Laryngeal cancer risk and common single nucleotide polymorphisms in nucleotide excision repair pathway genes ERCC1, ERCC2, ERCC3, ERCC4, ERCC5 and XPA

Because the molecular mechanisms underlying the development of laryngeal cancer are not well understood, we conducted a case–control study to determine the association between eight common SNPs in NER pathway genes and risk of laryngeal cancer, and the association between genetic polymorphisms and environmental factors. A 1:1 matched case–control study of 176 cases and 176 controls was conducted. Laryngeal cancer cases were more likely to smoke and drink (all P values < 0.05). Subjects with the ERCC1 rs11615 CC genotype and C allele had an increased risk of laryngeal cancer. Similarly, individuals with the ERCC5 rs17655 GG genotype and G allele had an increased risk of laryngeal cancer. Gene–gene interaction analysis showed that subjects carrying ERCC1 rs11615 C allele and XPG/ERCC5 rs17655 G allele had a greatly increased risk of breast cancer. Stratified analysis revealed that the interaction between polymorphisms of ERCC1 rs11615 and ERCC5 rs17655 and smoking on cancer risk was statistically significant, and ERCC1 rs11615 polymorphisms also had a significant interaction with drinking habit. In conclusion, our study suggests that ERCC1 rs11615 and ERCC5 rs17655 polymorphisms are associated with increased risk of laryngeal cancer, and that they confer more risk among smokers and drinkers.     

Genetic polymorphisms of xeroderma pigmentosum group D gene Asp312Asn and Lys751Gln and susceptibility to prostate cancer: A systematic review and meta-analysis

Many studies have reported the role of xeroderma pigmentosum group D (XPD) with prostate cancer risk, but the results remained controversial. To derive a more precise estimation of the relationship, a meta-analysis was performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between XPD Asp312Asn and Lys751Gln polymorphisms and prostate cancer risk. A total of 8 studies including 2620 cases and 3225 controls described Asp312Asn genotypes, among which 10 articles involving 3230 cases and 3582 controls described Lys751Gln genotypes and were also involved in this meta-analysis. When all the eligible studies were pooled into this meta-analysis, a significant association between prostate cancer risk and XPD Asp312Asn polymorphism was found. For Asp312Asn polymorphism, in the stratified analysis by ethnicity and source of controls, prostate cancer risk was observed in co-dominant, dominant and recessive models, while no evidence of any associations of XPD Lys751Gln polymorphism with prostate cancer was found in the overall or subgroup analyses. Our meta-analysis supports that the XPD Asp312Asn polymorphism contributed to the risk of prostate cancer from currently available evidence. However, a study with a larger sample size is needed to further evaluate gene–environment interaction on XPD Asp312Asn and Lys751Gln polymorphisms and prostate cancer risk.     

Association of two ERCC4 tagSNPs with susceptibility to atrophic gastritis and gastric cancer in Chinese

Genetic polymorphisms in excision repair cross-complementing group 4 (ERCC4) may contribute to the risk of cancer development. However, there are few reports regarding to susceptibility to gastric cancer (GC) or its precursor, atrophic gastritis (AG). Thereby, we investigated the association between two tag single nucleotide polymorphisms (tagSNPs) rs6498486 and rs254942, which represents the majority of common SNPs of ERCC4 gene, and the risks of GC and AG development in a sex- and age-matched case–control designed study. We found that rs6498486 polymorphism was associated with a reduced AG risk in total population (for AC vs. AA: OR = 0.69, 95%CI = 0.52–0.94, P = 0.016; for AC/CC vs. AA: OR = 0.68, 95%CI = 0.51–0.92, P = 0.010) as well as in the subpopulation of youngers (age < 60 years) (for AC/CC vs. AA: OR = 0.67, 95%CI = 0.45–0.99, P = 0.048). For the rs254942 polymorphism, compared with the common TT genotype, the genotypes of CT and CT/CC were only observed to reduce AG risk in the subgroups of males (for CT vs. TT: OR = 0.64, 95%CI = 0.45–0.90, P = 0.012; for CT/CC vs. TT: OR = 0.66, 95%CI = 0.47–0.92, P = 0.016) and youngers (for CT vs. TT: OR = 0.72, 95%CI = 0.53–0.97, P = 0.035; for CT/CC vs. TT: OR = 0.74, 95%CI = 0.55–0.99, P = 0.045). However, no significant statistical association of the two SNPs with GC susceptibility was observed in the total population. Only rs6498486 AC and AC/CC genotypes were found to be marginally associated with a reduced GC risk in the subgroup of males (for AC vs. AA: OR = 0.69, 95%CI = 0.49–0.99, P = 0.043; for AC/CC vs. AA: OR = 0.71, 95%CI = 0.50–0.99, P = 0.046). Our findings suggested that the ERCC4 rs6498486 and rs254942 may be associated with AG risk. Further validation of our results in larger populations and additional studies evaluating their molecular function are required.     

