A number of studies have been carried out to investigate the association of X-ray repair complementing defective repair in Chinese hamster cells 6 (XRCC6) polymorphisms and cancer risks, and the results remained inconsistent and inconclusive.To assess the effect of XRCC6 polymorphisms on cancer susceptibility, we conducted a meta-analysis, up to May 23rd 2014, 6267 cases with different types of tumor and 7536 controls from 20 published case–control studies. Summary odds ratios and corresponding 95% confidence intervals for XRCC6 polymorphism and cancer risk were estimated using fixed- or random-effects models when appropriate. Heterogeneity was assessed by chi-squared-based Q-statistic test, and the sources of heterogeneity were explored by subgroup analyses, logistic meta-regression analyses and Galbraith plot. Publication bias was evaluated by Begg funnel plot and Egger test. Sensitivity analyses were also performed.The rs2267437 polymorphism was associated with a significant increase in risks of overall cancers, breast cancer, renal cell carcinoma and hepatocellular carcinoma, and it could increase the cancer risk in Asian population; the rs5751129 polymorphism could increase the cancer risk in overall cancers; the rs132770 polymorphism was associated with the increased renal cell carcinoma risk; furthermore, the rs132793 polymorphism could decrease breast cancer risk and increase risks in “other cancers”.Overall, the results provided evidences that the single nucleotide polymorphisms in XRCC6 promoter region might play different roles in various cancers, indicating different cancers have different tumorigenesis mechanisms. Our studies may perhaps supplement for the disease monitoring of cancers in the future, and additional studies to determine the exact molecular mechanism might provide us with interventions to protect the susceptible subgroups. In the year of 2014, there will be 1,665,540 new cancer cases and 585,720 cancer deaths expected to occur; of these, 51.3% of the cases and 52.9% of the deaths occurred in males.3 In mammalian cells, DSB can be repaired mainly by non-homologous end joining (NHEJ) pathway, involving several DSB repair genes, such as X-ray repair complementing defective repair in Chinese hamster cells 6 (XRCC6).4 Genetic variations in NHEJ genes, such as single nucleotide polymorphism (SNP) might escape cell checkpoint surveillance, and can lead to suboptimal DNA repair, allowing DNA damage to accumulate, and finally trigger tumor initiation.7Genomic instability is one cause of carcinogenesis in human cancers, which could promote various mutations. DNA double-strand break (DSB) is the most serious type of damage, and the unpaired or incorrectly repaired DSB could lead to genomic instability.XRCC6 is a gene coding Ku70 protein. XRCC6 gene is one component of NHEJ pathway. It plays an important role in suppression of chromosomal rearrangements and maintenance of genome integrity, thus it is considered essential for genome stability and cell survival. Genetic polymorphism in the XRCC6 gene is hypothesized to have a critical role in tumorigenesis. A number of studies have been carried out to investigate the association of XRCC6 polymorphisms and cancer risks, such as breast cancer,9 lung cancer,10 hepatocellular carcinoma (HCC),12 glioma,13 and so on, however, the results are inconsistent and inconclusive. Also, several functional studies have been carried out to demonstrate the effects of XRCC6 polymorphisms on Ku70 transcriptional activity in limited types of cancers.16 The overall influence of XRCC6 polymorphisms on cancer risks is still ambiguous.XRCC6 polymorphisms and cancer19 are limited to one single polymorphism site. Systematic review of association between XRCC6 polymorphisms and cancer risk is lacking, and the role of XRCC6 in the etiology of cancer is still equivocal.Until recently, the meta-analyzes assessing the association between XRCC6 polymorphisms in Asian and European population and to investigate heterogeneity between the individual studies as well as the existence of potential publication bias. The results provided evidences that the SNPs in XRCC6 promoter region might associate with the cancer risks, while SNPs in the XRCC6 intron might not.We carried out a meta-analysis on all updated published case–control studies to estimate the overall tumor risk of XRCC6 gene polymorphisms were considered eligible. We searched the PubMed, Web of Science and Embase databases for all articles on the association between XRCC6 polymorphism and cancer risk (last search update May 23rd 2014). The following terms were used in this search: “Ku70, XRCC6 or X-ray repair complementing defective repair in Chinese hamster cells 6” and “cancer, carcinoma or tumor” and “polymorphism or polymorphisms”. Additional eligible studies on this topic were identified by a hand search of references of retrieved articles. Studies testing the association between XRCC6 gene polymorphism and cancer were included if all the following conditions were met30: the publication was a case–control study; the study provided the total number of cases and controls; the study provided available genotype frequency in case and control group, respectively; the study was published in English. The major exclusion criteria were as follows: duplicate data31; abstract, comment, review or editorial.19 Finally, 20 case–control studies including 6267 cancer cases and 7536 cancer-free controls were included in this meta-analysis, studying the association between different XRCC6 polymorphisms with various cancer risks in Asian and European population. The publication year of eligible studies ranged from 2003 to 2014. Among them, 17 studies concerning XRCC6 C1310G (rs2267437) polymorphism (case/control: 5061/6406), 7 studies concerning T-991C (rs5751129) polymorphism (case/control: 1875/3133), 9 studies concerning A-31G (rs132770) polymorphism (case/control: 4768/3517), 6 studies concerning intron 3 (rs132774) polymorphism (case/control: 1468/2738), 4 studies concerning A46922G (rs132793) polymorphism (case/control: 1824/1807), respectively. Polymorphisms of rs132778, rs12163239, and rs6519265 with only 1 concerned article were excluded.Studies dealing with the association between cancer risk and No contacts with authors were carried out. Ethical approval and informed patient consent was not required as this study was a literature review and had no direct patient contact or influence on patient care.Two investigators (Ren and Yan) independently extracted data from each study with a predefined review form, and discrepancies were resolved by consensus of all investigators. All study personnel were blinded throughout the meta-analysis. The following information was recorded for each study: the surname of first author, year of publication, cancer type, ethnicity, number of cases and controls, genotyping methods, matching variables, minor allele frequency in controls, and status of Hardy–Weinberg equilibrium (HWE).To assess the quality of each eligible case–control study, the same two investigators (Ren and Yan) worked independently to determine the adequacy of studies selection, and discrepancies resolved by discussion with all investigators. All assessors were blinded throughout the meta-analysis. The followings were assessed: the cases and control definition; the comparability of cases and controls on the basis of the design or analysis; the genotyping examinations of polymorphisms; the ascertainment methods for cases and controls; the sources of control; and HWE status of controls.Cases and controls were marched in all the 20 studies. Among them, 12 studies provided age- gender-marched controls, 5 studies provided additional factor marched controls besides age and gender, such as ethnic background, residence area, individual habits, and 3 studies provided gender-marched controls  with 95% confidence intervals (95% CI). The significance of the pooled OR was determined by Z test, with P < 0.05 considered statistically significant. We evaluated the risk using the allele model (A vs. a), the homozygous model (AA vs. aa), the heterogeneity model (Aa vs. aa), the dominant model (AA + Aa vs. aa), and the recessive model (AA vs. Aa + aa). The chi-squared-based Q-statistic test was used to assess heterogeneity. When the result of the heterogeneity test was P < 0.05, the random-effects model was used (the DerSimonian and Laird method).33 Otherwise, the fixed-effects model was selected (the Mantel–Haenszel method).34 To explore sources of heterogeneity across studies, we did subgroup analyses and logistic meta-regression analyses.35 Galbraith plot was also used to explore sources of heterogeneity when meta-regression analyses could not find the heterogeneity source.36 Subgroup analysis based on ethnicity, cancer types , source of controls , HWE status of controls (HWE consistent: P > 0.05 and HWE inconsistent: P < 0.05) was performed. Funnel plots and Egger linear regression were used to diagnose a potential publication bias.37 For the possible publication bias, trim and fill method was used to evaluate the influence to the result.38 Sensitivity analyses were performed to assess the stability of the results by excluding one study at a time. All analyses were done, using STATA software, version 10.0 . All graphs were obtained also by STATA software. All the P values were two-sided. Data from this meta-analysis are presented in accordance with the checklist proposed by the Meta-Analysis of Observational Studies in Epidemiology group.39Deviation from HWE in the control group was examined by χXRCC6 polymorphisms were included in this meta-analysis. Study characteristics are summarized in Tables Overall, 20 studies including 6267 cases and 7536 controls, concerning 5 XRCC6 C1310G (rs2267437) polymorphism, T-991C (rs5751129) polymorphism, A-31G (rs132770) polymorphism, intron 3 (rs132774) polymorphism, A46922G (rs132793) polymorphism, respectively. Among the 20 studies, 6 investigated breast cancer, 3 investigated renal cell carcinoma (RCC), 2 investigated HCC, 2 investigated lung cancer, and 1 for oral cancer, childhood leukemia, esophageal cancer, gastric cancer, bladder cancer, glioma, head and neck cancer each. There were 4 studies of European descendents, 16 studies of Asian descendents, among which 15 studies were of Chinese population. For the selection of controls, 4 studies were population-based case–control studies, while the remaining 16 were hospital-based case–control studies.The 20 articles concerned Several genotyping methods were used, including Taq-Man, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), MassARRAY. 