IL-1RA VNTR and IL-1α 4845G>T polymorphisms and risk of idiopathic male infertility in Iranian men: A case-control study and an in silico analysis

Association of PADI4 Gene Polymorphisms With Susceptibility to Rheumatoid Arthritis: Evidence From 24 Case-Control Studies

This study aims to investigate the association of rs11203366, rs11203367, rs874881, rs2240340 and rs1748033 polymorphisms of protein-arginine deiminase type 4 (PADI4) gene with the risk of rheumatoid arthritis (RA) through a meta-analysis that was followed with a bioinformatics approach. The data were collected from reputable articles and underwent quantitative analysis, followed by in silico analysis using some bioinformatics tools. The results showed that rs874881 polymorphism in Latino (G vs. C: OR = 1.35, 95% CI = 1.11-1.65, p = 0.003; GG + CG vs. CC: OR = 2.02, 95% CI = 1.41-2.89, p = 0.0001; CG vs. CC + GG: OR = 1.38, 95% CI = 1.04-1.83, p = 0.027; GG vs. CC: OR = 2.09, 95% CI = 1.35-3.23, p = 0.001; CG vs. CC: OR = 1.98, 95% CI = 1.36-2.87, p = 0.00033) and rs1748033 in Caucasian population (T vs. C: OR = 1.25, 95% CI = 1.07-1.45, p = 0.005; TT vs. CT + CC: OR = 1.34, 95% CI = 1.09-1.64, p = 0.005, TT + CT vs. CC: OR = 1.26, 95% CI = 1.09-1.44, p = 0.001; TT vs. CC: OR = 1.59, 95% CI = 1.13-2.23, p = 0.007; CT vs. CC: OR = 1.20, 95% CI: 1.04-1.39, p = 0.015) are associated with increased risk of RA. Moreover, rs11203366 (G vs. A: OR = 1.46, 95% CI = 1.19-1.78, p = 0.0002, GG vs. AG + AA: OR = 1.42, 95% CI = 1.01-2.01, p = 0.043; GG + AG vs. AA: OR = 2.03, 95% CI = 1.45-2.86, p = 0.00004; GG vs. AA: OR = 2.29, 95% CI = 1.49-3.51, p = 0.0002; AG vs. AA: OR = 1.93, 95% CI = 1.35-2.76, p = 0.0003) and rs11203367 (T vs. C: OR = 1.50, 95% CI = 1.23-1.83, p = 0.00007; TT vs. CT + CC: OR = 1.56, 95% CI = 1.12-2.18, p = 0.009; TT + CT vs. CC: OR = 2.02, 95% CI = 1.43-2.84, p = 0.00007, TT vs. CC: OR = 2.43, 95% CI = 1.59-3.71, p = 0.0004; CT vs. CC: OR = 1.86, 95% CI = 1.30-2.68, p = 0.0007) had an impact in the Latino population. Bioinformatics tools showed the effect of these polymorphisms on gene function. These findings suggest that rs11203366, rs11203367, rs874881 and rs1748033 polymorphisms may be genetic risk factors for RA. Moreover, differences between populations suggest that ethnicity may play an important role in the effect of these polymorphisms on RA risk.

IL-6-174 G/C transversion might decrease male infertility risk: A case-control study

Background

Genetic predispositions have been identified as important factors in male infertility. Among the many genes related to male reproductive function, interleukin 6 (IL-6) has emerged as a key player. Despite the growing recognition of genetic factors in male infertility, the specific association between the IL-6-174 G/C genetic polymorphism and male infertility remains an area that needs further investigation.

Objective

This investigation explores the correlation between the IL-6-174 G/C transversion and male infertility.

Materials and Methods

In a case-control study, a total of 314 men who referred to the Kashan Infertility Center, Shahid Beheshti hospital, Kashan, Iran, were enrolled for IL-6-174 G/C polymorphism analysis. The study comprised 163 infertile participants as the case group and 151 fertile men as the control group. Following the screening, 2 ml of whole blood was collected from each participant. Cases were categorized into 3 subgroups based on World Health Organization criteria: (i) nonobstructive azoospermia (n = 42), (ii) oligozoospermia (n = 61), and (iii) asthenozoospermia (n = 60). After DNA extraction, genotypes of the samples at the -174 G/C (rs1800795) locus were determined using the polymerase chain reaction-restriction fragment length polymorphism method.

