al.-Basma Fertility Center. Suitable statistical tests and multifactorial dimensionality reduction (MDR) test were used to anticipate SNP-SNP interactions. Comparison of semen parameters revealed significant differences between cases and controls in terms of liquefaction time, sperm total motility, and normal form. Genotype frequencies of NOS3 G > T (GT), SOD2 A > G (AA and AG), EPHX2 T > C (CC and CT), and AHR G > A (GA and GG) were significantly different between cases and controls. Allele frequencies of SOD2 (G-allele), and EPHX2 (T-allele) also significantly varied between cases and controls. MDR analysis revealed that the NOS3, SOD2, and EPHX2 SNPs combination has the highest impact on SDF. The study findings suggest that genetic variations in genes involved antioxidant defenses contribute to abnormal SDF.

Genetic variations of antioxidant genes and their association with male infertility in Vietnamese men

BACKGROUND

Antioxidant genes, such as superoxide dismutase (SOD), catalase (CAT), and nitric oxide synthase (NOS), play critical roles in spermatogenesis and sperm functions. Polymorphisms of antioxidant genes have been shown to be strongly associated with sperm quality which affects male fertility.

METHODS

To investigate the association of antioxidant gene polymorphisms to male infertility in Vietnamese men, in this case-control study, using Sanger sequencing, we genotyped four variants SOD1:7958G>A, SOD2:c.47T>C, CAT:-262C>T, and NOS3:-786C>T.

RESULTS AND CONCLUSIONS

We identified SOD1:7958GA genotype and NOS3:-786CT genotype in the infertility group were significantly higher than in the control with OR = 2.191 (95% CI: 1.226-3.915, p = 0.004) and OR = 3.135 (95% CI: 1.591-6.180, p < 0.001), respectively. We also detected that the frequency of the SOD2:c.47TC genotype was significantly higher in the male infertility group than in fertile men (OR = 1.941, 95% CI: 1.063-3.595, p = 0.029). Gene-gene interactions between the SNPs of SOD1, SOD2, and CAT might increase the risk of male infertility patients. In particular, patients carrying the SOD1:GA+AA, SOD2:TC+CC, and CAT:CT/TT genotype pattern have an increased risk of male infertility (OR = 7.614, p = 0.007). To our knowledge, this is the first study to evaluate the association between the SOD1:7958G>A polymorphism and male infertility. Further studies with larger sample sizes and more genes are needed to better assess the association between variants of antioxidant genes and male infertility.

Genetic variations as molecular diagnostic factors for idiopathic male infertility: current knowledge and future perspectives

INTRODUCTION

Infertility is a major health problem, worldwide, which affects 10-15% of couples. About half a percent of infertility cases are related to male-related factors. Male infertility is a complex disease that is the result of various insults as lifestyle issues, genetics, and epigenetic factors. Idiopathic infertility is responsible for 30% of total cases. The genetic factors responsible for male infertility include chromosomal abnormalities, deletions of chromosome Y, and mutations and genetic variations of key genes.

AREAS COVERED

In this review article, we aim to narrate performed studies on polymorphisms of essential genes involved in male infertility including folate metabolizing genes, oxidative stress-related genes, inflammation, and cellular pathways related to spermatogenesis. Moreover, possible pathophysiologic mechanisms responsible for genetic polymorphisms are discussed.

EXPERT OPINION

Analysis and assessment of these genetic variations could help in screening, diagnosis, and treatment of idiopathic male infertility.

The "Hitchhiker's Guide to the Galaxy" of Endothelial Dysfunction Markers in Human Fertility

Endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and represents the first step in the pathogenesis of cardiovascular diseases. The evaluation of endothelial health is fundamental in clinical practice and several direct and indirect markers have been suggested so far to identify any alterations in endothelial homeostasis. Alongside the known endothelial role on vascular health, several pieces of evidence have demonstrated that proper endothelial functioning plays a key role in human fertility and reproduction. Therefore, this state-of-the-art review updates the endothelial health markers discriminating between those available for clinical practice or for research purposes and their application in human fertility. Moreover, new molecules potentially helpful to clarify the link between endothelial and reproductive health are evaluated herein.

