Genetic polymorphisms in glutathione S-transferase T1 affect the surgical outcome of varicocelectomies in infertile patients

Does Varicocele Repair Improve Conventional Semen Parameters? A Meta-Analytic Study of Before-After Data

PURPOSE

The purpose of this meta-analysis is to study the impact of varicocele repair in the largest cohort of infertile males with clinical varicocele by including all available studies, with no language restrictions, comparing intra-person conventional semen parameters before and after the repair of varicoceles.

MATERIALS AND METHODS

The meta-analysis was performed according to PRISMA-P and MOOSE guidelines. A systematic search was performed in Scopus, PubMed, Cochrane, and Embase databases. Eligible studies were selected according to the PICOS model (Population: infertile male patients with clinical varicocele; Intervention: varicocele repair; Comparison: intra-person before-after varicocele repair; Outcome: conventional semen parameters; Study type: randomized controlled trials [RCTs], observational and case-control studies).

RESULTS

Out of 1,632 screened abstracts, 351 articles (23 RCTs, 292 observational, and 36 case-control studies) were included in the quantitative analysis. The before-and-after analysis showed significant improvements in all semen parameters after varicocele repair (except sperm vitality); semen volume: standardized mean difference (SMD) 0.203, 95% CI: 0.129-0.278; p<0.001; I²=83.62%, Egger's p=0.3329; sperm concentration: SMD 1.590, 95% CI: 1.474-1.706; p<0.001; I²=97.86%, Egger's p<0.0001; total sperm count: SMD 1.824, 95% CI: 1.526-2.121; p<0.001; I²=97.88%, Egger's p=0.0063; total motile sperm count: SMD 1.643, 95% CI: 1.318-1.968; p<0.001; I²=98.65%, Egger's p=0.0003; progressive sperm motility: SMD 1.845, 95% CI: 1.537%-2.153%; p<0.001; I²=98.97%, Egger's p<0.0001; total sperm motility: SMD 1.613, 95% CI 1.467%-1.759%; p<0.001; l2=97.98%, Egger's p<0.001; sperm morphology: SMD 1.066, 95% CI 0.992%-1.211%; p<0.001; I²=97.87%, Egger's p=0.1864.

CONCLUSIONS

The current meta-analysis is the largest to date using paired analysis on varicocele patients. In the current meta-analysis, almost all conventional semen parameters improved significantly following varicocele repair in infertile patients with clinical varicocele.

Genetic variants in varicocele-related male infertility: a systematic review and future directions

Genetic association studies (GAS) may have the capability to probe the genetic susceptibility alleles in many disorders. This systemic review aimed to assess whether an association exists between gene(s)/allelic variant(s), and varicocele-related male infertility (VRMI). This review included 19 GAS that investigated 26 genes in 1,826 men with varicocele compared to 2,070 healthy men, and 263 infertile men without varicocele. These studies focussed on candidate genes and relevant variants, with glutathione S-transferase gene being the most frequently studied (n = 5) followed by the nitric oxide synthase 3 (NOS3) gene (n = 3) and the phosphoprotein tyrosine phosphatase 1 gene (n = 2). In one study the genes for NAD(P)H quinone oxidoreductase 1, sperm protamine, human 8-oxoguanine DNA glycosylase 1, methylenetetrahydrofolate reductase, polymerase gamma, heat shock protein 90, mitochondrial DNA, superoxide dismutase 2, transition nuclear protein 1, and transition nuclear protein 2, were assessed. There is no clear indication that any of these polymorphisms are sturdily associated with VRMI. However, three studies established that the polymorphic genotype (GT + TT) for rs1799983 polymorphism of the NOS3 gene is more frequent in varicocele patients. Further endeavours such as standardising reporting, exploring complementary designs, and the use of GWAS technology are justified to help replicate these early findings.

Varicocele associated male infertility: cellular and molecular perspectives of pathophysiology

BACKGROUND

Varicocele is a common risk factor associated with reduced male fertility potential. The current understanding of varicocele pathophysiology does not completely explain the clinical manifestation of infertility. The present treatment options such as antioxidant supplementation and varicocelectomy only helps ∼35% of men to achieve spontaneous pregnancy.

OBJECTIVE

This review aims to summarize the available knowledge on cellular and molecular alterations implicated to varicocele associated male infertility and also highlights the new knowledge generated by 'Omics' technologies.