60% (12/20) of these studies included described genotyping quality control measures, such as positive and negative controls, blindness to the case–control status, a different genotyping assay to confirm the data, and/or random repetition of a portion of samples.The G allele frequency in rs2267437 polymorphism varied widely between Asian and European ethnicities, ranging from 0.05 in an Asian population to 0.39 in a European Population. The mean frequency of G allele was 0.17 for Asian, and 0.38 for European , 1.09–1.62; recessive model (GG vs. CC/CG): OR = 1.21; 95% CI 1.00–1.47)  , HCC , and RCC . Similarly, significantly increased risks were observed in the Asian population  in rs2267437 polymorphism   . Galbraith plot was also used to detect the possible sources of heterogeneity when none of the above variables could explain the heterogeneity.There was heterogeneity among studies in overall comparisons and also subgroup analyses in 3 27), heterozygote model25, and dominant model25 by the Galbraith plot (Figure For the rs2267437 polymorphism, there was significant heterogeneity in overall comparisons of allele model, heterozygote model, and dominant model. None of the possible variables could explain the heterogeneity. The studies potentially causing between-study heterogeneity were identified in the allele model2 in all comparison models in rs5751129 polymorphism, and the “cancer type” could explain 100% of the τ2 in allele model in rs132793 polymorphism. Furthermore, the combination of “ethnicity” and “cancer type” could explain 100% of the τ2 in heterozygote and dominant model in rs132793 polymorphism.Meta-regression analysis indicated that the “source of control” could explain 100% of the τSensitivity analyses were performed by sequential removal of each eligible study to assess the influence of each individual study on the pooled OR in each comparison in the polymorphisms of rs2267437, rs5751129, and rs132793. The omission of any study made no significant difference, indicating that the results of this meta-analysis were statistically reliable (Figure Egger test reveals evidence of publication bias in rs5751129 polymorphism Figure  in allelXRCC6 polymorphisms and cancer risks based on 20 case–control studies. This is also the first time to explore the individual association between the polymorphisms of rs5751129, rs132774, rs132793, and cancer risk. The results provided evidences that the SNPs in XRCC6 promoter region might associate with the cancer risks, while SNP in the XRCC6 intron might not. In addition, the XRCC6 promoter SNPs might play different roles in various cancers, indicating that XRCC6 gene may have different roles in different cancer development, and different mechanisms promote the development of various tumors.In this study, we performed a systematic review of association between XRCC6 gene was involved in multiple cellular pathways, including NHEJ pathway of DSB repair.41 During DNA repair procedure, Ku70 acted as a scaffold to recruit the other NHEJ factors to the damage site after its bound to DNA ends.4 However, inaccurate repair could lead to cellular aberrant function, apoptosis, and chromosomal rearrangements, which promote carcinogenesis finally.42 Besides the influence of XRCC6 gene on DSB repair and genomic stability, it has some other NHEJ-independent effects. Such as the Ku70 protein in cytoplasm can prevent Bax translocate to mitochondria, and suppresses cell apoptosis.43 The defects in Ku70 may also influence cell proliferation.4415 The sequence variation in the rs2267437 may affect binding activity of the adjacent CACCC box with transcription factors, resulting in decreased Ku70 expression level, and the DSB repair activity thus was affected, finally leading to increased susceptibility to cancers.45 In our study, rs2267437 polymorphism was found to might increase the cancer risks in breast cancer, HCC and RCC, while may not function in lung cancer or some other cancers, and different ethnicities might influence the association.It has been demonstrated that the rs2267437 polymorphism could influence the expression level and stability of the Ku70 protein in breast cancer cells and RCC tissues.XRCC6 gene. This polymorphism was proved to be functional in HCC and RCC, with the normal tissues with C allele having a lower expression level of XRCC6 mRNA or protein.16 Our results indicated that rs5751129 polymorphism might play the same role in various cancers. The variation may influence the expression level or stability of XRCC6 mRNA via alternative spicing or other mechanisms. Individuals carrying C allele may exhibit heritable decreased DNA repair capacity phenotypes compared with those carrying T allele, thus they might have less protective effects on normal tissues, and increased cancer risks. However, when stratified by HWE status of controls, we found that significantly elevated risks were observed in HWE inconsistent studies, but not in HWE consistent studies. Thus there may be possibility that the presence of the C allele is in linkage disequilibrium with another mutation located outside the coding region in the XRCC6 gene, which may be important for the Ku70 expression.The rs5751129 polymorphism locates between rs132770 and rs2267437 in the promoter region of XRCC6 promoter. Our meta-analysis indicating that rs132770 polymorphism might affect RCC risk in a different way from in other cancers, the RCC pathogenesis mechanism might be distinguished from other cancers when rs132770 polymorphism involved. The results were consistent with the finding that the A allele of the rs132770 polymorphism could increase the expression levels of the Ku70 mRNA in normal tissue of RCC patients.21 Xu17 also collected 3 studies but failed to find any association. The negative results in Xu study might be due to the limited studies.The rs132770 polymorphism locates closer than rs5751129 polymorphism to the translation starting point in the XRCC6 gene, and until recently, the role of rs132793 in tumorigenesis is unclear. We hypothesized that the rs132793 polymorphism might influence breast cancer risk via some mechanisms different from other cancers. Functional studies should be carried out to explore the mechanisms involving rs132793 polymorphism in tumorigenesis in the future. The different ethnicities of the study population might influence the genetic effect of the rs132793 polymorphism on cancer susceptibility; anyhow, it seems not substantial in our study.It is interesting that the rs132793 polymorphism was found to play opposite roles in different cancers: it might decrease breast cancer risk, whereas increase cancer risk in “other cancers”, indicating that the rs132793 may play opposite roles in breast cancer contrast to other cancers. The rs132793 locates in the sequences downstream of stop code of Our results implied that rs132774 polymorphism have no association with cancer risk in Chinese population. To validate the results, more population-based studies in other populations should be carried out in the future.2 in the rs5751129 and rs132793 polymorphism, respectively. However, the combination of “ethnicities”, “source of control”, and “sample size” could explain only 17.6% of the τ2 in heterozygote model in rs2267437 polymorphism, implying that there may be other reasons accounting for the heterogeneity in the rs2267437 polymorphism. Publication bias was found in the rs5751129 polymorphism and trim and fill method could reduce the influence of publication bias in all models except recessive and homozygous model, implying that more cautions should be paid when elucidate the role of the rs5751129 polymorphism in cancer susceptibility. Anyhow, sensitivity analysis proved that the results of this meta-analysis were statistically reliable. Therefore, a methodologically preferable design, such as using population-based controls, is crucial to avoid selection bias and heterogeneity.There was heterogeneity among studies in rs2267437, rs5751129, and rs132793 polymorphisms. “Source of control” and “ethnicity”, “cancer type” might explain 100% of the τThe limitations of our meta-analysis should also be discussed. First, the non-English articles were excluded in our study, which thus may bias the results of our results. Second, some low-quality studies with deviation from HWE in the control group were included in our meta-analysis. Subgroup analysis were carried out by HWE status of controls in rs5751129 polymorphism and rs132770 polymorphism, and the opposite results were found in rs5751129 polymorphism between HWE consistent/inconsistent groups, implying that low-quality studies might influence the results in rs5751129 polymorphism. Third, the number of included studies was relatively small in some subgroups, thus the specific results should be interpreted with caution.XRCC6 SNP polymorphisms and cancer risk, supporting the existence of association between XRCC6 polymorphisms and cancer risks in different ethnicities and cancer types. The rs2267437 polymorphism was found to be associated with a significant increase in risks of overall cancers, breast cancer, RCC and HCC, and it might increase the cancer risk in Asian population. The rs5751129 polymorphism might increase the cancer risk in overall cancers, and the rs132770 polymorphism might be associated with the increased cancer risk in RCC. Furthermore, the rs132793 polymorphism could decrease breast cancer risk and increase risks in “other cancers”. However, there was no obvious association between XRCC6 polymorphisms and risks of some “other cancer”. This may be due to the limited studies included or limited sample size in “other cancers”. Therefore, more studies with large sample are required to further confirm the results in the future. Functional studies are also needed to elucidate the roles of XRCC6 promoter polymorphisms in cancer pathogenesis. Moreover, gene–environment and gene–gene interaction analyses, as well as haplotype analysis should be carried out to clarify the role of the XRCC6 genes in cancer. Our studies may perhaps supplement for the disease monitoring of cancers in the future, and additional studies to determine the exact molecular mechanism might provide us with interventions to protect the susceptible subgroups.In conclusion, this meta-analysis showed some evidence of the