Extracellular Vesicles and the Oviduct Function

In mammals, the oviduct (or the Fallopian tube in humans) can be divided into the infundibulum (responsible for oocyte pick-up), ampulla (site of fertilization), isthmus (where preimplantation embryos develop), and uterotubal junction (where embryos transit to the uterus). The oviductal fluid, as well as extracellular vesicles produced from the oviduct epithelial cells, referred to as oEVs, have been shown to improve the fertilization process, prevent polyspermy, and aid in embryo development. oEVs contain molecular cargos (such as miRNAs, mRNAs, proteins, and lipids) that can be delivered and fuse to recipient cells. oEVs produced from the ampulla appear to be functionally distinct from those produced from the isthmus. In multiple species including mice, cats, dogs, pigs, and cows, oEVs can be incorporated into the oocytes, sperm, and embryos. In this review, we show the positive impact of oEVs on gamete function as well as blastocyst development and how they may improve embryo quality in in vitro conditions in an assisted reproductive technology setting for rodents, domestic animals, farm animals, and humans.

Association of nitric oxide synthase 3 gene rs1799983 G/T polymorphism with idiopathic asthenozoospermia in Iranian Azeri males: a case-control study

OBJECTIVES

Recently, oxidative stress (OS) has been described extensively as an important cause of men infertility. The nitric oxide synthase 3 (NOS3) gene expression involved in normal spermatogenesis regulation in testis. Several single nucleotide polymorphisms (SNPs) on NOS3 gene are reported in association with sperm function and spermatogenesis impairment in infertile men. In present study, we investigated association of NOS3 gene rs1799983 G/T polymorphism in Iranian Azeri male with idiopathic asthenozoospermia (AZS).

METHODS

In this case-control study, we collected 50 males with idiopathic AZS as a case group and 50 age and ethnically matched male as healthy controls from East Azerbaijan area, Iran. The case and control groups genotyping was performed using tetra-primer amplification refractory mutation system-polymerase chain reaction (Tetra-ARMS PCR) method.

RESULTS

Genotype frequency in AZS patients was 40% GG, 60% GT, and 0% TT, whereas in healthy controls were 60% GG, 30% GT, and 10% TT. Statistical analysis showed that the GT heterozygous genotype frequency of NOS3 gene rs1799983 G/T polymorphism in AZS patients was significantly more than healthy controls (p>0.05).

CONCLUSIONS

We demonstrated that NOS3 gene rs1799983 G/T polymorphism was associated with AZS in Iranian Azeri men. However, more studies on different geographic areas, races and ethnicities are required to determine exact role of NOS3 gene rs1799983 G/T polymorphism in idiopathic AZS.

Investigation of the association of endothelial nitric oxide synthase (eNOS)-T786C gene polymorphism with the risk of male infertility in an Iranian population

Recent studies have demonstrated that making the sorts of oxygen reactive, such as nitric oxide, can cause oxidative lipid damage, protein damage, and damage to the DNA of cells. Sperm DNA damage effect on the reduction of sperm mobility and damage of acrosome membrane lead to the inability of sperm to fertilize the oocyte. Increasing expression of endothelial nitric oxide synthase (eNOS) gene is seen in various diseases such as cardiovascular and infertility diseases. This study aimed to assess the association between eNOS gene single nucleotide polymorphism/SNP (rs2070744, T786C) and risk of male infertility and the quality of sperm parameters in an Iranian population. In this case-control study, 100 infertile men were enrolled as a patient group. Control groups consisted of 100 fertile men. T786C genotypes were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results showed that T786C SNP, contained frequent genotype TC (p = 0.000; OR = 0.000; 95% CI = 0.000-0.015), TC + CC genotypes (p = 0.000; OR = 0.000; 95% CI = 0.000-0.015), and C allele (p = 0.000; OR = 0.00; 95% CI = 0.000-0.007), revealed a significant with male infertility. Based on the findings of this study suggested that although T786C SNP could not be applied as an appropriate genetic risk factor for male infertility, it probably may be considered a protective marker for other researchers. However, more comprehensive studies in different populations are required to confirm our data.