DNA repair pathway genes and lung cancer susceptibility: A meta-analysis

Objective

DNA repair pathway genes have been implicated to play an important role in the development of lung cancer. However, contradictory results are often reported by various studies, making it difficult to interpret them. So in this meta-analysis, we have assessed the association between lung cancer risk and two DNA repair pathway genes. XRCC1 and ERCC2, by analyzing 67 published case–control studies.

Research design and methods

We searched PubMed, Embase and Web of Science using terms “XRCC1” or “XPD” or “ERCC2” and “lung cancer” on August 1, 2012. Three criteria were applied to select included studies for resulting studies. Information was carefully extracted by two investigators independently. We used pooled odds ratio (OR) to assess the effect of a polymorphism, and a dominant model was applied where genotypes that contain the non-reference allele were combined together. All the calculations were performed using STATA version 11.0.

Main outcome measures and results

Three common nonsynonymous polymorphisms in XRCC1, codon 194, codon 280 and codon 399, and two common nonsynonymous polymorphisms in ERCC2, codon 312 and codon 751, were analyzed. The result showed in total population, Lys751Gln in ERCC2 is associated with an increase of lung cancer risk, with a summary OR as 1.15. No association was found for any other polymorphisms. When studies were stratified by ethnicity, the risk effect of Lys751Gln in ERCC2 was found only in Caucasians, not in Asians.

Conclusions

In conclusion, Lys751Gln in ERCC2 is associated with lung cancer, and the risk effect probably exists in Caucasians. By contrast, polymorphisms in XRCC1 are less likely to be susceptible to lung cancer risks.     

Association of single nucleotide polymorphisms of ERCC1 and XPF with colorectal cancer risk and interaction with tobacco use

We investigated the association between polymorphisms in excision repair cross-complementation group 1 (ERCC1) (rs3212986, rs2298881 and rs11615) and xeroderma pigmentosum-complementation group F (XPF) (rs2276466 and rs6498486) and risk of colorectal cancer. A 1:1 matched case–control study was conducted. Conditional regression analysis indicated that individuals carrying the ERCC1 rs3212986 TT genotype and T allele had a marginally increased risk of colorectal cancer when compared with subjects with the GG genotype. Similarly, subjects carrying the rs11615 TT genotype and T allele had a marginally increased risk of colorectal cancer when compared with those with the CC genotype. Stratified analysis revealed that individuals with rs3212986 TT who were current or former smokers had a significantly increased risk of colorectal cancer, and a significant interaction was found between this SNP and cigarette smoking. In conclusion, our study suggests that rs3212986 and rs11615 polymorphisms are associated with risk of colorectal cancer in a Chinese population, particularly in smokers. This finding could be useful in revealing the genetic characteristics of colorectal cancer, and suggests more effective strategies for prevention and treatment.     

Association between IL13 gene polymorphisms and susceptibility to cancer: A meta-analysis

Background/aims

Interleukin-13 (IL13) is an immunoregulatory cytokine which plays an important role in carcinogenesis through affecting tumor immunosurveillance. Many studies had reported the influence of IL13 rs1800925 and rs20541 polymorphisms on cancer risk, however, with inconclusive results. The aim of the present study was to conduct a meta-analysis to clarify the relationship.

