Insulin resistance (IR) and impaired insulin secretion contribute to type 2 diabetes and cardiovascular disease. Both are associated with changes in the circulating metabolome, but causal directions have been difficult to disentangle. We combined untargeted plasma metabolomics by liquid chromatography/mass spectrometry in three non-diabetic cohorts with Mendelian Randomization (MR) analysis to obtain new insights into early metabolic alterations in IR and impaired insulin secretion. In up to 910 elderly men we found associations of 52 metabolites with hyperinsulinemic-euglycemic clamp-measured IR and/or β-cell responsiveness (disposition index) during an oral glucose tolerance test. These implicated bile acid, glycerophospholipid and caffeine metabolism for IR and fatty acid biosynthesis for impaired insulin secretion. In MR analysis in two separate cohorts  followed by replication in three independent studies profiled on different metabolomics platforms , we discovered and replicated causal effects of IR on lower levels of palmitoleic acid and oleic acid. A trend for a causal effect of IR on higher levels of tyrosine reached significance only in meta-analysis. In one of the largest studies combining “gold standard” measures for insulin responsiveness with non-targeted metabolomics, we found distinct metabolic profiles related to IR or impaired insulin secretion. We speculate that the causal effects on monounsaturated fatty acid levels could explain parts of the raised cardiovascular disease risk in IR that is independent of diabetes development. Impaired glucose homeostasis leads to diabetes and cardiovascular disease and has two main components: failure to secrete enough insulin from pancreatic β-cells and reduced insulin-stimulated cellular uptake of glucose and other nutrients in target tissues . We used metabolomics analysis in non-diabetic persons to measure a non-selective range of small molecules including amino acids, lipids, and sugars. Pathway analysis highlighted distinct metabolic pathways linked to IR (e.g. bile acid production) and impaired insulin secretion (fatty acid biosynthesis), but causal directions remained unclear. Mendelian Randomization (MR) analysis can test for causal effects in observational studies in the absence of randomized controlled trials. Using MR analysis in up to four large independent studies, we found evidence that IR causes a decrease in levels of the main endogenous monounsaturated fatty acids palmitoleic acid and oleic acid, as well as suggestive evidence for higher levels of the amino acid tyrosine. We provide a possible explanation for parts of the diabetes-independent risk of cardiovascular disease in persons with IR. PCSK9, reduced low-density lipoprotein-cholesterol levels and lower coronary heart disease risk [Insulin resistance (IR) is a major precursor of type 2 diabetes (T2D) , and conase risk  predictease risk . Conversase risk .The causal effects of impaired insulin secretion and IR on blood metabolites have not been assessed before in a large-scale metabolomics framework and could pinpoint key mediators of the risk of adverse health events. We aimed to identify metabolic pathways related to IR and impaired early-phase insulin secretion during an oral glucose tolerance test (OGTT) in a large European sample and applied MR methods in additional cohorts to assess potential causal effects of impaired insulin secretion and IR. Using non-targeted metabolomics , we idenhttp://www.metaboanalyst.ca/) indicated significant enrichment of IR-associated metabolites in primary bile acid synthesis , glycerophospholipid metabolism  and caffeine metabolism  .The Uppsala Longitudinal Study of Adult Men (ULSAM) cohort of community-dwelling 71-year-old men provides the largest human sample combining plasma metabolomics with an OGTT and the hyperinsulinemic-euglycemic clamp method. We previously developed a bioinformatics pipeline for untargeted liquid chromatography/mass spectrometry (LC/MS) data  and werebolites) . Impaire2 >0.8) in lieu of unavailable SNPs  and hippuric acid  (p < 0.1) were detected for reduced levels of OA (p = 0.074) and 3α,6β,7β-trihydroxy-5β-cholanoic acid (p = 0.079) as well as for higher levels of monoacylglycerol (MAG) 18:1 (p = 0.079), MAG(18:2) (p = 0.064), MAG(14:0) (p = 0.077), and γ-tocopherol (p = 0.084)  and there was a trend for a level-raising effect on bilirubin (p = 0.071)  and the TwinGene study. We used the previously validated additive allelic genetic risk scores for IR (10 SNPs) and impaired insulin secretion (21 SNPs) as IVs  with proble SNPs . Associable SNPs . IV-expo= 0.018) . Causal = 0.084) . Impaire= 0.071) .p < 0.1) in up to 7,824 European individuals in the KORA F4/TwinsUK cohorts that underwent untargeted metabolomics profiling on a different LC/MS platform [p < 0.05 for significance in all replication analyses. Seven of the nine causally implicated metabolites for IR (excluding MAG(14:0) and 3α,6β,7β-trihydroxy-5b-cholanoic acid) and one of two (bilirubin) for impaired insulin secretion were available in KORA/TwinsUK. We replicated the causal effect of IR on POA  and the tentative effect on OA   and hippuric acid . A repeat analysis in a subset of 1,432 non-diabetic individuals in the KORA F4 cohort replicated the causal effect on POA  and the tentative effect on OA  (We attempted replication for metabolites with suggestive evidence of causation (platform . The lib= 0.078) . We coul= 0.082) .http://www.chargeconsortium.com/main/results) [IV = –0.29, 95% CI –0.54 to –0.05, p = 0.018) and OA .In a second attempt to replicate the causal findings for POA and OA, we obtained the publicly available GWAS results for FA fractions in plasma phospholipids from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium (results) . The CHAp = 0.267).We aimed to replicate the possible causal effect of IR on raised tyrosine using the summary meta-GWAS results from five cohorts of 8,330 Finnish individuals who underwent nuclear magnetic resonance metabolomics profiling . In thisp < 0.05) that was observed as a non-significant trend in each individual study. Given the risk of false positive findings due to multiple testing, these post-hoc findings should be interpreted with caution and require confirmation studies.Achieving adequate power in MR analysis requires large sample sizes . HoweverTo assess for violations of MR assumptions due to genetic confounding, horizontal pleiotropy and IV heterogeneity, we examined a) the association of individual SNPs with the risk factors ); b) thep < 0.1) in the MR discovery sample, we examined individual SNP effects on metabolite levels. The IV-exposure associations were derived from the GWAS results for homeostasis model assessment-IR  and corrected insulin response  in non-diabetic persons from the publicly available results of the Meta-Analyses of Glucose and Insulin-related traits Consortium . The association between SNPs and risk factors in MAGIC were consistent and did not indicate heterogeneity apart from one variant (rs11605924) that was associated with CIR in the unexpected direction . Although the intercept estimate in MR Egger regression for OA differed significantly from zero, it was small in magnitude  and the causal effect was reproduced . One important assumption of MR Egger regression–that any pleiotropic effects of IVs on the outcome be independent of IV strength [We tested for associations of genetic scores with potential mediator variables in age- and sex-adjusted linear regression in ULSAM, PIVUS and TwinGene  and confirection . As repostrength –cannot bSCD1 and its rodent equivalent scd1 in the EMBL-EBI Expression Atlas v3.0 (http://www.ebi.ac.uk/gxa/home). This gene encodes stearoyl-CoA desaturase 1 (SCD-1), the rate-limiting enzyme in the biosynthesis of OA and POA [scd1 expression was consistent with our findings—the IR-increasing condition down-regulated scd1 expression.To further assess our findings of a negative causal effect of IR on monounsaturated FA levels, we looked up gene expression data for  and POA . Among 2In the observational part of this multi-cohort study of blood metabolomics profiles, we identified bile acid, glycerophospholipid and caffeine metabolism as associated with IR, and FA biosynthesis as related to impaired insulin secretion. We discovered and replicated causal effects of IR on lower levels of the monounsaturated FAs POA and OA, as well as suggestive evidence for higher levels of the aromatic amino acid tyrosine. Sensitivity analyses did not indicate pleiotropic effects of the genetic instruments. Causal effects were largely unaffected by the exclusion of prevalent diabetes cases in the KORA/TwinsUK replication set. A small collection of publicly available experimental results in rodents supported our causal findings: All IR-increasing conditions were associated with a down-regulation of SCD-1, implying reduced endogenous production of OA and POA.scd1 knockout mice and hypertriglyceridemic persons, plasma FA composition reflects hepatic SCD-1 activity [The liver and adipose tissue are the main sites of de novo lipogenesis and SCD-1 is the rate-limiting enzyme for monounsaturated FA biosynthesis . It intractivity , 30. Henscd1 expression and ~90% reduced microsomal scd1 transcript levels compared to control mice [scd1 expression was downregulated by ~23% compared to controls [Experimental evidence for the inhibition of SCD-1 by IR stems from liver-specific insulin receptor knockout (LIRKO) mice that had ~80% reduced hepatic rol mice , 32. In controls .scd1 knockout mice with induced colitis [p = 0.035, after adjustment for BMI pBMI > 0.05) and POA levels  in contrast to the negative genetic associations in MR studies. This discrepancy is likely due to confounding factors such as dietary FA intake and highlights that MR studies have the power to disentangle causal mechanisms that may be obscured in cross-sectional studies. The hypothesized but untested relationship with cardiovascular disease requires investigation in future studies.Little is known about the causal effects of a genetic predisposition for IR on SCD-1 . Reduced colitis  or on a  colitis . Based o colitis , 40 and  colitis . A summaThe effect of IR on elevated tyrosine levels was observed as a non-significant tendency in all cohorts but reached nominal significance only after combination of estimates in meta-analysis. Although there is a considerable risk that this result is a false positive due to multiple testing, we still consider it an interesting finding worth investigating in larger MR studies, as it has not been reported before. Associations between worse IR/T2D risk and circulating tyrosine levels have been established in observational and longitudinal studies , 43. PosLimitations of our study include moderate power in MR studies and inherent limitations of the non-targeted metabolomics discovery platform to capture certain metabolites  and separate sugars and other non-polar molecules. We used an untargeted metabolomics approach that detected several thousand metabolic features, yet the limited availability of standard compound spectra in in-house and public libraries precluded the quantification of the entire spectrum of the plasma metabolome and may have biased the pathway enrichment analysis. Observational associations were established in an exclusively male, elderly European cohort (ULSAM) with unknown generalizability to other age and ethnic groups. The different metabolomics platforms between studies and the expression of FA levels in % of plasma phospholipids rather than absolute levels in CHARGE somewhat limit methodological consistency. However, this diversity also supports the robustness of findings that were replicated on different platforms. Causal relationships were consistent across studies but require validation in physiologic models of IR, particularly as some sources of bias  cannot be excluded. Whilst the unique contribution of our study is to assess causal effects on the plasma metabolome, we could not examine the reverse causality as no genetic instruments were available for the majority of metabolites. As illustrated above, relative levels of circulating POA and OA likely reflect endogenous biosynthesis, however, the exact contributions of SCD-1, exogenous sources, catabolism and excretion could not be addressed by our study and require experimental investigation. We used proxy outcomes (HOMA-IR and CIR) with available large GWAS results in sensitivity analyses rather than the exact same measures as in the main analysis.Strengths include the extensive testing for violations of MR assumptions, the replication of main findings in large independent cohorts that used different methods of quantification, and the use gold standard measures for IR. We detected no evidence of pleiotropy of genetic instruments whose associations with cardiometabolic traits were in the expected directions and causal estimates agreed between different analysis methods.In summary, our study in multiple independent cohorts of community residents indicates a causal effect of IR on circulating OA, POA, and tyrosine levels and provides new insights into the metabolomic signature of IR and impaired insulin secretion. It is to our knowledge the first large-scale attempt to explore the causal effects of genetic IR on a non-selected set of plasma metabolites. The potential implications of the presumed IR-induced inhibition of monounsaturated FA biosynthesis on health outcomes require validation in experimental models but may form part of the explanation for the elevated CVD risk in IR that is independent of T2D development.http://www2.pubcare.uu.se/ULSAM/) was started in 1970 and enrolled 81.7%  of all male residents of Uppsala county, Sweden, born between 1920 and 1924. On-going assessments every five to ten years include questionnaire, biochemical, and anthropometric examinations. The current study is based on the assessment at age 70 years, which included an OGTT and hyperinsulinemic-euglycemic clamp measurement.Detailed descriptions are available in http://www.medsci.uu.se/pivus/) enrolled 50%  of a random sample of Uppsala community residents aged 70 years in 2001 and features assessments including health questionnaires, blood sampling and clinical measurements every five years. The current study is based on the assessment at age 70 years.The PIVUS study (http://ki.se/en/meb/twingene-and-genomeeutwin) is a longitudinal study of 12,591 twins born before 1958 and registered in the Swedish Twin Registry with questionnaire assessments and blood sampling done between 1998 and 2002, and again between 2004 and 2008. The current study used a subcohort from a nested case-cohort design established for an earlier project [TwinGene .The Cooperative Health Research in the Region of Augsburg  study i2) who underwent blood metabolite profiling and health center assessment.TwinsUK is a predominantly female cohort of adult twins recruited from the general UK population. The current study is based on 17-to-85-year-old twins  from five cohorts—the Atherosclerosis Risk in Communities (ARIC) study, the Cardiovascular Health Study (CHS), the Coronary Artery Risk Development in Young Adults (CARDIA) study, the Invecchiare in Chianti (InCHIANTI) study, and the Multi-Ethnic Study of Atherosclerosis (MESA). Details on cohorts and recruitment are reported elsewhere [http://chargeconsortium.com/).The CHARGE consortium GWAS for plasma FA fractions  combinedlsewhere  and docu2.The Finnish consortium  combinedAll participants provided written informed consent prior to inclusion in the study and the research was approved by the Ethics Committees of Uppsala University  and Karolinska Institutet (TwinGene), or the respective Institutional Review Boards for the other cohorts. The study was conducted according to the principles of the Declaration of Helsinki.http://www.ebi.ac.uk/metabolights/).Untargeted metabolomics profiling of venous blood samples in the three Swedish cohorts was carried out by ultra-performance liquid chromatography (UPLC) on a Waters Acquity UPLC system coupled to a Waters Xevo G2-Time-Of-Flight-Mass Spectrometry (TOFMS) platform at Colorado State University . Data acquisition in the positive electrospray ion mode with a mass-to-charge ratio (m/z) range of 50–1,200 at 5 Hz was alternately performed at collision energies of 6V and 15–30V. Details on sample handling and data processing by XCMS in R  are avaiMetabolomics analyses in KORA and TwinsUK were carried out by the commercial company Metabolon, Inc. , which combined positive and negative ion-mode UPLC/tandem-MS with gas chromatography/MS. Following protein precipitation in methanol, samples for analyzed in duplicates and spectral annotation was performed against a standard compound library . As detailed in , fasting1H-nuclear magnetic resonance analysis windows optimized for lipoproteins, low molecular weight metabolites and lipid species, respectively [The Finnish study processed serum samples from all five sub-cohorts in one central laboratory by three complementary ectively , 49. For-1 x kg body weight-1 x min-1 per mU / l x 100; representing the amount of glucose metabolized per unit of plasma insulin during the clamp assessment), the insulinogenic index (IGI30) as a measure of glucose-stimulated insulin secretion [The outcomes were insulin sensitivity  are avadelta method, which we previously validated (Eq 2) [We used IV analysis to estimate the causal effect of IR/impaired insulin secretion on metabolite levels in PIVUS and TwinGene. The Wald ratio estimator  was obtad (Eq 2) .2 >0.8) for variants not directly genotyped. When no proxies were available, SNP scores were imputed as 2*risk allele frequency based on the 1000 Genomes Project phase 1 [http://pngu.mgh.harvard.edu/~purcell/plink/). The association between genetic IVs and metabolites was estimated in linear models adjusted for age, sex, the first three genetic principal components and cohort with metabolite levels (SD-unit) as outcome. Age- and sex-adjusted associations between genetic IVs and exposure (SD-unit) were obtained from Scott et al. [As IV, we used the IR and impaired insulin secretion genetic risk scores validated by Scott et al.  S2 Tabl. Because phase 1  . We also obtained the summary meta-GWAS statistics for serum tyrosine levels from a Finnish consortium study [grs.summary function in the gtx package in R [p < 0.1 at the discovery stage, for OA and POA in CHARGE, and for tyrosine in the Finnish consortium. Causal estimate from all cohorts were combined in inverse variance-weighted, fixed effects meta-analysis via metafor in R.We obtained the publicly available GWAS data for serum/plasma metabolite levels in 7,824 European adults in the KORA F4 and TwinsUK cohorts , as wellum study . Detailsum study , 46. We age in R . Regresshttps://github.com/andgan/metabolomics_pipeline), R scripts used for observational and MR analysis are available as well (https://github.com/chrnowak/metabolomics).R scripts for the full metabolomics pipeline in PIVUS, TwinGene and ULSAM are available online (S1 Text(DOCX)Click here for additional data file.S2 Text(DOCX)Click here for additional data file.S1 Fig(TIF)Click here for additional data file.S2 Fig(TIF)Click here for additional data file.S3 FigAssociations between genetic risk scores for IR (upper panel) and insulin secretion (lower panel) with cardiometabolic traits in ULSAM, PIVUS and TwinGene. Based on linear regression adjusted for age, sex, and cohort. Beta coefficients and 95% CIs indicate the SD-unit change in trait level per added risk allele. ALP = alkaline phosphatase, ALT = alanine amino transferase, ApoA1/B = apolipoprotein A1/B, BMI = body mass index, CK = creatinine kinase, CRP = C-reactive protein, DBP = diastolic blood pressure, Hb = hemoglobin, HDL-chol = high-density lipoprotein cholesterol, IGI30 = insulinogenic index, IL-6 = interleukin-6, LDL-chol = low-density lipoprotein cholesterol, SBP = systolic blood pressure, TG = triglycerides, WHR = waist-hip ratio(TIF)Click here for additional data file.S4 Fig(PDF)Click here for additional data file.S1 Table(XLSX)Click here for additional data file.S2 Table(XLSX)Click here for additional data file.S3 Table(XLSX)Click here for additional data file.S4 Table(XLSX)Click here for additional data file.S5 Table(XLSX)Click here for additional data file.