Association of single nucleotide polymorphism c.673C>A/p.Gln225Lys in SEPT12 gene with spermatogenesis failure in male idiopathic infertility in Northeast China

Male infertility is a complex multifactorial disease affecting approximately 10% of couples who want to have children. Some cases of infertility can be explained by genetic factors. Septins are members of the GTPase superfamily, which are involved in diverse biological processes including morphogenesis, compartmentalization, cytokinesis, and apoptosis. The septin 12 gene, SEPT12, is expressed exclusively in post-meiotic male germ cells and is considered as a critical gene for spermatogenesis. In this study, we evaluated 200 patients with non-obstructive azoospermia and detected mutations of 25 spermatogenesis-associated genes by targeted exome sequencing. We report a missense SEPT12 variant, c.673C>A/p.Gln225Lys, in an infertile man with non-obstructive azoospermia. The variation was located inside the GTPase domain and had a SIFT score of 0.02 (<0.50) and was considered to be 'probably damaging' by PolyPhen. This case may provide clues to help establish the relationship between SEPT12 gene alterations and some cases of idiopathic male infertility. The role of this variant should thus be investigated further.

Designing and Validation of One-Step T-ARMS-PCR for Genotyping the eNOS rs1799983 SNP

Background: The transversion of G to T (G894T) in human endothelial nitric oxide synthase (eNOS) gene has profound effects such as male infertility, recurrent miscarriage, multiple sclerosis and cardiovascular diseases. Objectives: Development of a new Multiplex Tetra-Primer Amplification Refractory Mutation System - Polymerase Chain Reaction (T-ARMS-PCR) for detection of rs1799983 (G894T) in the human eNOS was sought. Materials and Methods: A T-ARMS-PCR for rs1799983 polymorphism in a single-step PCR was carried out, and the results were confirmed by PCR-RFLP technique in 82 infertile men with varicocele. Results: The results showed that GG (varicocele infertile men), GT and TT genotypes appear to be 53.65%, 34.14%, and 12.19%, respectively. Full accordance between PCR-RFLP and T-ARMS-PCR methods for genotyping of rs1799983 polymorphism was found. Conclusions: This is the first work that describes a rapid, relatively cheap, high throughput detection of G894T polymorphism in eNOS that can be used in large scale clinical studies.

Molecular Analysis of rs2070744 and rs1799983 Polymorphisms of NOS3 Gene in Iranian Patients With Multiple Sclerosis

Introduction

Multiple Sclerosis (MS) is a disease of central nervous system that mainly causes lesions or plaques in the spinal cord and brain. The purpose of this study was to analyze the relation between c.-813C>T (rs2070744) and c.894G>T (rs1799983) polymorphisms of NOS3 gene and MS in Iranian patients.

Methods

A total of 78 patients with MS and 80 healthy controls were screened for NOS3 (rs2070744 and rs1799983) Single Nucleotide Polymorphisms (SNPs) by tetra-primer multiplex ARMS-PCR and PCR-RFLP.

Results

Genotype frequencies of the c.-813C>T polymorphism in patients compared to controls were as follows: 53.8% to 80.0% for TT genotype, 41.0% to 18.8% for TC genotype, and 5.1% versus 1.2% for CC genotype (P=0.001). The frequencies of GG genotype was 57.7% and 78.8% and for GT genotype of c.894G>T polymorphism in patients compared to control subjects was 42.3% and 21.2%, respectively (P=0.004).

Conclusion

Our results indicate that the studied NOS3 polymorphisms may be associated with MS in Iranian patients.

NOS3 gene variants and male infertility: Association of 4a/4b with oligoasthenozoospermia

Results of recent studies confirmed that oxidative stress negatively affects sperm motility and causes sperm DNA damage. Produced by nitric oxide synthase 3 (NOS3), nitric oxide is considered to be one of the important mediators of oxidative stress in testis tissue. The aim of this study was to assess the possible association of three genetic variants (rs2070744, rs1799983 and intron variant 4a/4b) in NOS3 gene and infertility occurrence in two groups of infertile men (idiopathic azoospermia and oligoasthenozoospermia) and fertile controls. Genotypes for the single-nucleotide genetic variants rs1799983 and rs2070744 were determined by PCR-RFLP, while genotyping of intron 4 variant 4a/4b was performed by gel electrophoresis of PCR products. Statistical analysis was performed by SNPStats software. No significant association between the three genetic variants of the NOS3 gene and infertility risk was determined comparing allele and genotype frequencies among group of patients diagnosed with azoospermia and the control group. Nevertheless, there was a significant positive association between 4a/4b and infertility in the group of males diagnosed with oligoasthenozoospermia, under overdominant genetic model. Our findings suggest that tandem repeat variant within intron 4 of the NOS3 gene is associated with an increased risk of infertility in men diagnosed with idiopathic oligoasthenozoospermia.