Methods

Twenty studies including a total of 6713 cancer cases and 8693 controls for IL13 rs20541 polymorphism and 4081 cancer cases and 6202 controls for IL13 rs1800925 polymorphism were included in the meta-analysis. Data were extracted from these studies and odds ratios with corresponding 95% confidence intervals were computed to estimate the strength of the association.

Results

Overall, the IL13 rs20541 polymorphism were associated with significantly decreased cancer risk in all genetic models (AA vs. GG: OR = 0.82, 95%CI = 0.71–0.95; GA vs. GG: OR = 0.92, 95%CI = 0.85–0.99; GA/AA vs. GG: OR = 0.90, 95%CI = 0.85–0.97; AA vs. GG/GA: OR = 0.85, 95CI% = 0.74–0.98). In the stratified analyses, significant effects were found among European populations, studies with population-based controls and studies of glioma. No influence of the IL13 rs1800925 polymorphism on the overall cancer risk was observed. However, in the stratified analyses, we found the IL13 rs1800925 polymorphism was significantly associated with decreased risk for glioma (CT vs. TT: OR = 0.72, 95%CI = 0.55–0.93; CT/TT vs. TT: OR = 0.76, 95%CI = 0.62–0.89).

Conclusion

Our meta-analysis suggests that the IL13 rs20541 polymorphism contributes to susceptibility to cancer, especially for glioma; and the IL13 rs1800925 polymorphism may be associated with glioma risk.     

Promoter polymorphisms in trefoil factor 2 and trefoil factor 3 genes and susceptibility to gastric cancer and atrophic gastritis among Chinese population

The polymorphisms in trefoil factor (TFF) gene family that protect gastrointestinal epithelium might influence individual vulnerability to gastric cancer (GC) and atrophic gastritis. We used the Sequenom MassARRAY platform to identify the genotypes of TFF2 rs3814896 and TFF3 rs9981660 polymorphisms in 478 GC patients, 652 atrophic gastritis patients, and 724 controls. For the TFF2 rs3814896 polymorphism, in the subgroup aged ≤ 50 years, we found that AG + GG genotypes were associated with a 0.746-fold decreased risk of atrophic gastritis [p = 0.023, 95% confidence interval (CI) = 0.580–0.960], a 0.626-fold decreased risk of GC (p = 0.005, 95% CI = 0.451–0.868), and a 0.663-fold decreased risk of diffuse-type GC (p = 0.034, 95% CI = 0.452–0.970) compared with the common AA genotype. For the TFF3 rs9981660 polymorphism, in the male subgroup, individuals with variant AG + AA genotype were associated with a 0.761-fold decreased risk of diffuse-type GC compared with the common GG genotype (p = 0.043, 95% CI = 0.584–0.992). Additionally, we found that in subjects aged ≤ 50 years compared with common AA genotype, TFF2 rs3814896 AG + GG genotypes were associated with increased TFF2 mRNA levels in the total gastric cancer specimens and in the diffuse-type gastric cancer specimens; and in males aged ≤ 50 years compared with common GG genotype, TFF3 rs9981660 AA + AG genotypes were associated with TFF3 mRNA levels in diffuse-type gastric cancer tissues and their corresponding non-cancerous tissues. To our knowledge, this is the first report of an association between the TFF2 rs3814896 AG + GG genotypes and decreased risks of GC, diffuse-type GC, and atrophic gastritis in younger people aged ≤ 50 years, and an association between TFF3 rs9981660 AG + AA genotype and decreased risk of diffuse-type GC in men. Moreover, we found that TFF2 rs3814896 AG + GG genotypes in people aged ≤ 50 years and TFF3 rs9981660 AG + AA genotypes in younger males with diffuse-type GC were associated with higher levels of TFF2 and TFF3 mRNA respectively.     

Analysis of DNA repair gene polymorphisms in glioblastoma

Background

Glioblastoma is the most common and aggressive primary brain tumor in adults. Despite several factors such as ionizing radiation exposure or rare genetic syndromes have been associated with the development of glioblastoma, no underlying cause has been identified for the majority of cases. We thus aimed to investigate the role of DNA repair polymorphisms in modulating glioblastoma risk.