MIF -173 G > C polymorphism on risk of tuberculosis (TB). We conducted a search of case-control studies on the associations of -173 G > C variant of MIF with susceptibility to tuberculosis in PubMed, ISI Web of Science, and Scopus. We extracted the data from eligible studies and achieved a meta-analysis to examine the relationship between MIF -173 G > C polymorphism and the risk of TB. Odds ratios (ORs) with the corresponding 95 % confidence intervals (CIs) were pooled to find out the impact of MIF -173G > C promoter polymorphism on TB risk. The pooled ORs were calculated for the codominant, dominant, recessive, and allelic model comparison. The findings revealed that MIF -173 G > C variant increased the risk of TB in codominant , and dominant  inheritance models tested. The results suggested that the MIF -173 C allele significantly increased the risk of PTB . The findings of this meta-analysis propose that MIF -173 G > C variant is associated with the risk of TB. More case-control studies with well-designed in different ethnic groups and larger sample size are needed to confirm the findings. The aim of the present meta-analysis was to find out the impact of  Mycobacterium tuberculosis (M. tuberculosis), is a main global public health problem and it is responsible for high mortality and morbidity worldwide particularly in Asia and Africa , mainly caused by man, 2010). World man, 2010). Thoughman, 2010). Previous studies in animals and humans have shown that, apart from environmental factors, genetic background of the host may play an important role in the development of TB  gene is located on long arm of chromosome 22 (22q11.2). The gene consists of three exons of 205, 173 and 183 bp separated by two introns of 189 and 95 bp . A -173MIF -173 G > C variant on risk of tuberculosis . The prMIF gene and tuberculosis; 2) studies enrolled more than 30 patients; 3) studies provided the genotype frequencies of MIF -173 G > A polymorphism in both cases and controls. Figure 1A comprehensive search of PubMed, Web of Science, Scopus, and Google Scholar was done from database for articles published up to April 04, 2016 without language restriction. The search strategy was “macrophage migration inhibitory factor or MIF” and “polymorphism or variant or mutation or genotype” and tuberculosis. Relevant studies which were eligible for the meta-analysis must meet the following criteria: studies were included in this meta-analysis if the met the following criteria: 1) case-control studies of the correlation between the -173 G > A variant of Extraction of the data was done by two independently authors. The following data were collected from each study including the first author's name, publication year, ethnicity of participants, genotyping methods of -176 G > C polymorphism, the sample size, and the genotype frequencies of the variant in both cases and controls.MIF -137 G > C gene polymorphism and TB. Hardy-Weinberg equilibrium (HWE) for each study was determined by the chi-square test. We performed the present meta-analysis using RevMan 5.0 software which was provided by the Cochrane Collaboration . All of the data in the studies are dichotomous data expressed as odds ratios (ORs) with 95 % confidence intervals (CIs) to assess the association between 2-test. The pooled ORs were calculated using the fixed-effect inverse variance analysis method or random-effect model (when heterogeneity among the studies was observed) for the allelic comparison (C v G) and genotypic comparisons of codominant (CG vs GG and CC vs GG), dominant (CG +CC vs GG), and recessive (CC vs CG+GG) genetic inheritance models. The significance of the pooled OR was assessed by the Z-test, and P < 0.05 was considered to be statistically significant. Publication bias was estimated by funnel plot. Statistical heterogeneity among the studies was evaluated using the Q-test and IAfter our selection, five case-control studies satisfied the inclusion criteria for our meta-analysis . Furthermore, the MIF -173 G > C variant increased the risk of TB in codominant , and dominant  inheritance models tested. But the variant was not associated with TB in recessive inheritance model . Five studies involving 929 cases and 876 controls were pooled together for assessment of the overall association between A funnel plot was generated as a visual aid to detect risk of publication bias Figure 3.MIF -173 G > C variant and TB risk. Our findings indicated that MIF -173 G > C polymorphism significantly increased the risk of TB susceptibility in codominant, dominant and allelic models. In the current meta-analysis, we summarized all of the available data regarding the association between MIF polymorphism increased the risk of immune disease. Liu et al. . Severaal. (2014) revealeMIF -173 G > C polymorphism contributed to the susceptibility of inflammatory bowel disease (IBD). In contrast, the findings of a meta-analysis performed by Falvey et al.  showed al. (2013) did notMIF -173 G > C polymorphism and cancer risk. They found that this variant was significant associated with cancer risk. The findings of another meta-analysis proposed that MIF -173 G/C gene polymorphism would be a risk factor for the gastrointestinal cancer and hematological malignancy  carriedal., 2015).MIF -173 G > C gene polymorphism may be associated with renal disease susceptibility, particularly in children. Moreover, the findings of a meta-analysis designated that this variant may be related to glucocorticoid resistance in child patients with idiopathic nephrotic syndrome . A metaal., 2015) showed There are several limitations of the current meta-analysis. First, only published data were entered in a few databases, consequently a publication bias may have happened. Second, the predisposition to TB is complex and in most cases does not depend on a single gene polymorphism, but somewhat on many gene variants or gene-environment interaction. MIF -173 G > C variant and risk of TB.In conclusion, the findings of this meta-analysis support an association between The authors declare no conflicts of interest.


Periodontal disease occurs relatively prevalently in people with chronic kidney disease (CKD), but it remains indeterminate whether periodontal disease is an independent risk factor for premature death in this population. Interventions to reduce mortality in CKD population consistently yield to unsatisfactory results and new targets are necessitated. So this meta-analysis aimed to evaluate the association between periodontal disease and mortality in the CKD population.2 statistic.Pubmed, Embase, Web of Science, Scopus and abstracts from recent relevant meeting were searched by two authors independently. Relative risks (RRs) with 95% confidence intervals (CIs) were calculated for overall and subgroup meta-analyses. Statistical heterogeneity was explored by chi-square test and quantified by the IP = 0.005), with a moderate heterogeneity, I2 = 52.2%. However, no evident association was observed between periodontal disease and cardiovascular mortality . Besides, statistical heterogeneity was substantial . Associations for mortality were similar between subgroups, such as the different stages of CKD, adjustment for confounding factors. Specific to all-cause death, sensitivity and cumulative analyses both suggested that our results were robust. As for cardiovascular mortality, the association with periodontal disease needs to be further strengthened.Eight cohort studies comprising 5477 individuals with CKD were incorporated. The overall pooled data demonstrated that periodontal disease was associated with all-cause death in CKD population  contains supplementary material, which is available to authorized users. In the past decade, chronic kidney disease (CKD) has received mounting attention as a leading public health problem worldwide . It is wPeriodontal disease is a common group of inflammatory diseases caused by interaction between gram-negative periodontal bacterial species and components of the host immune response . ReporteUp to now, individual study with respect to the relationship between periodontal disease and premature death in people with CKD was not convincing enough, which merely offered imprecise and inconsistent risk estimates –15. In 2Allowing for its potential but uncertain prognostic effects of periodontal disease in CKD and the need to adopt additional intervention, we therefore conducted a systematic review and meta-analysis to make clear the relevance between periodontal disease and mortality in people with CKD. The effects of diagnostic methods for periodontal disease and the severity of CKD were carefully considered in the present study.This systematic review and meta-analysis is conducted in accordance with the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines  and was Relevant studies were identified by searching the following data sources between 1950 and 1 October 2016: Pubmed, Embase, Scopus, Web of science and abstracts from the 2004–2015 European Renal Association European Dialysis and Transplant Association (ERA-EDTA) Congress. We used Medical Subject Headings (MeSH) and text words of chronic kidney disease, renal replacement therapy, dialysis, kidney transplantation, periodontal diseases and mortality by formulating optimally sensitive search strategies, see Supplementary Search Strategy. Additionally, manual review of reference lists of all included articles was also performed. All potentially eligible studies were retrieved and examined without the limit of languages. If the same cases were reported in more than one study, only the study with the most complete data was included.Inclusion criteria: (1) cohort studies that reported the relationship between periodontal diseases and the risk of mortality within adult CKD population, (2) studies in which death risks were evaluated according to periodontal status at baseline, (3) studies in which periodontal status was examined by professional dentists and (4) studies that contained the minimum information necessary to estimate the risk estimates  with 95% confidence interval (CI). Exclusion criteria: (1) cross-sectional studies, (2) studies without estimates of the HRs or RRs of death related to periodontal disease. In addition, no clinical interventions were compared within the included studies.Measurements for diagnose of periodontal disease mainly included pocket probing depth (PPD), clinical attachments levels (CALs), bleeding on probing, and the alveolar bone status evaluated by radiographic scans. The periodontal clinical examination involving both PPD and CALs measurements was selected as the gold standard, according to the guidelines of the American Academy of Periodontology . Besides2), including people undergoing dialysis and kidney transplantation.CKD was defined according to the KDOQI guideline  . Discrepancies between investigators were solved by a third reviewer (SM) until a consensus was reached. In addition, authors were contacted to identify the missing data and make sure issues of interest. Extracted data included the surname of first author, year of publication, study name, study location, stage of kidney disease , study design, sample size, age and gender of participants, duration of follow-up, baseline prevalence of periodontal disease, diagnostic criteria of periodontal disease and CKD, adjusted covariates in multivariable analyses. Adjusted risk estimates (HRs or RRs) were extracted for the following mergence and further analysis. We selected results from the full statistical model that adjusted for the largest number of potential confounders.The Newcastle-Ottawa scale was used to evaluate the quality of individual studies . In brieWe defined the main outcome of interest as all-cause mortality. The secondary outcome was cardiovascular mortality. We extracted risk estimates and 95% CIs  for outcomes with CKD patients who had no or mild periodontal diseases as the referent category.All analyses were conducted by using DerSimonian-Laird random-effects and inverse variance model. Multivariable-adjusted risk estimates of dichotomous data were pooled and RRs were presented.2 inspection were carried out to determine the heterogeneity between included studies. I2 > 50% or Q test P ≤ 0.1 were considered to be substantial heterogeneity.Chi-square test and ISubgroup analysis was conducted to assess the effect of CKD stage , adjustment for confounding variables, study design, study duration, regions, diagnostic criteria of periodontal disease, and reference population.P value <0.05 was considered statistically significant. All analyses were performed using STATA version 13.0 software .We performed sensitivity analyses by omitting individual studies stepwise and exploring the effect of individual studies on the overall estimates. Publication bias was evaluated by visual inspection of funnel plot symmetry and Egger’s regression test. All tests were 2-sided and n = 3) [n = 5) [n = 1) [n = 4 [n = 1 [n = 2 [We initially retrieved a total of 7772 titles and abstracts. Full-text articles of 24 were obtained for further assessment. We finally identified eight cohort studies in our meta-analysis, including seven prospective cohort studies , 23–27, n = 3) –30, stud [n = 5) –35, comm [n = 1) , inappro) [n = 4 –40; inte4 [n = 1 ), inappr1 [n = 2 , 43. FigFour studies used periodontal-disease-free participants as reference group , 25–27, Risk of bias in the included studies were summarized in Table 2 = 52.2%, P = 0.041). Therefore, subgroup analyses were conducted to explore sources of heterogeneity. As shown in Table P values for subgroup difference were 0.79, 0.77, 0.99 and 0.66, respectively. In addition, the extent of adjustment in multivariable analyses did not statistically influence the relationship between periodontal disease and all-cause death as well. However, estimate was slightly modified by the study duration (less than five years vs longer than five years) and diagnostic criteria for periodontal disease. After limiting to individuals with follow-up duration less than five years, increased risk of all-cause death was not observed, with RR = 1.116, 95% CI 0.855–1.457. Due to insufficient data, we were unable to further compare the modality of renal replacement therapy on the association between periodontal disease and all-cause death in CKD population.A total of eight cohort studies were included in the analysis of all-cause death, comprising 5477 participants and 1492 cases of all-cause death (data from Chen 2015  were notP = 0.000) when the study did not adjust for any confounders was omitted [P = 0.000. Interestingly, heterogeneity disappeared in the remained studies, with I2 = 0.0%, P = 0.700. Then we performed a cumulative analysis based on the remained studies in chronological order. Results demonstrated a stable, significant positive association between periodontal disease and all-cause death in