Several prospective cohort and case-control studies reported the inconsistent association between biospecimen composition of C20 and C22 long-chain (LC) n-3 polyunsaturated fatty acid (PUFA) and colorectal cancer (CRC) risk. The aim of the present study was to investigate the association of biospecimen LC n-3 PUFA with CRC risk based on prospective cohort and case-control studies.2I = 10.00%) and prospective cohort studies , respectively. A significant dose-response association was found of biospecimen C20:5n-3 (P for nonlinearity  = 0.02) and C22:6n-3 (P for trend  = 0.01) with CRC risk, respectively. Subjects without CRC have significantly higher biospecimen compositions of C20:5n-3 , C22:6n-3  and total LC n-3 PUFA  compared with those with CRC.Cochrane Library, PubMed, and EMBASE database were searched up to February 2014 for eligible studies. Risk ratios (RRs) or odds ratios (ORs) from prospective and case-control studies were combined using a random-effects model in the highest vs. lowest categorical analysis. Nonlinear dose-response relationships were assessed using restricted cubic spline regression models. Difference in tissue composition of LC n-3 PUFA between cases and noncases was analyzed as standardized mean difference (SMD). Three prospective cohort studies and 8 case-control studies were included in the present study, comprising 60,627 participants . Higher biospecimen LC n-3 PUFA was significantly associated with a lower risk of CRC in case-control (pooled OR: 0.76; 95% CI: 0.59, 0.97; The present evidence suggests human tissue compositions of LC n-3 PUFA may be an independent predictive factor for CRC risk, especially C20:5n-3 and C22:6n-3. This needs to be confirmed with more large-scale prospective cohort studies. Colorectal cancer (CRC) is the most frequently diagnosed, and has a higher incidence or mortality in both women and men in developed countries than in developing countries Accumulating evidences from in vitro and in vivo studies The aim of the present study was to examine the relationship between LC n-3 PUFA compositions in human biospecimens and CRC risk based on prospective cohort and case-control studies. Additionally, the differences in biospecimens (plasma/serum/erythrocytes/whole blood/AT) compositions of LC n-3 PUFA between cases and noncases were also investigated based on case-control studies. We therefore conducted a meta-analysis to clarify the role of tissue compositions of LC n-3 PUFA in the etiology of CRC.We identified prospective and case-control studies which reported the association between LC n-3 PUFA composition in biospecimen and CRC risk from PubMed, EMBASE and Cochrane Library database up to February 2014. Search strategy was  for PubMed,  for EMBASE and  for Cochrane Library databases. We also searched systematic reviews from the above-mentioned database, and check the reference lists to identify studies that might have been missed. We followed MOOSE guidelines of observational studies To examine the associations of human biospecimen LC n-3 PUFA with risk of CRC, the inclusion criteria were: 1) Participants: Any aged adults from the same population; 2) Exposure: LC n-3 PUFA compositions in human biospecimen (serum/plasma/whole blood/erythrocytes/AT); 3) Outcomes: evaluating CRC incidence as outcome variable and providing risk ratio (RR) or odds ratio (OR) with the corresponding 95% confidence interval (CI) of CRC for all categories of LC n-3 PUFA compositions; 4) Study design: prospective studies  and case-control study.To investigate the differences in human biospecimens LC n-3 PUFA compositions between cases and noncases, the inclusion criteria were: 1) Participants: both the cases and noncases in each study were from the same population; 2) Outcomes: human biospecimen compositions of C22:6n-3, C22:5n-3, C20:5n-3 or total LC n-3 PUFA in cases and noncases; 3) Study design: case-control study.In the present meta-analysis, biospecimen LC n-3 PUFA composition was defined as the sum of C22:6n-3, C22:5n-3, C20:5n-3 compositions in human biospecimens (serum/plasma/whole blood/erythrocytes/AT). Blood LC n-3 PUFA composition was defined as the sum of C22:6n-3, C22:5n-3, C20:5n-3 compositions in human blood (plasma/serum/erythrocytes/whole blood).Data extraction was finished independently and performed twice by two reviewers (XLR and FLW), and disagreements were reconciled by consensus. The following data were extracted form each original study: participant characteristics , biospecimen LC n-3 composition as exposure of interest , biospecimen compositions of C22:6n-3, C22:5n-3, C20:5n-3 and total LC n-3 PUFA in cases and noncases, adjusted covariates and RR (OR) including 95% CI for all categories of LC n-3 PUFA composition. Our search was restricted to human studies, and we did not contact authors for the detailed information of primary studies and unpublished studies.I2 statistic. I2 statistic describes the proportion of total variation attributable to between-study heterogeneity as opposed to random error or chance. We defined the low, moderate and high degrees of heterogeneity by I2 values of 25%, 50% and 75% as cut-off points I2 value greater than 50% as indicative of heterogeneity according to Cochrane Handbook. In the presence of substantial heterogeneity, stratified analysis was conducted to identify the possible sources of heterogeneity by study design (case-control and prospective study), different regions (Asia and West (Europe and USA)), gender (women and men) and biospecimen types (blood and adipose tissue). Meta-regression with restricted maximum likelihood (REML) estimation was conducted to assess the potentially important covariates exerting substantial impact on between-study heterogeneity. Sensitivity analysis was performed to evaluate possible influence of individual study with potential bias on overall risk. Publication bias was quantitatively examined by Begg's test and Egger's regression test We conducted two types of meta-analysis. Firstly, we performed a meta-analysis for the highest category vs. lowest. Multivariate adjusted RR (OR) for the highest vs lowest category to assess the association of biospecimen LC n-3 with CRC risk from each original study was firstly transformed to their logarithm (logRR or logOR), and the corresponding 95% CIs were used to calculate corresponding standard errors (selogRR or selogOR). Summary RR (SRR) including corresponding 95% CI as the summary risk estimate for all prospective and case-control studies was estimated using a random-effects model P-value for nonlinearity was calculated by testing the null hypothesis that the coefficient of the second spline is equal to zero P-value for nonlinearity >0.05), a linear dose-response analysis P-value less than 0.05 were considered statistically significant in the present study.Furthermore, the dose-response association of biospecimen LC n-3 PUFA with CRC risk was performed in the present study. Original studies with 3 or more categories were included in the dose-response analysis. Midpoint of upper and lower boundaries was taken as the dose of the quantile if the study only reported the range; if the highest quantile was open-ended, its dose was regarded as 1.2-fold the highest boundary We identified 599 potential studies from electronic search, and 515 studies were left after removing duplicates. Eleven relevant studies were eligible for the present study after full text review . A total2I = 0.00%) (I2 = 0.00%) and 0.68 , respectively (I2 = 47.60%).Overall, 3 prospective cohort = 0.00%) . Biospecectively . HoweverP for meta-regression  = 0.14). We further focused on the difference in pooled association estimate between prospective cohort and case-control study. In 3 cohort studies, biospecimen C20:5n-3, C22:6n-3 and LC n-3 PUFA was all significantly associated with the lower risk of CRC, and the pooled RR was 0.77 , 0.76 , and 0.76 , respectively. However, only one prospective cohort study separately reported an association between serum C22:5n-3 and CRC risk in Japan males and females I2 = 28.60%). In 4 case-control studies, higher biospecimen LC n-3 composition was also significantly associated with a lower risk of CRC , especially biospecimen C22:6n-3 , whereas biospecimen C20:5n-3 exhibited no significant association . There were 2 case-control studies reported the association of biospecimen C22:5n-3 with CRC risk 2I = 0.00%). However, the results of the meta-regression did not show the significant difference between the two study designs. No evidence of significant difference was found between other subgroups with meta-regression  and Egger's regression test (P for bias  = 0.175).In a sensitivity analysis, we sequentially omitted 1 study at a time and reanalyzed the remaining data. We found that exclusion of any individual study did not substantially change the overall association. In publication bias analysis, there was also no indication of publication bias as suggested by visual inspection of Begg's funnel plot (I2 = 0.00%) (I2 = 36.20%) and C22:6n-3 composition  (I2 = 17.60%)  . Similar= 0.00%) . However 17.60%) .P value  = 0.05). Furthermore, biospecimen compositions of C20:5n-3 and C22:6n-3 were both significantly higher in Asian noncases compared with cases, whereas no significant difference was observed in Western noncases compared with cases. There was no significant difference between the two populations with meta-regression  . The nonlinear association between biospecimen C22:6n-3 and CRC risk was not significant (P for nonlinearity  = 0.10), but the overall association in the linear dose-response model was significant (P for trend  = 0.012), with a 1% increment of biospecimen C22:6n-3 composition associated with 5% reduced risk of CRC . Likewise, three relevant studies were available to evaluate the dose-response relationship between biospecimen C22:5n-3 and CRC risk P for nonlinearity  = 0.10; P for trend  = 0.38)  . Six eli = 0.01) . A signi = 0.38) .To our knowledge, this is the first meta-analysis evaluating an association between biospecimen LC n-3 PUFA and CRC risk. Overall, our findings suggested that biospecimen composition of LC n-3 PUFA was inversely associated with CRC risk, especially C20:5n-3 and C22:6n-3. Tissue compositions of C20:5n-3, C22:6n-3 and total LC n-3 PUFA were all significantly lower in CRC subjects compared with controls without CRC.2) with promoting tumor growth effects 3) with suppressive effects in several cell types including CRC cells There are several hypothesized mechanisms explaining the possible protective role of tissue LC n-3 PUFA in the etiology of CRC carcinogenesis. The lower composition of LC n-3 PUFA in cases was observed in the present study, suggesting that the characteristic LC n-3 PUFA composition in biospecimen may be involved in the mechanism of CRC progression. Firstly, LC n-3 PUFA existing in biomembrane phospholipids has been found to be involved in the regulation of downstream receptor activity, cell proliferation and apoptosis process by alternation of the fluidity, structure and/or function of lipid rafts or caveolae located in cell surface In subgroup analyses by study design for the highest category vs lowest, the pooled association estimates of LC n-3 PUFA including the specific subtypes were all significant in prospective cohort studies, although the pooled estimate of C20:5n-3 and C22:5n-3 from case-control studies did not reach statistical significance. Prospective cohort studies greatly decreased the possibility of recall bias and selection biases, which are always inherent in retrospective case-control studies, in view of exposure information was collected before suffering from the disease. Thus, prospective cohort designs are warranted to elucidate causal relationships. In addition, the difference in the number and types of the potential covariates adjusted in multivariable statistic models probably resulted in the discrepant results between cohort and case-control studies. Therefore, we cannot exclude the possibility that the true associations might be distorted in case-control studies adjusting for few confounding factors. For the stratified analysis of LC n-3 PUFA composition between cases and noncases by biospecimen types, blood (serum/plasma/erythrocytes) compositions of LC n-3 PUFA revealed that a statistically significant difference between cases and noncases, but not AT. The heterogeneity between the two biospecimens may be partially explained by different metabolic characteristics of these human biospecimens (serum/plasma/erythrocyte/AT) as biomarkers. Plasma (serum) biomarker represents a combination of triacylglycerol, cholesterol esters and phospholipids found in lipoproteins, and reflects dietary intakes of the past few hours or days Several strengths could be highlighted in our study. Firstly, our present study showed a characteristic biospecimen compositions of LC n-3 PUFA associated with CRC risk, and further analyzed the difference in the compositions of biospecimen LC n-3 PUFA between CRC cases and noncases. In addition, a biomarker as an indicator of some biological state or condition can closely reflect an integrated measurement of diet over time, thus recall bias might not occur in case-control studies. Finally, no evidence of potential publication bias was observed in the present study, though publication bias could be of concern because small studies with null results tend not to be published. In addition, there are also several potential limitations in the present study. Firstly, meta-analyses of observational studies are susceptible to inherent biases , which might have affected the summarized results. Secondly, selection bias might be unavoidable, due to inclusion of case-control studies with regards to elucidating causal relationships. Thirdly, data on association of tissue biomarker with colon or rectal cancer risk was not provided by the original studies, respectively. Given that therapeutic strategy for colon cancer and rectal cancer may differ In conclusion, this meta-analysis provided a sufficient evidence that human biospecimen LC n-3 composition was inversely associated with the risk of CRC, especially C20:5n-3 and C22:6n-3. Populations without CRC have higher tissue compositions of C20:5n-3, C22:6n-3 and total LC n-3 PUFA than those with CRC. These evidences have important public health implications for CRC prevention. LC n-3 PUFA profile in human tissues may be an independent predictive factor for CRC risk. Future epidemiological studies should focus on whether the risk of colon or rectal cancer could be modified by increasing LC n-3 PUFA composition in human tissues, respectively. Nevertheless, the protective effect of human tissue LC n-3 PUFA on CRC risk needs to be replicated by further large-scale prospective studies.Checklist S1MOOSE Checklist of the Present Meta-Analysis.(DOC)Click here for additional data file.Table S1Observational studies Excluded from Meta-Analysis.(DOC)Click here for additional data file.


