PON1 gene. The PON1 gene has been implicated in the risk for PCOS, the influence of which appears to come from single nucleotide variants (SNVs) at multiple genetic loci. However, association study reports have been inconsistent which compels a meta-analysis to obtain more precise estimates.Etiology of polycystic ovary syndrome (PCOS) is attributed to genetic and environmental factors. One environmental factor is oxidative stress. Paraoxonase 1 (PON1) is an antioxidant high-density lipoprotein-associated enzyme encoded by the PON SNVs into three: LD1, LD2 and LD3. Second, frequencies of the variant (var), wild-type (wt) and heterozygous (het) genotypes were used for genetic modeling . Risk associations were expressed in terms of pooled odds ratios (ORs), 95% confidence intervals (CIs) and Pa-values. Evidence was considered strong when significance was high (Pa < 0.0001) and heterogeneity absent (I2 = 0%). Pooled effects were subjected to modifier (power), subgroup (Asian/Caucasian), outlier, sensitivity and publication bias treatments. Multiple comparisons were Bonferroni-corrected.From 12 publications, extracted genotype data were used in two genetic procedures. First, linkage disequilibrium (LD) was used to group eight var allele in the highly significant (Pa < 0.0001) overall  and Asian  outcomes. Of these two core outcomes, the Asian effect was homogeneous (I2 = 0%) but not the overall (I2 = 29%).This meta-analysis generated 11 significant outcomes, five in LD1, six in LD2 and none in LD3. All six LD2 outcomes did not survive the Bonferroni-correction but two of the five in LD1 did. These two core LD1 findings conferred greater odds of PCOS to the PON SNVs examined, two (rs854560 and rs662) were associated with PCOS risk. These 1.4-fold increased risk effects rendered Asians susceptible to PCOS. High statistical power, high significance, zero to low-level heterogeneity, robustness and lack of bias in the core outcomes underpinned the strong evidence for association.Of the eight The online version contains supplementary material available at 10.1186/s12958-020-00665-1. PON1 lies near the centromere, while PON2 is near the telomere with PON3 in between them [PON2 SNV, rs7493 (Ser311Cys), is a substitution of guanine to cytosine nucleotides that results in serine to cysteine amino acid substitutions at residue 311 [PON gene cluster [PON1 have been studied in regard to its enzyme activity and risk of diseases including PCOS [PON1 variants (var) have been reported to regulate PON1 expression and affect circulating serum levels as well as catalytic activity [PON1 expression [PON1 polymorphisms have been investigated in a variety of pathophysiological conditions that range from metabolic syndrome, cardiovascular diseases and stroke to diabetes. These reports collectively enabled better understanding of the genetic (in terms of transcription factor binding capacity and gene expression level) and physiological pathways conferring the importance of SNVs in oxidative regulation related to the etiology of PCOS. However, associations of the PON SNVs with PCOS risk have been contradictory, which gives reason to perform a meta-analysis of all eligible studies. Since the four previous meta-analyses [PON SNVs with PCOS risk. To this end, we apply a number of meta-analytical tools that yields fresh insight in the PON-PCOS associations.Polycystic ovary syndrome (PCOS) is a multifactorial and polygenic disorder . Geneticplicated . The PONeen them . The PON cluster , 11. Seving PCOS . Among ting PCOS , 14. Theactivity , 15. Thepression  by modulpression , 17 whilpression . PON1 poanalyses –21, new PON”, “paraoxonase”, “polymorphisms”, “polycystic ovary syndrome” and “PCOS” as medical subject heading and text, unrestricted by language and time span. References cited in the retrieved articles were screened manually for additional eligible studies. Inclusion criteria were: (i) case–control studies evaluating the association between PON variants and PCOS and (ii) genotype frequency data to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Exclusion criteria were: (i) animal studies, (ii) reviews, case report or case series, expert opinion and (iii) unusable genotype data.We searched MEDLINE using PubMed, Science Direct and Google Scholar for association studies as