Association between XRCC1 single-nucleotide polymorphisms and infertility with idiopathic azoospermia in northern Chinese Han males

XRCC1 Polymorphisms p.Arg194Trp, p.Arg280His, and p.Arg399Gln, Polycyclic Aromatic Hydrocarbons, and Infertility: A Case-Control and In Silico Study

XRCC1 is involved in repair of single-strand breaks generated by mutagenic exposure. Polymorphisms within XRCC1 affect its ability to efficiently repair DNA damage. Polycyclic aromatic hydrocarbons or PAHs are genotoxic compounds which form bulky DNA adducts that are linked with infertility. Few reports suggest combined role of XRCC1 polymorphisms and PAHs in infertility. Present study investigates association of three XRCC1 polymorphisms (p.Arg194Trp, p.Arg280His, p.Arg399Gln) with male and female infertility in a North-West Indian population using case-control approach. Additionally, in silico approach has been used to predict whether XRCC1 polymorphisms effect interaction of XRCC1 with different PAHs. For case-control study, XRCC1 polymorphisms were screened in peripheral blood samples of age- and gender-matched 201 infertile cases (♂-100, ♀-101) and 201 fertile controls (♂-100, ♀-101) using PCR-RFLP method. For in silico study, AutoDock v4.2.6 was used for molecular docking of B[a]P, BPDE-I, ( ±)-anti-BPDE, DB[a,l]P, 1-N, 2-N, 1-OHP, 2-OHF with XRCC1 and assess effect of XRCC1 polymorphisms on their interaction. In case-control study, statistical analysis showed association of XRCC1 p.Arg280His GA genotype (p = 0.027), A allele (p = 0.019) with reduced risk of male infertility. XRCC1 p.Arg399Gln AA genotype (p = 0.021), A allele (p = 0.014) were associated with reduced risk for female primary infertility. XRCC1 p.Arg194Trp T allele was associated with increased risk for female infertility (p = 0.035). In silico analysis showed XRCC1-PAH interaction with non-significant effect of XRCC1 polymorphisms on predicted binding. Therefore, present study concludes that XRCC1 polymorphism-modified risk for male and female infertility in North-West Indians without significant effect on predicted XRCC1-PAH interactions. This is the first report on XRCC1 in female 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.

Genetic Factors of Non-Obstructive Azoospermia: Consequences on Patients' and Offspring Health

Non-Obstructive Azoospermia (NOA) affects about 1% of men in the general population and is characterized by clinical heterogeneity implying the involvement of several different acquired and genetic factors. NOA men are at higher risk to be carriers of known genetic anomalies such as karyotype abnormalities and Y-chromosome microdeletions in respect to oligo-normozoospermic men. In recent years, a growing number of novel monogenic causes have been identified through Whole Exome Sequencing (WES). Genetic testing is useful for diagnostic and pre-TESE prognostic purposes as well as for its potential relevance for general health. Several epidemiological observations show a link between azoospermia and higher morbidity and mortality rate, suggesting a common etiology for NOA and some chronic diseases, including cancer. Since on average 50% of NOA patients has a positive TESE outcome, the identification of genetic factors in NOA patients has relevance also to the offspring's health. Although still debated, the observed increased risk of certain neurodevelopmental disorders, as well as impaired cardiometabolic and reproductive health profile in children conceived with ICSI from NOA fathers may indicate the involvement of transmissible genetic factors. This review provides an update on the reproductive and general health consequences of known genetic factors causing NOA, including offspring's health.

Analysis of STAG3 variants in Chinese non-obstructive azoospermia patients with germ cell maturation arrest

STAG3 is essential for male meiosis and testis of male Stag3^-/- mice shows the histopathological type of germ cell maturation arrest (MA). Whether variants of the STAG3 gene exist in Chinese idiopathic non-obstructive azoospermia (NOA) patients needs to be determined. We recruited 58 Chinese NOA men with MA who underwent testis biopsy and 192 fertile men as the control group. The 34 exons of the STAG3 gene were amplified using polymerase chain reaction (PCR) and sequenced. We identified eight novel single nucleotide polymorphisms (SNPs), including two missense SNPs (c.433T > C in exon2 and c.553A > G in exon3), three synonymous SNPs (c.539G > A, c.569C > T in exon3, and c.1176C > G in exon8), and three SNPs in introns. The allele and genotype frequencies of the novel and other SNPs have no significant differences between two groups. Our results indicated that variants in the coding sequence of the STAG3 gene were uncommon in NOA patients with MA in Chinese population. Future studies in large cohorts of different ethnic populations will be needed to determine the association between the STAG3 gene and NOA.