Methods

Genotypic and allelic frequencies of seven common polymorphisms in DNA repair genes involved in nucleotide excision repair (ERCC1 rs11615, ERCC2 rs13181, ERCC6 rs4253079), base excision repair (APEX1 rs1130409, XRCC1 rs25487), double-strand break repair (XRCC3 rs861539) and mismatch repair (MLH1 rs1800734) pathways were analyzed in 115 glioblastoma patients and 200 healthy controls. Haplotype analysis was also performed for ERCC1 rs11615 and ERCC2 rs13181 polymorphisms, located on the same chromosomal region (19q13.32).

Results

Our results indicated that carriers of the ERCC2 Gln/Gln genotype were associated with a lower glioblastoma risk (OR = 0.32, 95% CI 0.12–0.89; P = 0.028), whereas carriers of the MLH1 AA genotype were associated with an increased risk of glioblastoma (OR = 3.14, 95% CI 1.09–9.06; P = 0.034). Furthermore, the haplotype containing the C allele of ERCC2 rs13181 polymorphism and the T allele of ERCC1 rs11615 polymorphism was significantly associated with a protective effect of developing glioblastoma (OR = 0.34, 95% CI 0.16–0.71; P = 0.004).

Conclusions

These results pointed out that MLH1 rs1800734 and ERCC2 rs13181 polymorphisms might constitute glioblastoma susceptibility factors, and also suggested that the chromosomal region 19q could be important in glioblastoma pathogenesis.     

XRCC1 polymorphisms and differentiated thyroid carcinoma risk: A meta-analysis

The objective of this study is to quantitatively derive a more precise estimation of the association between X-ray repair cross-complementing group 1 (XRCC1) gene polymorphisms and differentiated thyroid carcinoma risk. A comprehensive literature search of three databases was conducted. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated with fixed-effect models and random-effect models when appropriate. Overall, no association of the XRCC1 Arg399Gln, Arg280His, and Arg194Trp polymorphisms with differentiated thyroid carcinoma risk was found. In subgroup analyses, a decreased differentiated thyroid carcinoma risk was observed among Caucasians (Gln vs. Arg, OR = 0.86, 95% CI = 0.77–0.96, P = 0.343 for heterogeneity; Gln/Arg vs. Arg/Arg, OR = 0.84, 95% CI = 0.71–0.98, P = 0.229 for heterogeneity; Gln/Gln vs. Arg/Arg, OR = 0.77, 95% CI = 0.60–0.99, P = 0.477 for heterogeneity; dominant genetic model, OR = 0.82, 95% CI = 0.71–0.95, P = 0.272 for heterogeneity), not among Asians. No publication bias was observed. Our results suggest that XRCC1 Arg399Gln polymorphism is not associated with differentiated thyroid carcinoma risk, while a decreased risk is observed among Caucasian population.     

No evidence of association between the synonymous polymorphisms in XRCC1 and ERCC2 and breast cancer susceptibility among nonsmoking Chinese

DNA repair proficiency has also been proposed as a potential susceptibility factor for breast cancer. Synonymous polymorphism roles of the DNA repair genes in relation to breast cancer remain largely unknown. Nonsmokers are a good model in which to investigate genetic susceptibility to cancer because they are at low-dose carcinogen exposure. To validate genetic biomarkers of the disease, we explored the effects of the two synonymous polymorphisms [Pro206Pro (rs915927) and Arg156Arg (rs238406)] in the DNA repair genes XRCC1 and ERCC2 at chromosome 19q13.2-3 on breast cancer susceptibility among nonsmoking Chinese. The study recruited 243 patients with breast cancer and 234 cancer-free controls matched to the cases by age (±3years), gender, nonsmoking status and ethnicity. Genotypes were determined using polymerase chain reaction-restriction fragment length polymorphism. No associations were observed between both individual single nucleotide polymorphisms or haplotypes and breast cancer susceptibility. After stratification, no effects were detected for age-dependent effects or menopause status in relation to breast cancer occurrence. No evidence of gene-gene interaction in breast cancer susceptibility was revealed. The two loci were at weak linkage disequilibrium (D' value=0.244, P=0.07). The present data suggest that XRCC1 Pro206Pro and ERCC2 Arg156Arg do not substantially influence breast cancer susceptibility among nonsmoking Chinese.     