MATERIALS AND METHODS

PubMed, MEDLINE, Cochrane and Google Scholar databases are searched using different combinations of keywords (varicocele, infertile/fertile men with varicocele, cellular changes, molecular mechanisms, proteome, epigenome, transcriptome and metabolome). A total of 229 relevant human and animal studies published till 2021 were included in this review.

RESULTS

Current understanding advocates oxidative stress (OS) as a major contributory factor to the varicocele associated male infertility. Excessive OS causes alteration in testicular microenvironment and sperm DNA fragmentation which further contributes to infertility. Molecular and omics studies have identified several promising biomarkers such as AAMP, SPINT1, MKI67 (genetic markers), sperm quality and function related protein markers, global sperm DNA methylation level (epigenetic marker), Hspa2, Protamine, Gadd7, Dynlt1 and Beclin1 (mRNA markers), PRDX2, HSPA, APOA2, YKL40 (seminal protein markers), total choline and PHGDH (metabolic markers).

DISCUSSION

Mature spermatozoa harbours a plethora of molecular information in form of proteome, epigenome and transcriptome; which could provide very important clues regarding pathophysiology of varicocele associated infertility. Recent molecular and omics studies in infertile men with varicocele have identified several promising biomarkers. Upon further validation with larger and well-defined studies, some of these biomarkers could aid in varicocele management.

CONCLUSION

The present evidences suggest inclusion of OS and sperm DNA fragmentation tests could be useful to the diagnostic workup for men with varicocele. Furthermore, including precise molecular markers may assist in diagnostics and prognostics of varicocele associated male infertility. This article is protected by copyright. All rights reserved.

Comprehensive Analysis of Global Research on Human Varicocele: A Scientometric Approach

Purpose

This study provides a comprehensive analysis of research trends on the etiology, mechanisms, potential risk factors, diagnosis, prognosis, surgical and non-surgical treatment of varicocele, and clinical outcomes before and after varicocele repair.

Materials and Methods

Varicocele studies published between 1988 and 2020 were retrieved from the Scopus database on April 5, 2021. Original studies on human varicocele were included, irrespective of language. Retrieved articles were manually screened for inclusion in various sub-categories. Bibliometric data was subjected to scientometric analysis using descriptive statistics. Network, heat and geographic mapping were generated using relevant software.

Results

In total, 1,943 original human studies on varicocele were published. These were predominantly from the northern hemisphere and developed countries, and published in journals from the United States and Germany. Network map analysis for countries showed several interconnected nodal points, with the USA being the largest, and Agarwal A. from Cleveland Clinic, USA, being a center point of worldwide varicocele research collaborations. Studies of adolescents were underrepresented compared with studies of adults. Studies on diagnostic and prognostic aspects of varicocele were more numerous than studies on varicocele prevalence, mechanistic studies and studies focusing on etiological and risk factors. Varicocele surgery was more investigated than non-surgical approaches. To evaluate the impact of varicocele and its treatment, researchers mainly analyzed basic semen parameters, although markers of seminal oxidative stress are being increasingly investigated in the last decade, while reproductive outcomes such as live birth rate were under-reported in the literature.

Conclusions

This study analyzes the publication trends in original research on human varicocele spanning over the last three decades. Our analysis emphasizes areas for further exploration to better understand varicocele’s impact on men’s health and male fertility.

Oxidative Stress: A Comprehensive Review of Biochemical, Molecular, and Genetic Aspects in the Pathogenesis and Management of Varicocele

Oxidative stress is a condition due to an imbalance between the concentrations of oxidants and antioxidants, and it is a well-recognized contributor in several male infertility conditions. Varicocele, a common vascular condition, may cause male infertility due to hyperthermia, hypoxia and/or exposure to toxic adrenal and renal metabolites. In this review, the mechanisms by which oxidative stress can affect cellular integrity and functions are described, along with molecular markers of cellular oxidative damage, and the most commonly performed techniques for their detection in seminal fluid. Moreover, we focus on the role of oxidative stress in the pathophysiology of varicocele based on recently published evidence from omics based studies, such as proteomics and genomics. Finally, we discuss strategies for the management of oxidative stress and the clinical guidelines for testing oxidative stress-related sperm DNA fragmentation in this group of patients.