In vivo and in vitro studies have indicated the link of cholesterol consumption and endometrial cancer risk, however, previous observational studies have yielded inconsistent results. Additionally, a previous meta-analysis published in 2007 found limited evidence of aforementioned association. Therefore, we performed the dose-response meta-analysis to address this concern. Studies were identified using the PubMed, EMBASE and Web of Science databases from the database inception to the end of June 2015 as well as by examining the references of retrieved articles. Two authors independently performed the eligibility evaluation and data extraction. The summary risk estimates and 95% confidence intervals (CIs) were summarized by the random-effects models. One cohort and nine case-control studies were included in the dose-response analyses. Risk of endometrial cancer increased by 6% for 100 mg/day increment in the dietary consumption of cholesterol (Odds ratio (OR) = 1.06; 95% CI = 1.00–1.12), with significant heterogeneity . When stratified by study design, the result was significant in case-control studies . Additionally, although the direction of the associations were consistent in the subgroup analyses stratified by study characteristics and adjustment for potential confounders, not all of them showed statistical significance. In summary, findings of the present dose-response meta-analysis partly support the positive association between dietary cholesterol consumption and risk of endometrial cancer. Since only one cohort study was included, more prospective studies and pooled analysis of observational studies are warranted to confirm our findings in the future. Endometrial cancer (EC) is the fifth most common cancer among women worldwide with almost 0.32 million new cases diagnosed in 2012 which accounted for 4.8% of all female cancer cases , diet maI2 = 66.0%) for saturated fatty acids, 0.98  for monounsaturated fatty acids, and 1.00  for polyunsaturated fatty acids intake [I2 = 62.3%, P for heterogeneity = 0.02) and 1.35  = 0.96–1.90, I2 = 68.3%, P for heterogeneity < 0.01) for the highest compared with the lowest intakes and dose-response analysis of per 150 mg/1000 kcal dietary cholesterol consumption, respectively [Experimental studies have proposed that several components of diet, especially lipids including saturated fatty acid, unsaturated fatty acid, and cholesterol intake have been proposed to influence EC risk by modulating the production, metabolism, and excretion of endogenous hormones –12. We rs intake . Whethers intake –16, but s intake –23. Resuectively . Howeverectively  but alsoectively . Severalectively , 18. TheOur initial search yielded a total of 4263 unique articles Figure . After tThe characteristics of these included studies are summarized in Table Table I2 = 64.2%, P for heterogeneity = 0.003)  (P for bias = 0.785) and Begg's test (P for bias = 0.858) showed no evidence of publication bias as well as visual inspection of the funnel plot , with significant heterogeneity ( = 0.67) . The EggI2 = 59.5%, P for heterogeneity = 0.011). Additionally, the results of meta-regression analyses did not show statistical significance.Table I2 = 44.7%, P for heterogeneity = 0.07) after omitting the study by Lucenteforte et al. [I2 = 53.7%, P for heterogeneity = 0.03) after omitting the study by McCann et al. [In sensitivity analyses around the assignment of the dose of the top categories of consumption in studies that did not report median values, the summary OR was not changed (OR = 1.02 for every 100 mg per day increment in consumption of cholesterol). Figure e et al.  to a hign et al. .In the systematic review and meta-analysis, we systematically reviewed and summarized the relationships between cholesterol consumption and incidence of EC. Our linear dose-response meta-analyses of 10 observational studies found that an increase in cholesterol consumption by 100 mg/day was associated with an 6% increased risk of EC. When stratified by study design, significant results were only observed among case-control studies. In addition, although the direction of this association was consistent in the other subgroup analyses, not all of them showed statistical significance.EC benefits of low cholesterol consumption have been supported by several lines of evidence. Cholesterol and estrogen are physiologically interconnected . As the Previous experimental studies suggested that circulating cholesterol levels were decreased as a result of estrogen therapy in postmenopausal women . In contDespite the publication of a meta-analysis investigating the association between dietary lipids and EC risk in 2007 , we deciWe acknowledge several limitations of our meta-analyses. Compared with randomized controlled trials, observational studies are more likely to inherent susceptible bias. High cholesterol consumption in diets may be related to higher body mass index, cigarette smoking and alcohol drinking, physical activity, and intake of total energy and other nutrients , 32. HowIn conclusion, results from this meta-analysis indicated that dietary cholesterol consumption was associated with EC among case-control studies, but was not associated with risk in cohort studies. Large prospective studies with better adjustment for potential confounders and are warranted to confirm the aforementioned association. Additionally, further evaluation of the impact of measurement errors on these risk estimates is also warranted.Two investigators (T-TG and Q-JW) systematically and independently searched PubMed, EMBASE, and Web of Science from the database inception to the end of June 2015 for epidemiological studies without restriction. The following search keywords were used: (diet OR dietary OR fat OR cholesterol) AND  AND (cancer OR tumor OR carcinoma OR neoplasm). This search strategy was validated in our previous meta-analyses , 36–40. Original studies were included if they (i) had an observational study design; (ii) evaluated the association between cholesterol consumption and EC risk; and (iii) presented relative risk (RR) or OR estimates with 95% CIs or necessary data for calculation ; OriginaTwo investigators (T-TG and Q-JW) extracted the data of these included studies. A third reviewer (Y-ZW) was involved to resolve all the differences. From each eligible study, these two investigators extracted information independently on first author, year of publication, geographic location, the number of cases and controls (in case-control studies) or the number of cases and population participants (in cohort studies), exposure assessment and categories, and study-specific adjusted estimates with their 95% CIs for the highest compared with the lowest category of intake (including adjusted confounders information if applicable). If there were multiple estimates for the association, we used the estimate adjusted for the most appropriate confounding variables, like previous studies , 42, 43.Since the relative rarity of EC in the general population as well as only one cohort study  was inclP-value by testing that these two regression coefficients were simultaneously equal to zero. We calculated a P-value for nonlinearity by testing that the coefficient of the second spline was equal to zero. The details of this method has been published elsewhere [To examine the associations between the cholesterol consumption and EC risk, the summary OR with 95% CIs were estimated by summarizing the risk estimates of each study using the random effect models (Stata META command) because the summaries of random effect model are relatively more conservative than fixed effect models . We summlsewhere , 54.For conducting the dose-response meta-analysis, the following information were needed: (i) the distribution of cases and non-cases and the risk estimates with the variance estimates for at least three quantitative exposure categories; (2) the median or mean level of these exposures in each category . Given this, ten studies met the criteria and were included in the dose-response analysis of cholesterol consumption and EC risk.versus case-control studies), type of control subjects , geographic location (North America versus Europe), validated food frequency questionnaire (yes versus no), number of EOC cases which was categorized by the mean value (≥ 450 versus < 450), and adjustment for potential confounders including total energy intake, body mass index, cigarette smoking, parity, oral contraceptive use, menopausal status, and hormone replacement therapy use. Heterogeneity between subgroups was evaluated by meta-regression (Stata METAREG command) [To investigate the possible sources of heterogeneity of main results, we carried out stratified analyses by the following study features: study design (cohort command) , 36, 44.P-value of 0.05 was used to determine whether significant publication bias existed. Additionally, sensitivity analyses were conducted by deleting each study in turn to reflect the influence of individual data on the overall estimate (Stata METAINF command). All statistical analyses were performed with Stata .Small study bias, such as publication bias was evaluated with Egger's regression asymmetry test  and Begg