Association of ERCC1-C118T and -C8092A polymorphisms with lung cancer risk and survival of advanced-stage non-small cell lung cancer patients receiving platinum-based chemotherapy: A pooled analysis based on 39 reports

The published data on the predictive role of ERCC1 polymorphisms in lung cancer risk and survival of patients with advanced non-small cell lung cancer (NSCLC) receiving platinum-based chemotherapy remains inconsistent. The aim of this meta-analysis was to determine the role of ERCC1 gene polymorphisms (C118T and C8092A) in this clinical situation. Eligible studies were included and assessed for quality using multiple search strategies. Thirty-nine published papers involving 9615 cases (4606 with Stage III/IV disease) and 5542 controls were included in the analysis. Pooled odds ratios (OR) or hazard ratios (HR) with 95% confidence intervals (CI) were used to estimate risk. ERCC1-C118T was associated with lung cancer risk. The OR was 0.90 (95% CI: 0.81–0.99, p = 0.043) in an additive genetic model (C allele vs. T allele) and 0.77 (95% CI: 0.63–0.95, p = 0.013) in a recessive genetic model (CC/CT vs. TT). The corresponding risk was 0.74 (95% CI: 0.58–0.94, p = 0.013) based on a homozygous comparison (CC vs. TT). No significant correlation was found for ERCC1 C8092A and there was no obvious relationship between ERCC1 C118T/C8092A polymorphisms and objective response to platinum-based chemotherapy. Overall survival (OS) of patients with non-small cell lung cancer (NSCLC) receiving platinum-based chemotherapy was significantly related to ERCC1 C118T (HR: 1.29, 95% CI: 1.07–1.56, p = 0.007, CT/TT vs. CC). There was no relationship between ERCC1 C8092A and survival (HR: 1.32, 95% CI: 0.84–2.10, p = 0.23, CA/AA vs. CC). These findings suggest that ERCC1 C118T polymorphisms may serve as a biomarker for lung cancer risk and have prognostic value in patients with advanced non-small cell lung cancer (NSCLC) undergoing platinum-based treatment. Further studies with larger numbers of subjects from a worldwide arena are needed to validate the associations.     

Poly (AT) deletion/insertion polymorphism of the XPC gene contributes to urinary system cancer susceptibility: A meta-analysis

Numerous studies have investigated the association between xeroderma pigmentosum complementation group C (XPC) poly (AT) deletion/insertion (PAT −/+) polymorphism and cancer susceptibility; however, the findings are inconsistent. Therefore, we performed a meta-analysis based on 32 publications including 10,214 cases and 11,302 controls to acquire a more robust estimation of the relationship. We searched publications from MEDLINE, EMBASE and CBM which assessed the associations between XPC PAT −/+ polymorphism and cancer risk. We calculated pooled odds ratio (OR) and 95% confidence interval (CI) by using either fixed-effects or random-effects model. We found that individuals carrying the PAT +/+ genotype have significantly increased cancer risk (PAT +/+ vs. PAT −/−: OR = 1.18, 95% CI = 1.03–1.35 and recessive model: OR = 1.19, 95% CI = 1.06–1.33). Further stratification analysis showed a significantly increased risk for prostate cancer (PAT +/+ vs. PAT −/−: OR = 2.20, 95% CI = 1.39–3.48, recessive model: OR = 2.07, 95% CI = 1.33–3.23 and PAT + vs. PAT −: OR = 1.39, 95% CI = 1.12–1.71), bladder cancer (recessive model: OR = 1.33, 95% CI = 1.03–1.72), Caucasian ethnicity (recessive model: OR = 1.21, 95% CI = 1.02–1.43), population-based studies (recessive model: OR = 1.23, 95% CI = 1.05–1.43) and studies with relatively large sample size (PAT +/+ vs. PAT −/−: OR = 1.18, 95% CI = 1.04–1.35 and recessive model: OR = 1.20, 95% CI = 1.08–1.33). Despite some limitations, this meta-analysis established solid statistical evidence for the association between the XPC PAT +/+ genotype and cancer risk, especially for urinary system cancer, but this association warrants further validation in single large studies.     

