DNA repair XRCC1 Arg399Gln polymorphism is associated with the risk of development of end-stage renal disease

Chronic Kidney Disease and Cancer: Inter-Relationships and Mechanisms

Chronic kidney disease (CKD) has been recognized as an increasingly serious public health problem globally over the decades. Accumulating evidence has shown that the incidence rate of cancer was relatively higher in CKD patients than that in general population, which, mechanistically, may be related to chronic inflammation, accumulation of carcinogenic compounds, oxidative stress, impairment of DNA repair, excessive parathyroid hormone and changes in intestinal microbiota, etc. And in patients with cancer, regardless of tumor types or anticancer treatment, it has been indicated that the morbidity and incidence rate of concomitant CKD was also increased, suggesting a complex inter-relationship between CKD and cancer and arousing increasing attention from both nephrologists and oncologists. This narrative review focused on the correlation between CKD and cancer, and underlying molecular mechanisms, which might provide an overview of novel interdisciplinary research interests and the potential challenges related to the screening and treatment of CKD and cancer. A better understanding of this field might be of help for both nephrologists and oncologists in the clinical practice.

Gene Polymorphism of XRCC1 in Systemic Lupus Erythematous

Introduction:

There are debates about the role of the X-ray repair cross-complementation group 1 (XRCC1) Arg399Gln gene in the pathogenesis of Systemic Lupus Erythematosus (SLE).

Methods:

The study was a case-control study carried out on 100 recently diagnosed SLE patients compared to 100 control subjects. The study of XRCC1 Arg399Gln polymorphism was performed by a polymerase chain reaction and restriction fragment length polymorphism.

Results and Discussion:

A higher frequency of ‘G’ allele in SLE (38.5%) versus control (32%) was noticed; however, this difference was not statistically significant (p = 0.174). Besides, a slightly higher frequency of G/G genotype was found in SLE (22%) vs. control (12%); again, this difference was not statistically significant (p = 0.157). A statistically significantly higher proportion of arthritis, serositis, and thrombocytopenia was observed in the A/A genotype (p = 0.010, 0.032, and 0.036, respectively). Furthermore, we noticed a statistically significant lower hemoglobin level in G/G genotype (p = 0.027). Otherwise, there was no statistically significant difference between the three genotypes regarding other parameters: photosensitivity, malar rash, oral ulceration, ANA, anti-dsDNA antibody, anemia, leucopenia, neurologic manifestations, and all lab parameters except hemoglobin level. Similar results were reported previously.

According to genotype, in the study of Clinical and laboratory parameters in SLE patients, a statistically significantly higher proportion of arthritis, serositis, and thrombocytopenia was observed in the A/A genotype (p =0 .01, 0.032, and 0.036 respectively). Furthermore, we noticed a statistically significant lower hemoglobin level in G/G genotype (p = 0.027). These findings suggest a pathogenic connection between the seriousness of the defective DNA repair and the autoimmune severity; such connection is consistent with that found in several murine models. Additionally, negative regulation of the genes encoding the proteins involved in the NER pathway in SLE patients, specifically and XPC, has been found previously.

Conclusion:

The present study highlights the higher insignificant increase of G allele and GG genotype of XRCC1 399 gene in patients with SLE compared to healthy control. This increase was significantly associated with anemia in patients, which may reflect the aggravation of environmental risk factors to SLE associated with the reduced repair of DNA. Further longitudinal studies are required to validate the present findings.

Polymorphism of the DNA repair gene XDP increases the risk of systemic lupus erythematosus but not multiple sclerosis in the Iranian population

BACKGROUND

Xeroderma pigmentosum group D ( XPD ) is an essential component of the nucleotide excision repair (NER) pathway, which can play a major role in DNA repair processes. A deficiency in this pathway was suggested as a causative factor of autoimmune diseases. Therefore, the current study aimed to investigate the relationship between XPD Lys751Gln polymorphism (rs13181) as one of the most common XDP polymorphisms and the risk of two important auto-immune diseases,namely systemic lupus erythematosus (SLE) and multiple sclerosis (MS) in the Iranian population.