Several studies showed that the genetic mutations in the folate-related enzyme genes might be associated with male infertility; however, the results were still inconsistent. We performed a meta-analysis with trial sequential analysis to investigate the associations between the MTHFR C677T, MTHFR A1298C, MTR A2756G, MTRR A66G mutations and the MTHFR haplotype with the risk of male infertility. Overall, a total of 37 studies were selected. Our meta-analysis showed that the MTHFR C677T mutation was a risk factor for male infertility in both azoospermia and oligoasthenoteratozoospermia patients, especially in Asian population. Men carrying the MTHFR TC haplotype were most liable to suffer infertility while those with CC haplotype had lowest risk. On the other hand, the MTHFR A1298C mutation was not related to male infertility. MTR A2756G and MTRR A66G were potential candidates in the pathogenesis of male infertility, but more case-control studies were required to avoid false-positive outcomes. All of these results were confirmed by the trial sequential analysis. Finally, our meta-analysis with trial sequential analysis proved that the genetic mutations in the folate-related enzyme genes played a significant role in male infertility. Infertility is a global health dilemma and a multifactorial disorder affecting approximately 10–15% of all couples. Half of these cases are estimated to be due to male factors156Folates are a group of inter-convertible co-enzymes that play essential roles in DNA synthesis, methylation reactions and protein synthesis. Folate deficiency may impair the function of these metabolic pathways and result in homocysteine (Hcy) accumulation, which further leads to excessive oxidative stress and chaotic methylation reactions. This series of processes is involved in a variety of diseases, including male infertility8The MTHFR gene is located on chromosome 1 (1p36.3), and its protein product catalyzes the reduction of methylenetetrahydrofolate  to methyltetrahydrofolate (5-methyl THF), which then donates a methyl group1012et al.et al. in 2014 that analyzed the same number of studieset al. performed a meta-analysis and found that the A1298C mutation was capable of causing male infertilityet al. held an opposite opinionRecently, the associations between four single nucleotide polymorphisms  and male infertility were widely studied among several ethnicities using different genotyping methods8141515http://www.cnki.net) and WanFang ( http://www.wanfangdata.com.cn)]. The following search phrases were used: (MTHFR or MTRR or MTR or MS) and (polymorphism or mutation) and male infertility. Additional studies were identified by hand, searching the references in original articles and review articles.We systematically collected all of the eligible literature from 01/01/2000 to 31/10/2014 by searching both the common English-language database (PubMed) and the Chinese literature databases [CNKI  evaluation of the MTHFR C677T, MTHFR A1298C, MTR A2756G or MTRR A66G mutations and male infertility risk; (b) a case control design; and (c) sufficient published data for estimating an odds ratio (OR) with a 95% confidence interval (CI). The major reasons for exclusion of studies were as follows: (a) not involving male infertility research; (b) reviews and repeated literatures; (c) not providing the source of cases and controls and other essential information; and (d) not designed as a case control or cohort study.The information was carefully extracted from all of the eligible literatures independently by two investigators based on the inclusion criteria listed above. For a conflicting evaluation, a consensus was reached by discussion. The following information was collected from each literature: the first author’s name, the year of publication, country of origin, ethnicity, genotyping method, numbers of genotyped cases and controls and Hardy-Weinberg equilibrium (HWE) in the controls. The different ethnic descents were categorized as Asian, European, American or African. The genotyping methods were divided into PCR-RFLP, Taqman, allele-specific PCR, SSCP-PCR and sequencing. The quality of the studies was assessed using the Newcastle-Ottawa scale (NOS)Crude odds ratios (ORs) with their corresponding 95% CIs were used to assess the strength of associations between the four mutations in the folate-related enzyme genes and male infertility risk. The pooled ORs were performed for the allele contrast (M versus W), homozygote model (M/M versus W/W), heterozygote model (W/M versus W/W), dominant model (W/M + M/M versus W/W) and recessive model (M/M versus W/M + W/W). Heterogeneity across the studies was evaluated by the chi-square-based Q test and was considered statistically significant if P < 0.10. The pooled OR was assessed in both the fixed-effects model (the Mantel–Haenszel method)www.ctu.dk/tsa). To avoid an increase of overall type I error, we performed trial sequential analyses and then calculated the heterogeneity corrected optimal information size (HOIS). HOIS was estimated according to an overall type-I error of 5%, a power of 95% and a relative risk reduction (RRR) assumption of 10%. A continuity correction of 0.5 was also applied in zero-event trials.We examined the reliability and conclusiveness of the available evidence using a novel statistical analysis software called TSA . In the meta-analysis, it is important to minimize the risk of making a false-positive or false-negative conclusion272831Through the literature search and selection based on the inclusion criteria, a total of 37 papers81114151617183334353637383940414243444546474849505152535455565758596061It was worth noting that there was significant heterogeneity in all of the genetic models. The subgroup analysis failed to reduce the heterogeneity. We then conducted Galbraith plot and meta-regression analysis to probe the source of heterogeneity. We did not find any explicit source of heterogeneity at last. Unacceptable heterogeneity was also observed when we investigated the associations between azoospermia and OAT with the C677T mutation. Through stratified analysis, the heterogeneity of the subgroup was decreased. The results of the meta-regression analysis suggested that ethnicity contributed to substantially altered heterogeneity, which was in accordance with the outcomes of the stratified analysis.For the MTHFR A1298C mutation, five types of genetic models did not produce any significant association among all of the eligible studies The A1298C mutation leads to a glutamine to alanine change at codon 429 and is detected in a regulatory region of the MTHFR enzyme. Eloualid et al. and the authors stated a significant association between this mutation and male infertility in an Asian population8MTR and MTRR, two important regulatory enzymes in the homocysteine metabolic pathway, map to chromosomes 1q43 and 5p15.31, respectively17http://rna.tbi.univie.ac.at/ cgi-bin/.RNAfold.cgi)The homocysteine/methionine cycle is one of the most important pathways of Hcy in most mammalian cells11Despite the overall robust statistical evidence generated through this analysis, some limitations should be addressed. First, identifying the source of heterogeneity was one of the most important goals of this meta-analysis. We only observed significant heterogeneity among all of the genetic models for the C667T mutation. Regretfully, despite great efforts, we failed to identify the source of heterogeneity. Incomplete data and redundant confounding factors might play a role to some degree. Next, our results were based on unadjusted estimates, while a more precise analysis should be conducted if all individual raw data were available, which would allow for the adjustment by other covariates, including folic acid and vitamin intake, drinking status, cigarette consumption, and other lifestyle factors. Third, male infertility is a broad concept that includes many types of disease, such as azoospermia, oligozoospermia, and teratozoospermia, among others. Additionally, male infertility is a multi-factorial disease that results from complex interactions among many genetic and environmental factors. Therefore, a more detailed subgroup analysis and combined effects analysis of the different SNPs are required. Last but not the least, an inadequate sample size may cause false-positive results. Although TSA is applied in our analysis, more studies involving A2756G, A66G, and American or African populations should be included.In conclusion, our meta-analysis with trial sequential analysis demonstrated the important role of genetic mutations in folate-related enzyme genes in male infertility. The identification of male infertility susceptible variants can provide new insight into its etiology. Well-established genetic markers surely would contribute to the early screening and prediction of male infertility. Although, many questions remain unanswered, we believe that genetic mutations in the folate-related enzyme genes are a promising avenue in the research on male infertility. Hence, we recommend the following: first, male infertility contains various diseases, each with a distinct pathogenesis. We should divide patients into corresponding groups based on the different types of male infertility and perform more case-control studies or comprehensive updated meta-analyses to probe the underlying mechanisms. Second, we should attempt to prevent false-positive and negative results by conducting the studies using a large sample with stratification by age, work environment, food habit, lifestyle and ethnicity. Lastly, as genetic background of male infertility is a complicated issue, the combined effects of different SNPs and congenital chromosomal abnormalities cannot be overlooked.How to cite this article: Liu, K. et al. Role of genetic mutations in folate-related enzyme genes on Male Infertility. Sci. Rep.5, 15548; doi: 10.1038/srep15548 (2015).


