Association of the c.-9C>T and c.368A>G transitions in H2BFWT gene with male infertility in an Iranian population

Impact of tobacco smoking in association with H2BFWT, PRM1 and PRM2 genes variants on male infertility

Tobacco's genotoxic components can cause a wide range of gene defects in spermatozoa such as single- or double-strand DNA breaks, cross-links, DNA-adducts, higher frequencies of aneuploidy and chromosomal abnormalities. The aim in this study was to determine the correlation between sperm quality determined by standard parameters, sperm DNA maturity tested by Chromomycin A3 (CMA3) staining, sperm DNA fragmentation tested by TUNEL assay and tobacco smoking in association with the single nucleotides polymorphisms (SNP) of three nuclear protein genes in spermatozoa (H2BFWT, PRM1 and PRM2). In this study, semen samples of 167 male patients were collected and divided into 54 non-smokers and 113 smokers. The target sequences in the extracted sperm DNA were amplified by PCR followed by Sanger sequencing. The results showed the presence of three variants: rs7885967, rs553509 and rs578953 in H2BFWT gene in the study population. Only one variant rs737008 was detected in PRM1 gene, and three variants were detected in the PRM2 gene: rs2070923, rs1646022 and rs424908. No significant association was observed between the concentration, progressive motility, morphology and the occurrence of H2BFWT, PRM1 and PRM2 SNPs. However, sperm parameters were significantly lower in heavy smokers compared to controls (p < 0.01) (sperm count: 46.00 vs. 78.50 mill/ml, progressive motility: 15.00% vs. 22.00%, and morphology 4.00% vs. 5.00%, respectively). Moreover, the heavy smoker individuals exhibited a considerable increase in CMA3 positivity and sDF compared to non-smokers (p < 0.01) (29.50% vs. 20.50% and 24.50% vs. 12.00%, respectively). In conclusion, smoking altered sperm parameters and sperm DNA integrity, but did not show a linkage with genetic variants in H2BFWT, and protamine genes (PRM1 and PRM2).

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.

Primate-specific histone variants

Canonical histones (H2A, H2B, H3, and H4) are present in all eukaryotes where they package genomic DNA and participate in numerous cellular processes, such as transcription regulation and DNA repair. In addition to the canonical histones, there are many histone variants, which have different amino acid sequences, possess tissue-specific expression profiles, and function distinctly from the canonical counterparts. A number of histone variants, including both core histones (H2A/H2B/H3/H4) and linker histones (H1/H5), have been identified to date. Htz1 (H2A.Z) and CENP-A (CenH3) are present from yeasts to mammals, and H3.3 is present from Tetrahymena to humans. In addition to the prevalent variants, others like H3.4 (H3t), H2A.Bbd, and TH2B, as well as several H1 variants, are found to be specific to mammals. Among them, H2BFWT, H3.5, H3.X, H3.Y, and H4G are unique to primates (or Hominidae). In this review, we focus on localization and function of primate- or hominidae-specific histone variants.

CAG Repeats in the androgen receptor gene is associated with oligozoospermia and teratozoospermia in infertile men in Jordan

CAG trinucleotide repeats are coded for the polyglutamine tract in the N-terminal of the androgen receptor (AR) gene which varies in normal individuals from 6 to 36 residues. In this study, we inspected the impact of the CAG repeats on the spermatogenic defects by measuring the size of AR-CAG repeats length in a cohort of 260infertile and 169 fertile Jordanian men. The infertile group included three subgroups of a zoospermic, oligozoospermic and teratozoospermia men. The CAG allele size was determined by direct sequencing. The results showed a significant association between the length of the AR-CAG repeats and men's infertility (p = .001). In particular, the current cohort demonstrated a significant association between the AR-CAG length polymorphism and oligozoospermia (p < .001) and teratozoospermia (p < .001) but not azoospermia. According to distributions of allele frequency, the risk of oligozoospermia was 5.5-fold greater than normal when alleles frequency > 20 repeats, while the risk of teratozoospermia was > 10.6 folds greater than normal when allele frequency > 22 repeats. In conclusion, our results underscored that the long repeats of the AR-CAG polymorphism within the normal range might be associated with abnormal spermatogenesis such as teratozoospermia and oligozoospermia and contributing to infertility in Jordanian men.