METHODS

165 SLE patients and 165 age- and gender-matched healthy controls, and 150 MS patients and 150 age- and gender-matched healthy controls were genotyped for XPD rs13181 A/C polymorphism using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

The results of the present study have indicated that both C allele frequency ( P = 0.012; odds ratio: 1.5; 95% confidence interval: 1.1-2.07) and CC genotype ( P = 0.007; odds ratio: 2.46; 95% confidence interval: 1.2-4.7) in SLE patient were significantly higher than those in control group. Furthermore, there were no significant differences between MS patients and normal subjects concerning the genotype and the allele frequencies.

CONCLUSION

Our findings suggested that XPD rs13181 A/C polymorphism may be a crucial risk factor for the development of SLE but not MS in Iranian patients.

Microbes in Tumoral In Situ Tissues and in Tumorigenesis

Cancerous tumors are severe diseases affecting human health that have a complicated etiology and pathogenesis. Microbes have been considered to be related to the development and progression of numerous tumors through various pathogenic mechanisms in recent studies. Bacteria, which have so far remained the most studied microbes worldwide, have four major possible special pathogenic mechanisms (modulation of inflammation, immunity, DNA damage, and metabolism) that are related to carcinogenesis. This review aims to macroscopically summarize and verify the relationships between microbes and tumoral in situ tissues from cancers of four major different systems (urinary, respiratory, digestive, and reproductive); the abovementioned four microbial pathogenic mechanisms, as well as some synergistic pathogenic mechanisms, are also discussed. Once the etiologic role of microbes and their precise pathogenic mechanisms in carcinogenesis are known, the early prevention, diagnosis, and treatment of cancers would progress significantly.

Genetic Variants Associated with Chronic Kidney Disease in a Spanish Population

Chronic kidney disease (CKD) patients have many affected physiological pathways. Variations in the genes regulating these pathways might affect the incidence and predisposition to this disease. A total of 722 Spanish adults, including 548 patients and 174 controls, were genotyped to better understand the effects of genetic risk loci on the susceptibility to CKD. We analyzed 38 single nucleotide polymorphisms (SNPs) in candidate genes associated with the inflammatory response (interleukins IL-1A, IL-4, IL-6, IL-10, TNF-α, ICAM-1), fibrogenesis (TGFB1), homocysteine synthesis (MTHFR), DNA repair (OGG1, MUTYH, XRCC1, ERCC2, ERCC4), renin-angiotensin-aldosterone system (CYP11B2, AGT), phase-II metabolism (GSTP1, GSTO1, GSTO2), antioxidant capacity (SOD1, SOD2, CAT, GPX1, GPX3, GPX4), and some other genes previously reported to be associated with CKD (GLO1, SLC7A9, SHROOM3, UMOD, VEGFA, MGP, KL). The results showed associations of GPX1, GSTO1, GSTO2, UMOD, and MGP with CKD. Additionally, associations with CKD related pathologies, such as hypertension (GPX4, CYP11B2, ERCC4), cardiovascular disease, diabetes and cancer predisposition (ERCC2) were also observed. Different genes showed association with biochemical parameters characteristic for CKD, such as creatinine (GPX1, GSTO1, GSTO2, KL, MGP), glomerular filtration rate (GPX1, GSTO1, KL, ICAM-1, MGP), hemoglobin (ERCC2, SHROOM3), resistance index erythropoietin (SOD2, VEGFA, MTHFR, KL), albumin (SOD1, GSTO2, ERCC2, SOD2), phosphorus (IL-4, ERCC4 SOD1, GPX4, GPX1), parathyroid hormone (IL-1A, IL-6, SHROOM3, UMOD, ICAM-1), C-reactive protein (SOD2, TGFB1,GSTP1, XRCC1), and ferritin (SOD2, GSTP1, SLC7A9, GPX4). To our knowledge, this is the second comprehensive study carried out in Spanish patients linking genetic polymorphisms and CKD.

Association of Polymorphisms in the DNA Repair Genes XRCC1 and XRCC3 with Systemic Lupus Erythematosus

Background:

Evidence suggests that DNA damage is implicated in the development of Systemic Lupus Erythematosus (SLE).

Objective:

Investigate the possible association of polymorphisms in the DNA repair genes XRCC1 and XRCC3 with SLE and its clinical and laboratory features.