Association of single-nucleotide polymorphisms in antioxidant genes and their gene-gene interactions with risk of male infertility in a Chinese population

The antioxidant defense system protects DNA from the damaging effects of oxidative stress and is hypothesized to be associated with an increased risk of male infertility. Polymorphisms in antioxidant genes and the gene-gene interactions associated with the antioxidant system may increase the potential risk of male infertility. In the present case-controlled study, the individual link between seven gene polymorphisms (NQO1 rs1800566, SOD2 rs4880, GSTM3 rs1571858, rs3814309, rs7483, GSTM5 rs11807 and GSTP1 rs1695) and the risk of male infertility was investigated. A total of 248 idiopathic infertility patients and 310 fertile controls were selected, and genotyping was performed using the Mass ARRAY platform. There were no significant associations between the seven polymorphisms and risk of male infertility. However, the analysis of gene-gene interactions showed a decreased risk of male infertility in GSTM3 rs3814309/NQO1 rs1800566 [CC x CT/TT; odds ratio (OR)=0.56, 95% confidence interval (CI)=0.34-0.92; P=0.022), and a significant association between a gene-gene interaction in GSTM3 rs1571858/NQO1 rs1800566 and azoospermia (AG/GG x CC; OR=3.84, 95% CI=1.25-11.81; P=0.019).

Glutathione S-transferase M1 and T1 null genotype frequency distribution among four tribal populations of western India

Glutathione S transferase (GST) family is a key contributor in the detoxification mechanism of our body.Deletion of the genes within this family has been reported in the failure of detoxification system, to some extent leading to various types of cancers and other life threatening diseases. The existing data and reports on the association of null genotype of both GSTM1 and GSTT1 genes for various diseases are inconsistent. But knowledge of the polymorphic distributions of genotypes in different populations is important for investigating the risk factors in different epidemiological studies. The present study thus aims to determine thefrequency of GSTM1 and GSTT1 null genotype frequency among four tribal groups, i.e. Mina, Garasia, Damor and Saharia of western India. A comparative analysis with different tribal as well as world population has also been undertaken to have a view of its worldwide frequency distribution. Our results reveal a frequency distribution varying from 22.6% to 66.9% with respect to GSTM1gene polymorphism and from 19.1% to 33.0% with respect to GSTT1 gene in the studied populations. To the best of our knowledge this is the first report on the GSTM1and GSTT1frequency distribution among the tribal population of western India and our study shows that the Mina tribal population has the highest frequency of GSTM1.

Genetics and epigenetics of varicocele pathophysiology: an overview

Varicocele is found in approximately 20% of adults and adolescents and in 19-41% of men seeking treatment for infertility. It is associated with a decrease in sperm count as well as sperm motility and morphology. The currently accepted description of the pathophysiology of varicocele does not explain all its clinical manifestations; therefore, other factors such as genetic and epigenetic changes, associated with the environment, might be involved in causing infertility and decrease in sperm quality. It has been reported that the varicocele-induced deterioration of testicular function is progressive and interferes with fertility; hence, early and efficient assessment of the genetic manifestations in patients would be important for developing future medical interventions. Chromosomal disorders, mutations, polymorphisms, changes in gene expression, and epigenetic changes have all been reported to be associated with varicocele. Several studies are underway to unravel the genetic basis of this disease, as it is important to understand the origin and the aggravating factors to ensure appropriate guidance and intervention. Here, we review the available literature regarding the genetic and epigenetic changes associated with varicocele, and how these alterations are related to the different clinical manifestations of the disease.

Association of polymorphisms in glutathione S-transferase genes (GSTM1, GSTT1, GSTP1) with idiopathic azoospermia or oligospermia in Sichuan, China

The reported effects of the glutathione S-transferase (GSTs) genes (GSTM1, GSTT1, and GSTP1) on male factor infertility have been inconsistent and even contradictory. Here, we conducted a case-control study to investigate the association between functionally important polymorphisms in GST genes and idiopathic male infertility. The study group consisted of 361 men with idiopathic azoospermia, 118 men with idiopathic oligospermia, and 234 age-matched healthy fertile male controls. Genomic DNA was extracted from the peripheral blood, and analyzed by polymerase chain reaction and restriction fragment length polymorphism analysis. There was a significant association between the GSTP1 variant genotype (Ile/Val + Val/Val) with idiopathic infertility risk (odds ratio [OR]: 1.53; 95% confidence interval [CI]: 1.11–2.11; P = 0.009). Similarly, a higher risk of infertility was noted in individuals carrying a genotype combination of GSTT1-null and GSTP1 (Ile/Val + Val/Val) (OR: 2.17; 95% CI: 1.43–3.31; P = 0.0002). These results suggest an increased risk of the GSTP1 variant genotype (Ile/Val + Val/Val) for developing male factor infertility. Our findings also underrate the significance of the effect of GSTM1 and/or GSTT1 (especially the former) in modulating the risk of male infertility in males from Sichuan, southwest China.