Oxidative stress markers in seminal plasma of idiopathic infertile men may be associated with glutathione S-transferase M1 and T1 null genotypes

This study aimed to investigate the association between glutathione S-transferase (GST) M1 and T1 null genotypes and thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC) and nitric oxide (NO) levels in male infertility. For this purpose, semen samples were collected from fertile and infertile subjects, and then they were genotyped for GSTT1 and GSTM1 genes using multiplex-PCR. The TBARS, TAC and NO levels in seminal plasma were then measured via the ferric-reducing ability of plasma (FRAP). A significant association was observed between GSTT1 null genotype and oligozoospermia, asthenozoospermia and teratozoospermia. But, the GSTM1 null genotype was merely associated with teratozoospermia. Moreover, the GSTT1-/GSTM1+ combined genotype was associated with all subgroups of male infertility. Besides, an association was observed between GSTT1-/GSTM1- genotype and asthenozoospermia and teratozoospermia. Further analysis showed that the GSTT1 null genotype was associated with increased NO in asthenozoospermia. Also, the GSTT1 null genotype was associated with increased TBARS in oligozoospermia and asthenozoospermia. As well, GSTM1 null genotype was associated with decreased TAC and increased NO in asthenozoospermia respectively. As a preliminary conclusion, the GSTM1 and GSTT1 null genotypes could be considered as genetic risk factors for male infertility, interfering with some oxidative stress markers in infertile men.

Association between polymorphisms in the XRCC1 gene and male infertility risk: A meta-analysis

BACKGROUND

X-ray repair cross-complementing group 1 (XRCC1) single nucleotide polymorphisms (SNPs) might correlate with male infertility susceptibility. This association has been described; however, the findings remain inconsistent. Consequently, this meta-analysis was conducted to characterize the relationship between XRCC1 SNPs and male infertility susceptibility.

METHODS/MAIN RESULTS

Studies were systematically searched in databases to evaluate the association between SNPs of XRCC1 and infertility in males. The effect measures chosen were the 95% confidence intervals (95% CIs) and odds ratios (ORs). A total of 7 studies, including 6 case-controlled studies on XRCC1 Arg399Gln and 3 case-controlled studies on XRCC1 Arg194Trp, were included. Ultimately, the results of this analysis revealed that XRCC1 Arg399Gln SNPs were significantly associated with infertility in males in homozygote comparisons (GG vs GA+AA: OR = 0.614, 95% CI: 0.40-0.937, P = .024). This meta-analysis did not demonstrate a relationship between XRCC1 Arg194Trp and male infertility risk.

CONCLUSIONS

Our study indicated that XRCC1 Arg399Gln polymorphism was associated with a significantly decreased male infertility risk, but not XRCC1 Arg194Trp.

Large-scale mtDNA deletions as genetic biomarkers for susceptibility to male infertility: A systematic review and meta-analysis

Several complex rearrangements such as deletions in mitochondrial DNA (mtDNA) have been identified in sperm deficiencies. This study aimed to investigate the association of common mtDNA deletions with male infertility using a meta-analysis approach. Standard databases were systematically searched to discover relevant studies. Pooled odds ratios (ORs) with corresponding 95% confidence intervals (CI) were estimated to analyze the association of mtDNA deletions with male infertility. Our data revealed a significant association between a common 4977-bp deletion and an increased risk of male infertility. A similar association was observed in an Asian population. Stratified analysis by infertility phenotype showed significant associations between the 4977-bp deletion and increased risk of asthenozoospermia, oligoasthenoteratozoospermia, and asthenoteratozoospermia. In addition, significant associations were found in studies with sample sizes >100, age of participants <45 years, subject selection according to WHO criteria, and studies of moderate to high quality. Regarding the other common mtDNA deletions, significant associations were observed between 7436-bp, 7599-bp, and 4866-bp deletions and the risk of male infertility. Our findings suggest that the 4977-bp deletion might be a risk factor for male infertility, especially in an ethnic and infertility phenotype dependent manner.