Methods:

This is a case-control study comparing the polymorphisms in the DNA repair genes XRCC1 and XRCC3 in SLE patients and control individuals. Genotyping for DNA repair genes was performed by polymerase chain reaction-restriction fragment length polymorphism in 76 patients and 82 healthy control individuals.

Results:

Our data indicated that the genotype frequencies in patients with the XRCC1 Arg399Gln and XRCC3 Thr241Met polymorphisms were similar to those observed in the control group (p > 0.05). However, the frequencies of the 399Gln allele (p = 0.023, OR = 0.58, 95% CI = 0.36–0.93) and 241Met allele (p = 0.0039, OR = 0.59, 95% CI = 0.36–0.98) were significantly lower in the patients than those in the control subjects.

Conclusion:

We demonstrated that 399Gln and 241Met alleles may play a protective role in SLE susceptibility.

Renal disease in Cockayne syndrome

BACKGROUND

Cockayne Syndrome (CS) is a rare autosomal recessive multi-systemic disorder, characterized; by developmental delay, microcephaly, severe growth failure and sensorial impairment. Renal complications have been reported but remain underinvestigated. The objective of this study was to perform a review of renal disease in a cohort of CS patients.

METHODS

We retrospectively collected relevant clinical, biochemical and genetic data from a cohort of 136 genetically confirmed CS patients. Blood pressure (BP), proteinuria, albuminemia, uric acid, creatinine clearance, renal ultrasounds and renal biopsy result were analysed.

RESULTS

Thirty-two patients had a renal investigation. We found that 69% of investigated patients had a renal disorder and/or an elevated BP. Fifteen out of 21 patients (71% of investigated patients) had an increased BP, 10 out of 16 patients (62% of investigated patients) presented with proteinuria and 4 of them had a nephrotic syndrome. Thirteen patients out of 29 (45%) had a decreased Glomerular Filtration Rate (GFR), 18 out of 25 patients (72%) had a hyperuricemia. No correlation with the genetic background or clinical types of CS was found, except for the renal clearance.

CONCLUSIONS

Renal disease, increased blood pressure and hyperuricemia were highly prevalent in our study. We believe that CS patients should benefit from a nephrological follow-up and that anti-uric acid drug and Angiotensin-converting enzyme (ACE) inhibitor should be discussed in these patients.

Role of DNA repair genes XRCC3 and XRCC1 in predisposition to type 2 diabetes mellitus and diabetic nephropathy

INTRODUCTION

Increasing number of experimental and clinical studies suggest a strong relationship between hyperglycemia, oxidative stress, DNA damage and diabetic nephropathy (DN). Also, epidemiologic studies remark an enhanced risk of cancer with type 2 diabetes. This research aims to assess whether the X-ray cross complementing group 3 (XRCC3) gene T241M polymorphism (rs861539) and X-ray cross complementing group 1 (XRCC1) gene A399G polymorphism (rs25487) are related with predisposition to type 2 diabetes mellitus (T2DM) and to diabetic nephropathy in Turkish population.

MATERIALS AND METHODS

Polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) was performed to identify the distribution of genotypes and frequency of alleles of T241M polymorphism of the XRCC3 gene (XRCC3 T241M) and A399G polymorphism of the XRCC1 gene (XRCC1 A399G). The study population included 238 subjects residing in Istanbul, Turkey; 116 with T2DM, 50 with DN and 72 with normal glucose metabolism.

RESULTS AND CONCLUSION

Polymorphic Gln allele of XRCC1 gene was significantly related with T2DM and DN (OR 3.09, 95% CI 1.14-8.40 and OR 3.29 95% CI 1.23-8.80, respectively) however, there was no statistical association of XRCC3 T241M with T2DM or DN. The results of this study suggest that XRCC1 399Gln polymorphism is related with an increased susceptibility to T2DM and DN in the studied Turkish population.

An African perspective on the genetic risk of chronic kidney disease: a systematic review

BACKGROUND

Individuals of African ethnicity are disproportionately burdened with chronic kidney disease (CKD). However, despite the genetic link, genetic association studies of CKD in African populations are lacking.