Results

Our genetic investigation demonstrated a significant association between the GC genotype and male infertility. Furthermore, a correlation was observed between the heterozygous GC genotype and reduced risk of oligozoospermia and asthenospermia. Additionally, the C allele was correlated with a decreased risk of infertility and specific subgroups such as oligozoospermia and asthenospermia.

Conclusion

Our findings suggest that the IL-6-174 G/C transversion could potentially serve as a protective genetic factor against male infertility.

A common genetic variation in paraoxonase 1 and risk of breast cancer: a literature review, meta-analysis, and in silico analysis

Paraoxonase 1 (PON1), an enzyme with multifactorial antioxidant activity, has a protective role against oxidative stress, which is supposed to contribute to the development of cancers including breast cancer. The aim of this study was to examine the correlation of PON1-L55M common genetic polymorphism with the risk of breast cancer in a meta-analysis approach which was followed by an in silico analysis. The eligible studies were collected from valid electronic databases such as Google Scholar, PubMed, Embase, and Web of Science. Quantitative synthesis was performed to report the strength of PON1-L55M polymorphism with breast cancer. Some bioinformatics tools were used to analyze the effects of L55M variation on PON1 gene function. The meta-analysis revealed that there are significant associations between the mentioned polymorphism and breast cancer in M vs. L, MM vs. LL, LM vs. LL, MM + LM vs. LL, and MM vs. LL + LM genetic models. Besides, similar results were observed in the stratified analyses based on ethnicity, genotyping method, Hardy-Weinberg equilibrium in control groups, and sample size. Bioinformatics analysis revealed that the PON1 could be damaging to the protein function. Our findings propose that the PON1-L55M genetic polymorphism might be a genetic risk factor for the risk of breast cancer.

Influence of FOXP3 gene polymorphisms on the risk of preeclampsia: a meta-analysis and a bioinformatic approach

BACKGROUND AND AIM

Preeclampsia (PE), a multifactorial disorder, is the main cause of maternal mortality and morbidity. Genetic polymorphisms in key proteins involved in the immune system may change the risk of PE risk. In this study, we examined the association of two rs2232365 and rs3761548 common polymorphisms of the FOXP3 immune response gene with PE susceptibility by a meta-analysis which was followed by an in-silico analysis.

MATERIALS AND METHODS

Through a systematic search in databases including PubMed, MEDLINE, Google Scholar, and Science Direct, we find eligible studies for meta-analysis. Some bioinformatics tools were used to detect the impact of rs2232365 and rs3761548 polymorphisms on the FOXP3 gene function.

RESULTS

Our data revealed that there is a significant association between rs3761548 polymorphism and decreased risk of PE. In addition, we observed a significant association between rs2232365 and increased risk of mild preeclampsia. Also, our bioinformatic analysis showed that both rs2232365 and rs3761548 polymorphisms could affect FOXP3 gene function.

CONCLUSION

Based on our findings, the rs3761548 genetic variation could be a protective factor against PE risk. While the rs2232365 polymorphism may be a genetic risk factor for mild preeclampsia. Therefore, as a preliminary study, these genetic variations could be considered molecular biomarkers for PE disorder.

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 -592C>A Variation of IL-10 Gene and Susceptibility to Chronic Periodontitis: A Genetic Association Study and In-Silico Analysis

OBJECTIVES

Chronic periodontitis (CP) is a common inflammatory disorder with a considerable impact of genetic variations in the interleukin family on predisposition to this disease. This study aimed to investigate the association between the -592C>A polymorphism of the interleukin 10 (IL-10) gene with CP risk in an Iranian population. This experimental study was followed by a meta-analysis and in silico examination.

