Backgroud: Pre-eclampsia (PE) is a common pregnancy-induced hypertension disease. Some case–control studies reported the association between vascular endothelial growth factor (VEGF) gene polymorphisms  and PE risk. However, these associations were inconsistent in several studies. Therefore, we conducted this meta-analysis to assess the role of VEGF gene polymorphisms in PE more precisely.Methods: Eligible studies were searched in PubMed, Embase, Web of Science and Chinese  and WanFang) databases. Statistical analyses were performed by Stata 12.0 software. Odds ratio (OR) and 95% confidence interval (CI) were used to assess the strength of the association. In addition, subgroup analyses, sensitive analyses and publication bias analyses were performed to further assess this meta-analysis.Results: In total, 21 studies were included in the meta-analysis covering 2018 cases and 2632 controls. There were significant associations between VEGF polymorphisms  and PE risk in the overall populations. In the subgroup analyses, we found that rs3025039 polymorphism was associated with the increased risk of PE among Chinese. As for rs2010963 polymorphism, a significant association was observed in subgroup of Caucasian.Conclusion: The present study suggested that the two VEGF gene polymorphisms  are associated with increased risk of PE in different ethnic groups, which means that the targets may be useful genetic markers for early prediction of PE. Pre-eclampsia (PE), a common pregnancy disease diagnosed by hypertension and proteinuria, occurs in approximately 2–8% of pregnancies ,2. PE isin utero [The vascular endothelial growth factor (VEGF) gene, located on chromosome 6p21.3, is a key regulator of angiogenesis and vascular function. Therefore, VEGF is vital for the formation of trophoblasts, embryonic vasculature and maternal and foetal blood cells in utero . Abnormain utero ,9.The associations between polymorphisms of the VEGF gene and PE have been extensively studied . HoweverThis meta‐analysis was conducted in accordance with the guidance of the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) statement . The PRIThe inclusion criteria were as follows: (i) studies which estimated the associations between VEGF rs2010963 or rs3025039 and the susceptibility to PE; (ii) case–control studies or cohort studies of PE; (iii) patients must be clinically diagnosed for PE (blood pressure ≥ 140/90 mmHg on two measurements with ≥1+ proteinuria or 300 mg/24 h after the 20th week of pregnancy); (iv) reported the allele frequencies of both cases and controls for different genotypes; (v) genotype distribution in the control group confirmed by Hardy–Weinberg equilibrium (HWE). The exclusion criteria of the meta-analysis were: (i) non-human studies, meta-analysis, comments, letters, reviews, mechanism studies or studies without controls, (ii) studies with overlapping or incomplete data. When overlapped population between studies was identified, only the newest or most complete article was included in the analysis. According to the corresponding criteria, two independent authors screened the articles.Data were extracted by two authors independently from each study. The following information was collected: first author, publication year, participants’ country, ethnicity , sample size, study design (case–control or cohort), genotyping method, alleles and genotype frequency distribution in cases and controls, and the major conclusion of the study. When incomplete or apparent conflicting data were found in the article, we made an attempt to contact authors. Inconsistencies in data interpretation were resolved with discussion. The Newcastle–Ottawa Quality Assessment Scale (NOS) was employed to evaluate the methodological quality of the identified articles, and scores ranging from 0 (the worst) to 9 (the best) were assigned based on the quality of the studies. The studies with no less than 5 stars were considered to be of high quality.P<0.05). Stata 12.0 was used to perform quantitative meta-analysis. The association was estimated with four models: Allele comparison model, Dominant model, Recessive model and Homozygote model. The four models of the data analysis were conducted by the random-effects model to prevent exaggerated results. The association between the VEGF rs3025039 or rs2010963 and PE risk was assessed by the raw odds ratios (ORs) with 95% confidence intervals (CIs). The Student’s t test was used to determine the significance of the crude OR, and P<0.05 was considered statistically significant. In addition, heterogeneity assumption among the included researches was evaluated by the Chi-square and 2I, which was regarded to be statistically significant if P<0.10. And 2I values of 25, 50 and 75% were nominally assigned as low, moderate and high estimates. To insure that any single study did not cause an obvious influence to the whole effects, sensitivity analysis was performed to estimate the validity and stability of the study. In addition, to further analyze the source of the heterogeneity and the specific association between the VEGF polymorphism and PE, studies were also divided into several subgroups on the basis of the country, the ethnicity of the related population and the genotyping method. Egger’s test was performed to estimate the potential publication bias.First, deviation from HWE in the distribution of allele frequencies was estimated again by the chi-square test  and others were acceptable. An analysis of 1148 cases and 1388 controls for rs2010963 showed the C allele in allele comparison model, CC and CG genotype in the recessive model and CC genotype in the homozygous model increased the risk of PE significantly , the Dominant model showed low heterogeneity (2I < 0.001%), the Recessive model showed high heterogeneity (2I = 71.6%) and the Homozygote model showed moderate heterogeneity (2I = 32.3%). However, no significant association was found in the Korea’s subgroup and other countries’ subgroup, and relatively high heterogeneity was observed in the almost all models of the two subgroups except in Dominant and Homozygote model of other countries’ subgroup, which indicated the differences of population countries were not the major cause of the heterogeneity for rs3025039 in this meta-analysis. Then, we performed an ethnic restriction including Xanthoderm, Caucasian and Indo-European hybrid for further subgroup analysis in rs3025039. No significant association was observed in the any model, and the heterogeneity of various models in different subgroups showed no significant reduction. Next, subgroup analysis was performed in rs3025039 according to the genotyping methods including MassARRAY system, Sequencing, PCR-RFLP and Snapshot. A significantly increased risk was found in the Sequencing and PCR-RFLP subgroup, but a protective effect was found in the MassARRAY system subgroup with Allele comparison model and Snapshot subgroup with Recessive model. The heterogeneity of all the subgroup in the four models were relatively low, which indicated that the genotyping methods might be the major source of the heterogeneity.The subgroup analyses were carried out due to the heterogeneity of result and biases of the different subgroups. The results of subgroup analyses were shown in P=0.046; Homozygote model: OR = 1.461, P=0.039), and other subgroups showed no obvious difference. Moreover, the heterogeneity of allele comparison model and homozygote model in Caucasian subgroup was low . However, the difference between the overall heterogeneity and subgroup heterogeneity was not apparent, illustrating that the ethnicity was not the important cause of heterogeneity in the meta-analysis. Regarding the genotyping methods subgroups, we divided into three groups: Sequencing, PCR-RFLP and other methods, owing to the duplicating number of the genotyping methods. The result of the Sequencing subgroup showed a statistically significant in Allele comparison model and Homozygote model with indistinctive heterogeneity . Besides, heterogeneity of the Sequencing and PCR-RFLP subgroups in all models was not significant (2I < 0.1%), while heterogeneity of other methods subgroups was higher. The results suggested that the source of the heterogeneity might be the genotyping methods, consistent with the conclusion above.For rs2010963, we performed the subgroup analysis based on ethnicity and genotyping methods, because the overlapping countries were limited. The subgroups of ethnicity were divided as the same as the subgroups of rs3025039. A significant association was observed in the Caucasian subgroup with both Allele comparison model and Homozygote model , Amosco et al. (2016), Salimi et al. (2015), Silva et al. (2014), Zhang Honghui et al. (2014), Procopciuc et al. (2014), Atis et al. (2012), Chen Baoli et al. (2011), Liu Shifang (2010)); second, multiple subgroups were divided to be analyzed; thereby a more adequate statistical power was gained in our study. Similar to the published researches, we found significant associations between the two VEGF gene polymorphisms  and PE, suggesting VEGF gene variants in rs3025039 and rs2010963 loci might be involved in the development of PE. Our results provide evidence of a significantly increased risk about rs3025039 polymorphisms for PE with the four models. Compared with the previous meta-analyses, a significantly increased risk for PE was observed in rs2010963 polymorphisms with less heterogeneity except for the Dominant model. In the stratified analysis by ethnicity and countries for rs3025039, a significantly increased risk of pre-eclampsia was observed in studies conducted among Chinese population. As for subgroup analyses of ethnicity in rs2010963, a statistically association was found in the Allele comparison and the Homozygote models of Caucasian.2I < 40%, P>0.10), where the results of the PCR-RFLP and Sequencing were consistent with the total result , but different from the result of the other genotyping methods. Similarly, the heterogeneity of the three subgroups covering PCR-RFLP and Sequencing and other methods was different for rs2010963 polymorphism. The heterogeneity of the PCR-RFLP and Sequencing subgroup was quite low , whereas the heterogeneity of the other methods subgroup was extensive (2I > 40%). The reason could be that studies in each subgroup are relatively few or different genotyping methods may influence the genotyping result. This observation is similar to previous studies, in which differences in genotyping methods might contribute to heterogeneity [In addition, the heterogeneity could be accounted for by the subgroup analysis of genotyping methods. For rs3025039 polymorphism, the subgroup analyses of four genotyping methods including MassARRAY system, Sequencing, PCR-RFLP and Snapshot all showed low levels of heterogeneity , which may limit the statistical power. Third, the recruitment criteria of patients and controls varied in different studies. Finally, gene–gene or gene–environment interactions were not considered in the present study—such as age, smoking, alcohol status and mental state—which may have influenced the associations between VEGF gene polymorphisms and PE risk. Nevertheless, this meta-analysis improves our understanding of the associations between two polymorphisms of VEGF gene and the risk of PE.In conclusion, the two VEGF gene polymorphisms are associated with an increased risk of pre-eclampsia in different ethnic groups, respectively. A large number of and high-quality studies are required to establish more precise evidence and minimize the bias in meta-analysis.Click here for additional data file.