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.

Molecular mechanisms involved in varicocele-associated infertility

Varicocele is a pathologic enlargement of the pampiniform venous plexus within the spermatic cord, a condition that is a common cause of impaired sperm production and decreased quality of sperm. While varicocele is the most common surgically correctable risk factor for male infertility, not all males with varicocele experience infertility. In fact, most men with varicocele have normal spermatogenesis. Despite its prevalence, the molecular mechanisms of varicocele and its effect on testicular function are yet to be completely understood. We postulate that men with varicocele-associated infertility could have preexisting genetic lesions or defects in molecular mechanisms that make them more susceptible to varicocele-mediated testicular injury affecting spermatogenesis.

GSTM1 and GSTT1 null polymorphisms and male infertility risk: an updated meta-analysis encompassing 6934 subjects

Published data on the association between the GST genes polymorphisms and male infertility risk are inconclusive. We investigated GST genes polymorphisms in a large sample size case-control study, and conducted a literature-based meta-analysis of 6934 individuals. Our case-control study showed the GSTM1 null genotype was significantly associated with idiopathic oligozoospermia, while the null genotype of GSTT1 was significantly associated with normozoospermia and azoospermia. Additionally, significantly elevated GSTT1 expression levels were observed in present genotype compared with null genotype. In the meta-analysis, the null genotype of GSTM1 was associated with a significantly increased risk of male infertility. Furthermore, a stratification analysis showed that the risk of GSTM1 polymorphism was associated with male infertility in both Asian and Caucasian groups. Further studies of GSTM1 and GSTT1 with their biological functions are needed to understand the role of these genes in the development of male infertility.

Association of GSTM1 and GSTT1 genes with the susceptibility to male infertility: result from a meta-analysis

The deletion polymorphisms of the glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) genes were considered as candidates for genetic susceptibility factors of male infertility. Previous studies concerning the relationship between the null genotype of the two genes and male infertility have been reported in recent years. However, the results remain elusive. A meta-analysis was performed to estimate the relationship between the deletion polymorphism of the GSTM1 or GSTT1 gene, and male infertility in this study. Sixteen studies concerning the GSTM1 gene, including 2174 cases and 1861 controls, and 13 case-control studies on the GSTT1 gene with a total number of 1992 cases and 1617 controls were processed. The results showed that the null genotype of the GSTM1 gene was associated with male infertility in the overall populations (P=0.003, OR=1.40, 95%CI=1.12-1.75), especially in Caucasian (P=0.012, OR=1.50, 95%CI=1.09-2.07) as well as Chinese (P=0.001, OR=1.55, 95%CI=1.19-2.03). The null genotype of the GSTT1 gene was strongly related to male infertility only in Chinese (P=0.000, OR=1.70, 95%CI=1.34-2.14). These results indicated that the null genotype of the GSTM1 gene might contribute to the susceptibility of male infertility, whereas the null genotype of the GSTT1 gene may be a genetic susceptibility factor of male infertility for the Chinese.

Glutathione S-transferases gene polymorphisms and risk of male idiopathic infertility: a systematic review and meta-analysis

The Glutathione S-transferases (GSTs) polymorphisms have been implicated in susceptibility to male idiopathic infertility, but study results are still controversial. To investigate the genetic associations between GSTs polymorphisms and risk of male idiopathic infertility, a systematic review and meta-analysis were performed. Meta-analysis was performed by pooling odds ratio (OR) with its corresponding 95 % confidence interval (95 % CI) form studies in electronic databases up to March 16, 2012. Glutathione S-transferase M 1 (GSTM1) null genotype, Glutathione S-transferase T 1 (GSTT1) null genotype, and dual null genotype of GSTM1/GSTT1 were analyzed independently. 14 eligible studies with a total of 1,845 idiopathic infertility males and 1,729 controls were included. There were 13 studies on GSTM1 polymorphism, 10 ones on GSTT1 polymorphism and 5 ones on GSTM1-GSTT1 interaction analysis. Meta-analyses of total relevant studies showed GSTM1 null genotype was significantly associated with an increased risk of male idiopathic infertility (OR = 1.40, 95 % CI 1.07-1.84, P OR = 0.015). The GSTM1-GSTT1 interaction analysis showed dual null genotype of GSTM1/GSTT1 was also significantly associated with increased risk of male idiopathic infertility (OR = 1.85, 95 % CI 1.07-3.21, P OR = 0.028). Subgroup analyses by ethnicity showed the associations above were still statistically significant in Caucasians (For GSTM1, OR = 1.51, 95 % CI 1.11-2.05, P OR = 0.009; For GSTM1/GSTT1, OR = 2.10, 95 % CI 1.51-2.91, P OR < 0.001). This meta-analysis suggests GSTM1 null genotype contributes to increased risk of male idiopathic infertility in Caucasians, and males with dual null genotype of GSTM1/GSTT1 are particularly susceptible to developing idiopathic infertility.