A high incidence of myocardial infarction among patients with gout has been suggested by several observational studies. We performed a meta-analysis to evaluate the association between gout and the risk of myocardial infarction.The PubMed and Embase databases were searched from inception to October 2014 for cohort studies that evaluating the association between gout and the risk of myocardial infarction. Summary estimates were derived using a random-effects model and reported as relative risks (RRs) with 95% confidence intervals (CIs).p<0.001), and the association referred to non-fatal myocardial infarction  but not fatal myocardial infarction . The increased risk was observed in both women  and men . Stratified analysis revealed a gradual increase in myocardial infarction risk with a younger age of gout onset ; 45–69 years old ; ≥70 years old ).Five studies involving 8,656,413 participants with a total of 1000 MI events were included. Overall, gout was associated with an increased risk of myocardial infarction (RR 1.45; 95% CI, 1.19–1.75; This meta-analysis suggests that patients with gout have an increased risk of myocardial infarction. According to World Health Organization estimates, ischemic heart disease is the primary cause of death worldwide, accounting for 7.4 million fatalities ,2. MyocaGout is the most prevalent form of inflammatory arthritis in developed countries, the prevalence of gout in clinical practices in the UK and Germany is 1.4%, and this disease is estimated to affect 0.9% and 3.9% adults in France and the USA respectively –7. EpideWe adopted the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) checklist when reporting this review . We systWe applied the following inclusion criteria when selecting eligible studies: (i) cohort study; (ii) examination of the association between gout and the risk of MI; (iii) reported the effect size data such as odds ratios (ORs), hazard ratios (HRs) or relative risks (RRs) with 95% confidence intervals (CIs) or provided data allowing the calculation of these values.The following information were extracted from each included study: first author, publication year, country, population characteristics, cohort size, number of gout cases, number of MI events, follow-up duration, ascertainment of gout, assessment of MI, and adjusted covariates. Supplementary files were also examined for data abstraction. When necessary, we contacted the authors of included articles for additional data. Extracted data were entered into a standardized Excel  file. Data extraction was performed independently by two authors (SCL and LX). Any disagreement was resolved by discussion and consensus.The Newcastle–Ottawa Scale (NOS) was used to assess the quality of each included study . The quap <0.1) and measured with the I2 statistic, which was used to estimate the percentage of effect size variability that is attributable to heterogeneity across studies [I² values of 25%, 50%, and 75% were used as cut-off points for low, moderate, and significant degrees of heterogeneity respectively. A random-effects model was used regardless of heterogeneity. A p value <0.05 was considered statistically significant, unless where otherwise specified. We used STATA, version 12.0  to perform the statistical analysis.We used RR as the common measure of an association between gout and the risk of MI. We conducted additional analyses to evaluate the risks of fatal MI and non-fatal MI, as well as the risks in both women and men. Furthermore, we performed stratified analyses to evaluate differences in risk between age groups (20–44 years versus 45–69 years versus ≥70 years). Heterogeneity was assessed using the Cochran Q statistic ( studies –24. I² vA detailed flowchart of the search and selection results is shown in p <0.001), and significant heterogeneity was observed .Because of variations between studies with respect to use of the categories of MI, age and sex used in risk reporting, it was impossible to combine all five included studies and calculate a summary RR for each category.p <0.001); however, we found no significant association between gout and risk of fatal MI . We additionally performed a stratified analysis according to gender among patients with gout; the pooled estimated of multivariable-adjusted RRs for the risk of MI were  for female patients with gout and  for male patients, respectively ; in the 45–69 years age group ; and in the ≥70 years age group .Through a comparison of individuals with and without gout in each age group, we observed a gradual increase in MI risk with a younger age at gout onset. As shown in To the best of our knowledge, this is the first systematic review and meta-analysis to investigate the association between gout and the risk of MI. The pooled results of five cohort studies suggest that both male and female patients with gout have an increased risk of non-fatal MI, but not of fatal MI. Furthermore, stratified analyses revealed a gradient of increased MI risk with a younger age at gout onset.Although our meta-analysis indicated that patients with gout have an increased risk of MI, the underlying mechanism remains unclear and there are several possible mechanisms might explain the observed association. Hyperuricemia, which causes gout pathogenesis, and uric acid, which perpetrates hyperuricemia, have been found to associate with cardiovascular disease (CVD).The inflammatory response associated with gout is characterized simultaneously by the initiation of an acute attack and other typical complex interactions between various cell types . InflammHyperuricemia is known to associate with various risk factors of cardiac disease, such as hypertension and obesity; these are also associated with the activation of circulating platelets and microvascular changes potentially reflective of endothelial dysfunction, which, as a precursor, may be an important contributor to the increased risk of CVD –35. CorrTo some extent, the findings from our meta-analysis of previous studies are clinically significant. Despite significant heterogeneity, all of the consistent evidence revealed an increased risk of MI in patients with gout. However, gout was only found to associate with non-fatal MI, but not fatal MI; this might largely be because of mortality was not attributable to the fatal MI events, which were excluded from the analysis, or because a lower incidence of these events was observed . HoweverGender-related differences in the association between gout and MI remain poorly understood. As gout predominantly affects men, and only a handful of studies have included women, and there remains controversy about the strength of gender-related associations –17, 55. This study has several important potential limitations inherent to the meta-analytic design. The crucial limitation of our study is the observational nature of the investigations, which might introduces bias from various sources, as well as confounding from other risk factors that could provide an alternative explanation for the significant association observed between gout and the risk of MI. However, allowing for the impossibility of a randomized controlled trial, the included cohort studies had an average NOS of 8, which might reduces the likelihood of recall bias. Admittedly, the NOS has a low inter-reviewer reliability, therefore, the quality appraisal should be performed by at least two reviewers to reduce assessment bias .Second, our meta-analysis contained significant heterogeneity across studies in terms of the study design, follow-up duration, definition of gout, assessment of MI, as well as inconsistent adjustment for vascular risk factors in the multivariate analyses, which might have led to confounding bias; furthermore, inaccurate classification bias might also led to heterogeneity. Furthermore, the confidence intervals for the analysis of fatal MI were very wide, suggesting a possible association between gout and fatal MI that was simply not observed in this dataset, and additional studies will be needed to clarify this phenomenon. Other potential sources of bias are mainly attributable to the nature of data; most studies used data was from various healthcare databases, which usually lack modifying factors.A third limitation is that there only five articles were confirmed and available for inclusion in this study, rendering the results prone to influence from publication bias or random error, and lacking sufficient reliability to draw a conclusion in a definitive manner.Finally, although we searched without language restriction and used a comprehensive search strategy, some studies published in other journals or with negative findings might not appear in international journal databases and thus might not have been included in our meta-analysis.In conclusion, the results of this meta-analysis of five studies indicated that both male and female patients with gout have an increased risk of MI; however, this association remains with non-fatal MI, but not with fatal MI. Additionally, MI risk was found to increase in a gradient with a younger age at gout onset. Nevertheless, these results should be interpreted with caution, given the potential bias and confounding in the included studies.S1 PRISMA Checklist(DOC)Click here for additional data file.S1 Table(DOC)Click here for additional data file.S2 Table(DOC)Click here for additional data file.


Purpose. To study the effects of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) polymorphisms on age-related cataract (ARC). Methods. After a systematic literature search, all relevant studies evaluating the association between GSTs polymorphisms and ARC were included. Results. Fifteen studies on GSTM1 and nine studies on GSTT1 were included in this meta-analysis. In the pooled analysis, a significant association between null genotype of GSTT1 and ARC was found . In subgroup analysis, the association between cortical cataract (CC) and GSTM1 null genotype was statistically significant . In addition, GSTM1 null genotype was significantly associated with ARC causing risk to individuals working indoors and not individuals working outdoors. The association between GSTT1 null genotype and risk of ARC was statistically significant in Asians  but not in Caucasians. Conclusions. GSTM1 positive genotype is associated with increased risk of CC and loses the protective role in persons who work outdoors. Considering the ethnic variation, GSTT1 null genotype is found to be associated with increased risk of ARC in Asians but not in Caucasians. Cataract is one of the most common causes of visual impairment and blindness all over the world. 80% of cataract is age-related cataract (ARC), which is classified as cortical cataract (CC), nuclear cataract (NC), or posterior subcapsular cataract (PSC), according to the location of the opacity in the lens , 2. Alth GSTM1/T1 polymorphisms are the most common polymorphisms of GST enzymes, and they have been associated with many diseases, such as rheumatoid arthritis, age-related macular degeneration, oral leukoplakia, prostate cancer, lung cancer, and cervical neoplasia [There are many cellular defense mechanisms that protect the human lens from oxidative damage. The glutathione S-transferase (GST) is one of the detoxification enzyme systems and plays important role in inactivating endogenous and exogenous toxic products under oxidative stress. The GST isoenzymes have been reported to express classes, mu, theta, and pi, in human lens tissue –7. GSTM1eoplasia –13. GSTM1/T1 polymorphisms and ARC has been investigated in many studies however with conflicting results. Recently, a meta-analysis was performed to evaluate the association between GSTM1/T1 polymorphisms and ARC [ GSTM1/T1 polymorphisms in cataract have been published, shedding new light on the topic. We performed an updated meta-analysis of the available studies to better ascertain the association of GSTM1/T1 polymorphisms and the risk of ARC.Possible association between the and ARC . Ever si GST or GSTM1 or GSTT1” and “cataract or age-related cataract or senile cataract or ARC.” When there was more than one publication using the same patient sample, only the one with the largest sample size was selected.We conducted a comprehensive systematic search to identify relevant studies from Medline, Embase, PubMed, Web of Science, and China National Knowledge Infrastructure using keyword combinations: “glutathione S-transferase or GSTM1/T1 polymorphisms and ARC, and (3) providing the information on genotype frequencies of GSTM1/T1 polymorphism in both cases and controls. We collected the following information from each study as initial data: the first author's name, publication year, ethnicity (country), and the number of GSTM1 and GSTT1 genotypes in the cases and controls. The articles were reviewed independently by two investigators (Minjie Ye and Caiyuan Liu), who also extracted data. The quality of studies was also evaluated based on the STROBE quality score systems [Studies that met all the following criteria were regarded eligible: (1) case-control study, (2) investigation of the association between systems . A third GSTM1/T1 polymorphisms and risk of ARC was expressed as odds ratio (OR) and 95% confidence interval (CI). The statistical analysis was performed using Stata 11.0 . An I2 statistic was conducted to evaluate whether inconsistencies among studies were attributed