Association of XRCC1 Arg399Gln polymorphism with bladder cancer susceptibility: A meta-analysis

Genetic variations in DNA repair genes are thought to modify DNA repair capacity and may to be related to cancer susceptibility. However, epidemiological study results have been inconsistent. In this meta-analysis, we assessed 24 case–control studies of association between the X-ray repair cross complementing group 1 (XRCC1) Arg399Gln polymorphism and bladder cancer susceptibility in the general population and in Asian and non-Asian subgroups. A moderately significant association with bladder cancer risk was found for AG vs GG (OR = 1.110, 95% CI = 1.018–1.210). No significant associations with bladder cancer risk were found for AA vs GG (OR = 0.942, 95% CI = 0.823–1.077), the dominant model AA/AG vs GG (OR = 1.075, 95% CI = 0.990–1.167) and the recessive model AA vs AG/GG(OR = 0.890, 95% CI = 0.788–1.005). In subgroup analysis, a moderately significant association was also found for AG vs GG (OR = 1.091, 95% CI = 1.008–1.180) in non-Asian subgroup. The analysis suggests that the XRCC1 Arg399Gln polymorphism might be a moderate risk factor for bladder cancer, especially in non-Asian population.     

A nonsense mutation in the Xeroderma pigmentosum complementation group F (XPF) gene is associated with gastric carcinogenesis

XPF/ERCC1 endonuclease is required for DNA lesion repair. To assess effects of a C2169A nonsense mutation in XPF at position 2169 in gastric cancer tissues and cell lines, genomic DNA was extracted from blood samples of 488 cancer patients and 64 gastric tumors. The mutation was mapped using a TaqMan MGB probe. In addition, gastric cancer cell lines were transfected with mutated XPF to explore XPF/ERCC1 interaction, XPF degradation, and DNA repair by a comet assay. The C2169A mutation was not detected in 488 samples of blood genomic DNA, yet was found in 32 of 64 gastric cancer tissue samples (50.0%), resulting in a 194C-terminal amino acid loss in XPF protein and lower expression. Laser micro-dissection confirmed that this point mutation was not present in surrounding normal tissues from the same patients. The truncated form of XPF (tXPF) impaired interaction with ERCC1, was rapidly degraded via ubiquitination, and resulted in reduced DNA repair. In gastric cancers, the mutation was monoallelic, indicating that XPF is a haplo-insufficient DNA repair gene. As the C2169A mutation is closely associated with gastric carcinogenesis in the Chinese population, our findings shine light on it as a therapeutic target for early diagnosis and treatment of gastric cancer.     

Effects of polymorphisms in nucleotide excision repair genes on glioma risk in a Chinese population

We performed a case-control study to assess the relationship between six single nucleotide polymorphisms (SNPs) of xeroderma pigmentosum complementation group F (XPF) on glioma risk in a Chinese population. The six SNPs were genotyped in 330 glioma cases and 652 cancer-free controls using a 384-well plate format on the Sequenom MassARRAY platform (Sequenom, San Diego, USA). Rs1800067 did not follow the Hardy–Weinberg equilibrium in the control group, and the genotype distributions differed significantly between the two groups for SNPs rs1800067 and rs2276466. For rs1800067, the variant genotype T/T was strongly associated with an increased risk of glioma when compared with the A/A genotype (OR = 3.77, 95% CI = 2.38–6.01). Individuals with the rs1800067 G allele had a relatively high risk of glioma in a dominant model (OR = 3.47, 95% CI = 2.26–5.37). The rs2276466 G/G genotype was significantly associated with a moderate increased risk of glioma (OR = 1.82, 95% CI = 1.10–3.02) in a codominant model, and variation of rs25489 was associated with a 1.31- and 1.78-fold glioma risk in dominant and recessive models, respectively. Our study is the first to identify polymorphisms in rs1800067 and rs2276466 as correlated with glioma susceptibility.     