of August 03, 2019. The terms used were “PON SNVs examined and article features needed to tally the Clark-Baudouin score. Table P-values for the Hardy-Weinberg Equilibrium (HWE).Two investigators (AK and NP) independently extracted data and arrived at consensus. The following information was obtained from each publication: indications (yes/no) of whether each article was included in the four previous meta-analyses –21, firshttps://ihg.gsf.de/cgi-bin/hw/hwa1.pl with a two-tailed P < 0.05 indicating deviations. Data distribution was assessed with the Shapiro-Wilk test [We used the G*Power program  to evaluilk test .Methodological quality of the included articles was assessed with the Clark-Baudouin scale , the scoPON SNVs with risk of PCOS. Proximity of SNVs has been posited to cause observed phenotype associations [PON SNVs were grouped into three  values across the studies in LD2 and LD3 merited use of standard genetic models: (i) recessive: var-var versus het + wt-wt, (ii) dominant: var-var + het versus wt-wt and (iii) codominant: var versus wt [var allele with var-wt/wt-wt genotypes, (ii) wt allele with var-wt/wt-wt genotypes and (iii) wt-var (heterozygous) genotype with homozygous wt-wt and var-var genotypes.We performed LD analysis and adopted a suitable genetic model before examining associations of the ciations  and coulciations . Eight Pee Table  based onersus wt . BecausePa < 0.05, which were Bonferroni-corrected. Two indicators that were used to assess the strength of evidence were high significance (Pa < 0.00001) and homogeneity or zero heterogeneity (I2 = 0%). Analysis models for absence and presence of heterogeneity were fixed-effects [2-based Q test [PHET < 0.10 [2 statistic, which measures the degree of variability between studies [Risk association assessments were confined to HWE-compliant studies . Using r-effects  and rand-effects , respectd Q test  where siT < 0.10 , (ii) qu studies  and  Clark-Baudouin scores, methodological quality of the component studies was high. Table n = 7092), five [Table an study  was inclan study . Based o2), five , 46–48 wPON-PCOS associations to five SNVs .This meta-analysis generated 38 comparisons where 11 significant outcomes were confined to LD1 and LD2 (Tables Pa < 0.05). Of the five, two (Pa < 0.0001) survived the Bonferroni correction, found robust and both indicating increased risk in the var model. One was in the overall analysis seen in Fig. PHET = 0.17, I2 = 29%). This pooled effect had no evidence of publication bias (Begg-Mazumdar test: P = 0.19). The other Bonferroni-surviving outcome was homogeneous (I2 = 0%), and found in Asians . In contrast to the Asians, Caucasian outcomes were non-significant (Pa = 0.44–0.97). The mechanism of outlier treatment is visualized in the het LD1 overall comparison  and heterogeneous . Using the Galbraith plot, we identified the outlier [PHET = 0.60, I2 = 0%), acquired significance (Pa < 0.008), found robust and no evidence of publication bias (Eggers test: P = 0.53). However, this post-outlier pooled effect did not survive the Bonferroni correction.Table on Figs. , 4 and 5on Figs. , the poot Pa = 0.–0.97. ThPa = 0.005–0.03) with none surviving the Bonferroni correction. Of the six, two indicated reduced risks in the recessive and codominant models, both in power analysis . In contrast, the remaining four pooled ORs indicated increased risks, three of which were post-outlier derived in the overall analysis  and one in the pre-outlier Caucasian subgroup of the codominant model . Table Pa > 0.05). Of the five, four had pooled ORs that skirted the null effect (ORs 0.94–1.02).Table var outcomes met the criterion of high significance. However, only the Asian outcome met the other criterion of homogeneity. Nevertheless, these two core findings identified the PON rs854560 and rs662 SNVs to be associated with risk of PCOS. The LD groups differed by ethnicity, where a significant codominant risk effect in the LD2 was found in Caucasians  but not in Asians . In LD1, on the other hand, significant risk effects were found in all genetic models in Asians (Pa = 0.0001–0.03) but not in Caucasians (Pa = 0.44–0.97). Two notes regarding power outcomes (i) LD1 Asian increased risk effects were also powered and homogeneous in the var comparison; and (ii) LD2 power effects