to heterogeneity rather than chance. When there was no heterogeneity of the results of the publications, we used the fixed effects model (Mantel-Haenszel method) [The association between method) . Otherwi method) . Subgrou GSTM1 genotype , and nine studies were included in the meta-analysis of GSTT1 . For the meta-analysis of GSTM1, six studies on Asians and nine on Caucasians were included. While for the analysis of GSTT1, two studies on Asians and seven studies on Caucasians were included. The characteristics of the studies included in the meta-analysis are presented in Flow diagram of studies included in this meta-analysis is provided in  GSTM1 and GSTT1 genotypes is shown in Figures  GSTM1 null genotype and ARC in the overall analysis . The association between GSTT1 null genotype and risk of ARC was statistically significant .The forest plot of the GSTM1 null genotype and risk of ARC was not significant in Asians or Caucasians . Similar results were found for the association between GSTT1 null genotype and risk of ARC in Asian female or male group . When analyzed by subtypes of ARC, the GSTM1 null genotype was significantly correlated with CC . GSTT1 null genotype was significantly correlated with PSC . However, there were no significant associations between GSTT1 null genotype and NC or MT . In subgroup analyses, by the work place, we found that the association between GSTM1 null genotype and ARC was statistically significant in the indoor subjects but not in the outdoor subjects . Similarly, the combination of GSTM1 positive and GSTT1 positive/GSTM1 positive and GSTT1 null genotypes was not associated with ARC risk . The results of subgroup analyses are presented in To investigate the association between profiles of GSTM1 , but no publication bias was detected for GSTT1 .Funnel plots and Egger's test were generated to evaluate potential publication bias for GSTM1  and GSTT  to investigate the possible contribution of insults . Conside GSTM1 null genotype was not associated with the ARC risk in Asian populations. Interestingly, the result of subgroup analyses based on ethnic illustrated that the GSTM1 null genotype was associated with decreased CC risk (P < 0.001). Meanwhile, in subgroup analysis by the work place, we found that GSTM1 positive genotype was not associated with decreased risk of ARC in outdoor subjects. Why does the GSTM1 positive genotype increase the CC risk and lose its protective role in individuals who were occupationally exposed to sunlight? The following reasons may account for the results. (1) Despite the fact that GST enzymes are important in defense against oxidative stress, they also participate in reactions that create toxic products which may result in structural alterations to the proteins and then cause lens opacification [ GSTM1 may lose its ability to prevent cataract development. (3) Absence of the protection of GSTM1 enzyme may stimulate other cellular defense mechanisms to detoxify the substrates. (4) It has been reported that UVB (ultraviolet radiation b) irradiation results in inhibitory effect on GST activity in the skin [Inconsistent with the previous meta-analysis, our finding indicated that thefication . (2) Thethe skin . Therefo GSTT1 null genotype was associated with increased risk of ARC in the Asians but not in the Caucasians, which may be due to the difference between ethnic and the distributions of GSTT1 null genotype. It has been reported that the frequency of the GSTT1 null genotype is higher in Asian population compared with other populations [ GSTT1 null genotype is nearly 50% in both the Chinese and Japanese populations [ GSTT1 gene polymorphism. This could partly explain why the GSTT1 null genotype is associated with increased risk of ARC in the Asian population. In subgroup analyses stratified by subtypes of ARC, we also found that the GSTT1 null genotype increased the risk of CC and PSC.In our study,ulations . The freulations –40. Neveulations , 42. Thu GSTM1 positive and GSTT1 null genotype in ARC development, investigation of the association between the combination of GSTM1 positive and GSTT1 null genotypes and ARC risk should be suggested. Therefore, we did this analysis and found the combination of GSTM1 and GSTT1 null genotypes was associated with 1.281-fold increased risk of ARC, although the association was not significant.Considering the role of GST polymorphisms and human skin and colon mucosa [ GSTM1/T1 polymorphisms and ARC.Gender differences have also been observed on the association betweenn mucosa , 44. ThuDespite the fact that we made an accurate and comprehensive analysis, limitations still existed in our study. First, our meta-analysis only included studies with accessible full-text articles, in English or Chinese. Therefore, the absence of some otherwise eligible studies that were unpublished or reported in other languages could lead to some inevitable publication bias. Second, due to the lack of detailed data, subgroup analysis stratified by habits like smoking and alcohol consumption was not conducted. Third, the type and degree of opacification were classified using the lens opacities classification system II (LOCS II) or lens opacities classification system III (LOCS III). Difference of classified methods among the studies might have affected the results. GSTM1 positive genotype is associated with increased risk of CC and loses the protective role in persons who work outdoors. GSTT1 null genotype confers increased risk of ARC in Asians but not in Caucasians.In summary, this study suggested that


Angiotensin I-converting enzyme (ACE) is crucial in the renin–angiotensin–aldosterone system. ACE insertion/deletion (I/D) polymorphism is a common genetic variation of this gene and is associated with several disease phenotypes. However, the results of published studies on the influence of this polymorphism on renal transplantation are inconsistent. Therefore, a meta-analysis was performed to evaluate the association between ACE I/D polymorphism and prognosis of kidney transplantation.A meta-analysis was performed based on 21 case–control studies from 12 publications (1497 cases and 2029 controls) and 10 studies with quantitative values from 5 publications (814 patients). Pooled odds ratios (ORs) and weighted mean differences (WMDs) with their corresponding 95% confidence intervals (CIs) were used to estimate associations.ACE I/D polymorphism was found to be associated with acute rejection (AR) in genotypes DD+ID versus II  and with serum creatinine concentration after renal transplantation in genotypes DD versus ID . Stratified analysis revealed that recipients transplanted within a year had higher serum creatinine concentrations in the DD versus ID model. No significant association was found between hypertension and ACE I/D polymorphism.ACE I/D polymorphism is associated with AR and allograft function after kidney transplantation. Renal transplantation is considered the best therapeutic approach for patients with end-stage renal disease because it significantly improves the quality of life of patients . Graft fThe renin–angiotensin–aldosterone system (RAS), which regulates homeostasis, vascular tone, blood pressure and salt balance, plays important roles in renal and cardiovascular physiologies –10. AngiThe gene encoding ACE is located in chromosome 17, and individual patients may exhibit presence  or absence  of a 287-base pair Alu repeat sequence in intron 16 of this gene . Thus, pMany studies have investigated the association between ACE I/D polymorphism and renal transplantation, but their results are inconsistent. Considering the decentralised nature of patient data and inconsistent conclusions amongst the reported articles, it has been extremely difficult to assess the validity of the proposed theories of associations. Furthermore, a thorough study of the prognostic aspect of kidney transplantation and ACE I/D polymorphism remains lacking to date. In this study, we performed a meta-analysis to investigate whether ACE allele genotype has any influence on the prognosis of kidney transplantation.To obtain relevant literature, a systematic search was performed using the PubMed and Embase (1966 to March 2014) databases with the following keywords: (‘ACE’ or ‘angiotensin converting enzyme’), (‘polymorphism’), , (‘transplant’ or ‘transplantation’),  and . Only articles written in English were included in the search. All eligible publications on the association between kidney transplantation and ACE I/D polymorphisms were searched. The references listed in the articles found were used as sources of supplementary information. All eligible studies on the association between ACE I/D polymorphisms and kidney transplantation were considered for inclusion using the following criteria: (1) studies must be published in English; (2) studies must be a case–control or cohort study of renal transplant recipients; and (3) studies should have provided data on the ACE genotypes II, ID and DD. In particular, detailed numbers of genotypes must have been provided to calculate the odds ratio (OR) or weighted mean difference (WMD) and the corresponding 95% confidence intervals (95% CIs). The exclusion criteria were as follows: (1) studies not evaluating the correlation between ACE I/D polymorphism and kidney transplantation; (2) animal or cellular studies; (3) reviews, comments, meta-analysis or abstracts; (4) studies that lack a control group; and (5) paediatric studies. For studies with overlapping case series, the largest sample sizes were considered.Information from the publications that met the above criteria was carefully extracted by two independent investigators (Zhengkai Huang and Bian Wu). A third investigator (Jun Tao) subsequently reviewed the results. Discussions were personally conducted to reach a consensus in case of a disagreement. The following items were extracted from each article: first author’s name, publication year, ethnicity, genotyping method, source of controls, numbers of case and control patients in each genotype, time points, prognostic indicator and Hardy–Weinberg equilibrium (HWE) of genotype distribution. Ethnicity was categorised according to research area. When the data were not directly provided, we calculated the number based on its percentage and total amount presented by the articles. Only information from one replicate randomly selected among repeated measurements was used. In addition, serum creatinine level and blood pressure were converted to identical units of measurement for ease of comparison.Pooled OR or WMD and the corresponding 95% CIs were calculated to estimate the strength of association between ACE I/D polymorphism and prognosis of kidney transplantation. A random- or fixed-effects model of rejection events, serum creatinine concentrations and hypertension was used in this meta-analysis. ORs were accurately measured for DD versus ID+II, DD+ID versus II, DD versus II, ID versus II and D allele versus I allele. Meanwhile, WMDs were determined for DD versus II, DD versus ID and ID versus II. In addition, subgroup stratification analyses were performed according to ethnicity or time points after transplantation to explore the association of ACE I/D polymorphism with transplantation outcomes.Q and I2 statistic tests were used to evaluate heterogeneity. I2 > 50% indicates heterogeneity [I2 > 50%, the random-effects model was used; otherwise, the fixed-effects model was utilised. The allele frequencies of the ACE I/D polymorphism from each included article were determined through allele counting. Furthermore, HWE was examined using Chi-square tests. To evaluate publication bias, Begg’s test and funnel plot were used [ogeneity . When Iere used , 17. In Using the search strategies mentioned above, 83 articles were initially identified. Of these, 40 articles were selected for full-text review and 43 were excluded according to the inclusion/exclusion criteria. A total of 27 of the 40 articles were excluded after full-text review because of paediatric recipients or unavailable information. The total baseline characteristics of the included studies are shown in Tables In this meta-analysis, a significant association was detected between ACE I/D polymorphism and AR. The genotype model DD+ID versus II (dominant model) showed a significant difference in AR . However, the other genotypes did not show any association: DD versus II, OR = 2.11, 95% CI = 0.91–4.00; ID versus II, OR = 1.39, 95% CI = 0.96–2.02; DD versus ID+II (recessive model), OR = 1.52, 95% CI = 0.86–2.70; D allele versus I allele, OR = 1.50, 95% CI = 0.92–2.45 , Fig 2. Ten studies measured serum creatinine in the three ACE I/D genotypes after renal transplantation. Regardless of the time points after transplantation, a significant difference in serum creatinine level was found in the DD versus ID model . However, this was not found in the DD versus II and ID versus II models , O'Brien, RP. et al.  examinedIn conclusion, ACE I/D polymorphism is associated with AR and allograft function after kidney transplantation. Early identification of ACE I/D genotype can significantly improve the outcome of patients. Well-designed and large-scale studies are necessary to further verify the present findings.S1 Checklist(DOC)Click here for additional data file.S2 Checklist(DOC)Click here for additional data file.S1 File(DOC)Click here for additional data file.