Association of the Glutathione S-transferases M1 and T1 polymorphism with male infertility: a meta-analysis

BACKGROUND

Genes of different pathways regulate spermatogenesis, and the complexity of the spermatogenic process indicates that polymorphisms or mutations in these genes could cause male infertility. Published data on the association between the GSTM1 and GSTT1 polymorphism and male infertility risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed.

METHODS

A total of 11 studies regarding GSTM1 and 9 studies regarding GSTT1 between 1999 and 2012 were identified through researching MEDLINE, EMBASE and the Chinese Biomedical Database. It was performed to obtain summary estimated odd ratios and 95 % confidence intervals of GSTM1 and GSTT1 for male infertility, with attention to study quality and publication bias.

RESULTS

Overall, a significant association was seen between GSTM1 (OR=1.20, 95 % CI=1.02-1.40, P(heterogeneity) =0.000, P=0.027) genotypes and male infertility. Significant associations were also observed in subgroups of Caucasian populations (OR=1.65, 95 %CI=1.16-2.34, P(heterogeneity) =0.006, P=0.005), but were not observed in Asian populations (OR=1.09, 95 % CI=0.72-1.65, P(heterogeneity) =0.054, P=0.697) when stratified by ethnicity. While there was no significant association was seen between GSTT1 (OR=1.00, 95 % CI=0.74-1.35, P(heterogeneity) =0.000, P=0.980) null genotypes and male infertility. Simultaneously, significant associations were not observed in subgroups of Caucasian populations (OR=0.94, 95 %CI=0.44-2.00, P(heterogeneity) =0.000, P=0.867) and Asian populations (OR=0.93, 95 % CI=0.46-1.87, P(heterogeneity) =0.002, P=0.838) when stratified by ethnicity.

CONCLUSION

Our results suggest the GSTM1 null genotype contributes to male infertility susceptibility, while GSTT1 gene polymorphisms are not associated with male infertility in our study.

The glutathione-S-transferase gene polymorphisms (GSTM1 and GSTT1) and idiopathic male infertility risk: a meta-analysis

Published data on the association between male infertility and the glutathione-S-transferase (GST) gene polymorphism are inclusive. To drive a more precise estimation, we performed a meta-analysis based on 1897 cases and 1785 controls from 15 published case-control studies. PubMed and CBMdisc literature research were conducted to identify all eligible studies investigating such a relationship. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to estimate the strength of the association. In the overall analysis, the frequency of glutathione-S-transferase Mu-1 (GSTM1) null genotype was significantly associated with susceptibility to idiopathic male infertility. In further stratified analysis by sperm concentration of the case group, no significantly increased risk of azoospermia was found in either GSTM1 null or glutathione-S-transferase Theta-1 (GSTT1) null genotype. Compared with a significant relationship between GSTM1 null genotype and oligoasthenoteratozoospermia (OAT), GSTT1 null genotype was not associated with the OAT risk. Additionally, a subgroup analysis on ethnicity showed no notable association between the polymorphism and the risk of idiopathic male infertility in any of GSTM1 null and GSTT1 null genotype, neither in Asian nor in European populations. In conclusion, these results support that the GSTM1 null genotype mainly contributes to idiopathic male infertility susceptibility, particularly to OAT.

GSTM1 null genotype contributes to increased risk of male infertility: a meta-analysis

BACKGROUND

Many studies have investigated the association between Glutathione S-Transferase M 1 (GSTM1) null genotype and risk of male infertility, but the impact of GSTM1 null genotype on infertility risk is unclear owing to the obvious inconsistency among those studies. This study aimed to quantify the strength of association between GSTM1 null genotype and risk of male infertility.

METHODS

We searched the PubMed, Embase and Wangfang databases for studies investigating the association between GSTM1 null genotype and risk of male infertility. We estimated pooled odds ratio (OR) with its 95 % confidence interval (95 % CI) to assess this possible association.