However, there is controversy concerning the association of IL28B polymorphisms with the outcome of hepatitis B virus (HBV) infection, with several studies obtaining inconsistent results. We performed a meta-analysis to evaluate the role of 3 single nucleotide polymorphisms (SNPs) rs12979860, rs12980275 and rs8099917 in the progression of HBV infection, overall and by ethnicity.Interleukin (IL) Searched PubMed, Embase and Wiley Online Library electronic databases using ‘interleukin 28B’, ‘IL 28B’, ‘IL 28B polymorphism’, ‘hepatitis B virus’, ‘HBV’, and performed meta- analysis for rs12979860, rs12980275 and rs8099917 in Asian and Caucasian populations under the dominant recessive and allele model.IL28B polymorphism rs12979860 had no association with HBV persistence . Similarly, neither rs12980275 nor rs8099917 had associations with HBV persistence . There was also no significant association of IL28B polymorphisms with persistent HBV infection in Asians or Chinese. There was no evidence of an association of rs12979860 with the HBV-related hepatocellular carcinoma susceptibility .Eighteen studies were found in total and used for this meta-analysis, including 5587 cases and 4295 controls. The IL28B polymorphisms had no association with the outcome of HBV infection overall, nor in the Asians and the Chinese. These 3 SNPs might not be relevant to the development of HBV infection. Hepatitis B virus (HBV) is a serious public health issue which contributes to the global burden of disease. According to the World Health Organization, HBV claimed 887,000 lives in 2015 and resulted in 257 million chronic carriers in 2017 , as wellHBV is a contagious liver disease that can be acute or chronic. Some people who get HBV recover completely from the acute illness, while others may develop a lifelong infection, which increases the risk of liver cirrhosis, liver failure and hepatitis hepatocellular carcinoma (HHC). HCC is the third leading cause of cancer death globally , and 78%IFN-λ3) coded by interleukin (IL) 28B polymorphisms has an anti-viral effect and could impede the HBV replication in hepatocyte cell lines. In recent years, several genome-wide association studies (GWAS) indicate the 3 single-nucleotide polymorphisms (SNPs) rs12979860 C/T, rs12980275 A/G and rs8099917 T/G, located on IL28B are associated with liver diseases [IL28B polymorphisms predict the serological response to Pegylated interferon-α (PEG-IFN-α) in terms of HBeAg sero-conversion that relate to HBV infection [IL28B with HBV infection suggests a potential therapeutic target.Cytokines and regulatory molecules made a major contribution to the immune-pathogenesis of HBV infection. The cytokine Interferon-λ3  studies providing odds ratios (OR) and 95% confidence intervals (CI) for the dominant model , recessive model , and allelic model ; (iv) case-control study design; (v) diagnosis of chronic HBV carriers based on seropositive results for hepatitis B surface antigen (HBsAg) for more than 6 months; diagnosis of HBV recovery based on seropositive results for hepatitis B core antibody (anti-HBc) and hepatitis B surface antibody (anti-HBs) without HBsAg for at least 6 months. The exclusion criteria were: (i) studies lacking healthy controls or HBV recovered controls; (ii) studies with inaccurate or insufficient information on IL28B genotypes and the genetic models of interest; (iii) studies not designed as a case-control study; (iv) studies including participants testing positive for antibodies against HCV and HIV.The inclusion criteria were as follows: (i) studies of persistent HBV infection patients, i.e. chronic carriers with chronic hepatitis or liver cirrhosis or hepatocellular carcinoma as cases, and healthy participants without HBV infection or HBV recovered patients as controls; (ii) studies with precise P-value derived from Hardy-Weinberg equilibrium (HWE) in controls.We reviewed and identified all relevant publications according to the selection criteria, and extracted all available data for the eligible studies. The extracted information for each study included: name of the first author, year of publications, country of origin, ethnicity, SNP, number of genotyped cases and controls, and The quality of each study was evaluated based on the Newcastle-Ottawa Scale (NOS), and 7–9 stars was perceived as high quality . The appIL28 polymorphisms rs12979860, rs12980275, rs8099917 with persistent HBV infection from which we reported ORs and 95% CIs from 3 genetic models. We also compared HCC patients as cases with healthy controls or recovery controls, used ORs and 95% CIs derived from the allelic model to examine the association of rs12979860 with the occurrence of HBV-related HCC. Stratified analysis was performed by ethnicity. Heterogeneity between studies was assessed by the chi-square-based Cochran’s Q-test and Higgins (I2) statistics, and the significance level was set at P = 0.1. Sequential omission of individual studies was conducted as a sensitivity analysis to test the heterogeneity. The impact of the 3 SNPs throughout meta-analysis was combined using a fixed-effects model (P ≥ 0.1 and I2 ≤ 0.25) and a random-effects model (P < 0.1 or I2 > 0.25). Visual inspection of asymmetry in the funnel plot was used to assess publication bias. Furthermore, Begg’s test and Egger’s test were also performed as a sensitivity analysis to examine publication bias. A P-value < 0.05 indicated publication bias was significant across studies. Trim and fill analysis was also conducted as a sensitivity analysis to diagnose publication bias in this meta-analysis. The statistical analysis was conducted by using R software, Version 3.3.3.We assessed the association of The study selection and inclusion process are illustrated in Fig. These 18 publications , the dominant model , or the recessive model . As few studies provided sufficient information on rs12980275 and rs8099917, these 2 SNPs were only considered in a dominant model. There was no association of these genotypes with HBV persistent infection .The association between IL28B polymorphisms  were associated with persistent HBV infection in Asian or Chinese populations. For Asians, rs12979860 had no association with HBV infection in the allelic, dominant or recessive model . SNPs rs12980275 and rs8099917 also had no association with HBV infection in Asians using a fixed-effects model . In Chinese, none of these 3 SNPs were associated with HBV persistence  . However, heterogeneity in the dominant model for IL28B polymorphisms  was significant. Subgroup analyses were carried out to identify sources of heterogeneity. After stratifying by Asian population, there was no heterogeneity for rs12980275 and rs8099917 in the dominant model . However, heterogeneity in CC vs CT + TT for rs12979860 was still higher than 25%. We further performed the subgroup analysis stratified by Chinese population, but heterogeneity remained for CC vs CT + TT . Sequential omission of individual studies . In addition, there was a significant decline in heterogeneity (I2 = 27%), with excluding the study of Ren S [Heterogeneity of the associations between of Ren S . HoweverHeterogeneity of these 7 studies was 70%. Sensitivity analysis was performed using the sequential omission approach. However, the heterogeneity remained high, and a random-effects model was used to estimate the pooled ORs. The overall result was not influenced by the sequential omission approach. The 7 pooled ORs and corresponding 95% CIs were presented in Additional file In overall and subgroup analysis, publication bias occurred in the allelic and dominant model for rs12979860 and occurred in the dominant model for rs8099917. Begg’s rank correlation, Egger’s weighted regression and trim and fill method were used as the sensitivity analysis to examine the publication bias .There was no obvious asymmetry in the funnel plot for the total population or the Asian population. No publication bias was observed for the association of SNP rs12979860 with HBV-related HCC susceptibility  with HBV persistence. Then we assessed the association of the SNP rs12979860 with the risk of HBV-related HCC. Overall, there was no strong evidence of an association of IL28B polymorphisms with HBV infection. As such, these 3 SNPs do not appear to be risk factors for hepatitis B progression. This meta-analysis provides a reliable and comprehensive assessment of the association of IL28B polymorphisms with HBV infection. This study is the first systematic review that included all relevant eligible English publications in the recent 8 years. Meanwhile, it had a larger sample size comprising 5587 cases and 4295 than previous studies [In this meta-analysis, we examined the association of  studies , 37. Pre studies , 39.IL28B polymorphisms are unrelated to HBV infection, assessed from HBsAg seroclearance, rather than the risk of persistent HBV infection and progression of HBV-related HCC. Moreover, according to the strict inclusion criteria we excluded some studies [Firstly, rs12979860, rs12980275 and rs8099917 had no association with HBV persistence, overall or by subgroup although the heterogeneity was still higher than 25% but was not explained by any individual study. This meta-analysis is consistent with the study of DH Lee  showing  studies , 39 incl studies . However studies . They fo studies . Meanwhi studies . However studies .IFN-λ3 is coded by the IL28B gene and has an antiviral effect on chronic HCV [IL28B polymorphisms with HCV infection. However, the nucleotide analogs may have an additional pharmacological effect by inducing IFN-λ3 production, which facilitates interferon-stimulated genes and decreases the production of HBsAg [IL28B polymorphisms with HBV infection [IL28B polymorphisms predict HBV infection. There is a possibility of producing a false positive result. In the study of Martin MP [IL28B genes would potentially increase the likelihood of false positive in our estimate.onic HCV . Many stonic HCV –47 have of HBsAg . Moreovenfection . Althougnfection , 27, 32 artin MP , despiteIL28B gene as a major determinant of the course of HCV infection, and experimental evidence indicates that IFN-λ3 coded by IL28B gene has an anti-tumor effect [Secondly, rs12979860 had no association with the risk of HBV-related HCC, overall or by subgroup. No publication bias was found by either Begg’s rank correlation method or Egger’s weighted regression method. Nevertheless, this estimate might be underpowered due to the limited number of studies. We obtained consistent findings with a few studies , 17, 26.r effect , 51. Ther effect . Hence tIL28B gene with the disease.Another thing we would highlight about the HBV-related HCC, is that it is thought to involve the interaction between environmental factors and inherited susceptibility . For insIL28B with HBV infection. The unknown history of HBV exposure in the controls or relatively small sample size of the study reduces power to identify genetic variants with modest effect [This study is a candidate gene association study which is different from GWAS. Candidate gene studies are relatively cheap and quick to perform, and are concentrated on the selection of a putative candidate genetic variants according to its relevance in the mechanism of the disease investigated. However, candidate gene studies are susceptible to publication bias, and they are underpowered due to high rates of false positive findings and low rates of replication . In contt effect .Conventionally, the association between genotype variants and