Increasing evidence suggests that smoking may increase the incidence of prosthesis-related complications after total hip arthroplasty (THA). We performed a meta-analysis of cohort studies to quantitatively evaluate the association between smoking and the risk of prosthesis-related complications after THA.Relevant articles published before August 15, 2014, were identified by searching the PubMed, EMBASE and Cochrane library databases. Pooled risk ratios (RRs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated with either a fixed- or random-effects model.Six cohort studies, involving a total of 8181 participants, were included in the meta-analysis. Compared with the patients who never smoked, smokers had a significantly increased risk of aseptic loosening of prosthesis , deep infection  and all-cause revisions . However, no significant difference in the risk of implant dislocation  or length of hospital stay  was found between smokers and nonsmokers.Smoking is associated with a significantly increased risk of aseptic loosening of prosthesis, deep infection and all-cause revisions after THA, but smoking is not correlated with a risk of implant dislocation or the length of hospital stay after surgery. Total hip arthroplasty (THA) is a highly effective treatment for end-stage osteoarthritis or rheumatoid arthritis of the hip joints when conservative therapy has failed because it contributes to excellent pain relief and great improvement in the hip joint function and patient quality of life ,2. HowevRecently, various investigations have demonstrated that patients' own lifestyles may impact the outcomes of elective orthopedic surgery; among them, smoking has been widely accepted as an important risk factor for the development of postoperative complications –5. It waAlthough several published investigations have identified the association between smoking and the incidence of prosthesis-related complications after THA, the outcomes have been inconsistent –14. For This meta-analysis was conducted according to the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines . We systTwo independent reviewers first screened the titles and abstracts to identify the relevant investigations. Then, full articles were read to include the eligible studies that met the following criteria: (1) used a cohort study design, (2) evaluated the association between smoking and the risk of any prosthesis-related complication after THA, and (3) provided sufficient data for calculating the risk ratio (RR) or weighted mean difference (WMD) with a 95% confidential interval (CI). Reviews, editorials, letters, conference abstracts and studies that did not report the necessary information were excluded.For every eligible study, the following data were extracted by two independent reviewers: surname of the first author, publication date, study location, study population characteristics, total number of patients, follow-up duration, number of patients who had prosthesis-related complications and who required revisions, length of hospital stay after THA, controlled confounders and methods used for controlling the confounders.The quality of all included studies was assessed based on the Newcastle-Ottawa Scale (NOS), a validated tool for assessing the quality of observational studies . StudiesThe WMD with a 95% CI was calculated for continuous outcomes, and RR with a 95% CI was carried out for dichotomous outcomes. As some studies did not report the mean and standard deviation for the length of hospital stay, the methods suggested by Greenland  were uti2 statistic. If p<0.1 or I2 >50%, the heterogeneity was considered statistically significant and a DerSimonian and Laird random-effects model was utilized to combine the data; otherwise, a Mantel-Haenszel or inverse-variance fixed-effects model was used to calculate the pooled RR or WMD among studies. Sensitivity analysis was conducted by omitting one study in each turn and pooling the data of the remaining studies to explore the possible explanations for high heterogeneity and to determine the stability of the outcomes. The publication bias was not evaluated because the number of involved studies was too small (n<10) [Heterogeneity across investigations was evaluated using the Cochrane Q test and Il (n<10) . All anaA flow diagram showing the study selection process is presented in The primary characteristics of the 6 cohort studies are summarized in 2 = 0%). We found that smokers had a significantly increased risk of aseptic loosening of hip prosthesis compared to those who never smoked   .2 = 0%). Meta-analysis of the included studies suggested a significantly increased risk of deep infection in the smokers after THA . We also pooled the RR of deep infection in 2 studies that reported data on current smokers, former smokers and nonsmokers, respectively. Compared with the patients who never smoked, both current smokers  and former smokers  had a significantly higher risk of deep infection . No significant difference in the risk of implant dislocation was found between smokers and nonsmokers   .2 = 64%), a random-effects model was employed. Compared with nonsmokers, smokers had a significantly increased risk of revisions after THA . Subgroup analysis was performed for retrospective cohort studies. The heterogeneity was low across 3 retrospective studies (I2 = 22%), and smokers had a significantly higher risk than nonsmokers   . Sensiti2 = 83%). The length of hospital stay did not differ significantly between smokers and nonsmokers following THA  (2 = 0). However, no significant difference was observed .Three studies, with a total of 5218 patients, were suitable for meta-analysis on the length of hospital stay after THA. A random-effects model was used due to the high heterogeneity across studies (I65–0.72) . We exclIn our meta-analysis of 6 cohort studies, smokers had a significantly higher risk of aseptic loosening of prosthesis, deep infection and all-cause revisions after THA than the patients who never smoked. However, no association was observed between smoking and the risk of implant dislocation or length of hospital stay after surgery.2 = 66%). Therefore, this study should not be used. According to the outcomes of the present meta-analysis, we found that smoking was associated with a 2.05-fold increased risk of aseptic loosening of prosthesis after THA. It has been proposed that a negative balance between the rate of bone growth and bone resorption around the prosthesis results in the development of aseptic loosening [Aseptic loosening of prosthesis is one of the most common complications, which can result in THA failure. In this meta-analysis, 3 studies were used to evaluate the risk of aseptic loosening of prosthesis after THA in the smokers. We excluded 1 study that lacked raw data, which demonstrated that agriculture work rather than smoking or other lifestyle features had a significant relationship with prosthetic loosening based on adjusted RR . In thisoosening . Nicotinoosening . Moreoveoosening . HoweverDeep infection after THA is a serious, even devastating, complication that requires surgical and long-term medical management ,25. ReceIn addition to aseptic loosening of prosthesis and deep infection, a variety of other complications, such as implant dislocation, prosthesis instability, liner breakage and periacetabular fracture, lead to the failures of THA. In the present meta-analysis, no association was found between smoking and the risk of implant dislocation, which is correlated with the BMI  and alcoAlthough a higher risk of postoperative complications was reported in the smokers , there wAccording to the study by Moller et al. , smokingThere are some potential limitations in this investigation. First, the studies involved in the meta-analysis were all cohort studies, and observational studies can only provide information about correlations; but they do not reveal causality. Second, the definitions of smoking status are diverse and ambiguous. For example, in the study by Meldrum et al. , the autThe present meta-analysis suggests that smoking is associated with significantly increased risks of aseptic loosening of prosthesis, deep infections and all-cause revisions after THA, but smoking does not increase the risk of implant dislocation or length of hospital stay. More well-designed investigations, both epidemiological and mechanistic, are required to validate our findings.S1 PRISMA Checklist(DOC)Click here for additional data file.S1 Table(DOC)Click here for additional data file.


CYP19A1 single-nucleotide polymorphisms (SNPs) are associated with clinical response (CR) and adverse effects (AEs) among BC patients treated with AIs. The aim of this study was to analyze the association between CYP19A1 polymorphisms and AI treatment in BC patients.Many clinical trials have shown the efficacy of aromatase inhibitors (AIs) in the management of breast cancer (BC). There is growing evidence that CYP19A1 variants and treatment response among BC patients.A systematic review was performed in MEDLINE, EMBASE, and LILACS. A meta-analysis was conducted to compare the association between P = 0.002). Seven studies analyzed the association between AEs with different polymorphisms of CYP19A1. Although there was a statistically significant association with musculoskeletal adverse events  and with vasomotor symptoms  in individual studies, similar associations were not observed in further studies. No statistically significant association between musculoskeletal AEs and SNPs rs4646, rs10046, rs727479, and rs1062033 was found.A total of 12 studies were included in the final analysis. There was significant variation among the populations studied and the SNPs and outcomes investigated. A meta-analysis was only possible for the evaluation of SNP rs4646 vs. the wild-type variant with respect to time to progression (TTP) among metastatic BC patients treated with AI. TTP was significantly increased in patients with the rs4646 variant compared with the wild-type gene (hazard ratio (HR) = 0.51 , CYP19A1 polymorphisms on clinical outcomes were most often detected in individual studies, suggesting that longer-term studies will better clarify these associations. Additional studies are needed to clarify the predictive value of other SNPs and whether CYP19A1 genotyping should be used to guide AI treatment.These findings suggest that the presence of the rs4646 variant may be a predictive factor of the benefit of AI treatment for BC. The effects of  Breast cancer (BC) is the most common cancer among women, and it accounts for the majority of cancer-related deaths among women worldwide, representing 23 % of all cancer diagnoses and 14 % of cancer-related deaths. In developing countries, BC has also replaced cervical cancer as the current leading cause of cancer deaths among women ; P = 0.044). In addition, for rs7176005, the homozygous variant genotypes (TT) were associated with a higher odds of VMS . Finally, the rs16964189 SNP was associated with the occurrence of VMSs for the homozygous TT genotype . Park et al. ; P = 0.007. However, this association was not found in any other of the 29 SNPs analyzed. Furthermore, Henry et al. [CYP19A1 SNPs) in 432 BC patients and observed a non-significant increase in MS-AEs when at least eight rs60271534 repeat alleles were present . No other associations were identified.In relation to treatment-related MS-AEs, Liu et al.  found thy et al.  analyzedP = 0.01), but no other significant associations were reported. Finally, Mao et al. [P = 0.57), rs727479 (P = 0.94), rs10046 (P = 0.20), or rs11575899 (P = 0.80). For SNP rs60271534, subjects with at least one TTTA 7-repeat allele had a non-significant 1.7-fold increase in odds of AIAA  after correcting for multiple testing, whereas patients with at least one TTTA 8-repeat allele had a lower risk of aromatase inhibitor-associated arthralgia (AIAA) . In addition, Napoli et al. [P = 0.03) and hip (P = 0.03) compared with other genotypes (AG + GG).Park et al.  describeo et al.  analyzedi et al.  analyzedCYP19A1 genotypes and clinical outcomes following treatment with AIs in BC patients. A total of 12 studies were included in this systematic review. To our knowledge, this is the first systematic review and meta-analysis published on the association between CYP19A1 polymorphisms and AI treatment in BC patients.There is growing evidence that polymorphic gene variants can contribute to differences in complex traits between individuals, and the assessment of genes involved in drug metabolism will provide valuable information for treatment planning. Although AI efficacy among BC patients has been proven, there is significant variability in response rate and AE frequency. Therefore, tests that are able to predict treatment response and prognosis would be valuable in the management of these patients. We investigated evidence of the association between TTP was analyzed as an outcome in four studies , 24, 40.P = 0.007), but the same was not observed for SNP rs10046 (P >0.05). In contrast, Miron