were protective (18–23%) in the recessive and codominant models. Reduced risk effects (15–16%) were also observed in the het outcomes of LD1 , where the phenotypic difference (increased risk versus reduced risk) between var and het suggests a heterosis phenomenon. Heterosis occurs when subjects heterozygous for a specific genetic polymorphism show a different phenotype from homozygotes [PON-PCOS associations, which is further driven by interactions between genetic and non-genetic risk factors. Gene-gene and gene-environment interactions have been reported to have roles in the associations of PON variants with PCOS. All 12 included articles acknowledged the role of environment but haplotype analysis was addressed in only four (33%) of the component studies [PON, one article [In the main findings, the two LD1 ozygotes , conferr studies , 49. In  article  examinedPON1 variants with PCOS have been addressed in four meta-analyses [PON1 only but our study included PON2 (rs7493) on account of its full LD with rs705379 and rs854572 of PON1. To our knowledge, this is the fifth meta-analysis to address the PON-PCOS associations, but the first to accomplish the following: (i) perform an umbrella review (Table n = 12) of included articles; and (iii) operate within LD parameters. These features render our study as most comprehensive, managing to accomplish two things: (i) fill the gaps and update the meta-analysis knowledge of the PON SNV-PCOS associations and (ii) minimize the methodological problems that beset primary studies including limited statistical power, unrecognized confounding factors, misleading definition of phenotypes and stratification of populations [The role of analyses –21, whicanalyses –21 examiew Table ; (ii) apulations .PCOS is a reproductive endocrinopathy  that is PON SNVs.Limitations of our study include: (i) six 50%) of the included primary 12 articles were underpowered. However, statistical power at the aggregate level was more than adequate and (ii) credible subgrouping was suggested at no more than two levels % of the ; (iii) pPON variants associated with PCOS. Subgrouping delineated ethnic-specific effects rendering var carrier Asians susceptible. Future studies exploring other ethnic groups would substantiate conclusions on these PON-PCOS associations with sample sizes appropriate for detecting small genotypic risks.Bonferroni-corrected significance identified rs854560 and rs662 (LD1) as the Additional file 1:Table S1. Quantitative features of the included PON-PCOS studies. Table S2. Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Table S3. Comparisons between meta-analyses that examined the PON variants associations with PCOS.


Background: One of the most frequently used medications for treating gastrointestinal disorders is proton pump inhibitor (PPI), which reportedly has potential adverse effects. Although the relationship between the use of PPIs and the risk of pancreatic cancer has been extensively investigated, the results remain inconsistent. Hence, this meta-analysis aimed to evaluate such relationship. Methods: We searched for literature and subsequently included 10 studies . The pooled odds ratio (OR) and 95% confidence intervals (CI) for pancreatic cancer were estimated using a random-effects model. We also conducted sensitivity analysis and subgroup analysis. Results: The pooled OR of the meta-analysis was 1.698 , with a substantial heterogeneity . Even when studies were excluded one by one, the pooled OR remained statistically significant. According to the stratified subgroup analyses, PPI use, and pancreatic cancer incidence were positively associated, regardless of the study design, quality of study, country, and PPI type. Conclusion: PPI use may be associated with the increased risk of pancreatic cancer. Hence, caution is needed when using PPIs among patients with a high risk of pancreatic cancer. Pancreatic cancer is one of the deadliest malignancies, with a high mortality rate. According to the GLOBOCAN 2018 database, it is the seventh leading cause of cancer deaths in the world .Helicobacter pylori, and hepatitis B or C virus infection, were also reported [Pancreatic cancer has many risk factors, including diabetes mellitus, chronic pancreatitis, and pancreatic cyst ,5,6. Sevreported ,12,13,14H. pylori