disease in candidate gene studies was discovered from case-control studies. However, there might be a spurious correlation despite the observed statistical significance. Candidate gene studies are prone to false positive findings for the following reasons. Firstly, the allele may be in linkage disequilibrium with an allele at another locus that directly affects the expression of the phenotype. Secondly, the allele itself is functional and directly affects the expression of the phenotype . ThirdlyIL28B polymorphisms. Thirdly, this meta-analysis included a total of 5587 cases and 4295, comprising 4913 cases and 3865 controls for rs12979860 C/T, 3765 cases and 2506 controls for rs12980275 A/G, and 3912 cases and 2900 controls for rs8099917 T/G, which were even more than twice the subjects included in previous studies. In addition, we performed a more comprehensive subgroup analysis by ethnicity, because of potential differences between populations. Lastly, this study is the first systematic review that included all relevant eligible English publications in the recent 8 years. Systematic reviews provide a synthesis of evidence for clinical decisions. Hence having an up-to-date and comprehensive review is imperative.There were also several advantages that would further strengthen this study compared to previous similar studies. Above all, the publications we included in this meta-analysis were high-quality based on the NOS score, which increased the internal validity. Moreover, we followed the strict inclusion criteria such as no-coinfection with HCV or HIV, which decreased the bias generated by correlations of these diseases with IL28B polymorphisms were different, which might reduce the reliability. Lastly, although we included 18 studies in this meta-analysis, the presence of heterogeneity and publication bias indicated potential issue. There was still a great need for large, high methodological quality publications from a genome wide association study in both Caucasian and Asian populations to verify our findings.The findings of this systematic review and meta-analysis were limited by several factors. Firstly, the study design included only case-control studies. However, genetic case-control studies are susceptible to selection bias. The key requirement for a case-control study to avoid selection bias is that the cases and controls are selected from the same underlying population, which is difficult to ascertain. Thirdly, the genotype distribution deviated from HWE in 1 study, which might be attributed to population stratification or potential selection bias. Fourthly, we did not have original data for all studies to account for potential confounding however, genetic case control studies are not open to confounding, because few factors are determinants of genetic make-up. Fifthly, the assay methods used to characterize the polymorphisms differed in these studies, i.e. the sensitivity and specificity of identifying IL28B with HBV infection, in the absence of GWAS for this specific association. However, there were still several limitations that might influence the effect of genetic factors on disease outcome. Further well-designed large-scale studies, especially related to the gene-ethnic group and phenotype-environmental interaction are warranted to confirm the real contribution of these polymorphisms to the outcome of HBV infection.Genetic epidemiology is a vital composition of public health research. However, spurious associations might also generate inefficient treatments and waste medical resources. This study is a cost-effective approach to investigating the association of Additional file 1: Supplement 1. Minor allele frequencies of IL28B polymorphisms in persistent HBV infection patients. Supplement 2. Heterogeneity analysis of each IL28B polymorphism.


However, the association was still unconfirmed. Here, we first recruited 490 GC patients and 1476 controls, and conducted a case-control study. And we did not find any association between rs3746444 T>C SNP polymorphism and risk of GC. Subsequently, we conducted a meta-analysis to explore the association of mir-499 rs3746444 polymorphism with GC development. Two authors searched the PubMed and EMBASE databases up to October 15, 2019 independently. Finally, nine literatures involving 12 independent studies were included. In total, 3954 GC cases and 9745 controls were recruited for meta-analysis. The results suggested that allele model, homozygote model and recessive model could increase the risk of overall GC . When we excluded the studies violated HWE, this association was also found in allele model (P = 0.020) and dominant model (P= 0.044). In subgroup analyses, we identified that rs3746444 SNP in mir-499 increased the risk of GC in Asians and gastric cardiac adenocarcinoma (GCA) subgroups. No significant bias of selection was found . Test of sensitivity analysis indicated that our findings were stable. Additionally, we found that the power value was 0.891 in the allele model, suggesting the reliability of our findings. In summary, our analysis confirmed the association between rs3746444 and the risk of GC, especially in Asians and in patients with GCA.The relationship between rs3746444 T>C single-nucleotide polymorphism (SNP) in  Gastric cancer (GC), a commonly malignant disease, which ranks the fifth in terms of cancer diagnose but the third in terms of cancer death  . ComparemicroRNA- (mir-) has about 22 nucleotide molecules. Recently, many types of mir- have been found. It is established that mir- regulates the expression of the target genes. Accumulating evidences have indicated that mir- is very important for adjusting and controlling the various functions in body. Abnormal expression of mir- may lead to a variety of disorders. Mir-499 is a common mir- and extensively studied its potential role in the development of cancer. More and more evidences have indicated that Mir-499 plays a vital role in growth and migration [miR-499-5p might facilitate the progress of colorectal carcinoma and could be considered as a therapeutic target for the treatment [miR-499 signature from the serum was identified to be correlated with prognosis of lung carcinoma [miR-499-3p expression was increased in signet-ring cell of GC [mir-499 could be implicated in carcinoma development.In human, igration , inflammigration . A recenarcinoma . Comparell of GC . In viewMir-SNPs could affect the normal expression of mir-. Of late, some studies have sought the relationship of loci in mir-499 with cancer. Rs3746444 T>C SNP is located in mir-499 and extensively studied the association of this SNP with cancer risk. Meta-analyses have established the correlation between this SNP and the risk of overall cancer [mir-499 rs3746444 SNP and GC risk have been conducted [mir-499 rs3746444 SNP to GC is more conflicting. On this issue, it is necessary to carried out a more precise assessment. Thus, considering the effect of rs3746444 SNP on the risk of GC, we first recruited 1966 subjects (490 GC patients and 1476 controls), and conducted a case–control study. Subsequently, an updated pooled-analysis was carried out to clarify the role of rs3746444 SNP on the development of GC.Single-nucleotide polymorphisms (SNPs) may be the most frequent mutation. l cancer . Most ofl cancer ,12,13. Tl cancer . Howeveronducted ,21. The Mir-499 rs3746444 SNP was selected to studied. The related information of mir-499 rs3746444 SNP was summarized in In this investigation, 490 histopathologically confirmed GC cases were enrolled from Union Hospital  and the No.1 People’s Hospital of Zhenjiang City , between May 2013 and June 2016, and 1476 hospital-based controls were also recruited as we mentioned in our previous study . All GC 2-test was conducted to compare the difference in the distribution of genotype frequencies between two groups. SAS 9.4 software  was harnessed to analyze the data. The P value less than 0.05 was considered as statistically significant.The χThis meta-analysis was reported following the guideline of Preferred Reporting Items for Meta-analyses (PRISMA) (Supplementary Table S1. The checklist of PRISMA) .microRNA-499 OR mir-499 OR rs3746444) AND (SNP OR mutation OR variant OR polymorphism) AND (cancer OR carcinoma) and (gastric OR stomach OR esophagogastric junction OR gastric cardiac). References in reviews and the included articles were manually searched and checked the potential data. In literature searching process, there was no language limited.Two authors (G. Rong and S. Zhang) searched the PubMed and EMBASE electronic databases up to October 15, 2019 independently. The strategy of literature searching was presented as following:  we could extract the original data from the eligible study to get the pooled odds ratios (ORs) and 95% confidence intervals (CIs). The corresponding criteria of exclusion were: (a) repeated data; (b) genotype data were not presented in publication; (c) only focusing on the prognosis of GC; and (d) comments, review and meta-analysis. Two authors (G. Rong and S. Zhang) performed the procedure of data extraction independently. The following original information was selected and extracted: publication year, first author, race, country, number of subjects, method of polymerase chain reaction, mir-499 rs3746444 genotype data. If any disagreement emerged, the third author (W. Tang) was invited. The final decision was made by a vote during this process.In this meta-analysis, the included investigations should accord with the selecting criteria: (a) done as a retrospective study or a case–control study; (b) evaluated the association of mir-499 rs3746444 SNP, rs3746444 C allele was used as the reference. The relationship was evaluated by using STATA software (version 12.0). We used an online calculator (http://ihg.gsf.de/cgi-bin/hw/hwa1.pl) to determine whether the genotype distribution of mir-499 rs3746444 agreed with Hardy–Weinberg equilibrium (HWE) [Q-statistical test and 2I test to study the heterogeneity. When significant heterogeneity (2I>50% or P<0.10) was found, the random-effects model (the DerSimonian–Laird method) was used [. T), homozygote model (CC vs. TT), recessive model (CC vs. TT/TC), and dominant model (CC/TC vs. TT) were calculated. Region of GC was defined as gastric cardiac adenocarcinoma (GCA), non-GCA and mixed. Bgger’s Funnel plots and Egger’s test were used to check whether there was an evidence of publication bias. Quality evaluation was carried out with a Newcastle–Ottawa Quality Assessment Scale. The quality of the include study was defined as high quality (scores ≥ 7 stars) and low quality (scores < 7 stars) [For um (HWE) . Since twas used ,27. And was used ,29. Four7 stars) .mir-499 rs3746444 SNP were 69.82%, 26.69% and 3.49% in 490 non-GCA patients and 71.88%, 25.82% and 2.31% in 1476 hospital-based controls, respectively. As summarized in In total, 1966 subjects (490 non-GCA patients and 1476 controls) were recruited in the present study. The TT, TC and CC genotype frequencies of First, 44 literatures were searched from EMBASE and PubMed databases. As shown in P = 0.002, P =0.009), recessive model (P =0.013) and dominant model (P =0.061) suggested that allele, homozygote and recessive genetic models could increase the risk of overall GC, while the dominant model might not confirm the risk to overall GC. If we excluded the studies violated HWE, this SNP was also found to be correlated with GC susceptibility .In a subgroup analysis for ethnicity, we identified that rs3746444 was associated with