et al. [P >0.05) but did identify an association between OS and rs10046 (P = 0.003). These conflicting data suggest that CYP19A1 genotypes may be associated with OS in BC patients treated with AIs. However, the magnitude of this association appears highly variable between patients.Liu et al.  reportedn et al.  found noP = 0.011), TTF and PFS (no significance association with any SNP) were quite limited in terms of number and heterogeneity of studies, but the overall lack of effect observed may indicate that there are in fact no differences or that the follow-up times used were insufficient to detect relapse/recurrence.The variations in the definitions of DFS, PFS and TTF among studies limited pooling in our analysis. The results involving DFS  that could influence the outcomes analyzed.Furthermore, it is important to mention that this systematic review/meta-analysis might have some publication bias, because we prioritized the inclusion of English publications. Moreover, it is well known that often studies that find negative results, i.e., with no statistically significant correlation between genetic polymorphisms and clinical outcomes, are more rarely published, which may cause a possible limitation in this kind of study. This meta-analysis did not use single patient data, which although more challenging, may have certain advantages over aggregate-level analyses . FurtherCYP19A1 polymorphisms and clinical outcomes and AEs in BC patients receiving AIs. The effects of CYP19A1 polymorphisms on clinical outcomes were most often detected in individual studies, suggesting that longer-term studies will better clarify these associations. Results, such as the association of SNP rs4646 with longer TTP as well as the association of rs934635 and M_5_3 haplotype with VMS and the genetic variants M_3_5, rs700518 and rs60271534 with osteoarticular symptoms, are significant outcomes indicating the impact of these variants on treatment with AIs in BC. Hence, CYP19A1 polymorphisms are potentially useful biomarkers for predicting prognosis and AE profiles in BC patients and may become a promising tool to aid physicians in making therapeutic decisions in the future, although the exact role of CYP19A1 has yet to be clarified when taking the different clinical settings and disease stagings into account. Additional studies must be conducted with larger sample sizes, more homogeneous patient populations , and using standardized outcomes and genotyping strategies to allow for a comprehensive understanding of these associations.This systematic review of the literature revealed associations between


N-glycomic analysis of plasma proteins was performed in Japanese semisupercentenarians (SSCs) (mean 106.7 years), aged controls (mean 71.6 years), and young controls (mean 30.2 years) by liquid chromatography/mass spectrometry (LC/MS) using a graphitized carbon column. Characteristic N-glycans in SSCs were discriminated using a multivariate analysis; orthogonal projections to latent structures (O-PLS). The results obtained showed that multi-branched and highly sialylated N-glycans as well as agalacto- and/or bisecting N-glycans were increased in SSCs, while biantennary N-glycans were decreased. Since multi-branched and highly sialylated N-glycans have been implicated in anti-inflammatory activities, these changes may play a role in the enhanced chronic inflammation observed in SSCs. The levels of inflammatory proteins, such as CRP, adiponectin, IL-6, and TNF-α, were elevated in SSCs. These results suggested that responses to inflammation may play an important role in extreme longevity and healthy aging in humans. This is the first study to show that the N-glycans of plasma proteins were associated with extreme longevity and healthy aging in humans.An  Aging is not caused by a single factor or process; it is modulated by various genetic and environmental factors such as oxidative stress and lifestyle. However, the mechanisms underlying the aging process currently remain unclear . SemisupSince post-translational modifications to proteins do not occur according to a genetic template, they are sensitive to various biological changes. Typical modifications to proteins, such as phosphorylation, glycosylation, and acetylation, depend on the activities of enzymes such as kinases, glycosyltransferases, and acetylases, respectively. Since the aging process is modulated by environmental factors, e.g. oxidative stress, heat shock, etc , a focusN-linked glycosylation (N-glycan), which is covalently conjugated to asparagine residues in a consensus sequence (Asn-X-Ser/Thr), is synthesized in the endoplasmic reticulum, in which a lipid-linked precursor oligosaccharide is attached to a protein, followed by the concerted action of glycosyltransferases in the Golgi apparatus. More than half of mammalian proteins are estimated to be glycosylated. Human plasma proteins, except for albumin and CRP (C-reactive protein), are mostly modified by glycans. Furthermore, since plasma proteins are derived from various tissues and organs, their properties are affected by the physiological or pathological conditions of various tissues and organs, indicating that plasma proteins and their glycans are good targets for monitoring healthy conditions.Glycosylation is one of the most common post-translational modifications to proteins. Recent studies suggest that glycans modify the functions of proteins and play important roles in various biological processes such as molecular recognition, cell adhesion, and immunological defense systems. The biosynthesis of glycans is known to depend on the activities of glycosyltransferases (transfer of sugars) and glycosidases (hydrolysis of sugars), and their activities are easily altered by changes in the physiological conditions of cells. Therefore, although glycans are highly susceptible to changes in the biological environment such as those caused by various disorders –7 and agN-glycan structures have a number of positional isomers and anomeric configurations including branching; therefore, they are very diverse. As a result, difficulties have been associated with obtaining N-glycan structural information until recently. Among several analytical methods, mass spectrometry (MS) is currently the most efficient and promising analytical tool for elucidating N-glycan structures. N-Glycan analyses have often been performed using liquid chromatography (LC) and capillary electrophoresis in combination with MS  value to the corresponding error was summarized in N-glycans that carrying this value larger than 1.5 were considered to be characteristic N-glycans in SSCs  was observed in some N-glycans between SSCs and aged controls, slight increases or decreases was detected in SSCs.We performed a one-way analyses of variance (ANOVA) on the peak area ratios of each N-glycans of SSCs and aged controls were determined using a sialic acid (NANA) fluorometric assay. After the preparation of N-glycans from plasma proteins, as described in Materials and Methods section, sialic acid was released by an incubation with A. ureafaciens sialidase. Sialic acid in plasma N-glycans was significantly higher in SSCs than in aged controls . *p < 0.05, different from SSC). These results were consistent with the increase in sialylated N-glycans in SSCs obtained by LC/MS.The contents of sialic acid in the plasma Plasma biomarkers in SSCs and the controls were measured . AlbuminN-glycans in SSCs. We performed an N-glycomic analysis of plasma proteins in SSCs, a model of human longevity, using LC/MS and O-PLS. The results obtained showed that multi-branched and highly sialylated N-glycans as well as agalacto- and/or bisecting N-glycans were higher, whereas biantennary N-glycans were lower in SSCs than in young and aged controls. This is the first study to demonstrate that N-glycans are associated with extreme longevity and healthy aging in humans.In the present study, we investigated longevity-associated N-glycan profiles in human plasma or serum were recently examined using several methods: DNA sequencer-assisted, fluorophore-assisted carbohydrate electrophoresis (DSA-FACE) [N-glycans and corresponding decreases in digalactosylated biantennary N-glycans [N-glycan (No. 15 in N-glycan is age-associated changes.The effects of aging on SA-FACE) –20, nanoSA-FACE) , 22, UPLSA-FACE) , and hydSA-FACE) , 24–26. -glycans . Additio-glycans , 28. In N-glycans , and O-acetylated forms [On the other hand, the increases in multi-branched and highly sialylated rthritis , ulceratrthritis , and chrrthritis . Howeverrthritis , and we ed forms –35 need N-glycans and reported that non-fucosylated biantennary glycans were significantly higher in the offspring of nonagenarians (90 years old) than in controls [N-glycans described above are associated with longevity.In the Leiden Longevity study, Ruhaak et al. examined longevity-associated controls . HoweverN-glycans has been implicated in several diseases including cancer [N-glycans in SSCs may not have been altered.No significant feature of fucosylated glycans was observed in the present study. The fucosylation of g cancer . Since tN-glycomes in human plasma revealed polymorphisms in several glycogenes [MGAT5, which codes for the enzyme involved in the generation of multi-branched N-glycans, while another was SLC9A9, which codes for a proton pump affecting Golgi pH linked to the sialylation of glycans. Further studies are warranted in order to determine whether these genes show any polymorphisms in SSCs, the findings of which may contribute to a better understanding of the roles of glycans in human longevity.Human longevity may be associated with genes . Severalycogenes ; one wasN-glycans in SSCs. These N-glycan changes may play a role in anti-inflammatory responses against enhanced chronic inflammation. Thus, proper responses to inflammation through N-glycan modulations may be key for longevity and healthy aging in human. Future studies, including those involving different genders and ethnicities, are needed in order to obtain more detailed insights into the biological resilience of SSCs.In conclusion, we herein identified an enhancement in multi-branched and highly sialylated S1 Fign. Vertical and horizontal axes of each panel represent the relative abundance and retention time of LC/MS, respectively. (A) positive ion mode, (B) negative ion mode.Base peak chromatograms of 5 young controls, 5 aged controls, and 6 SSCs were obtained from LC/MS(PDF)Click here for additional data file.S2 FigN-glycan was calculated against the total peak area of all identified N-glycans in the (A) positive and (B) negative ion modes. Shadowed, open, and closed columns represent young controls, aged controls, and SSCs, respectively. "Glycan composition" represents each deduced glycan composition from mass spectra. Numbers in parentheses indicate isomers. Data represent the mean ± standard deviation (SD) . Row data were summarized in N-acetylhexosamine; NeuNAc, N-acetylneuraminic acid; dHex, deoxyhexose; NH4, ammonium.The peak area ratio of each (PDF)Click here for additional data file.S3 FigRegression equation; y = 1*x-3.393e-006; R2 = 0.9556. Shadowed symbols, young; open symbols, aged; closed symbols, SSCs.(PDF)Click here for additional data file.S4 FigN-glycans in SSCs. N-glycans not shown here were deduced by each calculated exact mass. Numbers of the N-glycans correspond to N-acetylglucosamine; yellow circle, galactose; green circle, mannose; purple diamond, N-acetylneuraminic acid; red triangle, fucose.Spectra represent increased and decreased (PDF)Click here for additional data file.S5 FigN-acetylhexosamine; NeuNAc, N-acetylneuraminic acid; dHex, deoxyhexose; NH4, ammonium.(A) An O-PLS score plot between young controls (shadowed), aged controls (opened), and SSCs (closed). R2X  = 0.2635(PDF)Click here for additional data file.S6 FigN-acetylhexosamine; NeuNAc, N-acetylneuraminic acid; dHex, deoxyhexose.(A) An O-PLS score plot between young controls (shadowed), aged controls (opened), and SSCs (closed). R2X  = 0.4163(PDF)Click here for additional data file.S7 FigN-glycans in each ion mode. In the case of No. 2 and No.18, the data of the negative ion mode were used because the absolute pq[N-glycans in SSCs, (B) Decreased N-glycans in SSCs, *p < 0.05, **p < 0.01, vs SSC.The numbers of graphs correspond to the glycan numbers in (PDF)Click here for additional data file.S1 Table1Numbers in parentheses represent isomers, and "N" or "P" in parentheses indicates the data obtained from negative or positive ion mode, respectively. 2Hex, hexose; HexNAc, N-acetylhexosamine; NeuNAc, N-acetylneuraminic acid; dHex, deoxyhexose; NH4, ammonium. 3RT represents retention time.(PDF)Click here for additional data file.S2 Table1Numbers in parentheses represent isomers, and "N" or "P" in parentheses indicates data obtained from the negative or positive ion mode, respectively. 2Hex, hexose; HexNAc, N-acetylhexosamine; NeuNAc, N-acetylneuraminic acid; dHex, deoxyhexose; NH4, ammonium.(PDF)Click here for additional data file.