Background: Associations between human leukocyte antigens (HLA) alleles and cervical cancer are largely representative of squamous cell carcinoma (SCC), the major histologic subtype. We evaluated the association between HLA class I  and class II (DRB1 and DQB1) loci and risk of cervical adenocarcinoma (ADC), a less common but aggressive histologic subtype.Methods: We pooled data from the Eastern and Western US Cervical Cancer studies, and evaluated the association between individual alleles and allele combinations and ADC . Risk estimates were calculated for 11 a priori  and 38 non a priori common alleles, as odds ratios (OR) and 95% confidence intervals (CI), adjusted for age and study. In exploratory analysis, we compared the risk associations between subgroups with HPV16 or HPV18 DNA in ADC tumor tissues in the Western US study cases and controls.Results: Three of the a priori alleles were significantly associated with decreased risk of ADC ; one was associated with increased risk [B*07:02 ]. Among alleles not previously reported, DQB1*06:04  was associated with decreased risk of ADC and remained significant after correction for multiple comparisons, and C*07:02  was associated with increased risk. We did not observe a difference by histologic subtype. ADC was most strongly associated with increased risk with B*07:02/C*07:02 alleles  and decreased risk with DRB1*13:02/DQB1*06:04 .Conclusion: Results suggest that HLA allele associations with cervical ADC are similar to those for cervical SCC. An intriguing finding was the difference in risk associated with several alleles restricted to HPV16 or HPV18-related tumors, consistent with the hypothesis that HLA recognition is HPV type-specific. Cervical cancer is the second leading cause of cancer in women world-wide, and infection with oncogenic human papillomavirus (HPV) types is required for the development of these malignancies. While HPV infections with oncogenic types are common in women, only a small subset of infected individuals develop cervical cancer for reasons not yet fully understood . There aIn addition to known HPV cofactors, it is hypothesized that host genetic factors play a significant role in susceptibility to cervical precancer and cancer. Studies in Scandinavian countries, with well-established population registries, provide evidence for familial aggregation in cervical cancer incidence  –11. ThosFurther evidence for genetic factors in cervical cancer is provided by studies that show associations with specific human leukocyte antigens (HLA) alleles –20. The As SCC constitutes the major histologic type of cervical cancers, it remains unclear if HLA associations are different between SCC and ADC. Two recent genome-wide association studies of cervical cancer have identified strong associations between cervical cancer and single nucleotide polymorphisms in 6p21.3, the same region of the HLA loci , 14, howOur objective was to investigate HLA class I and II associations with ADC using pooled data from two US case–control studies of cervical cancer.in situ or invasive cervical ADC or invasive cervical SCC between January 1986 and June 1998 or between January 2000 and December 2004. Case women were identified from the FHCRC-based cancer surveillance system (CSS), a surveillance, epidemiology, and end results (SEER) registry , and frequency matched to the cases by age (5 years strata) and area of residence. In addition, control women with a hysterectomy were excluded (n = 139). After restricting to women for whom there was testing for HLA class I and II alleles, there were a total of 468 women with ADC (ICD-O morphology codes 8140–8561), 481 women with SCC (ICD-O morphology codes 8010–8077), and 513 controls in the Western US study .We pooled data from two US case–control studies of cervical cancer, one conducted by the Fred Hutchinson Cancer Research Center (FHCRC): referred to here as the “Western US cervical cancer study” ; and theregistry . In situThe Eastern US cervical cancer study was a multi-center case–control study, conducted between July 1994 and March 1996. Cases were incident invasive primary cervical cancer identified from six medical centers  in the Eastern US. Population controls were females (women with hysterectomies were not eligible to be controls) identified through RDD, matched to the cases (2:1) on age (5 year strata), clinic, race/ethnicity, and telephone exchange. There were a total of 162 women with ADC (ICD-O morphology codes 8140–8561), 179 women with SCC (ICD-O morphology codes 8010–8077), and 262 controls in the Eastern US study .Human leukocyte antigens class I and II loci were molecularly typed with DNA extracted from buffy coat collected from each participant as previously described , 20 usinIn the Western US cervical cancer study, HPV typing was performed on tumor tissue blocks from cases using PCR–RFLP as described in detail elsewhere ; HPV DNAIn the Eastern US cervical cancer study, HPV typing was performed on cervicovaginal cells  either sn = 49 alleles). Before the data were analyzed, we searched PubMed and identified 11 “a priori” alleles that were found to be significantly associated with cervical cancer in at least two previously published peer-reviewed reports. Search terms included HLA, cervical cancer, cervical SCC, cervical ADC, and included only studies that examined high-resolution HLA associations with SCC or ADC in English. Reference lists of related articles and recent review articles were also screened for additional citations . We reasoned that the HLA associations observed to date for SCC (or without regard to histology) would also be observed for ADC.To increase homogeneity, we restricted the analytic sample to individuals of Caucasian ancestry ( >85% of the study populations). To address our primary objective of investigating HLA associations with cervical ADC, the final analytic sample comprised 630 ADC cases and 775 controls. Between the two studies, we identified 166 HLA class I and II alleles that were tested in both studies. Only alleles with >5% prevalence in controls were included in the main analyses  and 95% confidence intervals (95% CI) for the association between individual alleles  and ADC risk were estimated using unconditional logistic regression and adjusting for study, and age at diagnosis. For the 11 a priori set of alleles, we performed analyses without adjustment for multiple comparisons. To adjust for multiple comparison for the remaining 38 alleles, we adopted a parametric bootstrap procedure to estimate the distribution of the minimum p-value among the 38 tests, under the global null hypothesis  and controls available from the pooled dataset. We reasoned that this comparison would allow us to determine which, if any, allele associations are unique to ADC. This investigation was carried out using polytomous logit regression models to test the hypothesis that, for any particular allele, the strength of the association differed between ADC and SCC (test of homogeneity).We further investigated the association of our significant ADC findings among SCC cases . Because of the lack of the control participant’s HPV status at the time/age the case was infected  which is the most ideal time for HPV exposure assessment , and becLastly, the joint effects of allele combinations were examined for each of the statistically significant alleles. We constructed variables to describe unphased combinations of significant alleles across the loci. To examine the independent and combined effects of these alleles on ADC risk, we constructed a categorical variable with mutually exclusive groups of single and multiple alleles compared to a reference group. The reference group comprised participants that did not carry any of the alleles that were present in the combination of interest. Two-sided statistical tests were performed at α = 0.05 level. SAS version 9.1.3 was used for all analyses.n = 311 in situ, n = 157 invasive) and 513 controls. The Eastern US study consisted of 162  cervical ADC cases, and 262 controls .The Western US study consisted of 468 cervical ADC cases .Table S3 in Supplementary Material presents HLA alleles with frequencies of >5% among controls for alleles that were typed in both studies. Out of the 166 alleles in both studies, 49 had frequencies >5% among the controls. The allele frequencies were largely similar across the two studies, with only seven of the allele frequencies statistically significantly different between the two study populations. We therefore combined the cohorts in subsequent analyses.DRB1*13:01 = 0.61, 95% CI: 0.41–0.93; ORDRB1*13:02 = 0.49, 95% CI: 0.31–0.77; and ORDQB1*06:03 = 0.64, 95% CI: 0.42–0.95). One class I allele was associated with increased risk of ADC .Table p = 0.02), and an increased risk associations for HLA-C*07:02 , which did not retain statistical significance after adjustments for multiple comparisons (p = 0.09).Of the remaining 38 alleles examined in Table n = 660 SCC cases), and observed that the associations for these HLA alleles, were similar between the two histologic types as shown in Table We also investigated the associations that were statistically significantly associated with ADC in this analysis with risk of SCC in data from the pooled studies . None of these alleles was associated with ADC in the analysis of all HPV types combined .In exploratory analyses, we examined the association of HLA alleles stratified by the case HPV status restricted to the Western study as described in the Section “Table a priori alleles at B*07:02 and decreased ADC risk with DRB1*13:01, DRB1*13:02, and DQB1*06:03. Among new findings of this study, we identified a decreased risk of ADC with HLA class II allele DQB1*06:04, which remained significant after correction for multiple comparison. This allele has not been reported in other studies that examined HLA associations with cervical SCC or without regard to histologic type. The prevalence of DQB1*06:04 was 7.2% in the combined control population , and it was significantly correlated with DRB1*13:02 , suggesting that the inverse association we observed is likely due to linkage disequilibrium or its combination with DRB1*13:02, an allele that has been reported to be inversely associated with cervical cancer in other studies  by themselves, while in combination, they occurred in over 2% of the cases and 5% of the controls. This observation likewise indicates that the inverse association may be due to the individual alleles, the combination of alleles, or some marker in linkage with the combination of alleles.The large sample size, well-characterized population-based studies, and high-resolution molecular typing of HLA alleles are substantial strengths of this analysis. There are several limitations to be considered. The HLA genotyping was performed in two different regions of the country, and genetic background may be different. Even though we restricted to Caucasian ancestry and controlled for study in the models, we may not have eliminated residual confounding from population stratification. Furthermore, it is possible that general laboratory differences in practice and protocol could have led to the non-differential misclassification of the exposure and thus the attenuation of associations. Since both studies were restricted to those with Caucasian ancestry, there may be different allele frequencies within different geographic regions or subpopulations of the US. Even so, none of the alleles identified as being statistically significantly associated with ADC differed by study.Another limitation was that, for the Western study, not all biopsies or surgical tissues were available for HPV DNA typing of tumor tissue. While we can assume most if not all cervical cancer cases were HPV-positive for one or more carcinogenic types –31, our In summary, pooling of these two studies provided a large sample size to assess the role of HLA on the risk of ADC, and provided evidence that the HLA class I and II associations for ADC are similar to those reported for SCC. Larger studies with detailed HPV assessment coupled with high quality genetic data are needed to further evaluate the effects of HLA and cervical ADC by HPV genotype.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.http://www.frontiersin.org/Journal/10.3389/fonc.2014.00119/abstractThe Supplementary Material for this article can be found online at Click here for additional data file.