infection. Considering that PPIs are well tolerated and highly effective, their use has increased dramatically [Clostridium difficile infection in the colon [Proton pump inhibitors (PPIs) are one of the most widely used medications for treating gastrointestinal disorders. Since their introduction into clinical practice in the late 1980s, PPIs have been approved for both acute and chronic management of several gastrointestinal diseases, such as peptic ulcer disease, gastroesophageal reflux disease, and Zollinger–Ellison syndrome. They are also effective in preventing nonsteroidal anti-inflammatory drug (NSAID)-associated gastroduodenal mucosal injury and eradicating atically . As theiatically . PPIs mahe colon . Long-tehe colon . PPIs’ ihe colon ,21. Prolhe colon . Moreovehe colon . The asshe colon .Indeed, the use of PPIs is associated with the increased risk of gastric cancer and hepatocellular carcinoma ,26,27,28However, only few studies investigating the association between PPI use and risk of pancreatic cancer have been published, reporting equivocal results. Therefore, in this meta-analysis, we aimed to investigate the association between PPI use and the risk of pancreatic cancer.We conducted a literature search to retrieve articles concerning the association between PPI use and the risk of pancreatic cancer between November 2018 and April 2020 (last date searched). We searched in the following four databases: PubMed, SCOPUS, Cochrane library and Google scholar. The keywords used for literature search were: “proton pump inhibitor” OR “proton pump inhibitors” OR “PPI” OR “PPIs” AND “pancreatic cancer” OR “pancreatic neoplasm” OR “pancreatic ductal adenocarcinoma” OR “pancreatic adenocarcinoma”.Following the inclusion and exclusion criteria, three authors  independently searched the literature and extracted eligible articles. Articles written only in English were selected, while the duplicated articles were eliminated. After the irrelevant articles were excluded by screening the titles and abstracts, the full-text articles of the remaining articles were reviewed, and the required information was then collected. Thereafter, we exported the results to a reference manager (EndNote) file. In the case of discrepancy, we consulted another author (HJK) and determined the final decision by mutual discussion. To identify any other relevant articles, we also searched the references of each article. This meta-analysis conformed to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement .The inclusion criteria were as follows: (1) human studies; (2) case–control or retrospective cohort studies; (3) studies reporting or containing the association between PPI use and the risk of pancreatic cancer; (4) studies reporting the incidence or prevalence of pancreatic cancer; (5) studies providing available data to calculate the odds ratio (OR) or hazard ratio (HR) with 95% confidence intervals (CI), with P values; and (6) articles written in English.Conversely, the exclusion criteria were as follows: (1) duplicated articles; (2) abstracts, case reports, comments, and reviews; (3) in vivo studies  and in vitro studies ; (4) studies regarding the mortality or survival rate of pancreatic cancer in patients who had used PPIs; (5) other languages; and (6) studies without relevant data.For the meta-analysis, we extracted data regarding the PPI exposure and pancreatic cancer incidence from each study. We double-checked all studies and resolved the differences by discussion and consensus. For each study, the following information was recorded: publication details (including the name of the first author and the year of publication), country of publication, study design, characteristics of the studied population (including mean age and ratio of sex), outcome (including OR and 95% CI), the diagnostic criteria of pancreatic cancer, and the definition of PPI exposure.For the early undiagnosed pancreatic cancer symptoms that often present as nonspecific abdominal symptoms, PPIs may have been administered to alleviate these symptoms. Hence, to reduce protopathic bias, we excluded pancreatic cancer cases that were diagnosed within 1 or 2 years after PPI exposure in six of the selected articles ,34,35,36Using the Newcastle–Ottawa Scale (NOS) , we assep value of the χ2-based