people with CKD, shown in Additional file P = 0.000, as depicted in Additional file Sensitivity analyses were conducted by excluding individual studies stepwise. Results revealed that relative risks of all-cause death were not remarkably changed, thereby indicating that our results were hardly influenced by small-study effects. The pooled RR was 1.194 .Of included eight studies, four studies reported the relevance between periodontal disease and cardiovascular mortality –15, 23. P values for subgroup difference were 0.23, 0.78, 0.94, respectively.Subgroup analysis was also performed according to study design, duration of follow-up and reference population. Results indicated that the association between periodontal disease and the risk of cardiovascular death was consistent among subgroups, with P = 0.011. Moreover, only mild heterogeneity was found in the remained studies, I2 = 37.3%, P = 0.203.Eliminating one study at a time, except the study by Palmer , all yieP = 0.228. Funnel plot was not conducted for the risk of cardiovascular mortality because of too few included studies, with P value for Egger’s regression test was 0.116.Evidence for publication bias was not noticeable for all-cause death risk on the basis of visual inspection of the funnel plot Fig.  and the As far as our review team is aware, this study is the first meta-analysis comprehensively evaluating the association of periodontal disease with all-cause and cardiovascular mortality in people who have CKD. A previous systematic review of observational studies by Ruospo et al. have investigated the prevalence and severity of oral disease in adults with CKD, which told us that oral disease is common in CKD people, presented with high incidence of periodontitis, edentulism, mucosal disease, salivary abnormalities and bad oral hygiene . HoweverGiven that smoking is a shared risk factor for periodontal disease and mortality , 46, we Inconsistency was observed while data were pooled from few studies with follow-up duration less than 5 years. This phenomenon might remind us of the existence of a time lag, with regard to the long-term effect of periodontal disease on the risk of all-cause death in people with CKD.It is puzzling that meta-analysis of data from large prospective cohort studies showed that CKD people with periodontal disease were not at an increased risk of all-cause death, with RR = 1.146, 95% CI 0.929–1.414. The study by Palmer is one of the three largest cohorts. Adequate evidence revealed that this study, which was based on the ORAL-D cohort study, is the biggest source of heterogeneity among eight included studies. Strangely enough, full-text articles of corresponding data have not yet been published in authority journal, instead, only some related conference abstracts are found , 28. TheAssociations between CKD and periodontal disease have been documented in numerous studies –49. BidiAnother explanation for the increased mortality may be related to poor nutritional status, such as lower albumin and elevated blood urea nitrogen (BUN), Cr levels. Malnutrition is extensively found in CKD population, which impairs the immune defense of the hosts and markedly changes the oral microbial ecology , 57. ThrExcept the potential existence of direct pathways explaining the link between periodontal disease and bad clinical outcomes, it is also plausible that they share similar risk factors in CKD population, such as smoking status, diabetes and hypertension. Corresponding adjusted results were mentioned above, which manifested that other pathogenic mechanisms, other than common risk factor, may take a bigger part in this process.Different from all-cause death, the definite relevance between periodontal disease and cardiovascular mortality in CKD people is not observed in the present meta-analysis, which excludes the mechanism that elevated all-cause mortality is mediated by cardiovascular disease progression. A large number of publications have suggested that periodontal disease correlated significantly with death from various kinds of cancer , 61, diaTo the best of our knowledge, this meta-analysis is the first of its kind to investigate the controversial issues of whether periodontal disease is associated with all-cause and cardiovascular mortality in CKD population. As some detail data were obtained by contacting with authors, this meta-analysis incorporated some extra unpublished data. In addition, we only included population-based cohort studies, which provide the highest level of evidence in the observational studies.Limitations of this meta-analysis should be acknowledged, too. Firstly, because of the limited number of original studies and the inevitable methodological limitations of observational studies, our results should be prudently considered as relevant inference and hypothesis-exploring. Just as other results from observational studies, associations do not imply causality certainly.Secondly, Some studies failed to report the severity of periodontal disease , 27, andThirdly, unadjusted estimate from the study of Blach was also pooled in our meta-analysis.Fourthly, statistical heterogeneity could not be fully explained after subgroup analyses. We were unable to further investigate the heterogeneity of gender, modalities of renal replacement therapy, method of measuring periodontal disease from other sources, due to the rather small number of included studies.Fifthly, periodontal disease represents a potentially modifiable risk factor for individuals with CKD. However, longitudinal changes in periodontal conditions during follow up period was not illustrated in almost all studies and it might partially affect the estimates.Finally, limited information available on periodontal disease and cardiovascular death is also a drawback to our study. Thus this result should still be treated with caution.Overall, our findings demonstrated that periodontal disease is significantly associated with an increased risk of all-cause death in people have CKD. However, no adequate evidence proves that periodontal disease is also of an elevated risk for cardiovascular death so far. This meta-analysis of cohort studies incorporated the latest available proof and provided up-to-date insights into the relationship of periodontal disease and mortality risks in CKD people. More high-quality and large scale epidemiological cohorts are required to further establish and verify this association. Additionally, animal studies are also necessary to explore the underlying mechanisms.Additional file 1: Table S1.Adjustments in studies included in the meta-analysis. (DOCX 75 kb)Additional file 2: Figure S1.Forest plot of cumulative meta-analysis by adding a single study according to the publication year. (TIFF 250 kb)Additional file 3: Figure S2.Sensitivity analysis: Forest plot of risk of all-cause death limiting to studies with low risks of bias. (TIFF 252 kb)


A variety of studies have observed that the single nucleotide polymorphisms (SNPs) matrix metalloproteinase-9 (MMP-9) gene may be associated with the risk of gastric cancer(GC), and a cytosine (C) to thymine (T) mutation at the -1562 site of the MMP-9 gene promoter is reported to be closely related to the susceptibility. However, because of the conflicting results of these studies, we undertook a systematic meta-analysis to assess the association between the SNPs and the risk of gastric cancer.A computerised literature search was conducted within the databases of PubMed, EMBASE, and ISI Web of Knowledge for studies on the genetic association of MMP-9-1562C/T and gastric cancer published from 2004 to 2015. The pooled odds ratio (OR) and 95% confidence intervals (CI) were estimated for each genotype using the dominant, recessive, co-dominant, and allelic models of the matrix metalloproteinase 9.Our analysis indicated a significant association of MMP-9-1562C/T with gastric cancer .Our meta-analysis results demonstrated that MMP-9-1562C/T promoter polymorphisms increase the risk of developing gastric cancer. Gastric cancer is one of the most common cancers worldwide and one of the most common causes of cancer-related deaths in the developed world (fourth for men and fifth for women). An estimated 951,600 new stomach cancer cases occurred in 2012, as well as 723,100 deaths due to stomach cancer [Matrix metalloproteinases (MMPs) are a class of proteolytic enzymes that are closely related to tumorigenesis, invasion and metastasis. Depending on their substrate specificity and domain structure, MMPs can be divided into five divergent groups: collagenases, gelatinases, stromelysins, matrilysins and membrane-type MMPs . Matrix Recently, several studies have revealed that promoter polymorphisms of Matrix metalloproteinase-9, may contribute to gastric cancer in humans. The results by Japanese researchers in 2005 indicated that the T allele in the MMP-9 promoter is associated with the invasive phenotype of gastric cancer . Recent Our investigators independently conducted a systematic literature search in PubMed, Chinese National Knowledge Infrastructure (CNKI), EMBASE, WanFang (Chinese) Database, Chinese Biomedical Literature Database, and VIP (Chinese), with the last search update on January 1, 2017. We selected only studies in English and Chinese. We used the terms “(Gastric cancer) and ” or the equivalent Chinese terms to search the databases. In addition, we manually searched the reference lists of the included studies, as well as recent reviews, for further relevant studies  evaluation of the association between matrix metalloproteinase-9 and risk of GC; (2) report of case-control studies or nested case-control studies; (3) and reported sufficiently detailed genotype data necessary to calculate odds ratio (OR) and 95% confidence intervals (CI). Investigators applied the inclusion criteria to each study by screening its title, abstract, and full text.For each included study, the following information was collected: name of first author, year of publication, research design, geographical distribution of participants, ethnic background definitions, numbers of case and control groups, methods of DNA extraction and genotype. For studies that provided incomplete or no gene frequency data, the associated data for MMP-9 were obtained through genotype calculations. The data from each locus were divided into following two subgroups: gastric cancer and healthy control. Any dispute was resolved by discussion with all investigators.Q-test to assess the heterogeneity of each study. Second, according to heterogeneity results, we used either the Mantel-Haenszel fixed-effects model [P value < 0.1 as an indicator of significant heterogeneity for the random-effects model. For the fixed-effects model, a P value > 0.1 was used as an indicator of significant heterogeneity. In addition, we used a funnel plot and Egger's test to assess publication bias with a P < 0.1 indicating statistical significance. All P-values were regarded as two sided. All aforementioned statistical analyses were completed using STATA version 10.0 software .In this article, we performed our meta-analysis on dominant, recessive, co-dominant and alleles genotype models of the MMP-9 locus. We calculated pooled OR with a 95% CI to evaluate the association of the locus with gastric cancer. First, we conducted a ts model  or the Dts model  to calcuWe chose a total of nine papers to estimate the association of MMP-9 polymorphisms with gastric cancer. The details of the research and selection process are presented in the flowchart shown in Figure In addition, we evaluated the quality of the included studies according to the Newcastle-Ottawa Scale (NOS) . This scIn this study, by conducting the combined analysis, we observed a statistical divergence between SNP MMP-9 and risk of GC in all genetic models Table . The T aP value > 0.1 for Egger's test further verified these results  family comprises more than 20 enzymes and plays critical roles in cellular apoptosis, angiogenesis, tumour growth and metastasis. As essential regulators of the microenvironment of the cell, MMPs are capable of degrading extracellular matrix (ECM) by cleaving it, which is considered as a barrier in cellular invasion . The ECMAlveolar macrophages, polymorph nuclear leukocytes, osteoclasts and malignant cells primarily express MMP-9 , which iMMP-9-1562C/T is one of the polymorphism positions in the MMP-9 gene promoter contig sequence. A cytosine (C) to thymine (T) transition at nucleotide -1562 in the promoter region of the MMP-9 gene generates low activity for C/C and high activity for C/T and T/T genotypes in gene transcription .The activity of increasing MMP-9 could be downregulated by many extracellular factors, such as MMP-1, -3, -7, -10, -26, trypsin-2 and neutrophil elastase . Among tSome studies have found a protective effect against digestive cancers  and lungThe present study had some limitations that must be discussed. First, although we collected all eligible studies, the number of studies was small, which meant that analyses may not have had enough statistical power to explore the association of these polymorphisms with cancer susceptibility. As we all known, any interpretation of meta-analysis must be bounded within its limited context, and thus, only further and larger-scaled studies can lessen the likelihood of type I and type II errors. Second, the lack of available information about adjusted ORs by age, gender, smoking status and different histological types of gastric cancer, especially diets and alcohol consumption, prevented a more precise evaluation. Objectively speaking, it is necessary to evaluate the roles of those special environmental and lifestyle factors. Third, we cannot ignore the possible existence of gene–gene interactions. Ideally, we should evaluate the gene only after determining the roles of MMPs’ inhibitors, such as TIMP-1, TIMP-2, TIMP-3, and TIMP-4, in the development of gastric cancer. Moreover, some polymorphisms may play different roles in different tissues among people with different genetic backgrounds. A lack of data on ethnicity analysis prevented us from conducting a subgroup analysis on different populations. In spite of this, our meta-analysis has several strengths. First, our results arise from an analysis that combined the data of several studies rather than evaluating the studies independently. This significantly enhanced the statistical power of the analysis and helped us to reach a more reliable conclusion. Second, we tested publication bias and detected none, which indicates a minimised chance of misleading results.In conclusion, the results of our meta-analysis demonstrated that promoter region polymorphisms of the MMP-9 gene were associated with the susceptibility of gastric cancer. More comprehensive studies may eventually result in a better understanding of the association of MMP-9-1562C/T polymorphisms with gastric cancer.