Genetics of male infertility: from research to clinic

Male infertility is a multifactorial complex disease with highly heterogeneous phenotypic representation and in at least 15% of cases, this condition is related to known genetic disorders, including both chromosomal and single-gene alterations. In about 40% of primary testicular failure, the etiology remains unknown and a portion of them is likely to be caused by not yet identified genetic anomalies. During the last 10 years, the search for 'hidden' genetic factors was largely unsuccessful in identifying recurrent genetic factors with potential clinical application. The armamentarium of diagnostic tests has been implemented only by the screening for Y chromosome-linked gr/gr deletion in those populations for which consistent data with risk estimate are available. On the other hand, it is clearly demonstrated by both single nucleotide polymorphisms and comparative genomic hybridization arrays, that there is a rare variant burden (especially relevant concerning deletions) in men with impaired spermatogenesis. In the era of next generation sequencing (NGS), we expect to expand our diagnostic skills, since mutations in several hundred genes can potentially lead to infertility and each of them is likely responsible for only a small fraction of cases. In this regard, system biology, which allows revealing possible gene interactions and common biological pathways, will provide an informative tool for NGS data interpretation. Although these novel approaches will certainly help in discovering 'hidden' genetic factors, a more comprehensive picture of the etiopathogenesis of idiopathic male infertility will only be achieved by a parallel investigation of the complex world of gene environmental interaction and epigenetics.

eNOS gene T786C, G894T and 4a4b polymorphisms and male infertility susceptibility: a meta-analysis

The association between polymorphism of eNOS and male infertility in several studies was controversial. To explore a more precise estimation of the association, a meta-analysis of eight case-control studies, including 1,968 cases and 1,539 controls, were selected. The meta-analysis was conducted by calculating the pooled odds ratio (OR) with a 95% confidence interval (95% CI). Overall, the association between T786C and risk of male infertility was obvious (TC vs. TT: OR, 1.20; 95% CI, 1.01-1.42; CC vs. TT: OR, 3.37; 95% CI, 1.65-6.87; TC/CC vs. TT: OR, 1.47; 95% CI, 1.25-1.73; CC vs.

TT/TC

OR, 3.18; 95% CI, 1.54-6.56; TC vs. TT: OR, 1.65; 95% CI, 1.27-2.03). However, no overall association was observed between the other two polymorphisms of eNOS (G894T and 4a4b) and male infertility. Stratified analysis showed that significantly strong association between T786C polymorphism and semen quality was present in all three types of male infertility (azoospermia, oligozoospermia and asthenozoospermia). In the subgroup analysis based on ethnicity, both T786C and 4a4b could influence the risk of male infertility in Asian and Caucasian. Further studies of polymorphisms of eNOS with their biological functions are needed to understand the role in the development of male infertility.

Aberrant expression of TAR DNA binding protein-43 is associated with spermatogenic disorders in men

Loss of function of TAR DNA-binding protein (TDP-43) has been implicated in neurodegenerative disorders in both humans and animal models. TDP-43 has also been shown to be cis-acting transcriptional repressor of the acrosome vesicle (Acrv) gene in mice. In the present study, we investigated the expression of the TDP-43 transcript (TARDBP) and protein in germ cells from 11 fertile and 98 subfertile men to verify its potential association with poor seminograms. The expression profile of TDP-43 was characterised in immature germ cells and spermatozoa from semen from fertile and subfertile men using reverse transcription–polymerase chain reaction, western blotting and immunofluorescence. Although germ cells from subfertile men tested negative for TARDBP, the full-length message of the same was detected in fertile men. TDP-43 was detected in spermatozoa from fertile men using western blot analysis and immunofluorescence. The expression of this protein was negligible in spermatozoa from men with primary spermatogenic dysfunction. We conclude that a deficiency in the TDP-43 expression is associated with defective spermatogenesis and male infertility. We propose that TDP-43 could be used as a marker of male factor infertility.