New onset diabetes after transplantation (NODAT) is a serious complication following solid organ transplantation. There is a genetic contribution to NODAT and we have conducted comprehensive meta-analysis of available genetic data in kidney transplant populations.Relevant articles investigating the association between genetic markers and NODAT were identified by searching PubMed, Web of Science and Google Scholar. SNPs described in a minimum of three studies were included for analysis using a random effects model. The association between identified variants and NODAT was calculated at the per-study level to generate overall significance values and effect sizes.CDKAL1 rs10946398 p = 0.006 OR = 1.43, 95% CI = 1.11–1.85 , KCNQ1 rs2237892 p = 0.007 OR = 1.43, 95% CI = 1.10–1.86 , and TCF7L2 rs7903146 p = 0.01 OR = 1.41, 95% CI = 1.07–1.85 .Searching the literature returned 4,147 citations. Within the 36 eligible articles identified, 18 genetic variants from 12 genes were considered for analysis. Of these, three were significantly associated with NODAT by meta-analysis at the 5% level of significance; Evaluating cumulative evidence for SNPs associated with NODAT in kidney transplant recipients has revealed three SNPs associated with NODAT. An adequately powered, dense genome-wide association study will provide more information using a carefully defined NODAT phenotype. New onset diabetes after transplantation (NODAT), also known as post transplantation diabetes mellitus (PTDM), is a serious complication of solid organ transplantation . It affeReview of the literature was performed to identify all published genetic variants associated with NODAT in a kidney transplant population. Studies carried out in NODAT populations following other forms of organ transplant (such as liver transplant) were not included. PubMed, Web of Science and Google Scholar were searched from their inception until May 2015 with no language restrictions, using the following keywords: ‘New Onset Diabetes’, ‘Diabetes Mellitus’, ‘Gene’, ‘Genetic’, ‘Genotype’, ‘Transplantation’, ‘Transplant’, ‘Polymorphism’, ‘Mutation’, ‘NODAT’ and ‘PTDM’ (Post-Transplantation Diabetes Mellitus). Bibliographies for all identified articles and reviews were examined to identify further publications not found in the original search.Studies were included when there was a minimum of three studies investigating the association of a specific variant with NODAT. Studies were deemed eligible if they fulfilled the following criteria: (a) published in a peer reviewed journal article or conference abstract using original data; (b) were conducted in a kidney transplant population in a case-control manner for NODAT; (c) included patients diagnosed with NODAT; (d) included controls who had undergone kidney transplantation but did not develop NODAT during follow-up. Authors were contacted if further essential information was required or if there was a query regarding eligibility. If sufficient information could not be obtained, the study was excluded, as were studies that duplicated data.Data was manually extracted from the studies. Information was gathered on study size, numbers of cases versus controls, ethnicity, genotyping methods, recorded odds ratios and p values. If ethnicity was not explicitly stated, this was inferred from the geographical location of the recruitment site and/or contact with authors. Deviation from Hardy-Weinberg Equilibrium was measured using genotype counts with a threshold of p <0.0001. Funnel plots of standard error of the log-odds-ratio against the log-odds-ratio were produced to estimate publication bias. Power calculations were conducted using StatCalc version 6.2 statistic used to describe percentage variation across studies. Meta-analysis was performed using a random effects model for variants replicated in three or more eligible studies, with significance value set at p <0.05.Heterogeneity was calculated using a Cochrane Q test for heterogeneity with the Ihttp://tech.cochrane.org/revman)[All meta-analyses were performed using Review Manager software version 5.3.5 (RevMan 5.3) (g/revman).Funnel plots of standard error of the log-odds-ratio against the log-odds-ratio were produced to estimate publication bias. These were assessed by visual inspection. Funnel plots are capable of detecting publication bias which would be undetected by more formal statistical tests. Statistical tests such as Egger’s test were not conducted in this review due to the small number of studies in the meta-analyses, which were not sufficient to distinguish chance from asymmetry.The preliminary literature search yielded 4,147 citations, 40 of which were relevant studies investigating NODAT and 36 of which had all the required information to allow the extraction of variant information . Data waOf the 36 studies deemed eligible for inclusion, 16 studies were carried out in Asian populations, 16 in Caucasian populations and 4 in populations of mixed ethnicity. The literature review revealed 18 genetic variants considered for association with NODAT that were reported in a minimum of three studies across 12 genes .CDKAL1 rs10946398 p = 0.006 OR = 1.43, 95% CI = 1.11–1.85 , KCNQ1 rs2237892 p = 0.007 OR = 1.43, 95% CI = 1.10–1.86 , and TCF7L2 rs7903146 p = 0.01 OR = 1.41, 95% CI = 1.07–1.85   .Power calculations  suggest TCF7L2 rs7903146, CDKAL1 rs10946398 and KCNQ1 rs2237892 at the significance level p<0.05.Thorough investigation of genetic variants reportedly associated with NODAT in kidney transplant patients has revealed significant associations by combined analysis. Three SNPs were significantly associated with NODAT–Many of the studies used in this investigation focused on genes previously associated with type 2 diabetes (T2D),36. NODATCF7L2 (transcription factor 7-like-2) has been previously linked to T2D, and has been cited as one of the most important signals associated with T2D [TCF7L2 influences risk of T2D but a number of theories have been put forward. It may affect blood glucose homeostasis by altering levels of glucagon-like peptide 1 in the gut, or it may decrease insulin secretion via the pancreatic beta, adipose or liver cells [with T2D . The T awith T2D ,53. It ier cells . rs79031er cells . There iCDKAL1 (cyclin dependent kinase 5 regulatory subunit associated protein 1 like 1) has been associated with impaired insulin secretion and the development of T2D in both European and Han Chinese populations by GWAS [CDKAL1 encodes a methylthiotransferase which is thought to regulate the CDK5 protein which stimulates production of insulin as well as other processes in the pancreatic beta cells [CDKAL1 may increase risk of T2D [CDKAL1 gene. An alternative splicing product of CDKAL1 (CDKAL1v1) is increased in individuals homozygous for the minor C allele at this locus. It has therefore been suggested that this particular variant influences splicing of the gene [ by GWAS  and the  by GWAS . CDKAL1 ta cells . In thisk of T2D  and NODAthe gene .KCNQ1 is also an established T2D risk factor and has been associated with gestational diabetes [KCNQ1 cause a variety of disorders including hereditary long QT syndrome (Romano-Ward syndrome)[diabetes –62. Varisyndrome). It is esyndrome). Pancreasyndrome). The varsyndrome).These genetic variants are all established T2D risk factors and several variants have been implicated in potential mechanisms contributing to diabetes. Therefore, it is not surprising that these variants are linked to NODAT, another form of diabetes, since the mechanisms controlling insulin production and maintenance of stable glucose levels will both be similar in T2D and NODAT. The meta-analyses conducted on the other variants identified in the literature did not reach statistical significance. This may have been for several reasons, including the small number of studies, small numbers of study participants, or varying phenotypic definitions. Of note, our meta-analysis incorporates data from both candidate gene and genome-wide association studies.KCNJ11 rs5219 and ADIPOQ rs1501299. KCNJ11 rs5219 is an established T2D risk factor in a gene encoding a voltage gated potassium channel. ADIPOQ rs1501299 has been previously associated with NODAT as well as breast cancer, prostate cancer and T2D complications such as heart disease. Adiponectin encoded by ADIPOQ is involved in lipid metabolism and insulin sensitivity and making this an attractive candidate for association with NODAT. Neither of these particular variants reached the p<0.05 significance threshold following meta-analysis which could mean they are not associated with NODAT or that the association is only present in certain populations.A number of variants which were associated with NODAT in previous studies were not found to be associated with NODAT following meta-analysis. Notable variants which did not reach significance after meta-analysis include de novo prolonged use of insulin and/or oral hypoglycaemic medication following transplant. A more rigorously defined NODAT phenotype may facilitate more reproducible results between studies. There were a small number of studies available for many of the variants; larger, carefully phenotyped studies would provide better power to identify alleles robustly associated with NODAT. There was a varying degree of heterogeneity noted between studies, some of which was likely due to different ethnicities considered. In addition, the variations in prescribed immunosuppressive regimens, and their differential effects on NODAT incidence, were not accounted for in many of the studies. It is of note that the Belfast derived data was from the single transplant centre for Northern Ireland. TCF7L2 rs7903146 variant was only nominally associated with NODAT (p = 0.01), but this association was replicated with the same direction of effect across five independent collections. Possible interactions among the genetic variants identified have not been investigated and this is a further limitation of the study.This study does have a number of limitations. The definition of NODAT differs from centre to centre as highlighted by the varying prevalence of NODAT reported in This is a thorough overview of all reported genetic factors influencing the development of NODAT in the current literature. Analysis revealed a significant association between NODAT and three established T2D risk factor variants. Functional studies will be required to further investigate these variants and associated pathways to gain a complete perspective on their effects. In order to obtain more consistency between studies and identify risk alleles with smaller effect sizes, larger participant numbers through multi-centre collaboration and harmonised phenotypic definition of NODAT is required. An adequately powered, dense genome-wide association study will provide more information using a carefully defined NODAT phenotype.Hypothesis free approaches such as the GWAS carried out by McCaughan and colleagues for NODAT are advantageous to identify new biological targets and therapeutic pathways and should also be carried out in other populations and ethnicities to better understand the genetic architecture underlying this disease .S1 TableThis table describes the power which this study had to identify significant genetic variants. The power was based on 607 cases, 2360 controls and dependent on the Minor Allele Frequency, significance sought, and effect size (reported for each variant in (XLSX)Click here for additional data file.S2 TableDescribes how this manuscript conforms to the PRISMA 2009 guidelines.(DOCX)Click here for additional data file.