RAGE gene polymorphisms and AAA has not yet been determined. The present study was aimed at analyzing the potential association between the RAGE gene polymorphisms and AAAs. A cohort of 381 patients and 436 age-matched healthy controls were genotyped to detect the three RAGE polymorphisms  using SNaPshot. Our study demonstrated a significant difference in the genotype and allele frequencies of the RAGE G82S polymorphism between the AAA patients and the controls. Further stratification by gender and smoking status revealed that the presence of the RAGE 82S allele confers a higher risk for developing AAA in men and smokers. Moreover, AAA patients with the variant 82S allele of RAGE presented with reduced serum soluble RAGE (sRAGE) production, and this decrease was more significant in men and smokers with AAA. Our study provides preliminary evidence that the 82S allele of RAGE is a risk factor for AAA. This new piece of knowledge regarding RAGE may be clinically important for the prevention and therapy of AAAs.Accumulating evidence has suggested that receptor for advanced glycation end products (RAGE) is involved in the development and progression of human abdominal aortic aneurysms (AAAs). However, the association between Human abdominal aortic aneurysm (AAA), a major disease affecting the aorta, is the most common type of aneurysm in humans . Ruptureβ-amyloid peptide [κB), mitogen-activated protein kinase (MAPK), and protein kinase C (PKC) but also induces cytokine production and inflammatory reactions, all of which are involved in the development and progression of AAAs [ In vivo evidence also demonstrated that the inhibition of AGE signaling via targeted gene deletion of RAGE dramatically reduced the incidence of AAA in a mouse model [Receptor for advanced glycation end products (RAGE), a member of the immunoglobulin (Ig) superfamily, can interact with a broad range of ligands, including advanced glycation end products (AGEs), S100/calgranulins, high mobility group box-1 (HMGB1) protein, and  peptide . The bin of AAAs . In cont of AAAs . In vivose model . Moreovese model . These l RAGE is located in the major histocompatibility complex locus on chromosome 6p21.3, and a number of polymorphisms have been identified [ RAGE gene. The −429 T/C and −374 T/A polymorphisms have been shown to exert significant effects on the transcriptional activity [ RAGE gene have been studied for their associations with various diseases, including Crohn's disease, systemic lupus erythematosus, Alzheimer's disease, multiple sclerosis, and cardiovascular diseases [ RAGE polymorphisms and AAA has not yet been determined. In light of the significant role of RAGE in the pathogenesis of AAA, the present study aimed to investigate the association of the RAGE polymorphisms  with AAA in a case-control study of the Han Chinese population.The gene encodingentified . The thractivity , and theactivity . The fundiseases –20. HoweOur study consecutively recruited 381 patients  with AAA from the Department of Vascular Surgery at the First Affiliated Hospital of Harbin Medical University from 2004 to 2013. The AAA diagnosis was confirmed using ultrasound scanning and spiral computed tomography, which can detect a dilatation of the abdominal aorta. The AAA was defined as a focal dilation of the abdominal aorta at least 50% larger than the normal diameter. Patients with connective tissue disease, chronic renal failure, a known inflammatory or malignant disease, or familial AAAs were excluded from the study. A total of 436 age-matched control subjects  from the same geographical area  were recruited within the same period, and the aortic diameters of the control subjects were defined as a range from 19 to 22 mm.Written informed consent was obtained from each participant prior to enrollment in the study. This study was approved by the Ethics Committee of Harbin Medical University and was conducted according to the principles of the Declaration of Helsinki.Genomic DNA was isolated from whole blood samples from all of the patients and controls by TIANamp Blood DNA Kit  according to the manufacturer's instructions and stored at −20°C. RAGE gene polymorphisms −374 T/A (rs1800624), −429 T/C (rs1800625), and G82S (rs2070600) were genotyped using the SNaPshot technique. The primers used were listed in TheBlood samples were collected as soon as the diagnosis was established. The sRAGE levels in the sera were determined in duplicate using Quantikine sandwich ELISA kits  according to the manufacturer's instructions.The AAA size was determined as the greatest diameter of the infrarenal aorta using ultrasound. The maximum transverse and anteroposterior diameter of the infrarenal abdominal aorta was detected by an experienced vascular sonographer using a color Doppler ultrasound  with a 5 MHz transducer. The reproducibility of aortic measurements is regularly assessed in the vascular surgery department. An abdominal aortic aneurysm is defined as a dilation of the aorta of at least 1.5 times its normal diameter or greater than a 3 cm diameter.t-test were used to compare the variables between the two groups. The Hardy-Weinberg equilibrium (HWE) was tested using a chi-squared test to compare the observed genotype frequencies with the expected ones among the control subjects. Association between the polymorphism and the risk of AAA was evaluated using logistic regression analysis and was adjusted by age, gender, smoking, hypertension, diabetes mellitus, and dyslipidemia. The comparisons of the serum sRAGE levels among the different RAGE polymorphisms between the patients and controls were evaluated using Student's t-test for the normally distributed data or a Mann-Whitney U test for the nonparametric data. The associations of the gene polymorphisms with the aortic diameter were analyzed using a multiple linear regression model. The criterion for significance was set at P < 0.05 for all of the tests.The statistical analyses were conducted using SPSS, version 19.0 . The clinical data are expressed as the means ± standard deviation (SD) for the continuous variables and as the medians and percentage for the quantitative variables; a chi-squared test and Student's The demographic characteristics of the participants are shown in  RAGE  polymorphisms in the patients with AAA and the control individuals are shown in  RAGE polymorphisms was not found in the genotype distributions of the AAA patients and the control subjects (data not shown). The comparison of the genotype distributions between the AAA subjects and the control subjects using the χ2 test revealed that there was a statistical association (P = 0.020) between the G82S polymorphism of RAGE and the risk for AAA (P = 0.11). However, in a recessive model (82GG versus 82GS + 82SS), a significant difference was observed in the AAA group when compared with the controls . The prevalence of the RAGE 82S allele frequencies was significantly higher in the patients than in the controls . There were no statistically significant differences in the −374 T/A and −429 T/C genotypes and allele frequencies between the AAA cases and the control subjects . When the sample was stratified according to smoking status, an increased risk associated with the variant genotypes and allele frequencies was more significant in the patients with AAA compared with the controls . However, when the sample was stratified by either age, diabetes, or hypertension, no significant differences in the genotype or allele frequencies were detected between the AAA cases and the controls (P > 0.05) (The associations between the > 0.05) .P = 0.035)  (P = 0.036) and the smoking patients  with the variant genotypes (82GG and 82GS)  . Moreove= 0.025) . However Figures . RAGE G82S polymorphism with the AAA aortic diameter were explored, and the results are shown in P > 0.05) (P = 0.044) (P > 0.05) (The associations of the > 0.05) . Interes= 0.044) . However > 0.05) . RAGE is associated with AAA. Further stratification revealed that men or smokers with the RAGE 82S allele may run a higher risk of acquiring AAA. Additionally, the serum sRAGE levels were significantly lower in AAA patients with the variant 82S allele than those carrying the major 82GG genotype.In this hospital-based, case-control study, we demonstrated for the first time that the G82S polymorphism ofκB, which is known to be a redox-sensitive transcription factor [κB signaling, which then triggers the release of inflammatory factors, cytokines, and chemokines, thereby contributing to the development and progression of AAA [ In vivo evidence also indicated that RAGE knockout mice are resistant to the formation of aneurysms [ RAGE alleles that contribute to the pathology of AAA remain undiscovered.As an inflammatory disease, the most significant pathologic feature of human AAA is the infiltration of inflammatory cells, including macrophages, monocytes, lymphocytes, and plasma cells, primarily to the outer part of the aorta . Previoun factor . On the n of AAA . Previoun of AAA . In vivoneurysms , suggest RAGE G82S polymorphism is associated with the risk of developing AAA. Our present findings imply that the G82S polymorphism of RAGE may serve as a genetic marker for predicting AAA in high-risk populations.Several large genome-wide association (GWAS) studies have been performed –26; howe RAGE G82S genotype and allele frequency were further stratified by age, gender, smoking status, diabetes, and hypertension, an increased risk was found in the male and smoking subgroups of the AAA patients compared to the controls. Therefore, it is highly speculated that environmental risk factors, gender, and smoking may have interplay with the RAGE genetic predisposition in the present study.The pathogenesis of AAA is the result of interactions between genetic predispositions and environmental factors. Epidemiological surveys demonstrated that the male sex is a risk factor for AAA, and males run a four- to five-time greater risk than females . Estroge RAGE results in glycine being changed to serine at position 82 of the third exon encoding the RAGE protein and has been shown to be associated with both reduced serum levels of sRAGE and increased sRAGE signaling compared with the more common G allele [κB, both of which have been implicated in the inflammatory response in AAA [ RAGE G82S S allele expressed lower sRAGE levels when compared with populations that carry the 82GG genotype. Given the key role of sRAGE in neutralizing circulating proinflammatory RAGE ligands, it is conceivable that the individuals with the 82S allele expressing reduced serum sRAGE levels may result in an increase in the amount of ligands, which may cause the subsequent cellular responses. Therefore, the individuals with the RAGE 82S allele will be more susceptible to RAGE ligand-induced inflammatory responses, which is a leading cause of AAA formation.The soluble form of RAGE (sRAGE) is a C-truncated secretory isoform of the receptor protein, which could work as a decoy receptor to abrogate RAGE signaling via inhibiting the binding of RAGE to its ligands. Therefore, the release of sRAGE may influence the regulation of RAGE-mediated functions in inflammatory events. The G82S polymorphism ofG allele , 29, 30.e in AAA . In the  apoE−/− mice [ RAGE G82S polymorphism and the AAA diameter in smoking patients. Smoking as an environmental risk factor for AAA is very convincing and has been known for decades [ RAGE) may work synergistically in the pathophysiology of AAA expansion.Accumulating epidemiological evidence confirmed that smoking is a significant contributing factor for AAA . Current−/− mice . These l decades . A study decades . Additio decades . Based o Chlamydia pneumoniae infection and immune responses, which have been suggested to play a pivotal role in the pathogenesis of AAA, may have complicated the association between the RAGE polymorphisms and AAA. Finally, other functional polymorphisms located in the major histocompatibility complex locus may also affect the expression of sRAGE and contribute to the AAA risk, and their combined effects should not be neglected for predicting the occurrence, severity, and outcome of AAA. Larger patient and control cohorts from different ethnic backgrounds will be needed to confirm the association of the RAGE gene polymorphism with AAA in other populations.Despite the evidence, our study has several limitations that should be accounted for when interpreting the results. First, the study sample was not sufficiently large, which may lead to nonrepresentative results. Therefore, the preliminary findings of the present study are not definitive and must be replicated in a larger population. Second, selection bias in the patient or control populations cannot be entirely excluded. Additionally, the information regarding the important risk factors of AAA, such as smoking, was gathered from a self-reporting questionnaire, which may also introduce information bias. Third, other risk factors in the study group, such as RAGE G82S polymorphism and the risk of developing AAA. Our findings support the notion that the G82S polymorphism of RAGE contributes to the development of AAA. In particular, males or smokers carrying the 82S allele of RAGE, which is associated with decreased sRAGE levels, may run a higher risk of developing AAA. Our study may provide clues for use in the evaluation of individual susceptibility to AAA and to explore effective measures for the control and prevention of AAA. However, this is a preliminary study, and the results need to be confirmed in a larger cohort.In conclusion, our study is the first to show a significant association between the