Methylation Status of MTHFR Promoter and Oligozoospermia Risk: An Epigenetic Study and in Silico Analysis

Objective

In this study, we evaluated the effects of promoter methylation of MTHFR on oligozoospermia risk, followed by an in silico analysis.

Materials and Methods

In a case-control study, semen samples were collected from infertile and healthy control men. MTHFR promoter region was amplified by methylation-specific polymerase chain reaction (PCR). Finally, the promoter region of MTHFR was analyzed by bioinformatics software.

Results

Our data revealed significant associations of CpG island promoter methylation with oligozoospermia in a case-control study. In silico analysis showed that promoter contains a strong nucleosome exclusion region, a bonafide CGIs, six PROSITE motifs without a defined TATA box and 14 transcription factor (TF) binding sites, which are directly involved in spermatogenesis

Conclusion

Based on our findings, methylation of the MTHFR gene promoter region may be a risk factor for oligozoospermia. However, this is a preliminary report representing data for future comprehensive studies to make a clinical conclusion on the potential biomarker role of methylation of this promoter in elevating susceptibility to oligozoospermia.

Association analysis of rs1695 and rs1138272 variations in GSTP1 gene and breast cancer susceptibility

Background:

The glutathione S transferases P1 (GSTP1) is one of the common type of the GSTs family. This gene has several genetic polymorphisms that the rs1695 and rs1138272 are the most common variations in this gene. This study aimed to examine the association of these genetic variations with breast cancer risk which was followed by bioinformatics analysis.

Materials and Methods:

In a case-control study, 200 participants including 100 women with breast cancer and 100 healthy women were enrolled. After blood sample collection and DNA extraction, the total genomic DNA was extracted from this sample. The SNPeffects online software was employed to evaluate the effects of rs1695 genetic variation on the GSTP1 protein structure.

Results:

Our data revealed that there is a significant association between rs1695 genetic variation and the risk of breast cancer in homozygote (OR= 3.1532, 95%CI= 1.1072 to 8.9798, p= 0.0315) and allelic (OR= 1.6098, 95%CI= 1.0577 to 2.4500, p= 0.0263) genetic comparisons. This despite the fact that the rs1138272 polymorphism was not associated with breast cancer risk. Our bioinformatics analysis based on WALTZ output showed that the rs1695 polymorphism reduces the amyloid propensity of the GSTP1 enzyme (dWALTZ= -228.00).

Conclusions:

Based on our findings, the rs1695 genetic variation is a genetic risk factor for breast cancer and it could be considered as a biomarker for screening of susceptible women.

Genetic Landscape of Nonobstructive Azoospermia and New Perspectives for the Clinic

Nonobstructive azoospermia (NOA) represents the most severe expression of male infertility, involving around 1% of the male population and 10% of infertile men. This condition is characterised by the inability of the testis to produce sperm cells, and it is considered to have an important genetic component. During the last two decades, different genetic anomalies, including microdeletions of the Y chromosome, karyotype defects, and missense mutations in genes involved in the reproductive function, have been described as the primary cause of NOA in many infertile men. However, these alterations only explain around 25% of azoospermic cases, with the remaining patients showing an idiopathic origin. Recent studies clearly suggest that the so-called idiopathic NOA has a complex aetiology with a polygenic inheritance, which may alter the spermatogenic process. Although we are far from a complete understanding of the molecular mechanisms underlying NOA, the use of the new technologies for genetic analysis has enabled a considerable increase in knowledge during the last years. In this review, we will provide a comprehensive and updated overview of the genetic basis of NOA, with a special focus on the possible application of the recent insights in clinical practice.