CTLA4) and primary biliary cholangitis (PBC) is still vague and blurred. The purpose of this study is to precisely estimate the association of the polymorphisms of CTLA4 with the risk of PBC by using a meta-analysis.  The connection between gene polymorphisms of cytotoxic T-lymphocyte-associated protein 4  and PBC were collected as of June 2016. The strength of correlation based on odds ratios (ORs) and its 95% confidence intervals (95%CIs) was computed by STATA.  PubMed and the Chinese National Knowledge Infrastructure (CNKI) database were used to search correlative literatures, and the documents which were about the relationships between the polymorphisms of  Generally, in rs231775, a significant risk was found in G allele, the value of OR was 1.32, and its 95%CI was 1.19 to 1.47. The same situation was found in A allele of rs231725, the value of OR was 1.33, and its 95%CI was 1.22 to 1.45. As genotypic level, different genotypic models were also found to have obvious relevance with PBC in rs231775 and rs231725. No obvious connections were found in other SNPs.  This study indicated that the polymorphisms of rs231775 and rs231725 would be the risk factors of PBC. Autoimmune diseases are resulted from the dysfunction of the immune system, which generate immune response to autoantigens. Primary biliary cholangitis (PBC) is one kind of specific autoimmune diseases, which can cause progression of fibrosis and cirrhosis in the liver and lead to liver failure finally –4. ThereCytotoxic T-lymphocyte-associated protein 4 (CTLA4) is expressed on the surface of activated T and transmits inhibitory signal, and it is also found on the surface of regulatory T cells. The functions of CTLA4 are to lower responses of T cell and maintain peripheral tolerance of T cell . The abn+ T cells are important factors in the pathogenesis [+ T cells are sensitive to E2 components of pyruvate dehydrogenase complexes (PDC-E2) which are abnormally expressed on the surface of biliary epithelial cells (BECs) and would result in apoptosis for these epithelial cells and destruction of the small bile duct [+ T cells. Thus, CTLA4 could be involved in the regulation of pathological processes of PBC, which might be a therapeutic for PBC. Two studies demonstrated that treatment with CTLA4-Ig, which can reduce self-reactive T cell activation and liver inflammation significantly, could obviously reduce the level of portal inflammation and biliary cell damage in the mouse model [As to PBC, CD8ogenesis . CD8+ T ile duct , 8. As aile duct . Bindingile duct . Then, Cse model , 12.CTLA4, have shown that CTLA4 plays a unique role in the pathogenesis and treatment of PBC.So, CTLA4 regulation plays an important role in the pathological process of PBC. Meanwhile, the results, which were shown in some researches about the treatment of Recently, genetic factors are deemed to be an important role in PBC, which is mainly in favor of familial clustering of PBC . Recent CTLA4 and other autoimmune diseases in recent literatures [CTLA4 and PBC. rs231775, rs231775, rs3087243, and rs5742909 are the most common four single-nucleotide polymorphisms (SNPs) to be widely studied [CTLA4 and the risks of PBC, those relative researches are necessary to be combined to conduct a meta-analysis. Several early systematic reviews which had been published mainly regarded the relationships between the polymorphisms in several SNPs and primary biliary cholangitis [CTLA4 and risks of PBC [There are several evidences to prove the connections between polymorphisms of eratures –17. In r studied –22. Thuslangitis . Howevers of PBC –35.CTLA4 and risks of PBC were researched on computer with retrieval words . At last, we found 26 studies contained relative contents about CTLA4 and PBC.We used PubMed and the China Knowledge Resource Integrated database up to June 2016, and related literatures about the relationships between the polymorphisms of The following conditions should be met in studies: firstly, literature should be a case-control study; secondly, outcome was about primary biliary cholangitis; and thirdly, odds ratio and its 95% confidence interval should be estimated with adequate data in literatures. Exclusive criteria: insufficient information for data extraction. At last, this meta-analysis included 16 literatures after 10 literatures were excluded.According to the inclusion conditions mentioned above, two researchers extracted data independently. The researchers gathered these data from each study: SNPs, name of the first author, date of publication, ethnicity, number of allele, and genotype. Diversities among researchers were solved with discussion.CTLA4 polymorphisms was assessed in a random-effect model or fixed-effect model by the estimated OR and its 95%CI. Assessing the difference between the CTLA4 polymorphisms and the PBC risk in Caucasian and Asian was also conducted by using subgroup analyzing. Z-test was used to compute the significant difference of pooled OR. The p value of Z-test was calculated to access significance. Because multiple comparisons were conducted in this study, the threshold of p values was corrected with formula 1 − (1 − p)1/n for the Bonferroni correction [Q-test was used to assess heterogeneity and calculate I2 statistic. When p was less than 0.05 or I2 was more than 50%, the results among the studies indicated significant heterogeneity. In addition, possible publication biases were estimated by Begg's funnel plot and Egger's regression; p value was calculated to access bias. When p was less than 0.05, a publication bias was considered to be existence. The validity and reliability of a meta-analysis were evaluated by conducting sensitivity analysis [The intensity of associations between PBC risk and rrection . Q-test analysis . All theCTLA4 SNPs after multiple comparison. The values of D' and r2 were calculated by SHEsis software  [D' > 0.8 or r2 > 0.4, linkage disequilibrium could be considered.In this study, linkage disequilibrium (LD) was used to measure the association among these four sis.php) . When D'CTLA4, the SNPs which were mostly consulted were rs231775, rs231725, rs3087243, and rs5742909. These SNPs were reported in 14, 6, 9, and 5 studies, respectively. The genotypes of controls were in line with Hardy-Weinberg equilibrium in most articles.In total, the number of cases and controls were 4422 and 5210 in 16 studies, respectively . As to CCTLA4 rs231775 polymorphism (G versus A: P(het) = 0.008, I2 = 54.1%; GG versus AA: P(het) = 0.032, I2 = 45.6%), rs3087243 polymorphism (GA versus GG: P(het) = 0.028, I2 = 53.5%; AA + GA versus GG: P(het) = 0.037, I2 = 51.2%), and rs5742909 polymorphism (T versus C: P(het) = 0.001, I2 = 69.4%; TC versus CC: P(het) = 0.01, I2 = 66.7%; and (TT + TC) versus CC: P(het) = 0.007, I2 = 69%). Therefore, we chose the random-effect model to generate extensive CIs in these genetic models, the rest of genetic models were used the fixed-effects model  with susceptibility to PBC are presented  of G versus A, GG versus AA, GA versus AA, (GG + GA) versus AA, and GG versus (AA + GA) were 1.32 (1.19–1.47), 1.72 (1.37–2.16), 1.27 (1.13–1.43), 1.38 (1.23–1.54), and 1.52 (1.35–1.71), respectively. As to each model, the p value was below 0.0001 , rs231725 (A versus G), rs3087243 (A versus G), and rs5742909 (T versus C) were 0.661, 0.806, 0.466, and 0.060, respectively. For Egger's test, p values of genetic models mentioned above were 0.952, 0.186, 0.061, and 0.029, respectively n1/. There are four SNPs in this study for multiple comparisons, and the original threshold of p value was 0.05. So, after calculating with above formula , p < 0.0127 was considered statistically significant.Multiple comparisons were conducted in this study. To minimize the type I error, the threshold of ce level . Then, tAs to the polymorphisms of rs231775 and rs231725, significant connections were found to be associated with PBC in all 5 genetic models. For patients in cases, the frequencies of allele and genotype in rs231775 and rs231725 were increased more significantly than those in controls. As to allele, the results of rs231775 were similar to the results of five published meta-analyses by Eskandari-Nasab et al. , Huang eAs to rs3087243, our analysis showed that both allele and genotype were negative associations with PBC in overall populations. For rs5742909, in codominant, dominant, and recessive models, there were no connections with susceptibility of PBC in Caucasian and Asian. These results were consistent with those in one meta-analysis, which was conducted by Li et al. , includiCTLA4 and the susceptibility to PBC. In order to solve these problems, further studies in various ethnicities are required.Through subgroup analysis, GG homozygosity of rs231775 and AA homozygosity of rs231725 were associated with the susceptibility to PBC both in Asians and in Caucasians. AA homozygosity of rs3087243 was protective against PBC in Asians and Caucasians. On the other hand, GA heterozygosity of rs231725 was associated with the susceptibility to PBC in Asians although it was not in Caucasians. GA heterozygosity of rs3087243 was protective against PBC in Asians although it was not in Caucasians. Thus, there may be a little different between Asians and Caucasians in the relationship between SNP polymorphism of D' and r2 were frequently used. They have quite different characteristics and could be applied for different purposes. Typically, r2 is useful in the context of association studies, D' is the measure of choice to assess recombination patterns in a given population [D' is 1. But the significance of values would be difficult to interpret when D' < 1. Meanwhile, when the sample size is small and the frequency of SNPs is low, the estimate of D' would be too large. In this case, even the sites of linkage equilibrium can get larger D' value, the actual meaning of the D' could easily be exaggerated. Then, the value of r2 could be more reliable under this condition. In this study, the frequency of genotypes in rs5742909 was much lower than the others  and genome-wide meta-analysis on PBC have been performed. From these literatures –47, therAs to GWAS, the relationship between mutations of SNPs and occurrence of disease might not be a necessity but a probability. So, a large number of samples should be analyzed for the association study between gene and disease. The number of cases which were enrolled in each publication of genome-wide association study of PBC was not enough comparing with the probability of gene mutation. Thus, some higher risk loci with lower mutation frequency could be concealed by lower risk loci with higher mutation frequency. Meanwhile, it was different from the GWAS that focused on the onset of disease, and the data of our meta-analysis might provide a point in the search for novel therapies that are urgently needed to improve outcomes for PBC patients.CTLA4 polymorphism and the association between CTLA4 and PBC were not reported in the GWAS of