the risk of GC in Asians .In this meta-analysis, we used Bgger’s funnel plots and Egger’s test to evaluate the potential bias among the included literatures. After viewing Bgger’s funnel plots, symmetrical figure was observed, suggesting no significant bias existing . Egger’sIn our study, heterogeneity was also evaluated. In dominant model, we identified significant heterogeneity. In order to explore the source of heterogeneity, subgroup analysis were harnessed. In subgroup analysis, we identified an association of the studies violated HWE, Asians, large sample size designed (≥1000 subjects), mixed GC, low quality studies and population-based study subgroups with major heterogeneity.We conducted a sensitivity analysis to assess the stability of the present findings by omitting each study in turn. We calculated ORs and CIs of remainers to evaluate the influence of each study on the overall results. The findings indicated that no individual study could alter the overall assessment significantly , which vIn the present study, we calculated the power value in the overall comparison. The value was 0.891 in the allele model, 0.766 in the homozygote model and 0.704 in the recessive model.Mir-499 may play an important role in the initial and progress of cancer. It was reported that mir-499-5p could promote progression of colorectal cancer and might be considered as a therapeutic target [mir-499 rs3746444 C-allele carriers with an increased susceptibility of cancer have been identified in some meta-analysis [mir-499 with GC risk was more conflicting. In this meta-analysis, we included 12 case–control studies with 3954 GC cases and 9745 controls to explore the relationship of rs3746444 with GC risk. We first confirmed that rs3746444 SNP in mir-499 was associate with the susceptibility of overall GC, especially in GCA and Asians subgroups.c target . In addic target . And thianalysis ,12,13. Oanalysis ,32,33. Aanalysis . And it mir-499 rs3746444 C-allele could promote a susceptibility of GC compared with mir-499 rs3746444 T allele [mir-499 rs3746444 C-allele was also associated with the development of GC [miR-499 and GC development. We also found that this potential association was significant, especially in Asians and GCA subgroups. Wang et al. have identified that mir-499, by reducing astrocyte elevated gene-1, plays a tumor-suppressive role in the development of hepatocellular carcinoma [mir-499 rs3746444 TC and CC genotypes have lower expression of miR-499a [mir-499 rs3746444 C-allele decrease the expression of the mir [mir-499 rs3746444 C-allele promotes a susceptibility of GC by inhibiting the expression of the mir-499. It is reported that inclusion of articles violated the HWE may lead to bias. Here, if we excluded these studies, this SNP also conferred a risk to overall GC. It is worth noting that we did not find an association between rs3746444 SNP and non-GCA risk in the current case–control study, which was consistent with the results of meta-analysis in subgroup analyses. The mechanism of GC in different region may be diverse [Mir-499 rs3746444 may play a different role in different type of GC. However, for lack of experimental data, we did not take them into account in the present study. In the future, more functional studies are needed to focus on the potential mechanism.In this pooled-analysis, we included 12 independent studies. These literatures were conducted in different races. In view of these studies, the conflicting findings were observed, which made this pooled-analysis interesting and imperative. Cai et al.’s investigation, in eastern China, suggested that the T allele . Additiont of GC . Howevernt of GC . The mosarcinoma . A previmiR-499a . It is fmiR-499a . And as  the mir . Thus, i diverse . Mir-499mir-499 rs3746444 SNP, we only detected a moderate heterogeneity in dominant genetic model. Subgroup analyses suggested an association of the studies violated HWE, Asians, large sample size designed (≥1000 subjects), mixed GC, low quality studies and population-based study subgroups with major heterogeneity. In addition, the power of the present study (α=0.05) was also evaluated. We found that the power value was 0.891 in the allele model, suggesting the reliability of our findings.Two significant problems, publication bias and heterogeneity, should be discussed. No significant publication bias was detected in our study, indicating the dependability of these findings. Between publications for helicobacter pylori, family history of cancer, tobacco using, alcohol consumption and other lifestyles), we only calculated the crude ORs with 95% CIs to determine the relationship of rs3746444 with GC susceptibility. The effect of those factors mentioned above was not taken into account. Thirdly, only the literatures published in English were eligible, which could lead to the bias of selection. Fourth, maybe it would be helpful to validate our findings with an independent cohort. However, due to lack of sufficient data, a cohort study was not performed. Finally, despite we first identified the relationship between rs3746444 and GC development, the function and mechanism of this polymorphism remained unknown.Despite the present study has pooled all publications and explored the association of rs3746444 with GC development, some limitations also should be addressed. First, only 12 independent case–control studies with 3954 GC cases and 9745 controls were eligible. Second, for lack of some important data (e.g. gender, age, the infection of In summary, our analysis confirmed the association between rs3746444 and the risk of GC, especially in Asians and in patients with GCA. Therefore, more studies are required to explore the potential mechanisms.Click here for additional data file.


The detection of long noncoding RNA (lncRNA) is a novel method for breast cancer diagnosis. The purpose of this meta-analysis was to evaluate the clinical significance of lncRNAs in identification of human breast cancer.  Electronic databases, including PubMed (176), EMBASE (167), Cochrane Library (4), Web of Science (273), CNKI (41), VIP (18), and wanfang (21), were searched for relevant original articles. Diagnostic capacity of lncRNAs was assessed by pooled sensitivity and specificity, area under the summary receiver operating characteristic curve (AUC), diagnostic odds ratio (DOR), and subgroup and meta-regression analysis. Stata and Meta-Disc software were used to conduct the meta-analysis.  33 articles including 4500 cases were identified in our meta-analysis. lncRNAs sustained a high diagnostic efficacy; the pooled sensitivity, specificity, AUC, and DOR of lncRNAs in differentiating BC from controls were 0.74 (95% CI: 0.69-0.78), 0.78 (95% CI: 0.72-0.83), 0.82 (95% CI: 0.79-0.85), and 10.01 (95% CI: 7.13-14.06), respectively. The subgroup analysis showed that the diagnostic efficacy of lncRNAs in Asian populations was higher than that in Caucasians; lncRNAs in BC were lower than those in TNBC and were higher in plasma and serum specimens than in tissues. In addition, heterogeneity was clearly apparent but was not caused by the threshold effect.  This meta-analysis suggested that lncRNAs might be promising biomarkers for identifying breast cancer, and its clinical application warrants further investigation. Breast cancer (BC) is the most common type of cancer in women worldwide. The proportion of BC in the incidence and mortality of female malignant tumors is increasing year by year . The incHistological evaluation of biopsy is the gold diagnosis standard for BC, which is invasive and fails to diagnose cancer at an early stage. Mammography X-ray imaging is widely used in BC screening and detection, but its application in radiation is limited . CurrentRecently, genome-wide transcriptome studies have confirmed the existence of a large number of long noncoding RNAs (lncRNAs) in the organism, which in the past were dismissed as simply transcriptional “noise” . lncRNAsThe diagnostic efficacy of lncRNAs in BC has been proved by many recent studies. However, which kind of lncRNA has higher diagnostic efficacy or lncRNA in which kind of sample might be more appropriate for BC diagnosis is inconsistent in different studies. For instance, the sensitivity and specificity of RP11-445H22.4 for BC were 92 and 74%, respectively , while tCRD42019139914. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) was followed [This review was registered in the PROSPERO International Prospective Register of Systematic Reviews and the registration number was The inclusion criteria were as follows: (1) patients were diagnosed with BC by histopathological examination; (2) studies evaluated the diagnosis capacity of lncRNA for BC; (3) trials were described as case-control study; (4) studies must provide enough data to evaluate diagnosis value of lncRNA in BC; and (5) all the publication languages were restricted to Chinese and English.Trials were excluded if they did not meet the criteria above and included the following: (1) reviews, abstracts, letters, meeting, and case reports; (2) animal studies or in vitro studies; (3) studies in respect of survival or prognosis of BC; (4) the research could not find the outcome measurements; and (5) duplicate publications. Two independent researchers assessed and selected related studies to exclude the references which did not meet the inclusion criteria. If the content of a study arouse controversy, it would be discussed until agreement was reached.Two independent investigators performed the data extraction using a standardized data collection form. The following information was collected from each study: (1) basic information including first author, publication year, and country; (2) the information about patients: ethnicity, sample type, sample size, and specimen source; (3) the information of methods: detection methods, lncRNA type, expression status, and reference gene; and (4) the outcomes: cutoff value and diagnostic 4-fold contingency table .The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) was applied to assess the quality of eligible studies and the risk of bias. In QUADAS-2 tool, patients through the patient selection, index test, and reference standard as well as flow and timing were discussed by 4 key domains and each of which contained applicability concerns and risk of bias. A score of 1 was given to low risk of bias or high concern about applicability, 0 to high or unclear risk or low or unclear concern. And any discrepancies were resolved through discussion.Q statistic and I2 tests. P < 0.05 or I2 > 50% was defined to have heterogeneity. We calculated sensitivity and specificity with their corresponding 95% CI using a bivariate model. The random effects model was used when there was significant statistical heterogeneity; otherwise, the fixed effects model was used [P < 0.05 was considered significant. All these analyses were conducted using Meta-Disc 1.4  and Stata 15.0 .The application value of lncRNA for diagnosing BC was assessed through calculating the corresponding 95% CI, sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic OR (DOR). The property of diagnostic tests was evaluated by DOR and summary receiver operator characteristics (SROC), and the pooled AUC value was calculated. Heterogeneity among studies was estimated using Cochran's was used . It was β-actin, and U6. These 33 selected cohorts were divided into 46 individual studies according to 30 lncRNAs . The characteristics of the included studies were shown in The detailed