Oxidative stress and male infertility: current knowledge of pathophysiology and role of antioxidant therapy in disease management

Infertility is a global health problem involving about 15% of couples. Approximately half of the infertility cases are related to male factors. The oxidative stress, which refers to an imbalance in levels of reactive oxygen species (ROS) and antioxidants, is one of the main causes of infertility in men. A small amount of ROS is necessary for the physiological function of sperm including the capacitation, hyperactivation and acrosomal reaction. However, high levels of ROS can cause infertility through not only by lipid peroxidation or DNA damage but inactivation of enzymes and oxidation of proteins in spermatozoa. Oxidative stress (OS) is mainly caused by factors associated with lifestyle. Besides, immature spermatozoa, inflammatory factors, genetic mutations and altering levels of sex hormones are other main source of ROS. Since OS occurs due to the lack of antioxidants and its side effects in semen, lifestyle changes and antioxidant regimens can be helpful therapeutic approaches to overcome this problem. The present study aimed to describe physiological ROS production, roles of genetic and epigenetic factors on the OS and male infertility with various mechanisms such as lipid peroxidation, DNA damage, and disorder of male hormone profile, inflammation, and varicocele. Finally, the roles of oral antioxidants and herbs were explained in coping with OS in male infertility.

Retinoic acid and 17β-estradiol improve male germ cell differentiation from mouse-induced pluripotent stem cells

This research aimed to explore the impacts of retinoic acid (RA)/17β-estradiol (E) induction and embryoid body formation to enhance differentiation of mouse-induced pluripotent stem cells (miPSCs) into male germ cells in vitro. Flow cytometry and qPCR were conducted to describe miPSCs differentiation process. Various temporal expression profiles of germ cell-related genes were traced. Stra8 gene expression increased in the RA group on the 4th day compared to other groups. The RA group experienced a more significant increase than E group. The expression of Sycp3 increased in RA + E group on 4th day compared with other groups. Expression of AKAP3 enhanced in the RA + E group than other groups on day 4. Moreover, miPSCs showed that this gene expression in the RA + E group was increased in comparison to RA and E groups on day 7. AKAP3 gene expression on day 7 of miPSCs decreased in RA and E groups. Flow cytometry data indicated that 3%-8% of the cells in sub-G1 stage were haploid after RA and E induction compared to other groups on day 4. This study showed that miPSCs possess the power for differentiating into male germ cells in vitro via formation of embryoid body by RA with/or E induction.

Retinoic acid and/or progesterone differentiate mouse induced pluripotent stem cells into male germ cells in vitro

Numerous reagents were employed for differentiating induced pluripotent stem cells (iPSCs) into male germ cells; however, the induction procedure was ineffective. The aim of this study was to improve the in vitro differentiation of mice iPSCs (miPSCs) into male germ cells with retinoic acid (RA) and progesterone (P). miPSCs were differentiated to embryoid bodies (EBs) in suspension with RA with or without progesterone for 0, 4, and 7 days. Then, the expression of certain genes at different stages of male germ cell development including Ddx4 (pre meiosis), Stra8 (meiosis), AKAP3 (post meiosis), and Mvh protein was examined in RNA and/or protein levels by real-time polymerase chain reaction or flow cytometry, respectively. The Stra8 gene expression increased in the RA groups on all days. But, expression of this gene declined in RA + P groups. In addition, an increased expression of Ddx4 gene was observed on day 0 in the P group. Also, a significant upregulation was observed in the expression of AKAP3 gene in the RA + P group on days 0 and 4. However, gene expression decreased in P and RA groups on day 7. The expression of Mvh protein significantly increased in the RA group on day 7. The Mvh expression was also enhanced in the P group on day 4, but it decreased on day 7, while this protein upregulated on day 0 and 7 in the RA + P group. The miPSCs have the capacity for in vitro differentiation into male germ cells by RA and/or progesterone. However, the effects of these inducers depend on the type of combination and an effective time.