Association of XRCC1 and ERCC2 promoters' methylation with chromatin condensation and sperm DNA fragmentation in idiopathic oligoasthenoteratozoospermic men

The aim of the study was to investigate whether the promoter methylation of XRCC1 and ERCC2 genes is associated with sperm DNA fragmentation and chromatin condensation in idiopathic oligoasthenoteratozoospermic men. This study involved 77 infertile men with idiopathic oligoasthenoteratozoospermia and 51 normozoospermic controls. The methylight method, TUNEL assay and aniline blue staining were used for the evaluation of XRCC1 and ERCC2 genes' methylation, SDF and sperm chromatin condensation, respectively. SDF (p = .004) and XRCC1 methylation (p = .0056) were found to be significantly higher in men with idiopathic OAT than in the controls, while mature spermatozoa frequency was higher in controls as compared to infertile men (p < .0001). No significant association was found between SDF and methylation of XRCC1 and ERCC2 genes (p = .9277 and p = .8257, respectively). However, compared to the cut-off point obtained by receiver operating characteristic analysis, a significant association was found between SDF and XRCC1 methylation, positive and negative methylation groups, generated according to the cut-off value for XRCC1. XRCC1 methylation was found to have a significant effect on chromatin condensation (p = .0017). No significant difference was detected among ERCC2 methylation, male infertility and SDF. In conclusion, XRCC1 methylation may have a role in sperm chromatin condensation and idiopathic OAT.

Association between X-ray repair cross-complementing group 1 Arg399Gln polymorphism and male infertility: An update meta-analysis

Numerous studies concentrate on the association between X-ray repair cross-complementing group 1 (XRCC1) gene polymorphism and male infertility; however, the results remain inconclusive and inconsistent. Hence, this meta-analysis was conducted to get a precise estimation of the correlation. PubMed, Web of Science, Embase, Scopus and China National Knowledge Infrastructure (CNKI) databases were searched to identify the all relevant studies before 3 May 2020. Summary odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to assess the strength of the association. Finally, six studies with 1,886 cases and 1,212 controls were included in our study. The result indicated that XRCC1 Arg399Gln polymorphism was significantly associated with male infertility under allelic model (A-allele vs. G-allele: OR = 1.183, p = .003), heterozygote genetic model (AA vs. GA: OR = 1.256, p = .027), recessive genetic model (AA vs. GG + GA: OR = 1.279, p = .012) and dominant genetic model (AA + GA vs. GG: OR = 1.218, p = .026). In addition, in Asian subgroup, statistic correlation remained significant in allelic model (A-allele vs. G-allele: OR = 1.145, p = .025) with rare heterogeneity (I²  = 0%). In summary, our meta-analysis suggested that XRCC1 Arg399Gln polymorphism was significantly associated with male infertility and the A-allele might be a risk factor for this disease, especially in Asians.

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.

Genetic defects in human azoospermia

As with many other diseases, genetic testing in human azoospermia was initially restricted to karyotype analyses (leading to diagnostic chromosome rearrangement tests for Klinefelter and other syndromes). With the advent of molecular biology in the 1980s, genetic screening was broadened to analyses of Y chromosome microdeletions and the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR). Decades later, the emergence of whole-genome techniques has led to the identification of other genetic defects associated with human azoospermia. Although TEX11 and ADGRG2 defects are frequently described in men with azoospermia, most of the causal gene defects found to date are private (i.e. identified in a small number of consanguineous families).