METHODS

In a case-control study, 270 subjects, including 135 patients with CP and 135 healthy controls, were enrolled. The -592C>A genotyping was performed using the PCR-RFLP method. In the meta-analysis, valid databases were systematically searched to identify relevant studies. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were computed to examine the association between -592C>A and CP. In silico analysis was conducted using bioinformatics tools to evaluate the impact of the -592C>A polymorphism on IL-10 gene function.

RESULTS

Our case-control study revealed a significant association between polymorphism and CP risk. Overall, we found significant associations between -592C>A genetic variation and CP and stratified meta-analysis. In silico analysis revealed that this polymorphism could change the pattern of the transcription binding site upstream of the IL-10 gene. It may also alter the hsa-miR-101-3p miRNA-targeted sequence upstream of IL-10.

CONCLUSIONS

Based on our results, the -592C>A variation in IL-10 may be a genetic risk factor for susceptibility to chronic periodontitis. However, further studies in different ethnicities and results adjusted for clinical and demographic characteristics are needed to obtain more accurate deductions.

CYP1A1 and GSTs common gene variations and presbycusis risk: a genetic association analysis and a bioinformatics approach

Antioxidant enzymes such as glutathione S-transferases (GSTs) and cytochromes P450 (CYPs) are involved in the metabolism and detoxification of cytotoxic compounds, as well as the elimination of reactive oxygen species (ROS). Therefore, alterations in the structure of these enzymes could result in prolonged production of ROS with subsequent risk of development of disorders such as presbycusis. This study aimed to investigate the association between CYP1A1 (rs4646903, rs1048943) and GSTs (GSTM1-deletion, GSTT1-deletion, GSTP1-rs1695) with presbycusis risk in an Iranian population which was followed by an in silico approach. In a case-control study, 280 subjects including 140 cases with presbycusis and 140 healthy controls were enrolled. Genotypes of single-nucleotide polymorphisms (SNPs) were detected by PCR-RFLP method and the genotype of the above mentioned deletions was determined by touchdown PCR. Some bioinformatics tools were employed to evaluate the impact of SNPs on the gene function. SNP analysis revealed that there are significant associations between rs1048943 (AG vs. AA: OR = 2.46, 95%CI = 1.30-4.65, p = 0.006; GG + AG vs. AA: OR = 2.53, 95%CI = 1.36-4.69, p = 0.003; G vs. A: OR = 2.36, 95%CI = 1.33-4.17, p = 0.003) and rs4646903 (C vs. T: OR = 1.45, 95%CI = 1.02-2.06, p = 0.040) variations and increased risk of presbycusis. However, there was no significant association between rs1695 and presbycusis risk. Also, significant associations were observed between GSTM1 (OR = 4.28, 95%CI = 1.18-15.52, p = 0.027) and GSTT1 (OR = 1.64, 95%CI = 1.02-2.65, p = 0.041) deletions and elevated risk of presbycusis. Moreover, the combination analysis revealed a significant association between GSTM1+/GSTT1- genotype and presbycusis susceptibility (OR = 1.63, 95%CI = 1.00-2.67, p = 0.049). In silico analysis revealed that the rs1048943 SNP could influence significantly on the RNA structure of CYP1A1 (distance: 0.1454; p value: 0.1799). Based on our findings, the rs4646903, rs1048943 SNPs as well as GSTM1 and GSTT1 deletions could be considered as genetic risk factors for the development and progression of presbycusis.

Association Analysis of Methylenetetrahydrofolate Reductase Common Gene Polymorphisms with Breast Cancer Risk in an Iranian Population: A Case-Control Study and a Stratified Analysis

Genetic polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene may alter the risk of breast cancer. This study aimed to investigate the association of MTHFR C677T and A1298C genetic polymorphisms with breast cancer risk in case-control studies which was followed by stratified analysis. In the case-control study, 300 subjects including 150 women with breast cancer and 150 healthy women were enrolled. After blood sample collection, the C677T and A1298C polymorphisms genotyping were done by the PCR-RFLP method. Our data revealed a significant association between MTHFR C677T and A1298C polymorphisms and breast cancer risk. But, as a preliminary study, stratified analysis revealed no significant association between C677T and A1298C polymorphisms and tumor size and also lymph node metastasis in breast cancer. According to the mentioned findings, the C677T and A1298C polymorphisms in the MTHFR gene could be molecular risk factors for breast cancer in our studied population. However, further studies with larger sample sizes are required to obtain a more accurate conclusion in stratified analysis.