screening process was shown in I2 values in sensitivity , specificity , PLR , and NLR . Therefore, the random effects model was adopted for further analysis. Forest plots of the results for the enrolled studies on the pooled sensitivity, specificity, and DOR were shown in Figures Significant heterogeneity was observed between studies for the high P value of 0.236 (P > 0.05), there was no heterogeneity from the threshold effect. In addition, the value of I2 > 50% indicated that there was heterogeneity of nonthreshold effect among these studies.Threshold effect and nonthreshold effect are two important reasons for heterogeneity of diagnostic tests. In this study, Spearman's correlation coefficient of sensitivity and specificity was selected as the representative way of exploring the threshold effect. Since the corresponding Spearman correlation coefficient was 0.178 with a In order to illustrate the source of heterogeneity, we performed subgroup analyses based on ethnicity, pathologic type, specimen, dysregulated state, and type of lncRNA. The details were shown in P = 0.186), pathologic type (P = 0.428), specimen (P = 0.157), and type of lncRNA (P = 0.296) did not significantly affect the pooled results. However, lncRNA expression status was associated with study heterogeneity (P = 0.070).Meta-regression analysis indicated that ethnicity ) and specific (0.80 (95% CI: 0.73–0.85)) to diagnosis of breast carcinoma . HoweverThe present meta-analysis for lncRNA expression profile in BC revealed that the pooled specificity and sensitivity were 0.74 (95% CI: 0.69-0.78) and 0.78 (95% CI: 0.72-0.83), which indicated its potential diagnostic capability. Diagnostic test performance was represented by DOR and area under SROC (AUC). The ideal SROC curve position for a perfect test is near the upper-left corner . The DORIn our subgroup analysis by ethnicity, the results showed that the diagnostic efficacy of lncRNAs in Asian populations was higher than that in Caucasians (sensitivity: 0.76 (95% CI: 0.71-0.80) versus 0.75 (95% CI: 0.71-0.78); specificity: 0.80 (95% CI: 0.75-0.84) versus 0.67 (95% CI: 0.49-0.80); AUC: 0.84 (95% CI: 0.81-0.87) versus 0.72 (95% CI: 0.52-0.86)). For tumor types, the diagnostic effect of lncRNAs in BC was lower than that in TNBC (AUC: 0.81 (95% CI: 0.77-0.84) versus 0.87 (95% CI: 0.84-0.90)). The plasma and serum specimen sensitivity (0.76 (95% CI: 0.70-0.81) and 0.78 (95% CI: 0.70-0.85)), specificity (0.83 (95% CI: 0.76-0.88) and 0.80 (95% CI: 0.70-0.87)), and AUC (0.86 (95% CI: 0.82-0.89) and 0.86 (95% CI: 0.83-0.89)) were higher than tissue sensitivity (0.65 (95% CI: 0.52-0.76)), specificity (0.71 (95% CI: 0.57-0.83)), and AUC (0.73 (95% CI: 0.69-0.77)). The diagnostic performance of lncRNA expression status suggested that upregulated lncRNAs (AUC: 0.84 (95% CI: 0.81-0.87)) were better than downregulated lncRNAs (AUC: 0.70 (95% CI: 0.65-0.73)). lncRNA-MALAT1 sensitivity was 0.81 (95% CI: 0.71-0.88), specificity was 0.77 (95% CI: 0.68-0.84), and AUC was 0.85 (95% CI: 0.82-0.88), which were superior to lncRNA-HOTAIR and lncRNA-H19. Our findings may further help guide therapeutic strategy in the clinic.P = 0.236), which suggested that threshold effect was excluded from the factors causing heterogeneity in the current study. Sensitivity analysis was next used to test if the heterogeneity came from any individual study. Our results indicated that the selected studies were homogeneously distributed. Subgroup and meta-regression analyses were utilized for other factors causing heterogeneity. We validated five covariates, including ethnicity (P = 0.186), pathologic type (P = 0.428), specimen (P = 0.157), type of lncRNA (P = 0.296), and expression status (P = 0.070). The data suggested that lncRNA expression status was associated with study heterogeneity. Finally, Deeks' funnel plot showed that there was no significant publication bias in the diagnostic meta-analysis for lncRNA. Unfortunately, we failed to find other sources.Exploring the sources of heterogeneity is critical to a meta-analysis. Since heterogeneity was obviously revealed by test results, we attempted to explain its sources. Threshold effect is a primary cause of heterogeneity in test accuracy studies. The Spearman correlation coefficient was 0.178 .In conclusion, this meta-analysis comprehensively investigated the application of lncRNAs as a promising biomarker for diagnosis of breast carcinoma. Before the clinical use of lncRNAs as a diagnostic marker, more large-scale prospective studies are warranted to identify which lncRNAs have a better diagnostic role in BC.


A meta-analysis was utilized to test the extent of the association between the initial results and the present report. It also provided to test the heterogeneity (variation) between the two studies.Replication studies are essential for identifying credible associations between alleles and phenotypes. Validation of genotype-phenotype associations in the sports and exercise field is rare. An initial genetic association study suggested that rs1049305 (C > G) in the 3′ untranslated region (3′UTR) of the aquaporin-1 (AQP1) gene was associated with marathon running (MR) performance level in Hispanic males. To validate this finding, we conducted a replication analysis in an independent case-control sample of Hispanic male marathon runners (p ≤ 0.05) association between rs1049305 (C > G) of the AQP1 gene and MR performance level. Association test results using a fixed effect model for the combined, original study and the present report, yielded an odds ratio = 1.28, 95% confidence interval = 1.13–1.45, p = 0.0001. The extent of the measures of heterogeneity was Tau-squared = 0, H statistic = 1, I2 statistic = 0, and Cochran’s Q test , indicated the variation between studies were due to chance and not to differences in heterogeneity between the two studies. Within the limitations of the present replication, contrast of two studies and its effects on meta-analysis, the findings were robust.The replication study showed a statistically significant . The meta-analysis provided further epidemiological credibility for the hypothesis of association between the DNA rs1049305 (C > G) variation in the 3′UTR of the AQP1 gene and MR running performance level in Hispanics male marathon runners. It is not precluded that a linked DNA structure in the surrounding molecular neighborhood could be of influence by been part of the overly complex phenotype of MR performance level. Replication studies of genotype-phenotype associations in the sports and exercise field literature are rare.Replication of findings from genetic association studies is a fundamental assessment process in research endeavors leading to new knowledge.AQP1 gene coexistent molecular mechanisms and their effects on marathon running performance phenotypes are major areas of inquiry in the science and medicine of sport and exercise.Aquaporins (AQPs) are integral membrane pore proteins, also known as water channels. The aquaporin-1 (AQP1) channel is the best known and most studied of the AQP family . The expX2, P = 0.005) between cases (fast marathon runners–the top three % of finishers) and controls (slow marathon runners–the low three % of finishers). The calculated odds ratio (OR) = 1.35. Its 95% confidence interval boundary was 1.08 to 1.67. The C-allele was more (P = 0.005) prevalent in the cases  than in the controls (slow runners). To date, these data have not been replicated.Evidence from a recent systematic review  on the an = 504). The findings revealed that the AQP1 rs1049305 C-variant was associated with the duration of the MR segment in three Ironman events. Triathletes who carried the C-allele completed the 42.2-km run stage faster  than triathletes with the GG genotype .The confirmation of a genetic-association finding is vital to identifying true positive genetic variants that may contribute to complex phenotypes, such as MR performance level  To confin = 50) versus non-carriers ; n = 41). That study revealed that AQP1 C-allele carries ran faster (P < 0.05) than non-carriers during the 10-km race. Those findings to a certain extent validated [The same association was found in another observational study using a genetic epidemiology model . In thatalidated . The genalidated , 12.To date, no exact replication , 13 of tThis observational study adheres to a genetic epidemiology model using a case-control design. All methods and procedures were identical to those described by Martinez et al. .n = 1430; cases n = 713 and controls n = 717) were male biologically unrelated volunteers, recruited during the activities of marathon (42 km) running events conducted between 2006 and 2012: Maratón de Culiacan, Gran Maratón Pacifico, Mazatlán, and Guadalajara International Marathon all held in México. The physical characteristics of the cases and controls are shown in Table The subjects in the present study  were also excluded. Subjects that participated in the initial study  were alsn = 713) were the top 3% of finishers of their respective age group, while controls (n = 717) were the lowest 3% of their respective age group.The official results of the competitions determined the classification as cases or controls. Cases  provided for the purification of genomic DNA from 10 mL of whole blood. The detailed procedures were those in the original study . The ampHI), both measures of polymorphism, followed the procedures described [H) in meta-analysis refers to the variation in study outcomes between studies. P values ≤ 0.05 were statistically significant.The statistical analysis of the actual replication study was identical to those in the original study . The polescribed , 18. Theescribed , which wescribed . The preescribed  was perfescribed  and the n = 713 and controls n = 717) while the initial study by Martinez et al. [n = 396 and controls n = 388). This replication study used 646 more subjects than the original study, which reduced the probability of a type II error.The present replication study involved 1430 subjects . chi-square test revealed a statistically significant (p = 0.02) difference in the genotype frequency distribution between the cases and controls. The present result replicates and validates the original study [As shown in Table al study , 9.TablP < 0.001) differences between the cases and controls. The C-allele was the less frequently observed in both cases and controls.Table p < 0.05) in the cases than in the controls. In the original study, 57% of the cases were carriers of the C-allele versus 49% for the controls. The computed OR = 1.35 and its 95% confidence interval extended from 1.08 to 1.67; p < 0.05. These findings also replicated and validated those of the original study [In the present study, the prevalence of C-allele carrier status was 59% (107 + 314/713) for the cases and 53% (79 + 301/717) for the controls. The calculated odds ratio (OR = 1.43) and its 95% confidence interval (1.21–1.68), suggested that the C-allele was more likely prevalent  probability measure of the likelihood that an individual will be heterozygous at the AQP1 rs1049305. Also, HI is a central measure in the study of genetic variation in populations. For two allele loci, like the one represented by the AQP1 gene rs1049305 (C > G), HI peaks at a value of 0.5.Table al study  and thosPIC value is an indicator of the probability that a marker locus (AQP1 rs1049305) is informative. It is estimated from the frequency of heterozygotes, determined by the number of marker alleles , and their respective