Essential Role of Histone Replacement and Modifications in Male Fertility

Spermiogenesis is a complex cellular differentiation process that the germ cells undergo a distinct morphological change, and the protamines replace the core histones to facilitate chromatin compaction in the sperm head. Recent studies show the essential roles of epigenetic events during the histone-to-protamine transition. Defects in either the replacement or the modification of histones might cause male infertility with azoospermia, oligospermia or teratozoospermia. Here, we summarize recent advances in our knowledge of how epigenetic regulators, such as histone variants, histone modification and their related chromatin remodelers, facilitate the histone-to-protamine transition during spermiogenesis. Understanding the molecular mechanism underlying the modification and replacement of histones during spermiogenesis will enable the identification of epigenetic biomarkers of male infertility, and shed light on potential therapies for these patients in the future.

Methionine Synthase Reductase-A66G and -C524T Single Nucleotide Polymorphisms and Prostate Cancer: A Case-Control Trial

Purpose:

Some variations in the sequence of methionine synthase reductase (MTRR) gene can increase the risk of various cancers such as prostate cancer. The aim of this study was to investigate the association between prostate cancer and the MTRR A66G and C524T gene single nucleotide polymorphisms (SNPs) using an in silico analysis.

Methods:

In this case-control study, 218 Iranian men, including 108 men with prostate cancer and 110 prostate cancer-free men, were enrolled. The MTRR A66G and C524T genotyping was performed by PCR-RFLP. Some of the bioinformatics tools were employed for the evaluation of polymorphism on the molecular aspects of the MTRR.

Results:

With regard to the MTRR A66G polymorphism, the genotype AG (OR: 0.85, 95% CI: 0.47-1.54, p= 0.6014), genotype GG (OR: 0.89, 95% CI: 0.42-1.87, p= 0.7512), and allele G (OR: 0.92, 95% CI: 0.63-1.35, p= 0.6686) were not associated with prostate cancer risk. However, the data for C524T SNP showed that the genotype CT was associated with prostate cancer risk (OR: 1.92, 95% CI: 1.06-3.47, p= 0.0308). Further, carriers of the allele T (OR: 1.80, 95% CI: 1.04-3.13, p= 0.0358) were associated with high risk of prostate cancer. In addition, bioinformatics analysis revealed that C524T SNP could affect some molecular aspects of the protein structure, while having no effect on the mRNA structure.

Conclusion:

The MTRR C524T is a genetic risk factor for prostate cancer; however, the MTRR A66G is not suggested as a suitable biomarker for prostate cancer. To obtain more reliable results, further studies are recommended to use larger sample sizes and investigate the effects of environmental factors.

Analysis of PRM1 and PRM2 Polymorphisms in Iranian Infertile Men with Idiopathic Teratozoospermia