Association of ApaI and TaqI polymorphisms in VDR Gene with Breast Cancer

Background:

Vitamin D inhibits cell proliferation via the vitamin D receptor (VDR), which may affect breast cancer risk. This study aimed to investigate the association of ApaI and TaqI polymorphisms of the VDR gene with breast cancer risk which followed by stratified analysis.

Materials and methods:

A case-control study was conducted on 150 breast cancer patients and 150 healthy controls. VDR ApaI and TaqI genotyping were performed by PCR-RFLP. Some demographic and pathologic features of patients were extracted from their archived files and then were analyzed by genotypes distributions.

Results:

For ApaI polymorphism, our data showed a significant difference between the patient and healthy groups for mutant allele carriers compared with those with AA genotype. Besides, statistical analysis showed that there was a significant association between the C allele and the increased risk of breast cancer. For TaqI polymorphism, statistical analysis revealed that there was a significant association between CC genotype and increased risk of breast cancer. Also, there was a significant association between the C allele and the increased risk of breast cancer. In a preliminary study, stratified analysis based on the size of tumor and lymph node metastasis revealed no significant association between two ApaI and TaqI variations and these parameters.

Conclusions:

Based on our results, the VDRApaI and TaqI variations could be considered as genetic risk factors for breast cancer. However, further studies with a larger sample size are required to obtain more accurate outcomes, especially in stratified analysis.

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.

Common gene polymorphism in ATP-binding cassette transporter A1 and coronary artery disease: A genetic association study and a structural analysis

ATP-binding cassette transporter A1 (ABCA1) has a crucial role in removing intracellular cholesterol and plays a protective role against atherosclerosis. Therefore, genetic polymorphisms in this gene may alter the susceptibility to coronary artery disease (CAD). This study was aimed to examine the association of rs2230806 (c.1051 G > A; p.R219K) variation in the ABCA1 gene with CAD in a case-control design which was followed by a meta-analysis and in silico approach. In the case-control study, 300 subjects including 150 individuals with CAD and 150 healthy controls were recruited. The c.1051 G > A genotyping was done by polymerase chain reaction-restriction fragment length polymorphism method. In the meta-analysis, eligible studies were collected from PubMed, Google Scholar, and ScienceDirect databases and pooled odds ratio, heterogeneity, publication bias, and sensitivity analyses were carried. Finally, some bioinformatics tools were employed to assess the impacts of p.R219K variation on ABCA1 protein structure. Our case-control examination showed a statistically significant association between c.1051 G > A genetic polymorphism and CAD risk. In addition, the meta-analysis showed reliable significant associations between c.1051 G > A transition and risk of CAD in the Caucasian population. In silico analysis showed that the p.R219K substitution could alter the secondary structure, hydrophobicity pattern, and Ramachandran plot of ABCA1. These findings elucidate that the c.1051 G > A variation could be a genetic risk factor for CAD and it could be considered as a prognostic and predictive biomarker for susceptible individuals.

Association of PON1-L55M Genetic Variation and Breast Cancer Risk: A Case-Control Trial

Background:

Paraoxonase 1 (PON1), a multifactorial antioxidant enzyme, has a defensive role against oxidative stress, which is believed to contribute to cancer development. This study aimed to investigate the association of PON1-L55M functional polymorphism with breast cancer risk.

Material and methods:

In the experimental study, blood samples were collected from 150 healthy women controls and 150 breast cancer subjects. The L55M genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism.