PBC, CTLA4 was the main focus of PBC in many candidate gene studies, and certain benefit results were obtained as a therapeutic target from CTLA4. CTLA4-Ig has been developed as an exciting outcome in mouse model of PBC [On the one hand, GWAS efforts have focused on the identification of association of genetic variants with PBC, but not with specific properties of disease such as response of treatment . As mentl of PBC , 12. BasCTLA4 could also impact Th1/2. Indeed, CTLA4-deficient mice and T cells were shown to be strongly trend a Th2 phenotype [CTLA4 could not be improved in GWAS, as to biliary cell damages in PBC, CTLA4 could influence the effect of these inflammatory cytokines, such as IL-12, and IL-23 [On the other hand, IL-12 signal pathway may be an important role for PBC through Th1/2 differentiation among these loci from GWAS, but henotype . This ishenotype . It is end IL-23 .CTLA4 that have ever been reported in the publication of candidate gene studies. It should be said that this study was a more comprehensive meta-analysis of association between CTLA4 and PBC. Our findings might illustrate that relevant research could still be gained from the candidate gene investigation.In view of the publication of the GWAS of PBC, our meta-analysis might be quite basic. However, we have collected sufficient documentations that have ever been published and analyzed four SNPs of In this meta-analysis, there were still some limitations to be existed. First, except race, there were other factors to be concerned, which included age, gender, and alcohol habit. It would be useful to understand that different risk factors might interact with the development of PBC as genetic variations. Secondly, some studies suggested that patients in PBC would also suffer other autoimmune diseases. Since, these literatures which we included did not mention whether other diseases were excluded in those patients, these situations may introduce errors during analyzing.CTLA4 may be risk factors for PBC in Asians and Caucasians. AA, GA genotype, and A allele of rs3087243 may be negatively associated with PBC in overall populations, especially in Asian. There was no significant connection with PBC in rs5742909 of CTLA4. Not only the impact on cytokine regulation but also the benefit results as therapeutic target, to some extent, CTLA4 still plays a role which could not be completely ignored in PBC.To sum up, this meta-analysis showed that the GG, GA genotype, and G allele of rs231775 and AA, GA genotype, and A allele of rs231725 in


PDCD1) gene polymorphisms and rheumatoid arthritis (RA) risk, but the results were controversial. To explore whether PDCD1 gene polymorphisms have an effect on RA risk, we conducted this meta-analysis to investigate the relationships between PDCD1 polymorphisms  and RA risk under 4 genetic models.Several studies investigated the relationship between programmed cell death 1 , and Chinese Biomedical Literature Database (CBLM) were systematically searched for all eligible case-control studies. The last search was updated on September 10, 2016. Studies were accessed using Newcastle-Ottawa Scale case control study (NOS), and the combined effect size was calculated using STATA software, version 12.0. The pooled odds ratio (OR) with 95% confidence interval (CI) was calculated to assess the association. Heterogeneity analysis and subgroup analysis were also performed. Sensitivity analysis and publication bias were also performed if necessary.This meta-analysis included 6 studies. The result demonstrated null association between rs36084323 (PD-1.1 G/A) polymorphism and RA susceptibility in all 4 genetic models. With regard to rs11568821 (PD-1.3 G/A), statistically significant association with RA risk was observed under allele model in Caucasians . There was no significant association between rs2227981 (PD-1.5 C/T) polymorphism and RA risk.The present study suggests that mutant A allele in rs11568821 (PD-1.3 G/A) might increase the susceptibility to RA in Caucasians. Genetic risks for RA have been acknowledged for years, various new genetic risk factors for RA were identified with the help of genome-wide association studies (GWAS), such as HLA-DRB1, PADI4, PTPN22, TNFAIP3, STAT4, AFF3, and CCR6.–6 Despite these risk factors, the contribution of these individual risk loci to the development of RA appears to be variable, the exact pathogenesis of RA still needs to be elucidated.Rheumatoid arthritis (RA) is a chronic inflammatory, autoimmune disease characterized by joint inflammation and synovitis, which could lead to cartilage and bone destruction, disability, and eventually, to systemic complications including cardiovascular and pulmonary disorders.PDCD1 or PD1), whose gene is localized on chromosome 2q37.3, is a member of the CD28/B7 family receptors, encoding a 55 kDa immunosuppressive receptor in T cells, B cells, and myeloid cells.PDCD1 is a necessary negative regulator of autoimmunity regulation; the interactions between PDCD1 and its ligands, PD-L1and PD-L2, have a negative effect in T cell receptor-mediated lymphocyte proliferation and cytokine secretion, and could inhibit CD28-mediated costimulation. It also regulated the induction and maintenance of T cell tolerance, which could protect tissues from effector T cell responses-mediated tissue damage.,10,11 For instance, a recent study indicated that PDCD1 upregulated on regulatory T cells enhances the suppression of CD8+ T cell immune response via the interaction with PD-L1 expressed on CD8+ T cells, and another study showed that genetic absence of PDCD1 promoted accumulation of terminally differentiated CD8+ T cells. The lack of PDCD1 could result in the development of autoimmune diseases, such as systemic lupus erythematosus (SLE), type I diabetes mellitus (T1DM), and ankylosing spondylitis (AS).Programmed cell death 1 , rs11568821 (PD-1.3 G/A), rs2227981 (PD-1.5 C/T), and rs2227982 (PD-1.9 C/T), which could influence the biological function of PDCD1. PDCD1 gene polymorphisms were found to be correlated with the risk of several autoimmune diseases, such as SLE, RA, diabetes mellitus, and multiple sclerosis (MS). Several studies aimed to investigate the relationship between PDCD1 gene polymorphisms and RA risk, but the results were controversial.–23 For instance, Prokunina et al confirmed there is an association between rs11568821 (PD-1.3 G/A) polymorphism and the risk of RA in the Caucasian population, which was supported by the study of Tahoori et al. However, Iwamoto et al and Liu et al hold a different opinion. In order to provide a comprehensive assessment of the association between the polymorphisms of PDCD1 and RA risk, we conducted this meta-analysis.RA is a chronic autoimmune and inflammatory disorder, featured by immune-mediated inflammatory circumstances of the synovium. In RA synovial fluid, the PD-12No ethical approval and informed consent are necessary for this meta-analysis, and it was reported following the PRISMA  statement.2.1PDCD1 OR PD-1 OR PD-1.1 OR rs36084323 OR PD-1.3 OR rs11568821 OR PD-1.5 OR rs2227981 OR PD-1.9 OR rs2227982, and polymorphism OR polymorphisms OR single nucleotide polymorphism OR SNP OR variation. Publication language was not restricted in our study selection. Additional eligible studies were identified by searching the references of all the selected articles.We systematically searched databases including PubMed, EMBASE, Web of Science, Cochrane Library China National Knowledge Infrastructure (CNKI), and Chinese Biomedical Literature Database (CBLM) for all eligible case-control studies with a retrieval strategy. The last search was updated on September 10, 2016. The following search terms were used: rheumatoid arthritis OR RA and programmed cell death 1 OR 2.2PDCD1 gene polymorphisms, including rs36084323 (PD-1.1 G/A), rs11568821 (PD-1.3 G/A), rs2227981 (PD-1.5 C/T), and rs2227982 (PD-1.9 C/T); and enough data were provided for analysis. Newcastle-Ottawa Scale was used to assess the quality of all the eligible studies in the following 3 aspects: selection, comparability, and exposure. Scores ranging from 0 to 9 were used to evaluate the quality of the original studies. A score of 6 or above was considered as high quality.Inclusion criteria of this meta-analysis were as follows: case-control studies; investigation of the relationship between RA risk with at least 1 of 2.3All the eligible studies were independently reviewed by 2 authors. Any disagreement about data was settled through a team discussion until a consensus was reached. For each study, the following data were collected: author list, year of publication, ethnicity, genotyping method, genotypes frequency in each polymorphism, diagnostic criteria, matching criteria, source of RA, source of control, and NOS scores.2.4PDCD1 polymorphisms and RA susceptibility. Chi-square test was used to evaluate whether the genotype distributions of each control group followed the Hardy-Weinberg equilibrium (HWE), significant P < .05 was considered statistically significant. Odds ratio (OR) and 95% confidence interval (CI) were calculated to evaluate the association between PDCD1 polymorphisms and RA risk in 4 genetic models which were dominant, recessive, codominant, and additive. Subgroup analysis was performed based on ethnicity (Asians or Caucasians). The chi-squared-based Q statistical test and I2 metric value were used to assess the statistical heterogeneity between studies. If the I2 value is >50% or PQ < .10, a difference in statistical heterogeneity existed, ORs were pooled by the random-effect model, otherwise, the fixed-effect model was applied. Publication bias was examined by a funnel plot and Egger test. If the P value in Egger test was less than .05, publication bias was statistically significant. Otherwise, the study was considered to have no publication bias.We performed a meta-analysis to assess the association between P values were considered 2-sided, unless otherwise stated.All statistical analyses were performed using Stata 12.0 software  and all 33.1–23 investigated the relationship of PDCD1 polymorphisms and RA risk fulfilled the eligibility criteria. The study selection process is shown in Figure –22 Three studies involving 1382 cases and 3720 controls focused on the relationship between rs11568821 (PD-1.3 G/A) polymorphism and RA.