Variations in Antioxidant Genes and Male Infertility

Oxidative stress and reactive oxygen species (ROS) are generated from both endogenous and environmental resources, which in turn may cause defective spermatogenesis and male infertility. Antioxidant genes, which include catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST), nitric oxide synthase (NOS), nuclear factor erythroid 2-related factor 2 (NRF2), and superoxide dismutase (SOD), play important roles in spermatogenesis and normal sperm function. In this review, we discuss the association between variations in major antioxidant genes and male infertility. Numerous studies have suggested that genetic disruption or functional polymorphisms in these antioxidant genes are associated with a higher risk for male infertility, which include low sperm quality, oligoasthenoteratozoospermia, oligozoospermia, and subfertility. The synergistic effects of environmental ROS and functional polymorphisms on antioxidant genes that result in male infertility have also been reported. Therefore, variants in antioxidant genes, which independently or synergistically occur with environmental ROS, affect spermatogenesis and contribute to the occurrence of male infertility. Large cohort and multiple center-based population studies to identify new antioxidant genetic variants that increase susceptibility to male infertility as well as validate its potential as genetic markers for diagnosis and risk assessment for male infertility for precise clinical approaches are warranted.

Human papillomavirus infection and fertility alteration: a systematic review

Background

HPV is the most prevalent sexually transmitted infection and its effect in cancer induction is well documented. HPV infections are mostly asymptomatic, but it is unclear whether HPV infections can result in alterations of reproductive health.

Objective

To determine the relationship between human papillomavirus infections and reproductive health in both men and women.

Methods

A systematic literature review was performed in PubMed and ScienceDirect data bases from January 1994 through August 2014.

Results

HPV infections are shown to be significantly associated to many adverse effects in the reproductive function. These adverse effects were reported in different levels from cells production to pregnancy and may be related to the infecting genotype.

Conclusions

It appears from this study that HPV detection and genotyping could be of great value in infertility diagnosis at least in idiopathic infertility cases. Like for the risk of carcinogenesis, another classification of HPV regarding the risk of fertility alteration may be considered after deep investigations.

Endothelial nitric oxide synthase gene polymorphism relationship with semen parameters and oxidative stress in infertile oligoasthenoteratozoospermic men

OBJECTIVE

To assess endothelial nitric oxide synthase (eNOS) gene polymorphism relationship with semen parameters and oxidative stress in infertile oligoasthenoteratozoospermic (OAT) men.

MATERIALS AND METHODS

Three hundred subjects were divided into healthy fertile men (n = 80) and infertile OAT men (n = 220). They were subjected to history taking, clinical examination, and semen analysis in addition to malondialdehyde and glutathione peroxidase estimation in seminal plasma. Polymorphisms of eNOS G894T and T786C genotypes in peripheral blood were identified by the polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Comparing infertile OAT men with fertile controls, eNOS genotype G894T demonstrated prevalence of 36.8% vs 50% for wild type (GG), 35.0% vs 47.5% for heterozygous type (GT), and 28.2% vs 2.5% for mutant homozygous type (TT). Compared with GG homozygotes, carriers with A allele exhibited >1.716-fold increased risk of OAT occurrence. Comparing infertile OAT men with fertile controls, eNOS genotype T786C demonstrated prevalence of 37.3% vs 51.3% for wild type (TT), 32.7% vs 45% for heterozygous type (TC), and 30% vs 3.7% for mutant type (CC) with significant differences. Compared with TT homozygotes, carriers with C allele exhibited >1.769-fold increased risk of OAT occurrence. G894T and T786C genotypes demonstrated significant negative correlation with sperm count, total sperm motility, sperm normal forms, and seminal glutathione peroxidase, and significant positive correlation with seminal malondialdehyde. G894T genotype demonstrated significant positive correlation with T786C genotype.

CONCLUSION

There is a significant relationship between eNOS genotypes T786C, G894T polymorphisms with decreased sperm parameters and increased seminal oxidative stress.