Cochrane Q tests and the inconsistency score (I2). The heterogeneity test addressed the null hypothesis that all studies in the meta-analysis share a common effect size. A significant χ2 test result (p < 0.05) indicated a significant heterogeneity. The high, moderate, low, and no heterogeneity corresponded to the I2 values of ≥75, 50–74, 25–49, and <25%, respectively. Potential publication bias was evaluated using Begg’s funnel plot and Egger’s regression test [p < 0.05 indicated a statistically significant publication bias. All analyses were conducted using the Comprehensive Meta-Analysis version 2.2.064, and the statistically significant level was 0.05.Using the DerSimonian–Laird method, we employed the random-effects model to estimate the summary OR and 95% CI , which wion test . Begg’s n = 33; SCOPUS, n = 106; Cochrane library, n = 12; and Google scholar, n = 12. After removing the duplicates, we identified 123 studies. After screening the titles and abstracts, we excluded 109 articles because they were considered irrelevant articles. After performing a full-text review of the 14 remaining articles, we excluded one article which had no full-text; two articles which were meta-analysis; and one article which had a different outcome. Ultimately, 10 studies met the inclusion criteria, and thereby were considered as eligible. Through database search and the reference list, we identified the first 163 potentially relevant articles: PubMed, Of these 10 studies, seven were case–control studies, and three were cohort studies. They were published between 2012 and 2020 in six countries. Three studies were conducted in the UK ,37,41, t2 = 98.75%, p < 0.001). Using the random-effects model, the meta-analysis of 10 studies revealed that PPI use was significantly related to pancreatic cancer risk . The log odds ratio also showed that PPI use had a significant association with the risk pancreatic cancer , with a substantial heterogeneity  compared with 1.647  of the cohort studies.As mentioned, seven and three of the 10 studies were case–control and cohort studies. According to the study design, the summary effect of case–control studies was significant, with an OR of 1.725 , whereas those with <6 stars are considered low quality (n = 6). With stratification by the quality of study, PPI use demonstrated a statistically significant positive association with the risk of pancreatic cancer, irrespective of the scale of quality. The effect size was 1.534  in high-quality studies and 1.824  in low-quality studies.In this meta-analysis, studies with seven to nine stars are considered high quality , and seven were published in Western countries (Europe and USA). With stratification by countries, both groups demonstrated a positive association between PPI exposure and pancreatic cancer incidence. The summary effect OR for the subgroup analysis of studies in Asian countries was 2.705 (95% CI: 0.751–9.746), whereas that in Western countries was 1.388 (95% CI: 0.996–1.934).According to PPI type, three of the 10 studies showed stratified results. The PPIs used in the studies were omeprazole, pantoprazole, lansoprazole, rabeprazole, and esomeprazole. This subgroup analysis showed the significant association between PPI use and pancreatic cancer risk. The OR of pancreatic cancer was 2.113 (95% CI: 0.697–6.411), 2.524 (95% CI: 0.484–13.156), 2.985 (95% CI: 0.771–11.556), 5.401 (95% CI: 1.984–14.703), and 2.583 (95% CI: 0.475–14.056) on omeprazole, pantoprazole, lansoprazole, rabeprazole, and esomeprazole, respectively.To clarify the association between PPI exposure and pancreatic cancer risk, we analyzed the dose–response and duration–response data. Of the 10 studies, five showed dose–response results, while the other five showed duration–response results. However, each study presented a different cutoff value of dose and duration. Therefore, we could not perform the subgroup analysis for both dose and duration of PPI.p = 0.840). When four studies were added using Duval and Tweedie’s trim-and-fill methods, the adjusted OR was 2.243 (95% CI: 2.179–2.308); hence, the impact of this bias was probably trivial.To detect publication bias, we employed the Egger’s regression and created the Begg’s funnel plots. As showed in This meta-analysis aimed to elucidate that the use of PPIs, one