The purpose of the study was to investigate the association between depression and/or depressive symptoms during pregnancy and the risk of an operative delivery or preeclampsia, and to quantify the strength of the association.A search of the PubMed, SCI/SSCI, Proquest PsycARTICLES and CINAHL databases was supplemented by manual searches of bibliographies of key retrieved articles and review articles. We aimed to include case control or cohort studies that reported data on antenatal depression and /or depressive symptoms and the risk of an operative delivery and/or preeclampsia.Twelve studies with self-reported screening instruments were eligible for inclusion with a total of 8400 participants. Seven articles that contained 4421 total participants reported the risk for an operative delivery, and five articles that contained 3979 total participants reported the risk for preeclampsia. The pooled analyses showed that both operative delivery and preeclampsia had a statistically significant association with antenatal depressive symptoms . When the pre-pregnancy body mass indices were controlled in their initial design, the risk for preeclampsia still existed , while the risk for an operative delivery became uncertain .Antenatal depressive symptoms are associated with a moderately increased risk of an operative delivery and preeclampsia. An abnormal pre-pregnancy body mass index may modify this association. Some evidence indicated that depression and/or depressive symptoms during pregnancy were significantly related to an operative delivery , 10, 18 The databases of PubMed, SCI/SSCI, Proquest PsycARTICLES and CINAHL were independently searched from their start date to September 2013 by the first author (Rong Hu) and the second author (Yingxue Li). The keywords that were utilized include the following: ①depression or depressive symptoms or mood disorder; ②pregnancy or pregnant or maternal or prenatal or antenatal or pre-partum or ante-partum; ③preeclampsia or PE or preeclamptic or EPH toxemia or EPH complex, or EPH gestosis or gestational hypertension or GH or pregnancy-induced hypertension or PIH or pregnancy toxemia or complications of pregnancy; and ①operative delivery or surgical delivery or cesarean delivery or instrumentally assisted delivery or forceps assisted delivery or vacuum assisted delivery. Each broad item that is listed above (①②③④) was combined with “AND” or “OR”  AND ① AND ②), and a similar strategy was used in all of the databases.Inclusion criteria included the following: 1) case-control or cohort designs; 2) an examination of the impact of depression and/or depressive symptoms during pregnancy on the incidence of an operative delivery and/or PE; 3) measurement of maternal depression and/or depressive symptoms during pregnancy; 4) available raw data, regardless of whether they were traced directly from the article, obtained from secondary data in the article or obtained from the authors. Studies were excluded if 1) they did not meet one of the inclusion criteria listed above; 2) antenatal depression measurement was pooled with other variables, such as anxiety, stress or mood disorders, or PE measurement was pooled with hypertensive syndromes; or 3) they were existing reviews, meta-analyses or hypothesis articles.Articles were first selected through a title and abstract scanning, and then by a full-text review, according to the inclusion and exclusion criteria described above. A manual search of bibliographies of the key retrieved articles and review articles was performed to identify possible omissions.The primary data of the included articles, as well as the quality assessment of those articles, were reviewed and extracted by the first and second author independently . Extracted data included the source of the article, study design, country, SES, sample size, number of participants in the study group and the control group, method of depression measurement, results, and maternal age. In the studies that provided more than one category of depression or depressive symptoms , the latter three categories of depression or depressive symptoms were combined to provide an effect estimate that could be compared with the minimal scale (which was regarded as the reference group in studies that did not have a category for “not depressed”), on the premise that the categories were mutually exclusive. If the categories were not mutually exclusive, the severe category would be compared to the minimal category. The request for primary data was sent to the two authors, and one reply was received . The artThe first and second authors  independently performed the quality assessment of the case control or cohort studies using the Newcastle-Ottawa Scale, which uses a “star system” (with the highest score being nine stars) to judge the articles based on three broad perspectives: study group selection, comparability of the groups, and the ascertainment of the exposure or outcome of interest .All of the reviewing processes were planned, conducted, and reported under the guidance of the standards of quality for reporting meta-analyses  .The association between depression and/or depressive symptoms during pregnancy and the risk for PE and an operative delivery that includes a cesarean section and an instrumentally assisted delivery was calculated by pooled odds ratios(OR) or pooled relative risk(RR), along with 95% confidential intervals, based on the study design of the included articles. Pooled OR was the exclusive effect size that could be used for combining case control studies while pooled RR provided the best estimates for combining cohort studies . When th2-based Q-test and I2 metric [2 was larger than 50%, it comparatively indicated a severe heterogeneity among the included studies. When PQ < 0.10, the heterogeneity was considered to be significant; and a random-effects model (inverse variance weighting method) was used. Otherwise, a fixed-effects model (Mantel-Haenszel method) was preferred for the meta-analysis. Sources of heterogeneity were, respectively, traced and evaluated through a meta-regression  and subgroup analyses for both of the outcomes, which included study type, SES of the participants, adjusting for pre-pregnancy BMI and the use of a reliable depression measurement, and antidepressant use.Inconsistency or heterogeneity across studies was quantified using the χ2 metric . When thA funnel plot was constructed and Begg’s test was performed to assess possible publication bias. P < 0.05 was considered predictive of a statistically significant publication bias. All of the statistical analyses were performed using Stata, version 12.0 .According to the search strategy, 3299 records were reviewed based on the titles and abstracts after 1241 duplicates were removed. Regarding the screened records, 3234 were excluded due to there being no report on the risk of an operative delivery and PE that was imposed by maternal depression and/or depressive symptoms during pregnancy. In total, 65 studies were preliminarily identified and were further assessed for eligibility through a full-text review. After a full text review, 12 studies were found to meet the inclusion criteria and 53 studies were excluded for different reasons. The detailed review process is shown in Q = 0.004 and I2 = 68.9%), and the corresponding forest plot can be seen in The detailed statistical results are presented in Q = 0.043, I2 = 56.5%, and PQ = 0.043, I2 = 56.5%, respectively). The pooled RR for the SES group subanalysis was significant for the mixed and unspecified SES group, which included 6 of the 7 articles , and heterogeneity was also found . Subgroup analyses for the study design were not performed because all of the 7 studies were cohort studies. In the subanalyses that were grouped by the use of reliable depression measures, a significant association with decreased heterogeneity was found in the “yes” group .We conducted a univariate regression model for each possible source of heterogeneity, and no significant source of heterogeneity was found . Further2 = 15.6%).The detailed statistical results are presented in Q = 0.099, I2 = 63.3%), whereas a significant association with less heterogeneity was found in the group with a reliable depression measurement . In the subanalyses that were based on whether adjustments were made for pre-pregnancy BMI (yes/no), a stronger association with less heterogeneity was found in the “no” group , but the association still existed in the “yes” group .We conducted a univariate regression model for each possible source of heterogeneity, and no significant source of heterogeneity was found . FurtherNo evidence of publication bias was found when a review of the funnel plots and Begg’s test was conducted.By conducting the meta-analyses, we found that the association between antenatal depressive symptoms and the risk of an operative delivery and PE was both moderate and statistically significant. Women with an elevated level of depressive symptoms were one to two times more likely to have an operative delivery or be afflicted with PE. Our results were consistent with the results of a large hospital-based study that was performed by Bansil et al. in 2010, in which the International Classification of Diseases, Ninth Revision, Clinical Modifications was used to diagnose depression, and statistically significant associations were found between depression among pregnant women and the risk for a cesarean section or preeclampsia . Our simIn subanalyses, the risk for both an operative delivery and PE in pregnancies that are complicated by depressive symptoms was higher among studies that did not adjust for pre-pregnancy BMI at their initial design, which suggests that pre-pregnancy BMI , maIn summary, our meta-analyses reveal that antenatal depressive symptoms are risk factors for an operative delivery and also for PE. Controlling for pre-pregnancy BMI and antidepressant use in studies that examine these associations appears to reduce the measured risk for an operative delivery and PE. An obstetrically validated depression measurement scale would more accurately detect depressive pregnant women. Compared to depressive pregnant women in the low SES group, the risk of operative delivery and PE was comparatively higher for those in the middle/unspecified SES group.Although the exact psychopathophysiology that is behind the results of the associations with an operative delivery and PE has not been elucidated, we propose several possibilities. Regarding the link between depressive symptoms during pregnancy and an operative delivery, the evidence is scarce. One possibility that is proposed by Chung is that depression may impair uterine contractility, similar to the effects of anxiety, which may result in the increased risk of an operative delivery . We propTo the best of our knowledge, this is the first meta-analysis to investigate the association between maternal depressive symptoms during pregnancy and the risk of an operative delivery, for which we found a moderate and statistically significant association, which suggests the importance of detecting and preventing depression in pregnant women. Although the association between antenatal depressive symptoms and PE was not first investigated in our meta-analysis, new studies were added to extend the previous meta-analysis in this respect, and a statistically significant association was found, which suggests that further biomedical research may be required on the causal pathway for PE. Lastly, a rigorous quality assessment procedure was applied in the appraisal of the included studies which sheds light on the mediating effect of the measurement of BMI and antidepressant use, and on the effect of the use of reliable depression measurement tools.Our meta-analysis has several limitations. Firstly, the number of included studies was relatively small, and the studies had relatively small sample sizes. Consequently, the heterogeneity across studies was prone to being incorrectly estimated as zero because the test for heterogeneity was poor at detecting true heterogeneity among studies with statistical significance . Next, tConsidering the limitations that were discussed above, additional epidemiological studies are needed to obtain a more robust estimation and a better understanding of the role of depression in operative deliveries and PE. If available, larger multi-center studies that include multiracial groups with low antidepressant exposure may be essential to confirm the independent risk of antenatal depression. This would allow for more evidence-based decisions to be made to balance the number of pregnant women who are treated for depression and the number not treated for depression. Additionally, it may be necessary to differentiate between the women’s preference for cesarean sections and obstetricians’ preference for performing a cesarean section in future research so that different populations could be targeted when endeavoring to reduce the events of cesarean sections in the clinic. Further observations are needed to confirm the impact of SES. Clinicians and health policy decision makers should take antenatal depression into account during the process of antenatal health care by using an initial screening for depressive symptoms and timely and appropriate interventions for detected depressive symptoms in pregnant women to prevent severe complications.S1 PRISMA Checklist(DOC)Click here for additional data file.