frequencies.p values, 0.0001 and 0.0007, for the combined FE association test were highly significant. This finding affirms the association between the AQP1 gene rs1049305 (C > G) and MR performance level. Figure Table The meta-analysis also provided four indicators of heterogeneity (variation) between the two studies under consideration. The extent of these four measures of heterogeneity is shown in Table 2 value reflects the between-study variance in our meta-analysis. Tau2 is a useful measure because it is sensitive to the effect size and not sensitive to the number of studies in the analysis. We can infer the present calculated Tau2 suggested that the total heterogeneity between studies = 0.TauH statistic (H) is the proportion of total variability due to heterogeneity. H does not depend on sample size and theoretically it ranges from a lowest value of one to infinity. A value of H = 1 represents complete homogeneity. In the present study, H = 1.Within the context of meta-analysis, I2 statistic is a descriptive value and not a measure of the real variation across the underlying true effects. Its scale ranges from 0 to 100%. I2 statistic is a choice test to quantify heterogeneity and calculates the percentage of variation across studies that is due to heterogeneity rather than chance. The present result of I2 = 0% indicated that all variability in effect size estimates is due to sampling error (chance) and does not require further explanation.The Q test (Q) statistic is to demonstrate heterogeneity but does not reveal its extent. It only indicates the statistical significance. The I2 statistic quantifies the magnitude of such heterogeneity. Q value is used to determine if variations are due to chance or they are due to differences between studies. Q is also called chi-square test for heterogeneity or homogeneity. A weakness of the Q statistic is its reduced power to detect true heterogeneity among studies when the meta-analysis includes a few studies. The present replication study is based on two studies. As a counterweight for the low power of Q, we opted to test for heterogeneity using an alpha level of 0.10, rather than 0.05, which increases the probability of finding heterogeneity. In the present study, the observed value for Q = 0.29; p value 0.59. Since the observed p value was higher than 0.10, then we assume variations are due to chance and not differences between studies.The purpose of the Cochran’s The strong association between AQP1 gene sequence variant rs1049305 (C to G) and marathon running is impressive, and we can infer that it promotes whole-body fluid regulation that affects many aspects of performance level. Regulation of water flow across cell membranes is essential for maintaining an appropriate fluid balance within the cell. Physical activity and exercise disturb muscle cell homeostasis. Depending on the exact nature of the stress, skeletal muscle may adapt by increasing size, improving neuromuscular performance, or increasing endurance . If eachAn adequate body fluid balance may improve blood flow through the smallest vessels, which will enhance oxygen delivery to the working muscles . MetabolReplication of findings from genetic association studies is a fundamental assessment process in research endeavors leading to new knowledge in genetic epidemiology and related scientific fields. The main functions of replication are the verification of a research finding or piece of knowledge, control of sampling error, control of artifacts, control of fraud, the generalization of results to a different or broader population, and the verification of the initial research hypothesis , 27. TheSome have argued that there is no such thing as an exact replication . The maiThe main finding of the present study was the replication of the association between the DNA sequence variant rs1049305 (C > G) in the 3′UTR of the AQP1 gene and MR performance level in Hispanic male marathon runners. The present exact replication process observed the same rigor, methods, means, ways, ethnic group, and personnel as described in the original study , 15. PreReplication or corroboration studies using comparable subjects and research design as those used in the initial study are rarely conducted in exercise and sports science research. Replication and corroboration attempts have violated the principle of specific physiological adaptations by training modality and or sports discipline. For instance, attempts to replicate genetic associations with candidate genes observed in endurance modalities  by examining subjects in team sports or activities with different metabolic demands. In the latter cases, such factor could lead to failure to replicate or even corroborate findings , 29. FaiThe present replication study assessed the validity of the findings of Martinez el al .. To enh∆ = 646) results in a greater statistical power than in the initial study. This study examined a highly specific human sample and a favorable statistical power. We are in the early stages of deciphering the complex polygenic biology  underlying MR performance level. The study of AQP1 deserves further detailed systematic scrutiny.The exact replication of the initial findings of Martinez et al.  is highl


Metabolic syndrome (MetS) has been associated with hypercoagulative status. However, previous studies evaluating the association between MetS and incidence of venous thromboembolism (VTE) after total joint arthroplasty (TJA) showed inconsistent results. We performed a meta-analysis to evaluate the influence of MetS on the risk of VTE following TJA.Cohort studies were identified by the search of PubMed, Embase, and the Cochrane’s Library databases. A random-effect model was used if considerable heterogeneity was detected; otherwise, a fixed-effect model was used. Subgroup analyses according to the category of VTE, definition of MetS, category of procedure, and follow-up durations were performed.p = 0.20; I2 = 69%). The results were not significantly affected by the diagnostic criteria of MetS, category of the procedure, and follow-up durations. Subgroup analyses showed that MetS was not associated with an increased the risk of pulmonary embolism , but an increased risk of deep vein thrombosis (DVT) after TJA .Seven cohort studies with 1,341,457 patients that underwent TJA were included, with 118,060 MetS patients (8.8%) at baseline. With a follow-up duration up to 3 months after surgery, 9788 patients had VTE. Pooled results with a random-effect model showed that MetS was not associated with increased overall VTE after TJA (adjusted risk ratio [RR] = 1.24, 95% confidence interval [CI] 0.89 ~ 1.72, Current evidence from observational studies suggests MetS might be associated with an increased risk of DVT but not PE after TJA. Patients undergoing total joint arthroplasty (TJA), including total knee arthroplasty (TKA) and total hip arthroplasty (THA), are at a higher risk for the development of venous thromboembolism (VTE) –3. DespiMetabolic syndrome (MetS) refers to a cluster of metabolic abnormalities including abdominal adiposity, insulin resistance, hyperglycemia, hypertension, and dyslipidemia , 8. AccuThe meta-analysis was designed and performed in accordance with the MOOSE   and CochElectronic databases of PubMed, Embase, and the Cochrane’s Library were systematically searched using the combination of the following terms:  “metabolStudies were included if they met the following criteria:  publisheLiterature search, data extraction, and study quality assessment were independently performed by two authors according to the predefined inclusion criteria. If inconsistencies occurred, discussion with the corresponding author was suggested to resolve the disagreement. The following data were extracted:  name of Q test was performed to evaluate the heterogeneity among the include cohort studies [I2 statistic was also calculated. A significant heterogeneity was considered if I2 > 50%. A random effect model was used to pool the results if significant heterogeneity was detected; otherwise, a fixed-effect model was used. Sensitivity analysis by omitting one study at a time was performed to evaluate the stability of the results [P < 0.05 was considered as statistically significant. The RevMan  and STATA software were used for the statistics.The association between MetS and VTE in patients after TKA or THA was measured by RRs. To stabilize its variance and normalized the distribution, RR data and its corresponding stand error (SE) from each study was logarithmically transformed . The Coc studies , 26, and results . To eval results . P < 0.0The flowchart of the database search was shown in Fig. Characteristics of the included studies were summarized in Table Q test = 0.001, I2 = 69%). Pooled results with a random-effect model showed that MetS was not associated with increased overall VTE after TJA  or VTE , but with an increased risk of DVT after TJA  or NCEP-ATP III criteria , THA , or both , 1 month , and 3 months .The funnel plots for the association between MetS and VTE after TKA or THA were shown in Fig. In this meta-analysis of cohort study, we found that MetS at baseline was not associated with an increased risk of overall VTE events in patients after TJA. Subgroup analysis showed that MetS was independently associated with an increased risk of DVT, but not PE in patients after TJA. Moreover, the results were not significantly affected by the diagnostic criteria of MetS, the types of surgical procedures, and the follow-up durations. Taken together, current evidence from observational studies suggests that MetS might be associated with an increased risk of DVT, but not PE in patients after TJA.To the best of our knowledge, our study is the first meta-analysis to evaluate the potential association between MetS and VTE risk in patients after TJA. Although we did not show that MetS was independently associated with an increased incidence of overall VTE, subgroup analysis suggests that MetS was associated with an increased risk of DVT but not PE in these patients. The potential reasons for the findings remain unknown. Generally, PE was resulted by thrombi from the lower extremities of patients with DVT. Due to the routine use of prophylactic measures against VTE in patients after TJA, the incidence of PE in these patients is lower than the incidence of DVT . In our The potential pathophysiological mechanisms underlying the association between MetS and increased risk of DVT after TJA may be multifactorial. Patients with MetS are characterized by a persistent activated chronic inflammatory response. Since inflammation is a major activator of coagulation, these patients are generally at hypercoagulative status, thereby vulnerable to venous thrombosis , 11. MorOur study has limitations, which should be considered when interpreting the results. Firstly, as a meta-analysis of observational studies, although we combined RR data after adjustment of potential confounding factors, we could not exclude other residual factors that may confound the association between MetS and DVT after TJA, such as the comorbidities of the patients and concurrent medications . SecondlIn conclusion, our meta-analysis showed that current evidence from observational studies suggests MetS might increase the risk of DVT but not PE in patients that received TJA. Although these findings should be validated in prospective studies, the results of this meta-analysis may suggest the importance of MetS control for reducing the risk of DVT after TJA.