Here, we provide an up-to-date overview of all the types of genetic defects known to be linked to human azoospermia and try to give clinical practice guidelines according to azoospermia phenotype. Along with homozygous mutations, polymorphisms and epigenetic defects are also briefly discussed. However, as these variations predispose to azoospermia, a specific review will be needed to compile data on all the particular genetic variations reported in the literature.

Deficiency of X-ray repair cross-complementing group 1 in primordial germ cells contributes to male infertility

X-ray repair cross-complementing group 1 (Xrcc1), a key DNA repair gene, plays a vital role in maintaining genomic stability and is highly expressed in the early stages of spermatogenesis, but the exact functions remain elusive. Here we generated primordial germ cell-specific Xrcc1 knockout (cXrcc1^-/-) mice to elucidate the effects of Xrcc1 on spermatogenesis. We demonstrated that Xrcc1 deficiency results in infertility in male mice due to impaired spermatogenesis. We found that cXrcc1^-/- mice exhibited smaller size of testes as well as lower sperm concentration and motility than the wild-type mice. Mechanistically, we demonstrated that Xrcc1 deficiency in primordial germ cells induced elevated levels of reactive oxygen species, mitochondria dysfunction, apoptosis, and loss of stemness of spermatogonial stem cells (SSCs) in testes. In Xrcc1-deficienct SSCs, elevated oxidative stress and mitochondrial dysfunction could be partially reversed by treatment with the antioxidant N-acetylcysteine (NAC), whereas NAC treatment did not restore the fertility or ameliorate the apoptosis caused by loss of Xrcc1. Overall, our findings provided new insights into understanding the crucial role of Xrcc1 during spermatogenesis.-Xu, C., Xu, J., Ji, G., Liu, Q., Shao, W., Chen, Y., Gu, J., Weng, Z., Zhang, X., Wang, Y., Gu, A. Deficiency of X-ray repair cross-complementing group 1 in primordial germ cells contributes to male infertility.

SNPs in ERCC1, ERCC2, and XRCC1 genes of the DNA repair pathway and risk of male infertility in the Asian populations: association study, meta-analysis, and trial sequential analysis

PURPOSE

We investigated if substitutions in the ERCC1, ERCC2, and XRCC1 genes of the DNA repair pathway correlate with non-obstructive azoospermia and male infertility.

METHODS

A total of 548 azoospermic infertile males and 410 fertile controls were genotyped for XRCC1 399A > G, 280G > A, and ERCC1 C > A 3' UTR and 541 azoospermic infertile males and 416 fertile controls were genotyped for ERCC2 751A > C using iPLEX Gold Assay. Meta-analyses were performed on XRCC1 399A > G (1022 cases and 1004 controls), ERCC1 C > A 3' UTR (879 cases and 1059 controls), and ERCC2 751A > C (914 cases and 850 controls) polymorphisms to quantitatively estimate the significance of the association between these polymorphisms and the risk of infertility.

RESULTS

Statistically significant association between ERCC2 751A > C SNP and male infertility was found using the codominant model (p = 0.03). Results of meta-analysis suggested a lack of correlation with male infertility risk, which could be due to pooling of studies from different ethnic populations. Due to limited the number of studies, a stratified analysis for different ethnic groups could not be performed.

CONCLUSION (S)

In conclusion, AA genotype of 751A > C SNP in ERCC2 correlated with a higher risk of male infertility and may contribute to an increased risk of azoospermia and male infertility in Indian men.

Analysis of CDK2 mutations in Chinese men with non-obstructive azoospermia who underwent testis biopsy

To examine whether mutations of the CDK2 gene exist in Chinese men with non-obstructive azoospermia (NOA) with different histopathology, we recruited 175 Chinese men with idiopathic NOA who underwent testis biopsy, including hypospermatogenesis, germ cell maturation arrest and Sertoli cell only syndrome. Genomic DNA was extracted from peripheral blood samples. Subsequently, the seven exons of the CDK2 gene were amplified using polymerase chain reaction with specific primers, respectively. The polymerase chain reaction products were sequenced on an automated sequencer. We identified four known single nucleotide polymorphisms: c.324G>A in exon 1; c.363T>C in exon 2; c.*570G>A; and c.*1160G>C in the 3' UTR of the CDK2 gene. Comparison of the genotype and allele frequencies showed no significant differences between NOA cases and controls for the four single nucleotide polymorphisms. Furthermore, no significant differences were found between each pathological group and control group, respectively. The results indicate that mutations in the coding sequence of the CDK2 gene may not be responsible for idiopathic NOA in Chinese men. Future studies in large cohorts of different ethnic populations are warranted to establish whether associations exist between the CDK2 gene and NOA.