METHODS

We conducted a systematic review to critically evaluate the existing studies on CKD genetic risk inferred by polymorphism(s) amongst African populations in Africa. The study followed the HuGE handbook and PRISMA protocol. We included studies reporting on the association of polymorphism(s) with prevalent CKD, end-stage renaldisease (ESRD) or CKD-associated traits. Given the very few studies investigating the effects of the same single nucleotide polymorphisms (SNPs) on CKD risk, a narrative synthesis of the evidence was conducted.

RESULTS

A total of 30 polymorphisms in 11 genes were investigated for their association with CKD, ESRD or related traits, all using the candidate-gene approach. Of all the included genes, MYH9, AT1R and MTHFR genes failed to predict CKD or related traits, while variants in the APOL1, apoE, eNOS, XPD, XRCC1, renalase, ADIPOQ, and CCR2 genes were associated with CKD or other related traits. Two SNPs (rs73885319, rs60910145) and haplotypes (G-A-G; G1; G2) of the apolipoprotein L1 (APOL1) gene were studied in more than one population group, with similar association with prevalent CKD observed. The remaining polymorphisms were investigated in single studies.

CONCLUSION

According to this systematic review, there is currently insufficient evidence of the specific polymorphisms that poses African populations at an increased risk of CKD. Large-scale genetic studies are warranted to better understand susceptibility polymorphisms, specific to African populations.

Oxidative Stress in Kidney Diseases: The Cause or the Consequence?

Exaggerated oxidative stress (OS) is usually considered as a disturbance in regular function of an organism. The excessive levels of OS mediators may lead to major damage within the organism’s cells and tissues. Therefore, the OS-associated biomarkers may be considered as new diagnostic tools of various diseases. In nephrology, researchers are looking for alternative methods replacing the renal biopsy in patients with suspicion of chronic kidney disease (CKD). Currently, CKD is a frequent health problem in world population, which can lead to progressive loss of kidney function and eventually to end-stage renal disease. The course of CKD depends on the primary disease. It is assumed that one of the factors influencing the course of CKD might be OS. In the current work, we review whether monitoring the OS-associated biomarkers in nephrology patients can support the decision-making process regarding diagnosis, prognostication and treatment initiation.

Association of RAC1 Gene Polymorphisms with Primary End-Stage Renal Disease in Chinese Renal Recipients

BACKGROUND/OBJECTIVE

RAC1 gene could influence susceptibility to renal failure by altering the activity and expression of Rac1, which is a member of the Rho family of small GTP-binding proteins. In clinical practice, renal transplantation provides the optimal treatment for people with end-stage renal disease (ESRD). The objective of this present study was to determine whether the RAC1 gene polymorphisms were associated with primary ESRD susceptibility in Chinese renal recipients.

METHODS

Six single nucleotide polymorphisms (SNPs) of RAC1 gene, including rs836488 T>C, rs702482 A>T, rs10951982 G>A, rs702483 A>G, rs6954996 G>A, and rs9374 G>A, were genotyped in 300 renal transplant recipients (cases) and 998 healthy Chinese subjects (controls) by using TaqMan SNP genotyping assay. Allele, genotype, and haplotype frequencies of the six SNPs were compared between cases and controls. Odds ratios (OR) and 95% confidence intervals (CI) were calculated in logistic regression models to evaluate the associations of the six SNPs with ESRD risk.

RESULTS

The genotype distributions for the six SNPs in controls were consistent with Hardy-Weinberg equilibrium (P > 0.05). Association analysis revealed that three SNPs were significantly associated with ESRD risk. Positive associations with ESRD risk were found for the rs836488, rs702482, and rs702483 in the co-dominant model (minor allele homozygotes versus major allele homozygotes); specifically, the frequencies of the minor allele homozygotes and the minor allele for the three SNPs were higher in the cases than in the controls. In addition, these three SNPs also had associations with increased ESRD risk under the additive model (P < 0.05), and positive associations were also found for the rs836488 in the dominant model (P < 0.05) and for the rs702483 in the recessive model (P < 0.05). All these associations were independent of confounding factors. The other three SNPs (rs10951982, rs6954996, and rs9374), in all comparison models, were not associated with ESRD risk (P > 0.05). In haplotype analysis, carriers with "C-T-G-G-G-G" haplotype had a significantly higher risk of ESRD compared with the most common haplotype "T-A-G-A-G-G" (P = 0.011, OR = 1.46, 95% CI = 1.09-1.94).