Single nucleotide polymorphisms (SNPs) in a number of genes involved in sperm maturation are considered as one of the main factors for male infertility. The aim of the present case-control study was to examine the association of SNPs in protamine1 (PRM1) and protamine2 (PRM2) genes with idiopathic teratozoospermia. In this case-control study, some SNPs in PRM1 (c.49 C>T, c.102 G>T and c.230A>C) and PRM2 (rs545828790, rs115686767, rs201933708, rs2070923 and rs1646022) were investigated in 30 idiopathic infertile men with teratozoospermia (case group) in comparison with 35 fertile men (controls). Genotyping of SNPs was undertaken using polymerase chain reaction (PCR)-direct sequencing. For PRM1, c.230A>C, as a synonymous polymorphism, was detected in both teratozoo- spermic men (heterozygous n=26, homozygous minor n=1) allele frequency C(48) A(52) and controls (heterozygous n=15, homozygous minor n=4). All cases and controls were genotyped for rs545828790 in PRM2, a missense poly- morphism, as well as rs115686767 and rs201933708, both of which synonymous variants. The findings showed an intronic variant in PRM2 (rs2070923) was also present in both groups. Also, rs1646022, a missense polymorphism, occurred in teratozoospermic men (heterozygous n=10, homozygous minor n=5) and controls (heterozygous n=13, homozygous minor n=2). However, there were no significant differences in SNPs of PRM1 and PRM2 between the two groups, however, for c.230A>C, the frequency of the CA genotype was significantly higher in infertile men with teratozoospermia (P=0.001). We demonstrate that PRM2 G398C and A473C polymorphisms were associated with the teratozoospermia and its genetic variation was in relation to semen quality, sperm apoptosis, and morphology in the Iranian population. This study is a preliminary study and presenting data as part of a future comprehensive study to clinically establish whether these gene polymorphisms are biomarkers for susceptibility to teratozoospermia.

Androgen receptor (AR)-CAG trinucleotide repeat length and idiopathic male infertility: a case-control trial and a meta-analysis

CAG trinucleotide repeats in androgen receptor (AR) gene encode a polyglutamine tract in AR N-terminal transactivation domain. Studies have been conducted to evaluate the effect of CAG repeat length on male infertility, which have yielded contradictory results. This study aimed to explore the number of AR-CAG repeats in 150 fertile controls and 150 idiopathic infertile men, divided into four azoospermia, oligozoospermia, asthenozoospermia, and teratozoospermia subgroups. In addition, a meta-analysis was conducted based on previous studies to assess the association of the mentioned variation with male infertility in recent years. Polymerase chain reaction (PCR) targeting followed by an electrophoresis on polyacrylamide gel was used for AR-CAG genotype detecting. Moreover, a systematic search was performed in PubMed, Web of Science, Science Direct, and Google Scholar databases to collect eligible studies for meta-analysis purpose. According to the results, a significant association was observed between increased length of AR-CAG polymorphism and male infertility (p< 0.0001). Furthermore, there were similar significant associations in the azoospermia (p= 0.048), asthenozoospermia (p= 0.013) and teratozoospermia (p= 0.002) subgroups. In addition, meta-analysis on forty studies showed a significant association between AR-CAG polymorphism in the overall analysis (SMD= 0.199, 95 % CI= 0.112-0.287, p<0.001) and the Caucasian subgroup (SMD= 0.151, 95 % CI= 0.040-0.263, p= 0.008). Our results elucidated that long stretches of CAG repeat might lead to AR dysfunction, contributing to male infertility especially in the Caucasian population.

IL-1ɑ C376A Transversion Variant and Risk of Idiopathic Male Infertility in Iranian Men: A Genetic Association Study

Background

IL-1α produced by Sertoli cells is considered to act as a growth factor for spermatogonia. In this study, we investigated the association of the C376A polymorphism in IL-1α with male infertility in men referring to the Kashan IVF Center.

Materials and Methods

In this case-control study, 2 ml of blood was collected from 230 fertile and 230 infertile men. After DNA extraction, the C376A variant was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). In addition, the molecular effects of the C376A transversion were analysed using bioinformatics tools.

Results

A significant association was observed between the homozygous genotype CC with male infertility [odds ratio (OR)=1.97, 95% confidence interval (CI)=1.14-3.41, P=0.016)]. Carriers of C (AC+CC) showed a similar risk for male infertility (OR=1.78, 95% CI=1.06-2.99, P=0.030). Also, allelic analysis showed that the C allele is associated with male infertility (OR=1.43, 95% CI=1.09-1.88, P=0.011). In sub-group analysis, we found that the AC genotype is associated with asthenozoospermia (OR=2.38, 95% CI=1.03-5.53, P=0.043). In addition, carriers of C were at high risk for asthenozoospermia (OR=2.25, 95% CI=1.01-4.10, P=0.047). Also, C allele was significantly associated with oligozoospermia (OR=1.44, 95% CI=1.01-2.06, P=0.049) and non-obstructive azoospermia (OR=1.67, 95% CI =1.04-2.68, P=0.034). Finally, in silico analysis showed that the C376A polymorphism could alter splicing especially in the acceptor site.