P = 0.950) compared with that of once per day. Compared with a bowel movement frequency of once per day, a bowel movement of more than once per day was also not related to elevated risk of colorectal cancer . The subgroup analyses indicated a low or high bowel movement frequency did not increase the risk of colon cancer . However, an increased frequency of bowel movements increased the risk of rectal cancer . The sensitivity analysis still supports the results. No significant publication bias existed. The data from cohort indicated that less bowel movement frequency was not associated with the risk of colorectal cancer. The frequency of bowel movement affects the risk of rectal cancer.Previous studies from case–control studies failed to draw reliable conclusions regarding the relationship between bowel movement frequency and the risk of colorectal cancer. To further examine this relationship, we collect the data from cohort studies that make a more accurate estimation. Several online data were searched from inception to February 29, 2020. Ten cohort studies involving 1,038,598 individuals were included in our study. The pooled results indicated that a bowel movement of less than once per day was not associated with the risk of colorectal cancer (relative risk (RR)= 1.00, 95% confidence interval (CI): 0.87–1.16,  Colorectal cancer is one of the most common cancers regardless of males and females . There wWe performed this meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement guidelines . This is a meta-analysis based on previous studies and the ethic approval is not applicable. The included studies have declared that they were approved by the ethics committee of their own. The studies have been carried out in accordance with the World Medical Association Declaration of Helsinki, and that all subjects provided written informed consent.We performed search in the PubMed, EMBASE, Web of Science, EMBASE, CNKI and Wanfang databases from their inception to February 29, 2020. The corresponding search terms mainly consisted of  AND  AND . The search strategy is presented in Supplementary material 2. We also checked the references lists of some of the reviews for additional potentially eligible studies. The search languages were restricted to English and Chinese.The exposure of interest was frequency of bowel movement. Almost all studies considered the frequency of once per day as the control. Therefore, normal bowel movement was defined as once per day. Abnormal bowel movement was defined as less than once per day or more than once per day. The outcomes of interest were colorectal cancer, including colon cancer and rectal cancer.Two investigators (L.Y.Y. and L.N.) performed the literature search, excluded duplicate studies, and scanned the titles and abstracts of studies, during which we intentionally expanded the search to include all potential studies. Finally, we reviewed the full texts of the selected studies for extracted data. The inclusion criteria included: (1) the study was a prospective or retrospective cohort study in a general population; (2) the study classified those with a bowel movement frequency of once per day as the unexposed group, and the rest were classified as the exposed group; and (3) the study provided sufficient data to calculate relative risks (RRs) and theirs 95% confidence intervals (CIs) for colorectal cancer, including the risk ratio and hazard ratio (HR). For studies with duplicated data, the most recent publication was used. Reviews, letters, comments, editorials, experiments and qualitative studies were excluded. Any disputes were resolved through discussion.The data extraction was performed by S.-L. and confirmed by other authors (Z.Q. and L.C.). For each study, we mainly extracted the following information: surname of the first author; publication year; country; type of study design (retrospective vs. perspective cohort); sample size; mean age or age range of study population; methods of bowel movement reporting (self-reported vs. others); follow-up period (year); colorectal cancer rates, including colon cancer and rectal cancer; adjusted factors in the multivariate analysis; risk ratios and 95% CIs in each study (adjusted and unadjusted); and events and nonevents in exposure group and control group.We used the Newcastle–Ottawa Scale (NOS) (cohort study version) for quality assessments of included studies . This scQ test and I2 statistic [Q test was a qualitative analysis, and P < 0.05 was considered significant heterogeneity. For the quantitative analysis, I2 ≤ 25% indicated low heterogeneity, 25% < I2 ≤ 50% for mild heterogeneity, 50% < I2 ≤ 75% for moderate heterogeneity, and I2 > 75% means high heterogeneity [P < 0.05 indicated statistically significant differences. All analyses were performed using Stata 14.0 and Review Manager Version 5.3 software.We used the RR as the measurement parameter for the relationship between bowel movement and colorectal cancer risk. The hazard risk was directly regarded as the RR. The corresponding 95% CIs were also calculated . We extrtatistic . The Cocogeneity . The hetogeneity ,21. P < Initially, we obtained 5745 records identified through the database search. Of these, 307 duplicates were excluded, and 5438 records were further screened. We further excluded 5404 records with obviously irrelevant topics or that were cross-sectional or case–control designs, case reports or other types of publications. Thirty-four records were assessed for eligibility by reviewing the full-text articles. We excluded 24 studies, including eight non-cohort studies, one study with insufficient data, three systematic reviews, one comment, one case report, three editorials, one letter, one prognosis analysis, one study among a special population, two duplicates and two unrelated topics. The list of the excluded studies with the exclusion reasons are presented in Supplementary Material S3. Finally, ten cohort studies were included ,22–30. TThe According to the NOS, these studies had generally good quality, with a mean of 8.3 points. The NOS scores ranged from 7 to 9. The details of each domain and item are presented in Supplementary Material S4.I2 = 94%, P < 0.001). Compared with the group with a frequency of once per day, the group with a frequency of <1 time per day did not have an elevated risk of colorectal cancer . Using a random effect model, we found that a bowel movement frequency of more than once per day was not associated with colorectal cancer occurrence compared with a frequency of once per day . Compared with a bowel movement frequency of once per day, the frequency of more than once per day was not related to colorectal cancer risk . The pooled results indicated that a bowel movement frequency of <1 day reduced the risks of colon cancer . We extracted eight sets of colon and rectal cancer data from ten studies. Mild heterogeneity was found in two subgroups, and fixed-effect models were used . The results indicated a non-significantly relationship between bowel movement frequency of more than once per day and the risk of colon cancer . Then, an analysis of the influence of a single study was performed by omitting one study at a time. The results remained stable .P > 0.05); but significant publication bias was found according to the unadjusted data of rectal cancer (>1 time per day).All the results of the publication bias analyses, including the overall pooled and subgroup analyses, are presented in The present meta-analysis comprehensively and systematically reviewed the data from cohort studies and found the following: (1) Overall, the unadjusted and adjusted pooled results indicated that a bowel movement frequency of <1 time per day was not associated with colorectal cancer compared with a frequency of once per day. (2) Compared with once per day, a bowel movement frequency of >1 time per day was also not related to colorectal cancer risk. (3) However, the subgroup analyses indicated that the frequency of >1time once per day increased the risk of rectal cancer but not colon cancer after adjusting for potential factors. The present study contained more than one million study participants and high-quality cohort study data, providing strong evidence supporting the association between bowel movement frequency and colorectal cancer risk.Two meta-analyses based from case–control studies have been published. The main findings were inconsistent with our pooled results. The differences between our study and the previous studies should be noted. First, the previous studies combined the data from case–control studies, while our study consisted of only cohort studies. Cohort studies better illustrate causal relationships than case-control studies. Second, in 1993, Sonnenberg and his colleagues performed a meta-analysis of fourteen case–control studies and reported that constipation increased the risk of colorectal cancer . In 20132 was significantly elevated in the gastrointestinal tract in people with diarrheal [2 can promote tumor growth by enhancing cell proliferation, prompting angiogenesis and inhibiting apoptosis [in vivo [2 can inhibit the production and effects of some inflammatory factors, such as IL-2, thereby inhibiting T-cell-related tumor immunity mediated by IL-2, suppressing immunity to rectal cancer [Previous studies suggested that constipation caused toxins to accumulate in the intestine over time, leading to the increased risk of colorectal cancer. The existing case–control studies also support this hypothesis. However, our results from the included cohort studies were in contrast with this hypothesis. We found a completely different result from those in previous research studies: the frequency of bowel movements may be associated with rectal cancer risk. It has also been reported that diarrhea and loose stools may stimulate the intestinal mucosa and induce the pathological proliferation of intestinal epithelial cells and abnormal intestinal epithelial structure and tumor formation. The production of irritants may be closely related to an imbalance in intestinal flora . Experimiarrheal . It was poptosis ,36. This[in vivo . Elevatel cancer . This maThe major strength of our study was the analysis of only cohort studies. A further strength was that the present studies consisted of more than 1 million study participants. Our study had several limitations. First, the bowel movement frequency was obtained from a self-reported questionnaire, and the reproducibility and validity of the responses were not confirmed. In addition, some recall bias may have existed. Second, the extracted data were from adjusted results, and the adjusted factors were different in some studies. Third, some studies also reported that some participants had taken laxatives before baseline data collection, potentially affecting the estimations.Overall, our meta-analysis suggested that a bowel movement frequency of less than one time per day was not associated with the risk of colorectal cancer compared with a frequency of once per day. Compared with a bowel movement frequency of once per day, the frequency of bowel movements did not increase the risk of colon cancer but elevated the risk of rectal cancer. Due to the study number limitation in the subgroup analyses, further research is needed to confirm this result. However, as an easily recognized symptom, abnormal frequency of defecation should be emphasized in the practice of self-health management and early screening for rectal cancer.Click here for additional data file.