Results:

Our analysis showed that the genotypes distribution is in Hardy-Weinberg equilibrium for both case and control groups. Our data revealed that there are significant associations between PON1-L55M polymorphism and breast cancer risk in homozygote (OR= 2.13, 95%CI= 1.14-4.00, p= 0.018), dominant (OR= 1.72, 95%CI= 1.07-2.76, p= 0.024), and allelic (OR= 1.55, 95%CI= 1.12-2.15, p= 0.008) models.

Conclusions:

Our results suggest that the PON1-L55M genetic variation could be a genetic risk factor for breast cancer risk and it could be considered as a molecular biomarker for screening of susceptible women.

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.

The survivin molecule as a double-edged sword in cellular physiologic and pathologic conditions and its role as a potential biomarker and therapeutic target in cancer

Survivin is a member of the family of apoptosis inhibitory proteins with increased expression level in most cancerous tissues. Evidence shows that survivin plays regulatory roles in proliferation or survival of normal adult cells, principally vascular endothelial cells, T lymphocytes, primitive hematopoietic cells, and polymorphonuclear neutrophils. Survivin antiapoptotic role is, directly and indirectly, related to caspase proteins and shows its role in cell division through the chromosomal passenger complex. Survivin contains many genetic polymorphisms that the role of some variations has been proven in several cancers. The -31G/C polymorphism is one of the most important survivin mutations which is located in the promoter region on a CDE/CHR motif. This polymorphism can upregulate the survivin messenger RNA. In addition, its allele C can increase the risk of cancers in 1.27-fold than allele G. Considering the fundamental role of survivin in different cancers, this protein could be considered as a new therapeutic target in cancer treatment. For this purpose, various strategies have been designed including the prevention of survivin expression through inhibition of mRNA translation using antagonistic molecules, inhibition of survivin gene function through small inhibitory molecules, gene therapy, and immunotherapy. In this study, we describe the structure, played roles in physiological and pathological states and genetic polymorphisms of survivin. Finally, the role of survivin as a potential target in cancer therapy given challenges ahead has been discussed.

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.

The regulatory role of Toll-like receptors after ischemic stroke: neurosteroids as TLR modulators with the focus on TLR2/4

Ischemic stroke is the most common cerebrovascular disease and considered as a worldwide leading cause of death. After cerebral ischemia, different pathophysiological processes including neuroinflammation, invasion and aggregation of inflammatory cells and up-regulation of cytokines occur simultaneously. In this respect, Toll-like receptors (TLRs) are the first identified important mediators for the activation of the innate immune system and are widely expressed in glial cells and neurons following brain trauma. TLRs are also able to interact with endogenous and exogenous molecules released during ischemia and can increase tissue damage. Particularly, TLR2 and TLR4 activate different downstream inflammatory signaling pathways. In addition, TLR signaling can alternatively play a role for endogenous neuroprotection. In this review, the gene and protein structures, common genetic polymorphisms of TLR2 and TLR4, TLR-related molecular pathways and their putative role after ischemic stroke are delineated. Furthermore, the relationship between neurosteroids and TLRs as neuroprotective mechanism is highlighted in the context of brain ischemia.

Survivin c.-31G>C (rs9904341) gene transversion and urinary system cancers risk: a systematic review and a meta-analysis

Aim: To investigate the possible association between survivin c.-31G>C (rs9904341) gene polymorphism and urinary system cancers by a meta-analysis approach. Methods: Standard electronic literature databases were searched to find eligible studies. The odds ratios (ORs) with 95% CIs were estimated to find the associations possibility. Results: Overall meta-analysis revealed significant associations between c.-31G>C transversion and risk of urinary tract cancers in dominant (OR: 1.34; 95% CI: 1.02–1.75; p = 0.035), recessive (OR: 1.52; 95% CI: 1.33–1.74; p < 0.001) and homozygote codominant (OR: 1.90; 95% Cl: 1.37–2.62; p < 0.001) genetic models. Conclusion: The c.-31G>C transversion might be a risk factor for urinary system cancers. However, more articles with different ethnicities will help to obtain a more accurate conclusion.

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.