Conclusion

This is the preliminary report on the association of IL-1α C376A polymorphism with male infertility in the Kashan population. This association shows that the IL-1α gene may be a biomarker for male infertility, and therefore needs additional investigations in future studies to validate this.

Association between two common transitions of H2BFWT gene and male infertility: a case-control, meta, and structural analysis

H2BFWT is one of the testis-specific histones that plays a fundamental role in spermatogenesis, and single nucleotide polymorphisms (SNPs) in this gene may result in male infertility. This study aimed to investigate the association between -9C>T and 368A>G transitions of H2BFWT gene and male infertility through a case-control, meta-analysis, and a bioinformatics approach. In this case-control study, 490 subjects including 240 idiopathic infertile men and 250 healthy controls were included. The -9C>T and 368A>G SNPs genotyping were performed by a PCR-RFLP method. To find eligible studies for meta-analysis, we searched valid scientific databases. The odds ratios with 95% confidence intervals were estimated to find the strength of these associations. Furthermore, the influences of two common transitions on the molecular features of H2BFWT were assessed by in silico tools. Our case-control data revealed that -9C>T is not associated with male infertility. But, there was a significant association between 368A>G and male infertility. In the meta-analysis, five eligible studies were included. Our data revealed significant associations between -9C>T, 368A>G, and male infertility in overall and stratified analyses. Moreover, structural analysis showed that 368A>G could affect the protein structure (SNAP prediction: non-neutral, score: 42, expected accuracy: 71%; SIFT prediction: deleterious, score: -2.55), while -9C>T may affect the binding nucleotide in the promoter region. Based on these findings, two aforementioned polymorphisms were associated with increased risk of male infertility. However, studies with larger sample size and different ethnicities are needed to obtain more accurate conclusions.

Association of GSTO1 A140D and GSTO2 N142D Gene Variations with Breast Cancer Risk

Background:

Polymorphisms in glutathione S-transferase (GST) genes may contribute to breast cancer risk. The aim of this study was to investigate any association of two common GSTO1 A140D and GSTO2 N142D gene polymorphisms with breast cancer risk in an Iranian population followed by a protein structure analysis.

Materials and Methods:

In the case-control study, 303 subjects comprising 153 women with breast cancer and 150 healthy controls were included. Genotypes of GSTO1 A140D and GSTO2 N142D polymorphisms were assessed by PCR-RFLP. Bioinformatics tools were employed to evaluate the damaging effects of A140D and N142D on the structures of GSTO1 and GSTO2 proteins.

Results:

Our genetic association study revealed that the GSTO1 A140D polymorphism was associated with breast cancer in a dominant model (OR= 1.75, 95%CI= 1.07-2.86, p= 0.026). Also, the A allele was significantly associated with breast cancer risk (OR= 1.69, 95%CI= 1.09-2.60, p= 0.018). With regard to the N142D polymorphism, there were significant associations between the GG genotype (OR= 2.20, 95%CI= 1.14-4.27, p= 0.019) and the G allele (OR= 1.47, 95%CI= 1.06-2.05, p= 0.021) and risk of breast cancer. Structural analysis revealed that A140D and N142D polymorphisms cause changes in both primary and secondary structures of GSTO1 and GSTO2, respectively.

Conclusion:

Based on our results, GSTO1 A140D and GSTO2 N142D polymorphisms could be genetic risk factors for breast cancer, but further studies with larger sample sizes focusing on different ethnicities are needed to obtain more comprehensive results.