Supplemental Digital Content is available in the text CAT gene polymorphisms and the risk of hepatocellular carcinoma (HCC).Reactive oxygen species (ROS) play critical roles in hepatocarcinogenesis. The catalase (CAT) enzyme is involved in the repair of ROS. Therefore, we investigate the association between A total of 715 subjects were divided into 4 groups: 111 chronic hepatitis B (CHB) patients, 90 hepatitis B virus (HBV)-related liver cirrhosis (LC) patients, 266 HBV-HCC patients, and 248 healthy controls. The polymerase chain reaction-restriction fragment length polymorphism strategy was used to detect CAT gene rs1001179, rs769217, and rs7943316 polymorphisms.P = 0.029), 1.48 , and 1.51 , respectively. Similarly, those individuals carrying the rs769217 TT genotype had a moderately increased risk of CHB, LC, and HCC, with adjusted ORs of 2.11 , 2.00 , and 1.93 , respectively. Moreover, subjects carrying the rs769217 CT genotype and at least 1 copy of the T allele (dominant model) were 1.78 times and 1.83 times more likely to develop HCC, respectively . This association between CAT rs769217 T alleles and HCC risk is significantly strengthened among men, nonsmokers, nondrinkers, and among individuals <50 years of age. Furthermore, we found 1 high-risk haplotype GTA for CHB  and 1 protective haplotype GCA for HCC risk . We did not found any significant difference in CAT rs1001179 and rs7943316 polymorphisms between controls and cases.Binary logistic regression analyses adjusting for sex, age, ethnicity, smoking and alcohol consumption, and body mass index suggested that subjects carrying the rs769217 T allele were at marginally increased risk of CHB, LC, and HCC, with adjusted odds ratios (ORs) of 1.51 (95% confidence interval [CI] = 1.04–2.20, Our findings suggest that the CAT rs769217 T allele is associated with increased risk of CHB, HBV-LC, and HBV-HCC in Guangxi population. Currently, the well-recognized risk factors for HCC include chronic viral hepatitis, smoking, alcohol consumption, aflatoxin exposure, and liver cirrhosis.5 However, only a fraction of people with established risk factors eventually develop HCC, suggesting that other genetic and environmental mediators may be involved in HCC development.Hepatocellular carcinoma (HCC) is one of the most frequently occurring cancers and a leading cause of cancer-related deaths worldwide.7 Oxidative stress can cause an imbalanced antioxidant defense system or excessive reactive oxygen species (ROS) production.8 ROS can cause severe DNA damage.9 Catalase (CAT) is an endogenous antioxidant enzyme involved in ROS neutralizing pathways that in turn are involved in mechanisms against oxidative stress.10 CAT can catalyze the conversion of hydrogen peroxide (H2O2) (a type of ROS), to water (H2O) and oxygen (O2), thereby preventing cell injury from ROS.10 Allelic variants in the antioxidant genes coding for CAT enzymes may have deleterious effects on the expression or function of CAT, which may result in lower CAT enzymatic activity and higher sensitivity to ROS.11 Therefore, genetic variations in CAT may alter ROS detoxification and increase oxidative stress, implicating oxidative DNA damage and modulating disease risk.11It has been suggested that oxidative stress plays a critical role in the initiation and progression of hepatocarcinogenesis.CAT gene, encoded by the nuclear chromosome 11p13, consists of 13 exons and 12 introns.12 A series of single-nucleotide polymorphisms (SNPs) in the CAT gene have been identified.14 Genetic polymorphisms located in the promoter region could influence rates of transcription, resulting in low CAT activity.15 The most studied mutation is the rs1001179 SNP, which is located in the 5′-UTR, the 262 base pairs from the transcription start site of the CAT gene.16 The variant A allele of the CAT rs1001179 polymorphism was associated with lower CAT enzyme activity compared with the G allele, and thus increased levels of ROS.16 Besides this SNP, rs769217 was a T/C silent substitution in CAT codon 389 of exon 9. Although it is a silent substitution, it contains hidden changes that constitute informative gene markers for the CAT gene.17 Another common polymorphism in the promoter region of the CAT gene consists of A to T at exon 2, codon 21.18 CAT rs7943316, which is situated inside the promoter region just proximal to the start site, may influence the gene expression by its position close to the start codon or linkage to the interest areas of the promoter where transcription factors are tied up.19The human 20 cervical cancer,21 prostate cancer,22 pancreatic cancer,23 and colorectal cancer24 in various races. Three studies to date have examined the influence of CAT polymorphism on the risk of HCC.26 One study, assessing 96 Moroccan patients with HCC, reported that male patients carrying the CAT rs1001179 TT genotype had a significantly higher risk of developing HCC compared with controls .26 One study, assessing 190 French patients with HCC, found no overall association with risk.25 Another study, assessing 106 Korean patients with HCC, also found nonsignificant association between CAT gene polymorphisms and HCC risk.27 However, the sample sizes of these 3 studies were very limited, and only 1 SNP (rs1001179 or rs7943316) of the CAT gene was investigated. In addition, the genotype distributions of the CAT polymorphisms vary with ethnicity, and until now no study has been carried out on the association between the CAT polymorphisms and HCC risk in the Chinese population. Therefore, we further evaluate the association between these 3 widely studied CAT gene polymorphisms  and the risk of hepatitis B virus (HBV)-related HCC in addition to chronic hepatitis B (CHB) and HBV-liver cirrhosis (LC) in the Guangxi Chinese population.Several research have investigated the association between the CAT SNPs rs1001179, rs769217, and rs7943316 polymorphisms and the risk of various cancers such as breast cancer,This was a retrospective, case–control study approved by the ethics committee of the First Affiliated Hospital of Guangxi Medical University, Guangxi, China. All of the involved patients and all healthy volunteers provided written informed consent. The cases were consecutively recruited from the patients who were evaluated and treated at the First Affiliated Hospital of Guangxi Medical University from April through October of 2014.30 Patients were all confirmed to have had a history of HBV infection for at least 6 months. CHB was defined as serum HBV-DNA levels of ≥1000 copies/mL and elevated alanine aminotransferase (ALT) or aspartate aminotransferase (AST) (>40 IU/mL). A total of 111 patients with CHB fulfilled the selection criteria and were successfully genotyped. HBV-LC was diagnosed based on the combination of clinical history, pathologic examination, imaging and laboratory data, and/or histology. At last, 90 HBV-LC fulfilled the selection criteria and were successfully genotyped. HBV-HCC was diagnosed based on either histological or cytological findings or on elevated serum alpha fetoprotein (AFP) levels (>400 ng/mL) combined with at least 1 positive liver image on computed tomography, magnetic resonance imaging, or ultrasonography. In our study, 266 HCC cases fulfilled the selection criteria and were successfully genotyped.The inclusion criteria are listed further and were also described in detail previously.Patients were excluded if they had any of the following conditions: other concomitant causes of liver disease or mixed etiologies ; had a family history of HCC or other concomitant malignant neoplasias; or had a history of autoimmune or inflammatory diseases such as systemic lupus erythematosus, diabetes mellitus, rheumatoid arthritis, or inflammatory bowel disease.Controls who were negative for HBV markers and without any clinical evidence of hepatic disease or tumor were randomly recruited from a pool of healthy volunteers who visited the general health check-up centers at the same hospitals during the same time frame. In this study, 248 healthy controls fulfilled the selection criteria and were successfully genotyped.Demographic and laboratory data were obtained using electronic medical records. Age, sex, history of smoking and alcohol use, ethnicity, and body mass index (BMI) were analyzed. Separated serum samples were tested for HBV and HCV markers, AFP levels, serum total bilirubin (TBIL), total protein (TP), albumin (ALB), gamma glutamyl transpeptidase (GGT), AST, and ALT. An alcohol drinker was defined as someone who consumed alcoholic beverages at least once per week for more than 6 months. Subjects were considered tobacco smokers if they smoked up to 1 year before the date of diagnosis for cases, or up to the date of interview for controls.http://www.ncbi.nlm.nih.gov/snp/), and estimated OR was 2.0. The inheritance model was recessive. Approximately 1 to 1 control–case ratio was chosen. According to the parameters mentioned earlier, the estimated 157 sample size had enough power to assess the risk of the CAT genetic variation on HCC development.We estimated the sample size using Quanto software (version 1.2.4) based on probability of α = 0.05 and β = 0.1 and assuming that the prevalence of the rs769217 CC genotype in the control group was 20.9%  were collected from all of the subjects in ethylenediaminetetraacetic acid-coated vials and stored at −20°C until DNA extraction. Genomic DNA was isolated from peripheral leukocytes using the phenol-chloroform extraction method. The blood samples were submitted to digestion in sodium dodecyl sulfonate, followed by phenol extraction twice and chloroform extraction once. DNA was then ethanol-precipitated and resuspended in buffer solution DNA concentration was determined spectrophotometrically.SmaI, BstXI, or HinfI restriction enzymes, respectively. The primers used for amplification and the cycling conditions are listed in Table Genotyping of CAT SNPs rs1001179, rs769217, and rs7943316 was performed by polymerase chain reaction (PCR) restriction fragment length polymorphism. The PCR was carried out in a final volume of 25 μL, consisting of 2 μL of genomic DNA, 1 μL of each primer, 12.5 μL of Green PCR Master Mix , and 8.5 μL of nuclease-free water. For rs1001179, rs769217, and rs7943316, 10 μL aliquots of the PCR products were digested in 1 μL of Digested fragments were separated by electrophoresis in 2% agarose gel containing GoldView I  and the fragments were visualized by the UV transilluminator Figure . To contIn addition, a total of 70 specimens (about 10%) were randomly selected and