–21,23 Another 3 studies including 1985 RA cases and 1400 controls studied the relationship between rs2227981 (PD-1.5 C/T) polymorphism and RA.,21,22 Moreover, rs11568821 (PD-1.3 G/A) was nonpolymorphic in Asians and so was rs2227981 (PD-1.5 C/T) in Caucasians. Because there were only 2 studies exploring rs2227982 (PD-1.9 C/T) polymorphism, we excluded it in our study. The general demographics characters of all these studies are shown in Table A total of 6 studies3.23.2.1For the association between rs36084323 (PD-1.1 G/A) and the risk of RA, 4 studies were included according to the match criteria. Significant heterogeneity existed in all genetic models, so we applied random-effect model. We found null association between rs36084323 (PD-1.1 G/A) and RA risk in any of the 4 genetic models based on random-effect model. Because there was only 1 study in Caucasian population, we conduct ethnicity subgroup analysis in Asians. Similarly, we failed to find any association in any of the 4 genetic models based on random-effect model. All the results are shown in Table 3.2.2As for rs11568821 PD 1.3 G/A), 3 studies were included. We applied fixed-effect model because there was no significant heterogeneity in any of the 4 genetic models. There was no rs11568821 (PD-1.3 G/A) polymorphism in Asian populations, we only conducted analysis in Caucasian. We observed significant correlation between rs11568821 (PD-1.3 G/A) and RA risk in addictive model and dominant model  in Caucasian. Table  G/A, 3 s3.2.3With regard to rs2227981 (PD-1.5 C/T), our study included 3 studies, which were conducted in Asian population. The results indicated that there was no significant association between rs2227981 (PD-1.5 C/T) polymorphisms and RA risk in any of 4 genetic models. All the results were listed in Table 3.2.4t = 0.18, P = .87 for rs36084323 [PD-1.1 G/A]; t = 0.97, P = .51 for rs11568821 [PD-1.3 G/A]; t = −0.18, P = .89 for rs2227981 [PD-1.5 C/T]). The shape of the Begg funnel plots in the overall population did not reveal any obvious asymmetry.Publication bias was assessed by Begg funnel plots and Egger test. Significant publication bias was not observed in any meta-analysis of the 3 polymorphisms under addictive model .RA is one of the most common and the typical representative of autoimmune diseases, characterized by synovial tissue inflammation and progressive destruction cartilage, which is one of the strongest predictors of long-term outcome and disability in RA patients.PDCD1 polymorphism and susceptibility to RA, the results remain controversial. In this meta-analysis, we quantitatively evaluated the correlation between 3 SNPs of PDCD1 gene and RA susceptibility.Though a number of studies have investigated the association between PDCD1 gene (Gene Bank accession no. AF363458). Transcription initiation is an important part of regulation in gene expression. Polymorphisms that occurred in the promoter could affect the normal process of gene activation and transcriptional initiation, thus increase or decrease the quantity of mRNA and protein. Theoretically, PD-1.1 should be the most likely polymorphism site associated with RA risk. However, we failed to detect significant association of rs36084323 (PD-1.1 G/A) polymorphism and RA risk according to our results. When further stratified by ethnicity, our results indicated null association in Asian populations. The limited studies and generally small sample size may affect the accuracy of this result especially given that only 1 study was conducted in Caucasian populations.The rs36084323 (PD-1.1 G/A) is located in the promoter of  Considering only 2 studies were involved in their study, our result improved the credibility of the conclusion. Even so, extra cautious should be taken because of the generally limited number of studies and the OR value, which was close to 1. The rs11568821 (PD-1.3 G/A) is located in intron 4, in general, polymorphic sequence variations are considered to be rather harmless, especially if located in noncoding parts of a gene. It may be that the Rs11568821 (PD-1.3 G/A) is not itself the responsible allele, but is in linkage disequilibrium with the true causative allele. Although rs11568821 (PD 1.3 G/A) polymorphism has been found to be significantly associated with the risk of developing RA, the interactive function of PDCD1 SNPs and other genes may have an important role in the etiology and development of RA.For rs11568821 (PD-1.3 G/A) polymorphism, statistical significance was observed between rs11568821 (PD-1.3 G/A) polymorphism and risk of RA. This result was consistent with a previous meta-analysis by Lee et al.Similar to rs36084323 (PD-1.1 G/A), there was null significant association between rs2227981 (PD-1.5 C/T) and susceptibility to RA under 4 genetic models. All 3 studies involved in the relationship between rs2227981 (PD-1.5 C/T) polymorphism and RA risk were from Asian populations. In order to further verify this result, studies from other populations should be addressed.PDCD1 gene, especially in different ethnic groups, so our analysis may have been underpowered. Second, confounding factors, publication bias, and heterogeneity may have distorted the results. Furthermore, we primarily collected data about the rs2227982 (PD-1.9 C/T) polymorphism and the RA risk, but only 2 studies were eligible and they were from different ethnicity so thus it were not included in our study.Some limitations of this study should be addressed. First, the number of studies fulfilled the eligibility criteria and finally included in this study were limited. Among which 4 studies reported the polymorphism of rs36084323 (PD-1.1 G/A) (3 from Asians and 1 from Caucasians); 5 studies reported the polymorphism of rs11568821 (PD-1.3 G/A) (2 from Asians and 3 from Caucasians); 3 studies reported the polymorphism of rs2227981 (PD-1.5 C/T) . This could not provide sufficient statistical power to study the exact effect of SNPs in In conclusion, we conducted a meta-analysis of all the eligible studies related to the rs36084323 (PD-1.1 G/A), rs11568821 (PD-1.3 G/A), and rs2227981 (PD-1.5 C/T), and susceptibility to RA. The results show that no significant relationships were observed between rs36084323 (PD-1.1 G/A) and rs2227981 (PD-1.5 C/T) polymorphisms and RA risk, neither in Caucasians nor Asians, while rs11568821 (PD-1.3 G/A) was observed to be significantly associated with risk of RA in Caucasians . The mutant A allele in rs11568821 (PD-1.3 G/A) polymorphism represents a higher risk of RA in Caucasians. However, as a limited number of eligible studies were included in this work, the reported results should be cautiously interpreted. For the purpose of obtaining more reliable results, it is necessary to conduct better-designed studies based on larger sample sizes in the future.


UGT2B15 gene D85Y polymorphism and prostate cancer have yielded contradictory results. We therefore systematically searched in the PubMed, EMBASE, Science Direct/Elsevier, CNKI, and Cochrane Library databases, and identified six relevant studies with which to perform a meta-analysis of the relation between UGT2B15 D85Y polymorphism and prostate cancer risk. Our meta-analysis revealed a significant association between UGT2B15 D85Y gene polymorphism and prostate cancer in all genetic models (P<0.05). The combined odds ratios and 95% confidence intervals were as follows: additive model, 0.53 and 0.32-0.88; dominant model, 0.51 and 0.33-0.79; recessive model, 0.76 and 0.60-0.96; co-dominant model, 0.55 and 0.35-0.86; and allele model, 0.70 and 0.55-0.89. These results are consistent with the idea that the UGT2B15 D85Y enzyme variant reduces the risk of prostate cancer by efficiently metabolizing dihydrotestosterone (DHT), which is associated with prostate cancer progression.UGT2B15 (uridine diphosphate-glucuronosyltransferase 2B15) catalyzes the conversion of lipophilic C19 steroid androgens such as dihydrotestosterone (DHT) into water-soluble metabolites that can be excreted. Studies of the association between the  Prostate cancer (PCa) is one of the most frequently diagnosed malignancies in men resulting in more than 250,000 deaths annually , 2. AlthUGT2B15 is expressed in many steroid-sensitive tissues like the prostate [The enzyme UGT2B15 belongs to a large group of UDP glucuronosyltransferases  of the eprostate  and its prostate .UGT2B15 gene that results from a single-base-pair change of guanine to thymine leads to a variant with higher Vmax with reduced risk of PCa [UGT2B15 D85Y gene polymorphism with prostate cancer risk.The D85Y polymorphism in the k of PCa . Since Uk of PCa –28. SomeUGT2B15 gene by using restriction fragment length polymorphism (RFLP) analysis after polymerase chain reaction (PCR) amplification.The details of the literature review process performed in this study are shown in Figure UGT2B15 D85Y gene polymorphism and prostate cancer in all the genetic models (P<0.05). The combined ORs and 95% CIs were as follows: additive model  models were analyzed by the random-effects model. The meta-analysis revealed significant association between the UGT2B15 D85Y gene polymorphism and prostate cancer. Studies have shown that androgens play important roles in the growth, proliferation and progression of prostate cancer. Therefore, our study showed that the UGT2B15 gene product that is involved in androgen metabolism played a critical role. Specifically, the data indicated that UGT2B15 Y85 was protective against prostate cancer.This study focused on six reports in the literature to analyze the association of the uridine diphosphate-glucuronosyltransferase 2B15 gene polymorphism with the risk of prostate cancer. Our results showed that all genetic models  demonstrated significant association between the UGT2B15 gene function [UGT2B15 and sipoglitazar exposure with nearly two-thirds of the inter-subject variability in sipoglitazar plasma exposure attributed to the UGT2B15 genetic variation [in vivo probe for glucuronidation by UGT2B15 [D85Y polymorphism was non-synonymous with function –31. Prevfunction . Furtherariation . All the UGT2B15 . SimilarUGT2A genes are primarily expressed in olfactory epithelium and are involved in terminating odorant signaling. The UGT2B enzymes  are widely expressed in the liver and extra-hepatic steroid target tissues mediating the conjugation of diverse steroid substrates [The UGT (UDP-glucuronosyltransferase) super- family of enzymes comprises endoplasmic reticulum-bound proteins that catalyze the glucuronidation of numerous compounds including drugs, carcinogens and hormones and the resultant inactive polar derivatives are excreted in bile and urine. The UGT1 enzymes on chromosome 2 are primarily involved in the conjugation of bilirubin, phenols, and estrogens. The larger UGT2B enzyme family (on chromosome 4) is grouped into two subfamilies with highly homologous members, namely UGT2A and UGT2B. The bstrates , 35. Seqbstrates . Althougbstrates –28.UGT2B15 gene, a guanine-to-thymine SNP was identified that resulted in an amino acid change from aspartate (D) to tyrosine (Y) at position 85 [max of UGT2B15 (Y85) was twice that of UGT2B15 (D85) for C19 steroids, such as 5-androstane-3, 17-diol and DHT [As a member of the UGT2B enzyme family, UGT2B15 is a key enzyme for the inactivation of DHT, an active androgen in prostate cells. In the human ition 85 . Althoug and DHT .et al. reported that the Vmax of the enzyme resulting from the Y allele was approximately twice compared to the D allele, although no significant differences were evident in the Kmax of the two enzymes. These findings implied that the D enzyme inefficiently metabolized