Genetic variants in nitric oxide synthase genes and the risk of male infertility in a Chinese population: a case-control study

BACKGROUND

In recent years, oxidative stress has been studied extensively as a main contributing factor to male infertility. Nitric Oxide, a highly reactive free radical gas, is potentially detrimental to sperm function and sperm DNA integrity at high levels. Thus, the aim of this study was to investigate the associations between five polymorphisms in nitric oxide synthase genes (NOSs) and the risk of male infertility and sperm DNA damage as well.

METHODS

Genotypes were determined by the OpenArray platform. Sperm DNA fragmentation was detected using the Tdt-mediated dUTP nick-end labeling assay, and the level of 8-hydroxydeoxyguanosine (8-OHdG) in sperm DNA was measured using immunofluorescence. The adjusted odds ratio (OR) and 95% confidence interval (CI) were estimated using unconditional logistic regression.

RESULTS

Our results revealed a statistically significant difference between the cases and controls in both genotypic distribution (P<0.001) and allelic frequency (P = 0.021) only for the NOS3 rs1799983 SNP. Multivariate logistic regression analyses revealed that rs1799983 was associated with a borderline significantly increased risk of male infertility (GT vs. GG: adjusted OR = 1.30, 95% CI: 1.00-1.70; GT+TT vs. GG: adjusted OR = 1.34, 95% CI: 1.03-1.74; P trend = 0.020). Moreover, NOS3 rs1799983 was positively associated with higher levels of sperm DNA fragmentation (β = 0.223, P = 0.044). However, the other 4 polymorphisms (NOS1 rs2682826, NOS1 rs1047735, NOS2 rs2297518, and NOS2 rs10459953) were not found to have any apparent relationships with male infertility risk.

CONCLUSIONS

Of five NOS gene polymorphisms investigated in the present study, we found NOS3 rs1799983 might cause oxidative sperm DNA damage, thereby contributing to male infertility.

Genetic variants within endothelial nitric oxide synthase gene and prostate cancer: a meta-analysis

Several variants within gene-encoding endothelial isoform of nitric oxide synthase have been reported to confer prostate cancer (PCa) susceptibility and/or progression. Nevertheless, studies referring to this issue have yielded inconsistent results. In order to elucidate the involvement of these variants in prostate carcinogenesis, we have conducted a meta-analysis of previously published case-control and relevant case-only studies. Eleven studies comprising in total 3,806 cases and 4,466 controls were included in the meta-analysis which yielded evidence of association of rs2070744 (ORCC = 1.43, 95% CI 1.04-1.97; p = 0.03) and intron 4a/b variant (ORab+aa = 1.47, 95% CI 1.00-2.14; p = 0.05) with PCa risk under recessive and dominant model, respectively. Furthermore, PCa patients carrying 4a/b a allele were found to have an increased risk of cancer progression to a less differentiated form, characterized by a high Gleason score (OR = 2.29, 95% CI 1.51-3.49; p < 0.01) and to higher TNM stage (OR = 2.55, 95% CI 1.71-3.81; p < 0.01). These results support the involvement of NOS3 variants in molecular pathogenesis of PCa.

Endothelial nitric oxide synthase gene polymorphisms and prostate cancer risk in Serbian population

Genome-wide association studies (GWAS) have identified over 46 SNPs associated with human prostate cancer (PCa). Some studies have shown correlation of the nitric oxide synthase (NOS) NOS3 gene polymorphisms with the risk and/or progression of PCa. This study aimed to evaluate the association of NOS3 gene polymorphisms (-786T>C, -764A>G, -714G>T, -690C>T, -649G>A and 894G>T) with PCa risk and progression. 150 patients with PCa, 150 patients with BPH and 100 age-matched healthy controls were recruited in this study. Genotyping of promoter polymorphisms was performed by bi-directional DNA sequencing, and for 894G>T by RFLP analysis. There was no significant association between the alleles and genotypes of these genetic variants and PCa risk. For -786T>C polymorphism, we found that C allele is associated with absence of metastases, assuming dominant genetic model (P = 0.049; OR, 0.50; 95% CI, 0.25-1.00). It was found that, compared with NOS3 -690C>T variant CC genotype, CT and TT genotypes confer decreased risk of developing metastases (dominant model, P = 0.015, OR, 0.24; 95% CI, 0.07-0.88) and show association with low clinical tumour stage, compared with stages T3 and T4 (dominant model, P = 0.046, OR, 0.20; 95% CI, 0.04-1.02). Genetic variants -764A>G, -714G>T, -649G>A were not detected in our study group. There is evidence of an inverse correlation of the NOS3 894G>T minor allele with high serum PSA (>20 ng/ml) (dominant model, P = 0.013, OR, 0.37; 95% CI, 0.17-0.82). Our results suggest that NOS3 gene polymorphisms are genetic susceptibility factors for the progression of PCa and patient outcome.