Introduction: Due to the introduction of low-dose computed tomography (CT) and screening procedures, the proportion of early-stage lung cancer with ground glass opacity (GGO) manifestation is increasing in clinical practice. However, its epidemiological characteristics is still not fully investigated.Methods: We retrieved all solitary GGO adenocarcinoma lung cancer (ADLC) on the PubMed, Cochrane Library, and Embase databases until January 1, 2019 and extracted the general information to perform the meta-analysis, mainly focusing on age, gender, and smoking status.Results: A total of 8,793 solitary GGO ADLC patients from 53 studies were included in this analysis. The final pooled analysis showed that the female proportion, average diagnosis age, and non-smoking proportion of solitary GGO ADLC was 0.62 , 56.97 , and 0.72 , respectively. The cumulative meta-analysis and meta-trend analysis confirmed that the average age at diagnosis has been decreasing while the non-smoking proportion significantly increased in the past two decades.Conclusions: From our epidemiological analysis, it demonstrates that the clinical characteristics of GGO lung cancer patients may be out of the high-risk factors. Therefore, we propose to reconsider the risk assessment and current lung cancer screening criteria. The ructures . A previructures . As the This study was reported on the basis of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines .Two individual researchers conducted the platform searches on the PubMed, Cochrane Library, and Embase databases. Literature retrieving was carried out through a combined searching of subject terms (“MeSH” on PubMed and “Emtree” on “Embase”) and free terms on the platforms of PubMed and Embase, and through keywords searching on platform of Cochrane Library. Detailed searching criteria used in the three electronic platforms are available in All available studies that had been published in English until January 1, 2019 on patients with solitary GGO ADLC were included, and the inclusion and exclusion criteria were listed. The inclusion criteria of study were (1) GGO manifestation and (2) finally pathologically confirmed ADLC. The exclusion criteria were the following: (1) studies with a design of literature review, systematic review, basic research, letter to editors, diagnostic study, and so on; (2) studies that include the following cases and cannot be ruled out—multiple GGO, benign GGO, or pure solid nodules; (3) studies that did not involve basic information of patients; and (4) studies using repeated patients cohorts with any other study. There were no limitations on the participants' nationalities.I2 (significance level at I2 > 50%) or using the Cochrane Q-test (significance level at P < 0.100). The cumulative meta-analysis was also performed, and the trend test was performed to confirm the trend of cumulative meta-analysis, as sorted by years. The methods of Begg's and Egger's regression asymmetry test were performed to test publication bias, and P < 0.050 and P < 0.100 were considered to be statistically significant publication bias for Begg's and Egger's, respectively,  and National Institute for Clinical Excellence (NICE) quality assessment scale were performed to assess methodological quality and risk of bias for cohort studies and case series studies, respectively. We extracted the general characteristics of GGO patients  to perform the meta-analysis. For the proportions of GGO adenocarcinoma of the female gender and the smoking histories, the single rate was determined, and the single mean value was used for the calculation of the average diagnosis ages of the patients. Meta-analysis was performed on all the data using fixed or random effect through heterogeneity, which was tested by estimating value of analysis . SensitiI2 > 50%).The process of eligible literature selection is presented in P-value of Begg's and Egger's test is > 0.1, indicating that there was no existence of publication bias  , and the ion bias . For aveion bias . The P-vct value . A totalct value . The P-v66–0.77) .P < 0.001) (P < 0.001)  , and the< 0.001) . The cum< 0.001) , which w< 0.001) .GGO-predominant lung cancers are typically characterized as non-invasively or minimally invasively low-grade adenocarcinomas and had good prognosis after surgical intervention . Early dOur study demonstrated that the majority of GGO ADLC patients are female with non-or light smoking history, and the average age at diagnosis has been significantly decreasing. This indicates that there are more lung cancers being detected from the traditionally “low-risk” groups, such as young female non-smokers. It is well-accepted that early detection of lung cancers is the most important procedure that contributes to improved survival outcomes and reduced lung cancer mortality. Therefore, we propose that, in order to identify these very early stage GGO lung cancer patients with low-risk factors, it is necessary to reconsider the risk assessment and current lung cancer screening criteria.All datasets generated for this study are included in the article/XL, FR, and SW retrieved and analyzed all of the data in the study. ZH and ZS revised the manuscript for important intellectual contents. SX and JC designed, checked, and supervised the study process. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Contrary results are available in the literature with inconclusive findings and none meta-analysis to gather these data.Chronic periodontitis (CP) is an immune-inflammatory disease that promotes tissue damage around the teeth. Among the several inflammatory mediators that orchestrate the periodontitis, there is the interleukin (IL)-2. Genetic variations in IL2 2) and Odds Ratio (OR) with 95% of Confidence Intervals (CI) calculations and a sensitive analysis to assess the accuracy of the obtained results. The publication bias was evaluated by Begg’ and Egger’s test with Comprehensive meta-analysis software. The value of P < 0.05 was considered as significant.A literature search was performed for studies published before June 11, 2019 in diverse scientific and educational databases. The data was extracted by two investigators and the statistical evaluation was performed by Review Manager statistical program with heterogeneity  as well as in the genotypic comparisons (P = 0.15). The Begg’s test and the linear regression Egger’s test did not show any evidence of publication bias risk (P > 0.05) which was corroborated by the absence of obvious asymmetry in Funnel plot graphic.Five studies were identified in diverse ethnical groups with 1425 participants. The − 330 T/G polymorphism in IL2 gene and CP in any allelic evaluation.This meta-analysis showed a non-significant association between − 330 T/G polymorphism in IL2  Periodontitis is characterized as a clinical condition caused by accumulative dental plaque in periodontium and host-immune response with tissue damage resulting in possible teeth loss . The disThe disease receives distinct classifications, which the chronic and aggressive periodontitis forms  are the most common in clinical with the CP characterized by slow and swift progression reaching subjects with increased mean of age .Several factors are involved in periodontitis development and progression from poor oral hygiene  to speciTaken the IL-2 and periodontitis, there are contradictory findings available in the literature that regarding the association between increased IL-2 levels and the disease. Some authors have showed significant higher levels of this cytokine in gingival fluid from patient with periodontitis than healthy controls . Howevergene is located in the chromosome 4q26-q27 region which polymorphisms in this gene were first described by Jonh et al. . No language restriction have been used in the systematic search that have approached studies published before June 11, 2019. The abstracts of the screened studies and their references were revised by the investigators to identify some potential additional studies.Two investigators independently have retrieved the available literature for studies that analyzed any possible association between the − 330 T/G in IL2 Two authors independently reviewed all the identified studies in the systematic search and have extracted the data by use of a standardized form that composed the table of characteristics of included studies. In attempt to assess the methodological quality of the included studies, the guidelines for systematic reviews of periodontal genetic association studies proposed by Nibali  have beeThe Review Manager software version 5.3  for systematic reviews and meta-analyses was the statistical program used in the calculations. On the other hand, the publication bias have been evaluated by the Comprehensive Meta-analysis statistical software version 3.3.070 (2014), available on-line as a trial.2), calculated by the chi-squared Q-based statistical test and by analysis of the Funnel plot graphic for heterogeneity. When the observed value of I2 presented a non-statistical significance  the authors used the Fixed-effect model for the pooled Odds Ratio (OR) calculation. When I2 presented a statistical significant value  the Random-effects statistical model was used for the OR calculations. The P value < 0.05 was considered as significant. To determinate the exact influence of the genetic variation in the meta-analysis calculations, six genetic models evaluated taking in base “M” as a mutant allele and “m” allele as a wild-type allele were calculated. Allelic comparisons: (I) M versus m -, (II) m versus M; Genotypic comparisons: (III) MM versus mm, (IV) mm versus MM; and the combinations among the genotypic variations: (V) MM versus mm + Mm and (VI) Mm versus MM + mm. The Begg’s test and Egger’s linear regression test (with P < 0.05) were the statistical analyses used to estimate the potential publication bias in this meta-analysis, the Funnel plot asymmetry was also considered. In addition, the authors have performed a sensitivity analysis to verify the robustness of the pooled results. There was the omission of one included study at a time to detect individual effects on the overall analyses. All the included data in the studies have been dichotomous data expressed as OR with 95% of confidence intervals (CI) to determinate the possible association between the polymorphism in IL2 gene and periodontitis.The presence or absence of true heterogeneity  nor wild type homozygous genotype was not associated with controls . All calculations was performed by means of the Random-effects statistical model due to increased I2 . In addition, there was no asymmetry in the funnel plot for publication bias validating the tests performed . Therefore, we have performed calculations for a stratified analysis based in these both ethnical groups.This meta-analysis has attempted to evaluate the influence of different ethnic groups in the results. As showed by Table gene and periodontitis in the ethnical evaluation. It is interesting to note the similar results for Caucasian and Asian ethnicities, despite the differences in MAF of T allele into these distinct populations.There was a major prevalence of T allele in − 330 T/G polymorphism in white individuals from United States population in comparison with African-American individuals  and presgene and periodontitis and brought significant number of participants, the meta-analysis showed important limitations that should be noted.Although, to the best our knowledge, this is the first meta-analysis to focus in to determinate the association between a polymorphism in IL2 P value does not always reflect the absence of clinical relevance [First, five studies were included in quantitative syntheses. This limited number of included studies is not sufficient to show robustness in results and may be a source of bias. However, seen this limitation we have performed accurate statistical methods to validate our findings. Second, important factors associated with patients were not available in included articles. A complete evaluation about adjusting factors such as: gender, smokers and non-smokers, stratified age data and others conditions that influence the development of periodontitis was not possible due to the limited included data in the studies. Third, periodontitis is a clinical condition that receives several classifications. An evaluation take in base others types of periodontitis also was not possible. Besides, a new classification for the disease has been proposed and must be considered by future studies . Fourth,elevance  what ledFurthers studies must be focused in attempt the real association between − 330 T/G polymorphism and periodontitis correlated with others factors that may promote progression of the disease  as well as others ethnical groups. Likewise, future studies to determinate the influence of haplotypes between this polymorphism with others genetic variations are required with more knowledge about genetic factors and risk of periodontitis development.gene and CP in any allelic evaluation with increased heterogeneity and absence of publication bias.In conclusion, into the limitations, this current meta-analysis showed a non-significant association between the − 330 T/G polymorphism in IL2 Additional file 1. PRISMA 2009 Checklist.