of the widely used medications for treating gastrointestinal disorders, has a possibility to increase the risk of pancreatic cancer. This study is meaningful in concluding the results of the prior observational studies. It analyzed 10 studies, which included a total of 948,782 patients, by using a random-effects model and showed that PPI exposure was associated with a high pancreatic cancer risk of 69.8%.This result could be supported by some theories whereby the PPIs may influence pancreatic cancer . Indeed,The first mechanism—that is, increased gastrin production—has a carcinogenic effect on pancreatic cancer pathophysiology. Gastrin is produced in neuroendocrine G cell in the antrum and acts physiologically as a hormone to stimulate acid secretion. As the released gastrin binds to CCK2 receptors on enterochromaffin-like (ECL) cells, ECL cells secrete histamine, which binds to H2 receptor on parietal cells and stimulates acid secretion . FurtherAs gastrin binds to CCK-2 receptor, the stimulated CCK-2 receptor activates several kinases and signaling pathways that are related to pancreatic adenocarcinoma upregulation ; some ofThe second mechanism is that microbe overgrowth according to gastric hypoacidity induces nitrosation. The association between nitrosamine and cancer was previously investigated, particularly in the cancer of the stomach, esophagus, nasopharynx, urinary bladder, and colon ,62. ExpoFurthermore, secretin acts as a carcinogen of pancreatic cancer. PPIs could induce the increase in secretin levels, consequently affecting pancreatic cell growth. Chronic secretin stimulation and NOC exposure potentially overwhelm DNA repair capabilities, acting synergistically to induce tumor development .Histamine-2-receptor antagonist (H2RA), an anti-acid agent similar to PPIs, induces hypergastrinemia and hypoacidity; hence, H2RA is also reportedly associated with pancreatic cancer; the studies are still underway .These mechanisms suggesting a biological link between PPI use and cancer risk have been found in other cancers . In addiIn this meta-analysis, the significant association of PPI use and pancreatic cancer risk was maintained in the sensitivity analysis, which excluded each study separately. In addition, the effect size in the subgroup analysis based on the type of study design, quality of study, and country of publication was also statistically significant. Interestingly, in the subgroup analysis based on PPI type, only rabeprazole showed a significant association between PPI use and pancreatic cancer risk. The reason could be that the number of studies (two studies) concerning rabeprazole was less than that in other PPI types, both studies were conducted in the same country, and one of these studies in particular had a very high OR. Otherwise, the peculiar pharmacodynamics that rabeprazole has the highest pKa could explain this result. The pKa is the pH at which 50% of the drug becomes ionized (protonated). According to the Henderson–Hasselbalch equation, the amount of drug ionized form, which cannot cross cell membranes and results in drug accumulation, depends on the pKa at a given pH. The pKa of the PPIs ranges from approximately 4.0 for omeprazole to around 5.0 for rabeprazole. Therefore, at any given pH, rabeprazole accumulation within the parietal cells would be approximately tenfold that for omeprazole. Given its higher pKa, rabeprazole is activated over a wider pH range; consequently, it is converted into the active metabolite more efficiently. Their accumulation in the parietal cell or acid-induced activation of the PPI prodrug contributes to faster onset and greater gastric acid suppression compared with the other PPIs ,78.However, this meta-analysis has several limitations. First, each study was inconsistent in defining the dose and duration of PPIs. Regarding the dose, one study used “pills/day” , whereasDespite these limitations, this meta-analysis is meaningful for assessing the effect of PPIs, which are commonly used in clinical trials, on its relationship with pancreatic cancer with high mortality.In conclusion, PPI use may be associated with the increased risk of pancreatic cancer. Therefore, medical professionals should carefully consider the prescription of PPIs for patients with a high risk of pancreatic cancer.