CONCLUSION

This study suggested that polymorphisms of RAC1 gene might influence the susceptibility to ESRD in Chinese Han population. Further studies are necessary to confirm our findings.

XRCC1 Arg399Gln and Arg194Trp polymorphisms and risk of systemic lupus erythematosus in an Iranian population: a pilot study

Background. Evidences are suggesting that DNA damage is implicated in development of systemic lupus erythematosus (SLE). Therefore we focused on two common XRCC1 polymorphisms (Arg399Gln and Arg194Trp) in SLE susceptibility in South East of Iran. Methods. Peripheral blood DNA was extracted from 163 SLE patients and 180 healthy controls. PCR-restriction fragment length polymorphism method was used for genotyping of XRCC1 Arg399Gln and Arg194Trp polymorphisms. Results. The frequency of Arg/Gln genotype of the XRCC1 Arg399Gln polymorphism was significantly lower in SLE patients than controls. Moreover, lower frequency of Arg/Gln genotype was found in SLE patients with malar rash compared to patients without this manifestation. No association was observed between XRCC1 Arg194Trp polymorphism and increased risk of SLE in studied population. Haplotype analysis revealed no correlation between four haplotypes of XRCC1 Arg399Gln and Arg194Trp polymorphisms and SLE risk. Conclusion. These findings suggest that XRCC1 399 Arg/Gln heterozygous genotype plays a protective role in SLE susceptibility.

Interplay between DNA repair and inflammation, and the link to cancer

DNA damage and repair are linked to cancer. DNA damage that is induced endogenously or from exogenous sources has the potential to result in mutations and genomic instability if not properly repaired, eventually leading to cancer. Inflammation is also linked to cancer. Reactive oxygen and nitrogen species (RONs) produced by inflammatory cells at sites of infection can induce DNA damage. RONs can also amplify inflammatory responses, leading to increased DNA damage. Here, we focus on the links between DNA damage, repair, and inflammation, as they relate to cancer. We examine the interplay between chronic inflammation, DNA damage and repair and review recent findings in this rapidly emerging field, including the links between DNA damage and the innate immune system, and the roles of inflammation in altering the microbiome, which subsequently leads to the induction of DNA damage in the colon. Mouse models of defective DNA repair and inflammatory control are extensively reviewed, including treatment of mouse models with pathogens, which leads to DNA damage. The roles of microRNAs in regulating inflammation and DNA repair are discussed. Importantly, DNA repair and inflammation are linked in many important ways, and in some cases balance each other to maintain homeostasis. The failure to repair DNA damage or to control inflammatory responses has the potential to lead to cancer.

Oxidative stress and nucleic acid oxidation in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have high cardiovascular mortality and morbidity and a high risk for developing malignancy. Excessive oxidative stress is thought to play a major role in elevating these risks by increasing oxidative nucleic acid damage. Oxidative stress results from an imbalance between reactive oxygen/nitrogen species (RONS) production and antioxidant defense mechanisms and can cause vascular and tissue injuries as well as nucleic acid damage in CKD patients. The increased production of RONS, impaired nonenzymatic or enzymatic antioxidant defense mechanisms, and other risk factors including gene polymorphisms, uremic toxins (indoxyl sulfate), deficiency of arylesterase/paraoxonase, hyperhomocysteinemia, dialysis-associated membrane bioincompatibility, and endotoxin in patients with CKD can inhibit normal cell function by damaging cell lipids, arachidonic acid derivatives, carbohydrates, proteins, amino acids, and nucleic acids. Several clinical biomarkers and techniques have been used to detect the antioxidant status and oxidative stress/oxidative nucleic acid damage associated with long-term complications such as inflammation, atherosclerosis, amyloidosis, and malignancy in CKD patients. Antioxidant therapies have been studied to reduce the oxidative stress and nucleic acid oxidation in patients with CKD, including alpha-tocopherol, N-acetylcysteine, ascorbic acid, glutathione, folic acid, bardoxolone methyl, angiotensin-converting enzyme inhibitor, and providing better dialysis strategies. This paper provides an overview of radical production, antioxidant defence, pathogenesis and biomarkers of oxidative stress in patients with CKD, and possible antioxidant therapies.