The XRCC1 Arg280His polymorphism contributes to cancer susceptibility: an update by meta-analysis of 53 individual studies

The X-ray repair cross-complementing group 1 (XRCC1) protein plays a central role in DNA repair pathways. Epidemiological studies have revealed the association between XRCC1 Arg280His polymorphism and cancer risk, but the results were inconsistent. We conducted this meta-analysis to assess the effect of XRCC1 Arg280His polymorphism on cancer susceptibility with accumulated data. Up to January 2012, 53 case‐control studies with 21,349 cases and 23,649 controls were available for our study. Summary odds ratios (OR) and corresponding 95% confidence intervals (CIs) for XRCC1 Arg280His polymorphism and cancer were estimated using fixed‐ or random-effects models when appropriate. Our meta-analysis identified that elevated cancer risk was statistically associated with the minor variant His allele and Arg–His/His–His genotypes both in the overall population (allele comparison, His versus Arg: OR = 1.16; 95% CI: 1.08–1.25; dominant comparison, Arg–His/His–His versus Arg–Arg: OR = 1.17; 95% CI: 1.08–1.27) and in terms of subgroup analyses by ethnicity for both Caucasians and non‐Caucasians. However, no significant result was observed in the stratified analysis by cancer type. Moreover, significantly increased cancer risk was observed in smokers. These findings indicated that XRCC1 Arg280His polymorphism may play a role in cancer development.     

Association between the XRCC3 T241M polymorphism and risk of cancer: Evidence from 157 case–control studies

The T241M polymorphism in the X-ray cross-complementing group 3 (XRCC3) had been implicated in cancer susceptibility. The previous published data on the association between XRCC3 T241M polymorphism and cancer risk remained controversial. Hence, we performed a meta-analysis to investigate the association between cancer susceptibility and XRCC3 T241M (61,861 cases and 84,584 controls from 157 studies) polymorphism in different inheritance models. We used odds ratios with 95% confidence intervals to assess the strength of the association. Overall, significantly increased cancer risk was observed in any genetic model (dominant model: odds ration [OR] = 1.07, 95% confidence interval [CI] = 1.00–1.13; recessive model: OR = 1.15, 95% CI = 1.08–1.23; additive model: OR = 1.17, 95% CI = 1.08–1.28) when all eligible studies were pooled into the meta-analysis. In further stratified and sensitivity analyses, the elevated risk remained for subgroups of bladder cancer and breast cancer, especially in Caucasians. In addition, significantly decreased lung cancer risk was also observed. In summary, this meta-analysis suggests the participation of XRCC3 T241M in the susceptibility for bladder cancer and breast cancer, especially in Caucasians, and XRCC3 T241M polymorphism is associated with decreased lung cancer risk. Moreover, our work also points out the importance of new studies for T241M association in some cancer types, such as gastric cancer, colorectal cancer, and melanoma skin cancer, where at least some of the covariates responsible for heterogeneity could be controlled, to obtain a more conclusive understanding about the function of the XRCC3 polymorphism in cancer development.     

Associations study of vitamin D receptor gene polymorphisms with diabetic microvascular complications: a meta-analysis

Background

Emerging evidence from preclinical and clinical studies has shown that vitamin D plays an important role in the pathogenesis of diabetic microvascular complications (DMI). Several potentially functional polymorphisms (ApaI, BsmI, FokI and TaqI) of vitamin D receptor (VDR) gene have been implicated in DMI risk, but individually published studies showed inconclusive results. The aim of this study was to quantitatively summarize the association between VDR polymorphisms and DMI risk.

Methods

We searched all the publications about the associations mentioned as above from PubMed and ISI database updated in December 2013. Meta-analysis of the overall odds ratios (ORs) with 95% confidence intervals (CIs) was calculated with the fixed or random effect model.