Genetic variants of eNOS gene may modify the susceptibility to idiopathic male infertility

In testis, eNOS is responsible for synthesis of nitric oxide (NO) which is an essential gas message regulator in spermatogenesis, suggesting that eNOS gene plays a role in normal spermatogenesis and the genetic variants of eNOS gene may be potential genetic risk factors of spermatogenesis impairment. In this study, the polymorphic distributions of three common polymorphism loci including T-786C, 4A4B and G894T in eNOS gene were investigated in 355 Chinese infertile patients with azoospermia or oligozoospermia and 246 healthy fertile men and a meta-analysis was carried in order to explore the possible relationship between the three loci of eNOS gene and male infertility with spermatogenesis impairment. As a result, allele -786C of T-786C (11.4% versus 6.5%, p = 0.004) and 4A of 4A4B (11.0% versus 6.3%, p = 0.005) as well as genotype TC of T-786C (22.8% versus 13.0%, p = 0.002) and AB of 4A4B (18% versus 11%, p = 0.015) were significantly associated with idiopathic male infertility. The haplotypes T-4A-G (7.4% versus 4.1%, p = 0.015) and C-4B-G (7.6% versus 4.4%, p = 0.028) could increase the susceptibility to male infertility, whereas haplotype T-4B-G (67.0% versus 75.2%, p = 0.002) might be a protective factor for male infertility. The results of meta-analysis revealed that the polymorphism of T-786C was associated with male infertility. These findings suggested that the variants of eNOS gene may modify the susceptibility to male infertility with impaired spermatogenesis.

Analysis of endothelial nitric oxide synthase (eNOS) G894T polymorphism and semen parameters in a Chinese Han population

Previous studies have shown that endothelial nitric oxide synthase (eNOS) gene may be involved in abnormal semen parameters. However, the relationship between eNOS G894T polymorphism and semen parameters remains controversial. The purpose of this study was to investigate the association of eNOS G894T polymorphism and semen parameters. The genotype frequency of eNOS G894T was determined in 270 idiopathic asthenozoospermia patients and 248 ethnically matched healthy volunteers using iPLEX genotyping assays on a MassARRAY(®) (Sequenom, San Diego, CA, USA) platform. The statistical analysis performed with Fisher's exact test showed no significant difference in frequencies of genotypes between both groups. The logistic regression showed that genotypes GT, TT and allele T were nonassociated with increased risk of asthenozoospermia in the patient group with ≤5% or >5% sperm with normal forms. The dependence on genotypes of semen parameters was further investigated in both patients and control group. There was no significant difference as compared to control group (P > 0.05). Our study indicated that eNOS gene G894T polymorphism may not have an adverse effect on semen parameters in a Chinese Han population.

Effects of the T-786C, G894T, and Intron 4 VNTR (4a/b) polymorphisms of the endothelial nitric oxide synthase gene on the risk of prostate cancer