Lack of association of angiotensin II type 1 receptor A1166C gene polymorphism with the risk of end-stage renal disease

The association between angiotensin II type 1 receptor (AT1R) A 1166C (rs5186) gene polymorphism and end-stage renal disease (ESRD) risk remains controversial. We aimed to assess the association between AT1R A1166C gene polymorphism and ESRD susceptibility by performing a meta-analysis. Eligible studies were searched according to a predefined criterion using electronic databases. Eight articles were identified for the analysis of the association between AT1R A1166C gene polymorphism and ESRD risk. A allele and AA genotype were not associated with ESRD risk in overall populations, Caucasians and Asians (overall populations: p = 0.834 and 0.832, Caucasians: p = 0.853 and 0.884, Asians: p = 0.243 and 0.982). CC and AC genotype were not associated with ESRD risk in overall populations, Caucasians and Asians (overall populations: p = 0.304 and 0.712, Caucasians: p = 0.510 and 0.987, Asians: p = 0.319 and 0.225). In conclusion, AT1R A1166C gene polymorphism may not be correlated with ESRD risk in overall populations, Caucasians and Asians. However, more studies should be performed in the future.

Association of genetic variations in X-ray repair cross-complementing group 1 and Tourette syndrome

BACKGROUND

X-ray repair cross-complementing group 1 (XRCC1) plays a central role in mammalian DNA repair process. The polymorphism rs25487 (Arg>Gln at codon 399) of this gene is common in Han Chinese population.

OBJECTIVES

The objective of this study was to analyze the association between this functional SNP of XRCC1 and Tourette syndrome (TS) in Han Taiwan Chinese population.

METHODS

Genotyping was performed by using PCR-RFLP method on 73 TS patients and 158 normal controls.

RESULTS

Our data indicated that genotype frequency of A/G polymorphism at codon 399 of the patients differed from the controls (P = 0.026, OR: 2.22, 95% CI: 1.22-4.03). The allele frequency analysis also showed significant differences with higher A allele frequency in patients (P = 0.015, OR: 1.70, 95% CI: 1.11-2.62).

CONCLUSION

Our study indicates that the functional SNP at codon 399 of XRCC1 is associated with TS development.

Lack of an association between vitamin D receptor BsmI gene polymorphism and the risk of end-stage renal disease: a meta-analysis

OBJECTIVE

To evaluate the association between vitamin D receptor (VDR) BsmI gene polymorphism and the risk of end-stage renal disease (ESRD).

METHODS

All eligible studies were included in our meta-analysis of a search of the PubMed, Embase, Cochrane and China National Knowledge Infrastructure (CNKI) databases according to predefined criteria. The fixed-effects or, in the presence of heterogeneity, random-effects models were used to calculate the pooled odds ratio (OR) and corresponding 95% confidence interval (CI).

MATERIALS

Six studies including 863 patients and 1,063 controls were recruited for the analysis of the association between the VDR BsmI gene polymorphism and the risk of ESRD.

RESULTS

The B allele/BB genotype was not associated with the ESRD risk in the overall population, Caucasians or Asians (overall population: p=0.492 and 0.382, Caucasians: p=0.765 and 0.522, Asians: p=0.607 and 0.481). The Bb/bb genotype was also not associated with the risk of ESRD in the overall population, Caucasians or Asians (overall population: p=0.556 and 0.166, Caucasians: p=0.770 and 0.965, Asians: p=0.411 and 0.098). The exclusion of any single study had little impact on the p value in the overall population. No evidence of publication bias was observed.

CONCLUSION

VDR BsmI gene polymorphism appears to not be associated with the risk of ESRD in the overall population, Caucasians or Asians. However, more studies should be performed in the future.