Results

Eight studies involving 2734 subjects were included. Allelic and genotypic comparisons between cases and controls were evaluated. Overall analysis suggests that no significant association was observed among the ApaI, BsmI, FokI and TaqI variants and DMI risk in diabetic patients (all P values > 0.05). In the stratified analysis, significant association was observed with diabetic nephropathy (DN) for VDR gene FokI polymorphism under a dominant model (OR 1.35, 95% CI 1.05–1.74, P = 0.02) in Caucasians.

Conclusions

This meta-analysis indicated that the FokI polymorphism in VDR gene might affect individual susceptibility to DN in Caucasians. Further investigations are needed to confirm our results.     

Association of polymorphisms in the interleukin-4 gene with response to hepatitis B vaccine and susceptibility to hepatitis B virus infection: A meta-analysis

Objective

The aim of this meta-analysis is to evaluate the associations between functional polymorphisms in the interleukin-4 (IL4) gene and individuals' responses to hepatitis B vaccine and their susceptibility to hepatitis B virus (HBV) infection.

Methods

A literature search on articles published before December 1st, 2012 was conducted in PubMed, Embase, Web of Science and China BioMedicine (CBM) databases. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Statistical analyses were performed using the STATA 12.0 software.

Results

Eight studies were eligible for inclusion in this meta-analysis, including five cross-sectional studies on individual's response to hepatitis B vaccine and three case–control studies on HBV infection risk. The meta-analysis results showed that the T allele of rs2243250, the T allele of rs2070874, and the C allele of rs2227284 in IL4 gene were associated with high responses to hepatitis B vaccine. Further subgroup analysis by ethnicity showed that there was a significant association between IL4 genetic polymorphisms and an individual's responses to hepatitis B vaccine among Asian populations, but similar association was not found among Caucasian populations. However, there was no evidence indicating a correlation between IL4 genetic polymorphism and susceptibility to HBV infection.

Conclusion

Our current meta-analysis suggests that rs2243250, rs2070874 and rs2227284 polymorphisms in IL4 gene may play an important role in determining the response to hepatitis B vaccine, especially among Asian populations. However, further studies are still needed to evaluate the associations between IL4 genetic polymorphisms and HBV infection risk.     

Matrix metalloproteinase-1 gene polymorphisms and periodontitis susceptibility: A meta-analysis based on 11 case-control studies

Matrix metalloproteinase-1 has been implicated in periodontal disease, but the association between the most-studied Matrix metalloproteinase-1 1G-to-2G polymorphism and the risk of periodontal disease were reported with inconclusive results. Therefore, the aim of this study was to investigate the association between the Matrix metalloproteinase-1 1G-to-2G polymorphism and periodontal disease. Electronic databases search yielded 11 studies with 1447 patients and 1710 control subjects evaluated the association of the polymorphisms of Matrix metalloproteinase-1 1G-to-2G and periodontitis risk were brought into this study. The association was evaluated by odds ratio (OR) and its 95% confidence interval (CI). The overall results showed that the variant genotypes were associated with a significantly increased risk of periodontitis (OR = 1.45, 95% CI = 1.02–1.26 for 2G/2G vs 1G/1G, and OR = 2.27, 95% CI = 1.22–4.23 for 2G/2G vs 1G/2G + 1G/1G). In the stratified analyses, there was a significantly increased risk for the studies of periodontitis (OR = 1.59, 95% CI = 1.15–2.21 for 2G/2G vs 1G/1G; OR = 3.48, 95% CI = 1.39–8.71 for 2G/2G vs 1G/2G + 1G/1G), which remained for the studies of Asian populations. And there was a significantly increased risk of severe periodontitis (OR = 2.15, 95% CI = 1.35–3.43 for 2G/2G vs 1G/1G; OR = 2.86, 95% CI = 1.31–2.64 for 2G/2G vs 1G/2G + 1G/1G; OR = 1.6, 95% CI = 1.12–2.39 for 1G/2G + 2G/2G vs 1G/1G; OR = 1.61, 95% CI = 1.28–2.03 for 2G allele vs 1G allele). The current study demonstrated that the Matrix metalloproteinase-1-1607 1G-to-2G polymorphism was associated with susceptibility to periodontitis, apparently, severe periodontitis.