RESULTS

Twelve case-control studies with 1, 589 infertility cases and 1, 537 controls were included. Meta-analysis of total 12 studies showed that GSTM1 null genotype was associated with increased risk of male infertility (OR = 1.34, 95%CI 1.02-1.77, P = 0.036). In subgroup analysis of Caucasians, there was also an obvious association between GSTM1 null genotype and increased risk of male infertility (OR = 1.51, 95%CI 1.11-2.05, P = 0.006). Sensitivity analyses by sequential omission of individual studies or omitting studies without high quality did not significantly alter the overall pooled OR. Cumulative meta-analysis further showed a trend of more obvious association as information accumulated. No evidence of publication bias was observed.

CONCLUSION

Meta-analyses of available data suggest that GSTM1 null genotype contributes to increased risk of male infertility.

Varicocele and male factor infertility treatment: a new meta-analysis and review of the role of varicocele repair

CONTEXT

Varicocele is a common condition, found in many men who present for infertility evaluation.

OBJECTIVE

To assess the effect of varicocelectomy on male infertility.

EVIDENCE ACQUISITION

A literature search was performed using Embase and Medline. Literature reviewed included meta-analyses and randomized and nonrandomized prospective (controlled and noncontrolled) studies. In addition, a new meta-analysis was performed.

EVIDENCE SYNTHESIS

Four randomized controlled trials reporting on pregnancy outcome after repair of clinical varicoceles in oligozoospermic men were identified. Using the random effect model, the combined odds ratio was 2.23 (95% confidence interval [CI], 0.86-5.78; p=0.091), indicating that varicocelectomy is moderately superior to observation, but the effect is not statistically significant. We identified 22, 17, and 5 prospective studies reporting on sperm concentration, total motility, and progressive motility, respectively, before and after repair of clinical varicocele. The random effect model combined improvement in sperm concentration was 12.32 million sperm per milliliter (95% CI, 9.45-15.19; p<0.0001). The random effect model combined improvement in sperm total and progressive motility were 10.86% (95% CI, 7.07-14.65; p<0.0001) and 9.69% (95% CI, 4.86-14.52; p=0.003), respectively. These results indicate that varicocelectomy is associated with a significant increase in sperm concentration as well as total and progressive motility. Prospective studies also show that varicocelectomy reduces seminal oxidative stress and sperm DNA damage as well as improving sperm ultramorphology. Studies indicate that a microsurgical approach to a varicocele repair results in less recurrence and fewer complications than other techniques.

CONCLUSIONS

Although there is no conclusive evidence that a varicocele repair improves spontaneous pregnancy rates, varicocelectomy improves sperm parameters (count and total and progressive motility), reduces sperm DNA damage and seminal oxidative stress, and improves sperm ultramorphology. The various methods of repair are all viable options, but microsurgical repair seems to be associated with better outcomes.

Glutathione S-transferase M1 and T1 polymorphisms in Turkish patients with varicocele

Several studies have shown that high oxidative stress levels are associated with varicocele. The GST (glutathione S-transferase) family of genes is critical in the protection of cells from oxidative stress because they utilise as substrates a wide variety of products of oxidative stress. The objective of this study was to assess the relationship between genetic polymorphism in GST-M1 and GST-T1 and varicocele using 109 varicocele patients and 123 controls. Varicoceles were clinically graded as Grade 1, Grade 2 and Grade 3. GST-M1 and GST-T1 genes were determined by polymerase chain reaction. Although the GST-M1 null genotype was higher in Grade 3 than in Grade 1, 2 and controls, there were no statistical differences between control group and varicocele groups according to GST-M1 and GST-T1 null genotype. Men with varicocele do not have more GST-M1 and GST-T1 null polymorphisms than men without varicocele. Additional studies are needed to assess the exact mechanism by which the varicocele corresponds to elevated ROS levels.

Genetic variations in human glutathione transferase enzymes: significance for pharmacology and toxicology

Glutathione transferase enzymes (GSTs) catalyze reactions in which electrophiles are conjugated to the tripeptide thiol glutathione. While many GST-catalyzed transformations result in the detoxication of xenobiotics, a few substrates, such as dihaloalkanes, undergo bioactivation to reactive intermediates. Many molecular epidemiological studies have tested associations between polymorphisms (especially, deletions) of human GST genes and disease susceptibility or response to therapy. This review presents a discussion of the biochemistry of GSTs, the sources-both genetic and environmental-of interindividual variation in GST activities, and their implications for pharmaco- and toxicogenetics; particular attention is paid to the Theta class GSTs.