DHT, resulting in a high DHT concentration in the prostate tissue. Higher levels of DHT were associated with prostate cancer development [Levesque elopment , 40. OurUGT2B15 D85Y gene variant in prostate cancer.However, there are few limitations in our study that need to be considered when interpreting the results of this meta-analysis. First, the sample size of each of the studies was relatively small with a total of 817 prostate cancer patients and 1000 normal controls investigated in the six studies. Second, several studies had to be excluded from the meta-analysis owing to lack of control data. Because of limited samples, subgroup analysis could not be performed and therefore, definitive conclusions could not be drawn regarding the clinical value of the UGT2B15 D85Y gene variant is protective against prostate cancer. The plausible reason is that the variant has enhanced ability to metabolize DHT, thereby reducing the risk of prostate cancer by decreasing testosterone levels. However, studies with larger sample sizes are necessary to confirm this finding.In summary, the results of this meta-analysis suggest that the UGT2B15 D85Y gene polymorphism and prostate cancer risk. Two independent reviewers searched PubMed, EMBASE, Science Direct/Elsevier, MEDLINE CNKI, and the Cochrane Library from their inception until June 2016 without restrictions on the language of the report or the study type. The search terms combined text words and MeSH terms. For example, the search terms for the uridine diphosphate-glucuronosyltransferase 2B15 gene were “uridine diphosphate-glucuronosyltransferase 2 family, polypeptide B15” “UGT2B15”, “UDP glucuronosyltransferase 2 family”, “polypeptide B15” or “ugt2b15”; those for prostate cancer were “prostate cancer”, “prostatic neoplasms”, “cancer of prostate”, “cancer of the prostate”, “neoplasms, prostate”, “neoplasms, prostatic”, “prostate neoplasms”, “prostatic cancer” or “PCa”; and those for the polymorphism were “SNP”, “single-nucleotide polymorphism”, “polymorphism”, “variation” or “mutation.” All related articles and abstracts were retrieved. In addition, references cited within relevant reviews were retrieved manually. The search focused only on full articles for the meta-analysis.This meta-analysis was restricted to published studies that investigated the association between The inclusion criteria for the studies were: (1) Studies that tested the association of uridine diphosphate-glucuronosyltransferase 2B gene variants with prostate cancer; (2) The case groups were prostate cancer patients and healthy individuals were controls and (3) Genotyping for the D85Y SNP was conducted using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The data extracted from relevant articles included eligible and genotyped cases with controls and the total numbers of cases and controls for each D85Y genotype.The exclusion criteria were: (1) Studies that were case reports, abstracts, reports from meetings, review articles or duplicated previous publications (2) Studies that lacked a control population and (3) Studies that lacked data on genotype frequencies.Two independent reviewers screened the titles and abstracts of all citations obtained from the literature search and retrieved those that met the eligibility criteria. If the decision based on the title and abstract was ambiguous, the final decision was made after reviewing the full text. Disagreements were resolved by consensus between the two independent reviewers or decided by a third reviewer.The following data were extracted from the papers by the three reviewers: author names, year of publication, country, the numbers of genotype, genotyping methods, the numbers of cases and controls in each study regarding D85Y genotype and the outcomes. Quantitative meta-analysis was performed and analyzed by the two reviewers using Review Manager (RevMan) software  and Stata software .2) in the pooled analyses. If the P-value was less than 0.1 or the I2-value was greater than 50%, the summary estimate was analyzed in a random-effects model. Otherwise, a fixed-effects model was applied. The association between D85Y polymorphism in the UGT2B15 gene and prostate cancer risk was investigated in the allelic (Y vs. D), additive (YY vs. DD), dominant (YY and YD vs. DD), recessive (YY vs. YD and DD) and co-dominant (YD vs. DD) models, respectively, where D represents aspartic acid and Y represents tyrosine. Further, publication bias was detected by visual symmetry of the funnel plots, with asymmetry suggesting possible publication bias. It was also assessed by Begg's and Egger's test in the meta-analysis. A P-value of less than 0.05 indicated publication bias.The combined odds ratio (OR) and its 95% confidence interval (CI) were calculated. Heterogeneity or variation between studies was assessed using the P-value and the I-square statistic (I


P = 0.003), but not in other four models. In conclusion, rs743572 may increase breast cancer risk in postmenopausal individuals, but not in premenopausal folks and general populations.Association between CYP17 T-34C (rs743572) polymorphism and breast cancer (BC) risk was controversial. In order to derive a more definitive conclusion, we performed this meta-analysis. We searched in the databases of PubMed, EMBASE and Cochrane for eligible publications. Pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were used to assess the strength of association between CYP17 T-34C polymorphism and breast cancer risk. Forty-nine studies involving 2,7104 cases and 3,4218 control subjects were included in this meta-analysis. In overall, no significant association between CYP17 T-34C polymorphism and breast cancer susceptibility was found among general populations. In the stratified analysis by ethnicity and source, significant associations were still not detected in all genetic models; besides, limiting the analysis to studies with controls in agreement with HWE, we also observed no association between CYP17 T-34C polymorphism and breast cancer risk. For premenopausal women, we didn't detect an association between rs743572 and breast cancer risk; however, among postmenopausal women, we observed that the association was statistically significant under the allele contrast genetic model (OR = 1.10, 95% CI = 1.03–1.17,  Breast cancer (BC), the most frequent malignant neoplasm among female worldwide, accounts for approximate 25% of women malignant tumor. It is reported that 1.67 million people were diagnosed as BC ever year, therefore it has become a serious health issue, especially in the developing countries . NeverthMany studies about the genetic mutations or SNP occurring in CYP17 gene could enhance CYP17’s transcription rate and increase the enzyme cytochrome P450c17 level, resuling in an increasing number of bioavailable estrogen, which is likely to affect the risk and aggressiveness of BC . But manAs showed in Figure Meta-analysis results among overall populations, distribution of this polymorphism in case groups and control groups are presented in Table P = 0.281), TT/CC , TC/CC , TT+TC/CC  and TT/TC+CC . Analogously, further subgroup analysis by ethnicity and source found similar results that in all the ethnic groups, HB group and PB group there is no significant correlation between rs743572 and BC susceptibility. Moreover, if we only analyze the studies with controls in agreement with HWE, no correlation between rs743572 and BC risk were observed  (Table P = 0.539), TC/CC , TT+TC/CC  and TT/TC+CC  . In postmenopausal women, significant correlation was found in T/C model , final consequences were not changed when we excluded the abovementioned four studies. Besides, after performing the sensitivity analysis, the pooled OR values were not statistically significant changed when we delete each of the researches, indicating that this study has good stability and reliability.Even though four researches included in our studies were not conformed to the HWE balance  AND (polymorphism OR variant OR genotype OR SNP) AND (CYP17 OR CYP17A1 OR P450c17). Besides, the references of the retrieved studies were also reviewed to identify additional eligible studies.The included studies must meet the following criteria: (1) case-control design; (2) investigating the association between CYP17 T-34C polymorphism and breast cancer risk; (3) sufficient genotyping data that could be used to calculate odds ratios (ORs) and 95% confidence intervals (CIs); (4) all the breast cancer subjects in case groups must be pathologically confirmed. The exclusion criteria were: (1) not case-control studies; (2) review article or commentary; (3) duplicate studies; (4) studies lacking relevant data.P value for Hardy-Weinberg equilibrium (HWE). In addition, we also evaluated the methodological quality of included studies based on Newcastle-Ottawa Scale (NOS), which scored studies according to three aspects: selection, comparability, and exposure. Therefore, all studies could be divided into three categories: “low quality” studies (score 0–3); “moderate quality” studies (score 4–6); “high quality” studies (score 7–9).Two reviewers independently extracted the relevant data from the included studies, and discrepancies were resolved during a discussion with a third author. The following information was extracted: the first author, year of publication, country, ethnicity, source of controls, number of cases and controls, and I2 test and Q test, P < 0.05 was considered statistically significant. For I2 test, the criteria for heterogeneity were as follows: I2 < 25%, no heterogeneity; 25%–75%, moderate heterogeneity; I2 > 75%, high heterogeneity. If the P value of Q test was < 0.1, the random-effects model was used; otherwise, the fixed-effects model was applied. Sensitivity analysis was performed by excluding one study at a time to assess the influence of each study on the pooled ORs. Begg’s funnel plot and Egger’s tests were used to examine publication bias and to evaluate the stability of the results by sensitivity analysis. The P value for Hardy-Weinberg equilibrium (HWE) in controls of every included study was calculated by Chi-square test. Subgroup analysis was performed according to ethnicity. All statistical analyses were performed using STATA version 10.0 software . All P values were two sided, and P < 0.05 was considered statistically significant.The association between CYP17 T-34C polymorphism and BC susceptibility was measured by pooled odds ratios (ORs) and 95% confidence intervals (CIs) in five genetic models, including an allele contrast genetic model, a homozygote genetic model, a heterozygote genetic model, a dominant genetic model, and a recessive genetic model. Pooled ORs were performed for homozygote comparison (TT vs. CC for rs743572), heterozygote comparison (TC vs. CC for rs743572), dominant model (TT/TC vs. CC for rs743572), recessive model (TT vs. TC/CC for rs743572) and allelic model (T vs. C for rs743572) respectively. Statistical heterogeneity was evaluated by