genotyped by DNA sequencing with an ABI Prism 3100 . The results of DNA sequencing were 100% concordant.2 test for continuous and categorical variables, respectively. Agreement with Hardy–Weinberg equilibrium (HWE) for each SNP was tested using a goodness-of-fit χ2 test. Genotype frequencies were compared among different groups using the χ2 test and Fisher exact test when appropriate. The haplotype analyses were performed using SHEsis software .31 A binary logistic regression model was used to obtain the estimated ORs and 95% confidence intervals (CIs) after adjusting for potential confounding variables such as sex, age, ethnicity, smoking and alcohol consumption, and BMI. To investigate the effect of other potential confounding variables on the association between CAT genetic variants and HCC risk, we also stratified our population according to sex, age, history of smoking, and alcohol consumption. A 2-tailed P value of <0.05 was considered statistically significant. All of the statistical analyses were performed in SPSS version 13.0 software .The distribution of the general demographic and clinical features between cases and controls was evaluated by using the 1-way analysis of variance test and the χP < 0.001), smoke more tobacco (P = 0.036), and drink more alcohol (P < 0.001). The values of AFP, TBIL, AST, and ALT were significantly higher in HBV-infected patients than in control subjects (P < 0.001). There were no significant differences for ethnicity, BMI, TP, ALB, and GGT between these 4 groups.The demographic and clinical characteristics of the controls and cases are shown in Table P = 0.684), rs7943316 (P = 0.263), and rs769217 (P = 0.052) were found to be in HWE in the control group.The allele and genotype distributions of CAT rs1001179, rs769217, and rs7943316 among the case and controls are presented in Table Logistic regression analysis for the CAT rs1001179 polymorphism  revealed no differences in allele and genotype distribution frequencies between cases and controls. The CAT rs1001179 polymorphisms were not associated with CHB, LC, and HCC risk in any analytic models. Similarly, logistic regression analyses did not reveal any significant difference in CAT rs7943316 polymorphisms between controls and cases (Table P = 0.029), 1.48 , and 1.51 , respectively. Similarly, those individuals carrying the rs769217 TT genotype had a moderately increased risk of CHB, LC, and HCC relative to the CC genotype, with adjusted ORs of 2.11 , 2.00 , and 1.93 , respectively. Moreover, subjects carrying the rs769217 CT genotype and at least 1 copy of the T allele (dominant model) were 1.78 times and 1.83 times more likely to develop HCC, respectively  .31 to evaluate the haplotype frequencies of polymorphisms located nearby at the same chromosome regions. The CAT rs1001179, rs769217, and rs7943316 haplotype frequencies are represented in Table P = 0.025) and HCC  risk. In contrast, we found 1 protective haplotype for HCC risk: GCA .We further performed the haplotype analysis using SHEsis softwareCAT genetic variants and HCC risk, we stratified our population according to sex, age, history of smoking, and alcohol consumption.To investigate the effect of other potential confounding variables on the association between P = 0.019; TT vs CC genotype: OR = 2.05, 95% CI = 1.12–3.76, P = 0.020; dominant model: OR = 1.85, 95% CI = 1.19–2.89, P = 0.007). No differences were observed in the genotype distributions of CAT rs1001179 and rs7943316 or in female subjects .When we stratified our population by sex, we found that male subjects carrying the rs769217 CT, TT, and the combined CT+TT genotypes were at increased risk of HCC .The stratification of our population by age indicated that younger (<50 years) subjects carrying the rs769217 TT genotype and at least 1 copy of the T allele (dominant model) had a significantly increased risk of HCC relative to the CC genotype, with adjusted ORs of 2.19 (95% CI = 1.05–4.58) and 1.88 (95% CI = 1.08–3.28), respectively  .Next, we investigated the effect of tobacco smoking on the association between CAT polymorphism and HCC risk. Patients with no history of smoking and with the rs769217 CT genotype and at least 1 copy of the T allele (dominant model) were 1.79 times and 1.76 times more likely to develop HCC compared with those carrying the CC genotype  .The stratification related to alcohol consumption indicated that patients with no history of alcohol consumption and who carried the rs769217 CT, TT, and the combined CT+TT genotypes had increased risk of HCC  were correlated with a significant increased HCC risk when compared with the CC homozygote. Moreover, we found 1 high-risk haplotype (GTA) for CHB  and HCC  and 1 protective haplotype (GCA) for HCC . The stratification analysis by different potential confounding variables demonstrated that the CAT rs769217 T allele enhances the HCC risk among men, younger patients, patients who do not smoke, and patients who do not consume alcohol. No significant difference was found in the distribution of genotypes and allele frequencies between cases and healthy controls for CAT rs1001179 and rs7943316 polymorphisms.The current study assessed the influence of 3 common SNPs polymorphisms in the 7 CAT, which is an endogenous antioxidant enzyme, can catalyze H2O2 to O2 and H2O, thus preventing cell injury from ROS.10 Therefore, CAT plays a significant role in protecting cells against severe oxidative stress. The functions of CAT derive from the polymorphisms of the CAT gene. Genetic variations in the CAT enzyme may modulate disease risk.11 Several studies have suggested that CAT polymorphisms might be associated with a risk of various cancers such as breast cancer,20 cervical cancer,21 prostate cancer,22 pancreatic cancer,23 and colorectal cancer.24Associations between oxidative stress and hepatocarcinogenesis have generally been investigated.26 The first association between CAT polymorphisms and HCC risk was reported by Lee et al in 2002.27 They included 106 patients with HCC, but found no associations between CAT gene rs7943316 polymorphism and HCC risk. In 2009, Nahon et al25 assessed 190 HCC patients with alcoholic cirrhosis but also found no associations between CAT gene rs1001179 polymorphisms and HCC risk. Another study was conducted by Ezzikouri et al26 in 2010 and involved 96 Moroccan patients with HCC. In contrast, Ezzikouri et al26 reported that male patients carrying CAT rs1001179 (−262 C > T) of the TT genotype had a significantly higher risk of developing HCC when compared with controls . However, these studies were both conducted with small sample sizes and investigated only 1 SNP of the CAT gene. Our present study investigated the association between 3 SNPs , polymorphisms of the CAT gene, and HBV-HCC risk in a larger sample size . Our findings suggested a significant association between CAT rs769217 polymorphisms and HCC development risk. With a larger total number of subjects, more robust results were obtained in the present study than in previous studies.Until now, there were only 3 studies that investigated the association between CAT polymorphisms and HCC risk.P = 0.019; TT vs CC genotype: OR = 2.05, 95% CI = 1.12–3.76, P = 0.020; dominant model: OR = 1.85, 95% CI = 1.19–2.89, P = 0.007). No differences were observed in the genotype distributions of CAT rs769217 in female subjects. The evidence for an increased risk of HCC in women but not in men is suggestive but not conclusive. The mechanisms underlying this gender difference are also still unknown. However, evidence has suggested that men exhibit lower CAT enzyme activity, suggesting that the male subgroup may be especially susceptible to cancer.32 On the other hand, the gender differences may be due to different dietary habits (such as consumption of fruit and vegetables) and differences in smoking and alcohol consumption between male and female patients.33Our results suggest a gender effect of the CAT rs769217 polymorphism on HCC risk. Men with the T allele had a significantly increased risk for HCC . In 2005, Fulle et alP values for the smokers and drinkers are not significant. This may be due to the limitation of numbers. Thus, the results would lack statistical power and robustness, and should be read with caution. However, we could not exclude the possibility that the difference was due to smoking and drinking status. The other possible reasons for these effects may be as follows: data from previous studies indicated that heavy smokers tend to have increased local CAT activities compared to light or nonsmokers.35 There was also evidence indicating that CAT activity can be degraded by ethanol administration; thus, CAT may have only a limited role in inactivating H2O2 in alcoholics.36 Therefore, a great confusion has arisen regarding the smoking and drinking status difference in the association between the CAT rs769217 polymorphisms and HCC risk, and these findings need to be confirmed by larger studies further.The current studyalso indicated that the association between the CAT rs769217 T allele polymorphisms and HCC risk varied according to patient history of smoking and alcohol consumption. The results unexpectedly suggested that nonsmokers and nondrinkers with rs769217 T allele are more likely to develop HCC. The evidence for these differences is suggestive but not conclusive. One of the potential explanations may be the result of the limited numbers. After stratifying our population by smoking and drinking status, sample size should be smaller in each subgroup. From our data, for rs769217, the OR values are similar between smokers and nonsmokers, drinkers and nondrinkers, although the CAT gene. It would be interesting to identify more SNPs in the CAT gene to investigate their associations with HCC risk. Thus, the results of this research must be interpreted cautiously considering objectives and limitations of this study.Several potential limitations of this study must be acknowledged. First, subjects in our study were recruited from only 1 hospital and limited to the Guangxi population. They may not be well representative of the entire Chinese population. Therefore, these findings may not be generalized to other populations. Second, the current research studied only 3 SNPs in the In conclusion, our findings indicate that the CAT rs769217 T allele has a significant association with increased risk of CHB, HBV-LC, and HBV-HCC in the Guangxi Chinese population.The authors would like to thank Scribendi.com for its linguistic assistance during the preparation of this manuscript.