Polymorphisms of DNA repair genes XRCC1 and LIG4 and idiopathic male infertility

Sperm DNA damage is one of the associated factors of idiopathic male infertility and abnormal spermatogenesis. This study was conducted to assess possible association between risk of male infertility with X-ray repair cross complementing group 1 (XRCC1) Arg399Gln (G to A) and DNA ligase 4 (LIG4) Thr9Ile (C to T) gene polymorphisms which are involved in different DNA repair pathways. In this case-control study 191 fertile and 191 infertile men (29-40 years old) were enrolled. The single-nucleotide polymorphism genotypes and alleles of XRCC1 Arg399Gln and LIG4 Thr9Ile were assessed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. There was no significant association between XRCC1 Arg399Gln polymorphism and risk of male infertility. The frequency of LIG4 Thr9Ile genotypes and alleles were statistically different between fertile and infertile men (p<0.001). We found that the CT genotype increased infertility risk more than threefold (OR, 3.12; 95% CI, 1.803-5.407). The LIG4 TT genotype carriers had decreased progressive motile sperm (p<0.05) and increased non-progressive motile sperm (p<0.001) compared with the CC genotype. Moreover, sperm concentration in subjects carrying the CT genotype was lower than that observed in CC carriers (p<0.05). The results revealed that the GG/CT and GA/CT combinations of genotypes increase the risk of infertility 3.5 and fourfold, respectively (p=0.021 and 0.004, respectively). This study demonstrated that there was an association between LIG4 Thr9Ile polymorphism and male infertility and suggests CT genotype as a risk factor for male infertility.

Association of NR3C1/Glucocorticoid Receptor gene SNP with azoospermia in Japanese men

AIM

The molecular pathogenesis of non-obstructive azoospermia (NOA) is unclear. Our aim was to identify the genetic susceptibility for NOA in Japanese men by using a combination of transcriptome network analysis and SNP genotyping.

MATERIAL AND METHODS

We searched for candidate genes using RNA transcriptome network analysis of 2611 NOA-related genes that we had previously reported. We analyzed candidate genes for disease linkage with single nucleotide polymorphisms (SNP) in the genomes of 335 Japanese men with NOA and 410 healthy controls using SNP-specific real-time polymerase chain reaction TaqMan assays.

RESULTS

Three candidate genes (NR3C1, YBX2, and BCL2) were identified by the transcriptome network analysis, each with three SNP. Allele frequency analysis of the nine SNP indicated a significantly higher frequency of the NR3C1 rs852977 G allele in NOA cases compared with controls (corrected P = 5.7e-15; odds ratio = 3.20; 95% confidence interval, 2.40-4.26). The other eight candidate polymorphisms showed no significant association.

CONCLUSION

The NR3C1 rs852977 polymorphism is a potential marker for genetic susceptibility to NOA in Japanese men. Further studies are necessary to clarify the association between the NR3C1 polymorphism and alterations of glucocorticoid signaling pathway leading to male infertility.

DNA repair genes XRCC1 and ERCC1 polymorphisms and the risk of sporadic breast cancer in Han women in the Gansu Province of China

AIMS

Polymorphisms in DNA damage repair genes may affect DNA repair capacity and modulate breast cancer susceptibility. In this study, we aimed to analyze two polymorphisms for each of the DNA repair genes X-ray repair cross-complementing group 1 (XRCC1) rs25487 and rs1799782 and excision repair cross-complementing group 1 (ERCC1) rs3212964 and rs11615, to evaluate their associations with the risk of sporadic breast cancer in Han women in the Gansu Province of China.

METHODS

Genotypes were determined by a polymerase chain reaction-based approach for 101 patients with breast cancer and in 101 disease-free controls.