Several studies have shown that nitric oxide (NO) and nitric oxide synthase (NOS) system plays an important role in carcinogenesis. Endothelial nitric oxide synthase (eNOS) gene polymorphisms significantly affects serum NO concentrations. Studies addressing the relationship between eNOS gene polymorphisms and prostate cancer (CaP) are very scarce. We examined the association between the 3 eNOS gene polymorphisms (T-786C, G894T, and 4a/b) with risk and clinical features of CaP. One hundred seventy patients with CaP (mean age 63.6 ± 12.4 years) and 340 age-matched healthy controls (mean age 64.9 ± 12.9 years) were recruited in this case-control study. Genotyping was performed by polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique. For T-786C polymorphism, we found that CC genotype was associated to CaP risk [odds ratio (OR) = 3.62, 95% confidence interval (CI): 1.89-7.74, P = 0.002), high grade tumor (OR = 2.46, 95% CI:1.78-4.72; P = 0.006), and advanced disease (OR = 4.67, 95% CI: 2.64-8.61; P = 0.002). Neither the CaP risk nor clinical features of CaP were associated with the G894T polymorphism. It was found that, compared with 4a/b bb genotype, the 4a/b "a" variant genotypes were associated with an increased risk of CaP in an allele dose dependent manner (OR = 2.12, 95% CI: 1.68-3.44; P = 0.031 for 4a/b ab genotype, and OR = 4.32, 95% CI: 2.21-6.08; P = 0.001 for 4a/b aa genotype). In addition, genotypes with the "a" allele of the eNOS 4a/b polymorphism predispose the patients to high grade (OR = 4.76, 95% CI: 2.74-8.62; P = 0.001) and advanced CaP (OR = 5.28, 95% CI: 3.64-8.72; P = 0.001). Furthermore, the T-Asp-b and C-Asp-b haplotypes were associated with a significantly decreased risk of CaP (OR = 0.44, 95% CI: 0.33-0.77; P = 0.004, and OR = 0.39, 95% CI: 0.26-0.61; P = 0.001, respectively). We found significant differences in genotype distribution and allelic frequencies between CaP patients and controls for the T-786C, and 4a/b eNOS polymorphisms.

Genetic causes of spermatogenic failure

Approximately 10%-15% of couples are infertile, and a male factor is involved in almost half of these cases. This observation is due in part to defects in spermatogenesis, and the underlying causes, including genetic abnormalities, remain largely unknown. Until recently, the only genetic tests used in the diagnosis of male infertility were aimed at detecting the presence of microdeletions of the long arm of the Y chromosome and/or chromosomal abnormalities. Various other single-gene or polygenic defects have been proposed to be involved in male fertility. However, their causative effects often remain unproven. The recent evolution in the development of whole-genome-based techniques and the large-scale analysis of mouse models might help in this process. Through knockout mouse models, at least 388 genes have been shown to be associated with spermatogenesis in mice. However, problems often arise when translating this information from mice to humans.

Single nucleotide polymorphisms in the SEPTIN12 gene may be associated with azoospermia by meiotic arrest in Japanese men

PURPOSE

To investigate the association between SEPTIN12 gene variants and the risk of azoospermia caused by meiotic arrest.

METHODS

Mutational analysis of the SEPTIN12 gene was performed using DNA from 30 Japanese patients with azoospermia by meiotic arrest and 140 fertile male controls.

RESULTS

The frequencies of the c.204G>C (Gln38His) allele and the CC genotype were significantly higher in patients than in fertile controls (p < 0.05).

CONCLUSION

The c.204G>C (Gln38His) variant in the SEPTIN12 gene was associated with increased susceptibility to azoospermia caused by meiotic arrest.

Male infertility and its causes in human

Infertility is one of the most serious social problems facing advanced nations. In general, approximate half of all cases of infertility are caused by factors related to the male partner. To date, various treatments have been developed for male infertility and are steadily producing results. However, there is no effective treatment for patients with nonobstructive azoospermia, in which there is an absence of mature sperm in the testes. Although evidence suggests that many patients with male infertility have a genetic predisposition to the condition, the cause has not been elucidated in the vast majority of cases. This paper discusses the environmental factors considered likely to be involved in male infertility and the genes that have been clearly shown to be involved in male infertility in humans, including our recent findings.

Single nucleotide polymorphism in the UBR2 gene may be a genetic risk factor for Japanese patients with azoospermia by meiotic arrest

PURPOSE

To investigate the association between the UBR2 gene and the risk of azoospermia caused by meiotic arrest.

METHODS

Mutational analysis of the UBR2 gene was performed using DNA from 30 patients with azoospermia by meiotic arrest to 80 normal controls.

RESULTS

The genotypic and allelic frequencies of c.1,066A>T variant were significantly higher in patient than control groups (p < 0.001).

CONCLUSION

The c.1,066A>T variant in the UBR2 gene is associated with increased susceptibility to azoospermia caused by meiotic arrest.