Association of angiotensinogen M235T gene polymorphism with end-stage renal disease risk: a meta-analysis

Association between angiotensinogen (AGT) M235T gene polymorphism and end-stage renal disease (ESRD) risk is still controversial. This meta-analysis was performed to evaluate the association of AGT M235T gene polymorphism with ESRD susceptibility. A predefined literature search and selection of eligible relevant studies were performed to collect data from electronic databases of PubMed, Embase and Cochrane Library. Sixteen literatures were identified for the analysis of association of AGT M235T gene polymorphism with ESRD risk. T allele and TT genotype were associated with ESRD susceptibility in Caucasians (T: OR = 1.13, 95 % CI: 1.02-1.25, P = 0.02; TT: OR = 1.22, 95 % CI: 1.03-1.45, P = 0.02). However, MM genotype might not play a protective role against ESRD risk in Caucasians. Furthermore, there was no a markedly positive association between AGT M235T gene polymorphism and ESRD susceptibility in overall populations, Asians and Africans. In conclusion, T allele or TT homozygote is associated with the onset of ESRD in Caucasians. However, more studies should be performed in the future.

Base excision repair gene polymorphisms are associated with inflammation in patients undergoing chronic hemodialysis

Chronic inflammation may increase the risk of mortality for patients undergoing hemodialysis, while enhanced oxidative stress and DNA oxidative damage are involved in the inflammatory response. The purpose of this study was to examine the associations between inflammation and polymorphisms in the base excision repair (BER) system, which protects against oxidative DNA damage, among hemodialysis patients. Data were analyzed from 167 hemodialysis patients and 66 healthy controls. All subjects were evaluated for the expression of inflammatory cytokines (IL-1β and IL-6) and genotyped for two BER genes, including hOGG1 c.977C>G, MUTYH c.972G>C and AluYb8MUTYH. The results showed that the hemodialysis patients had significantly higher levels of IL-1β and IL-6 than the healthy controls. In the healthy controls, no patterns of association were observed between the hOGG1 c.977C>G or MUTYH c.972G>C genotypes and IL-1β or IL-6 levels; however, patients with the MUTYH c.972G/G genotype presented higher levels of IL-1β than those with the C/C genotype. The AluYb8MUTYH genotype was strongly associated with increased IL-1β levels among controls and increased IL-1β and IL-6 levels among hemodialysis patients. Additionally, the synergetic effect of these variations of the BER genes on the levels of IL-1β and IL-6 was investigated. The combinations of the AluYb8MUTYH genotype with the hOGG1 c.977 C>G or MUTYH c.972 G>C genotypes were associated with the IL-1β and IL-6 levels in hemodialysis patients. This is the first report showing an association between BER genetic polymorphisms and the inflammatory state during hemodialysis; this association might be mediated by impaired anti-oxidant defense mechanisms.

Association of base excision repair gene polymorphisms with ESRD risk in a Chinese population

The base excision repair (BER) pathway, containing OGG1, MTH1 and MUTYH, is a major protector from oxidative DNA damage in humans, while 8-oxoguanine (8-OHdG), an index of DNA oxidation, is increased in maintenance hemodialysis (HD) patients. Four polymorphisms of BER genes, OGG1 c.977C > G (rs1052133), MTH1 c.247G > A (rs4866), MUTYH c.972G > C (rs3219489), and AluYb8MUTYH (rs10527342), were examined in 337 HD patients and 404 healthy controls. And the 8-OHdG levels in leukocyte DNA were examined in 116 HD patients. The distribution of MUTYH c.972 GG or AluYb8MUTYH differed between the two groups and was associated with a moderately increased risk for end-stage renal disease (ESRD) (P = 0.013 and 0.034, resp.). The average 8-OHdG/10⁶ dG value was significantly higher in patients with the OGG1 c.977G, MUTYH c.972G or AluYb8MUTYH alleles (P < 0.001 via ANOVA). Further analysis showed that combination of MUTYH c.972GG with OGG1 c.977GG or AluYb8MUTYH increased both the risk for ESRD and leukocyte DNA 8-OHdG levels in HD patients. Our study showed that MUTYH c.972GG, AluYb8MUTYH, and combination of OGG1 c.977GG increased the risk for ESRD development in China and suggested that DNA oxidative damage might be involved in such process.