RESULTS

We found that individuals with the AA genotype at XRCC1 rs25487 had a significantly increased risk of breast cancer compared with GG genotype (p<0.001, odds ratio [OR]=6.39, 95% confidence interval [CI]: 2.18-18.65). The dominant model showed that the combined rs25487 genotypes (AA+AG) increased the disease risk (p<0.001, OR=3.17, 95% CI: 1.76-5.72). However, no statistical associations were found between rs1799782 in XRCC1, or rs3212964 and rs11615 in ERCC1 and the risk of disease. In haplotype analysis, the GC haplotype in XRCC1 conferred an increased risk (p<0.001) with a 4.78-fold increase for each copy (95% CI: 2.52-8.72). Significant associations were also shown between the single nucleotide polymorphisms (SNPs) and the status of estrogen receptor (ER), progesterone receptor (PR), and HER-2.

CONCLUSIONS

The results suggest that the XRCC1 rs25487 polymorphism may increase the risk of breast cancer.

Association between DNA repair genes (XPD and XRCC1) polymorphisms and susceptibility to age-related cataract (ARC): a meta-analysis

BACKGROUND

DNA repair gene (XPD and XRCC1) polymorphisms have been considered as risk factors for the development of age-related cataract (ARC). To confirm the association between DNA repair gene (XPD and XRCC1) polymorphisms and the risk of ARC, a meta-analysis was conducted.

METHODS

A search was made of published literature from Institute for Scientific Information (ISI) Web of Knowledge, PubMed, Google Scholar, China National Knowledge Infrastructure (CNKI), and Wanfang Data. In addition, all studies evaluating the association between DNA repair genes (XPD and XRCC1) polymorphisms and the risk for ARC were included in our analysis. Pooled odds ratio (OR) and 95 % confidence interval (CI) were calculated by using fixed- or random-effects model. The Egger's test was used to check the publication bias.

RESULTS

Six studies on XRCC1 Arg399Gln (1,300 cases, 1,222 controls) and five studies on XPD Lys751Gln (1,092 cases, 1,061 controls) were included. For the XPD Lys751Gln (A/C) SNP, the overall analysis demonstrated that the CC genotype showed a significant association with a decreased risk for ARC compared with the AA genotype (OR = 0.59, 95 % CI, 0.38-0.92, P = 0.019). Similarly, the CC genotype showed a significant association with a decreased risk for ARC compared with the (AA + AC) genotype (OR = 0.65, 95 % CI, 0.43-0.98, P = 0.040). Subgroup analysis showed that the association between the CC genotype and decreased risk for ARC is statistically significant in Caucasians (OR = 0.41, 95 % CI, 0.24-0.73, P = 0.002) but not in Asians (OR = 1.06, 95 % CI, 0.51-2.19, P = 0.877). For the XRCC1 Arg399Gln (G/A) SNP, the overall analysis demonstrated that the A allele showed a significant association with an increased risk for ARC compared with the G allele (OR = 1.16, 95 % CI, 1.03-1.31, P = 0.015). Subgroup analyses exhibited that the association between the A allele and the risk for ARC was statistically significant in Asians (OR = 1.23, 95 % CI, 1.07-1.41, P = 0.003) but not in Caucasians (OR = 0.94, 95 % CI, 0.73-1.22, P = 0.660). Compared with the GG genotype, the GA genotype showed a significant association with an increased risk for ARC in Asians (OR = 1.32, 95 % CI, 1.08-1.61, P = 0.006) but not in Caucasians (OR = 0.58, 95 % CI, 0.27-1.26, P = 0.171). The Egger's test did not reveal an obvious publication bias among the included studies.

CONCLUSIONS

Our meta-analysis suggested that the CC genotype of XPD Lys751Gln (A/C) SNP seemed to portend a decreased risk for ARC in Caucasian populations but not in Asian populations. The A allele and GA genotype of XRCC1 Arg399Gln (G/A) SNP might increase risk for ARC in Asian populations but not in Caucasian populations. More researches with larger and more different ethnic populations on this issue are therefore necessary.