EPHX1 gene on warfarin maintenance dosages. Relevant literatures were searched using the PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, CBM, and CNKI databases without any language restrictions. STATA Version 12.0 software  was used for this meta-analysis. Standard mean difference and its corresponding 95% confidence interval (95% CI) were calculated. Seven studies met the inclusion criteria, including 2,063 warfarin-treated patients. Meta-analysis results illustrated that EPHX1 rs2292566 G>A polymorphism might be strongly correlated with a higher maintenance dose of warfarin. However, no interaction of EPHX1 rs4653436 A>G polymorphism with warfarin maintenance dosage was detected. A further subgroup analysis based on stratification by ethnicity indicated that EPHX1 rs2292566 G>A polymorphism was positively correlated with warfarin maintenance dosage among Caucasians, but not Asians. No associations were observed between EPHX1 rs4653436 A>G polymorphism warfarin maintenance dosage among both Caucasians and Asians. Our meta-analysis provides robust and unambiguous evidence that EPHX1 rs2292566 polymorphism may affect the maintenance dose of warfarin in Caucasians.We conducted a meta-analysis to investigate the influence of two common single nucleotide polymorphisms (SNPs) (rs2292566 G>A and rs4653436 A>G) in the  Warfarin is an anticoagulant normally involved in preventing thrombosis and thromboembolism, which is prescribed for patients with chronic atrial fibrillation, pulmonary embolism, deep vein thrombosis, recurrent stroke, and prosthetic heart valves –4. In clRecent studies suggested that microsomal epoxide hydrolase 1 (EPHX1) may alter the pharmacokinetics and pharmacodynamics of warfarin and have a clinically significant impact on warfarin maintenance dose , 15. EPH EPHX1 gene is located in the long arm of chromosome 1q42.1, consisting of 9 exons spanning approximately 35.48 kbps, and it encodes a protein of 455 amino acids  and [“single nucleotide polymorphism” or “SNP” or “polymorphism” or “mutation” or “mutant” or “variation” or “variant”] and [“Warfarin” or “Coumadin” or “Warfarin Potassium” or “Warfarin Sodium”]. There was no language restriction. We also did a manual search of reference lists from potentially relevant articles to identify other potential studies.A comprehensive search for related studies published before March 2014 was conducted on EPHX1 rs2292566 G>A and rs4653436 A>G polymorphisms on warfarin maintenance dosage, and the warfarin maintenance dose was defined by the international normalized ratio (INR) measurements [The studies which are in accordance with the following criteria were enrolled in the analysis: (1) clinical study focused on the influence ofurements ; (2) allAccording to the standardized form, data extraction from each included study was done by two authors. We evaluated the methodological quality of each included study based on the Newcastle-Ottawa Scale (NOS) criteria . BrieflyZ test was used to estimate the statistical significance of pooled SMDs. Heterogeneity among studies was estimated by the Cochran's Q-statistic and I2 tests [ Q-test shows a P < 0.05 or I2 test exhibits > 50% which indicates significant heterogeneity, the random effects model was conducted, or else the fixed-effects model was used [Meta-analysis was performed with the use of the STATA statistical software . Standardized mean difference  and 95% confidence interval (95% CI) were calculated as estimates of relative risk for warfarin maintenance dose under different genetic models. The 2 tests . If Q-tewas used . Meanwhiwas used .Initially, the highly sensitive search strategy identified 34 articles. We reviewed the titles and abstracts of all articles and excluded 15 articles; full texts were also reviewed and 10 articles were further excluded. One study was also excluded due to the lack of data integrity. Finally, 7 cohort studies with a total of 2,063 subjects met our inclusion criteria for qualitative data analysis , 29–38.  EPHX1 rs2292566 G>A polymorphism might be an underlying factor for increased maintenance doses of warfarin with warfarin maintenance dosage higher in individual with EPHX1 rs2292566 G>A mutation , while a similar result was not detected in the comparison of GA versus AA in the EPHX1 rs2292566 G>A mutation . However, no significant interaction of EPHX1 rs4653436 polymorphism with warfarin maintenance dosage was detected   . EPHX1 rs2292566 G>A polymorphism was associated with warfarin maintenance dosage among Caucasians , but not Asians  . Further subgroup analyses based on sample size and genotyping method revealed significant relationships between EPHX1 rs2292566 G>A polymorphism and an increased warfarin maintenance dosage in the large-sample-size and TaqMan assay subgroups, but not in the small-sample-size and non-TaqMan assay subgroups . Sensitivity analysis suggested that no single study could influence the pooled SMDs. Funnel plots demonstrated no evidence of obvious asymmetry existing. The Egger test also did not display strong statistical evidence for publication bias   . Neverth > 0.05) .1 2,3-epoxide and reduced vitamin K depletion [γ-carboxylation of vitamin K-dependent clotting factors, its depletion may lead to a reduction of the active clotting factors [ EPHX1 genetic variations may be crucial candidates in the influence of warfarin anticoagulant effect [EPHX1 is putative subunit of the vitamin K epoxide reductase (VKOR) and suggested to be a new genetic variant affecting the warfarin maintenance dose significantly , 20. Genepletion . Since t factors . As a ma factors . Therefot effect . EPHX1 gene and the warfarin dose requirement. Our findings showed a strong association between EPHX1 rs2292566 G>A polymorphism and warfarin maintenance dose, but similar association was not observed in the EPHX1 rs4653436 A>G polymorphism, implicating that EPHX1 rs2292566 polymorphism may be a significant predictor for the interindividual variability of warfarin maintenance dose. Nevertheless, the precise mechanisms that EPHX1 genetic polymorphisms affect the requirement of warfarin dose are still unidentified. One possible explanation could be that genetic mutations in the EPHX1 gene may result in amino acid substitution and have some impacts on the EPHX1 enzyme activity, with resultant impaired warfarin metabolism and clearance, thus contributing to interindividual dose variability [ EPHX1 rs2292566 G>A polymorphism as a novel predicting factor for variable warfarin response, reporting that alteration in the EPHX1 gene may change the pharmacokinetics and pharmacodynamics of warfarin exertion by inhibiting the activity of vitamin K epoxide reductase (VKOR), and thereby may influence warfarin maintenance dose [γ-carboxylation of vitamin K-dependent clotting factors in the hepatic system  [ EPHX1 genetic variant as a predictor of variable warfarin dose requirement because EPHX1 has been proposed as a putative subunit of VKOR [ EPHX1 rs2292566 G>A polymorphism may reduce VKOR activity and consequently give rise to active vitamin K deficiency, which may lead to a decrease of the active clotting factors. Additionally, it is plausible that patients with EPHX1 rs2292566 polymorphism may require a lower maintenance dose of warfarin. Furthermore, it should be noted that out of those six forest plots, there were only significant relationships between the comparison of GG versus AA and GG versus GA; no potential association was detected from the GA versus AA comparison in the EPHX1 rs2292566 G>A polymorphism; one possible explanation is that the existence of possible heterogeneity sources could have an influence on the overall outcome, so no significant relationship was observed between dose variations and certain allele types for the differences in ages or ethnic backgrounds [ EPHX1 rs2292566 G>A polymorphism was significantly associated with the warfarin maintenance dose, accounting for 1.7% of the variability in the dose [In the present meta-analysis, we investigated the relationship between two common SNPs (rs2292566 G>A and rs4653436 A>G) in theiability , 46. Paunce dose . Loebste, and X) . Further of VKOR . Therefokgrounds . Our resthe dose . EPHX1 rs2292566 G>A polymorphism and a lower maintenance dose of warfarin in Caucasians, while no similar association was detected among Asians, implicating that ethnicity differences may play an important role in the effects of variants in the EPHX1 gene on interindividual variability of warfarin maintenance dose. Although the potential mechanism of ethnicity differences is still not fully understood, we supposed that ethnicity may result in differences in alleles and genotypes among different ethnic populations. Sample size within those included papers were obviously different, and this stratified analysis revealed that a significant difference between EPHX1 rs2292566 G>A polymorphism and warfarin maintenance dose was observed within the larger sample sizes. In summary, our findings are consistent with the previous studies that EPHX1 rs2292566 G>A polymorphism may influence the warfarin dose requirement, suggesting that translation of this knowledge into clinical guidelines may offer a useful and informative route to improve therapeutic management during warfarin therapy.Considering the possibility of existing obvious heterogeneity, which may negatively affect our association study results, stratified analyses were carefully performed based on ethnicity, genotyping method, and sample size. Subgroup analysis after the heterogeneity test was also a required step for the secondary verification of our results. The results of subgroup analysis performed by ethnicity displayed significant associations between EPHX1 genetic polymorphisms with the warfarin dose requirements. Secondly, meta-analysis is a retrospective study that may inevitably induce subject selection bias and thereby have an impact on the reliability of our results. Thirdly, our meta-analysis failed to obtain original data from the included studies, which may limit further evaluation of potential role of EPHX1 genetic polymorphisms with the warfarin dose requirements.The current meta-analysis also had several limitations that should be acknowledged. First, our results lacked sufficient statistical power to assess the correlations of EPHX1 rs2292566 G>A polymorphism may affect the maintenance dose of warfarin in Caucasians, so EPHX1 rs2292566 G>A polymorphism could be a potential and practical biomarker for the interindividual variability of warfarin maintenance dose. However, due to the limitations mentioned above, more reliable research with larger sample sizes is still required to provide a more comprehensive and representative statistical analysis precisely.In conclusion, our meta-analysis provides robust and unambiguous evidence that