IL-8 -251 T>A, TNF-α -308 G>A, ICAM-1 K469E, ICAM-1 R241G, IL-6 -174 G>C, and PPAR-γ 34 C>G in modulating susceptibility risk in Malaysian colorectal cancer (CRC) patients. To investigate the frequencies and association of polymorphic genotypes of In this case-control study, peripheral blood samples of 560 study subjects (280 CRC patients and 280 controls) were collected, DNA extracted and genotyped using PCR-RFLP and Allele Specific PCR. The association between polymorphic genotype and CRC susceptibility risk was determined using Logistic Regression analysis deriving Odds ratio (OR) and 95% CI. IL-8 -251 AA and TNF-α -308 AA and variant A alleles were significantly higher in CRC patients. Investigation on the association of the variant alleles and genotypes singly, with susceptibility risk showed the homozygous variant A alleles and genotypes IL-8 -251 AA and TNF-α -308 AA to be at higher risk for CRC predisposition. Analysis based on age, gender and smoking habits showed that the polymorphisms IL8 -251 T>A and TNF – α 308 G>A contribute to a significantly higher risk among male and female who are more than 50 years and for smokers in this population.On comparing the frequencies of genotypes of all single nucleotide polymorphisms ( SNPs ) in patients and controls, the homozygous variant genotypes IL-8-251 T>A and TNF-α-308 G>A polymorphisms and CRC susceptibility risk in Malaysian patients. These two SNPs in inflammatory response genes which undoubtedly contribute to individual risks to CRC susceptibility may be considered as potential genetic predisposition factors for CRC in Malaysian population. We observed an association between variant allele and genotypes of  With more than one million new cases and half a million deaths every year worldwide, Colorectal cancer (CRC) is a major public health problem, in developed as well as in developing countries . CRC is a multifactorial disease and its onset is attributed to complex interactions between environmental, and host’s genetic predisposition factors. In addition to several environmental factors including life style habits and dietary factors, obesity, inflammation and diabetes are also risk factors for CRC . Biological, animal, clinical and epidemiological studies had indicated a clear association between CRC and inflammation . Patients with inflammatory bowel disease (IBD) including Crohn’s disease (CD) and ulcerative colitis (UC) have an increased risk of CRC . Approximately 1:6 individuals with IBD have been reported to develop CRC . Genetic factors, especially those associated with inflammation have been strongly suggested to be involved in IBD development and an association between inflammatory response genes and IBD development has been established . Chronic inflammation is a common underlying cause in the development of many gastrointestinal cancers including CRC and is considered as a predisposing factor for malignant transformation. Despite several evidences strongly implicating chronic inflammation as a culprit in colorectal carcinogenesis, surprisingly, little research has directly addressed the genetic predisposing factors which mediate inflammatory response and favors CRC development. Since inflammation constitutes one of the molecular networks underlying susceptibility to IBD and CRC, it was hypothesized that genes which mediate inflammatory response might be a group of candidate genes for CRC predisposition.IL-6), interleukin 8 (IL-8), tumour necrosis factor alpha (TNF-α), intercellular adhesion molecule 1(ICAM-1) and also peroxisome proliferator-activated receptor gamma (PPAR-γ) were selected as candidate genes for the present study as they are known to be important for inflammation of colorectum and their allelic variants have been shown to have biological effects. The genetic constitution of an individual also has been hypothesized to play an important role in sporadic CRC predisposition. A great deal of attention has been focused in the field of genetic variations in the host as factors contributing to cancer predisposition. Genetic polymorphisms (single nucleotide polymorphisms) have emerged in recent years as important determinants of disease susceptibility and severity. It is well documented that genetic variations, especially single nucleotide polymorphisms (SNPs) in genes involved in several biological pathways, play a key role in determining how individuals respond at the cellular level to various environmental conditions including inflammation. Polymorphisms (SNPs) of several cytokine genes have emerged as enhancers of susceptibility and severity of gastrointestinal malignancies . Researchers had identified several polymorphisms in regulatory regions of cytokine genes that could contribute to cancer progression . SNPs that occur in cytokines gene even in the promoter regions or other regulatory regions have also been reported to influence the development and the progression of CRC . Few genes such as interleukin 6 , is a pro-inflammatory, pleiotropic cytokine which has been implicated in the pathogenesis and progression of various cancers. The TNF-α-308 G>A polymorphism (rs 1800629) which involves a substitution of guanine (G) to adenine (A) at -308 bp position, is located within the 5′ flanking region which is a regulatory hot spot region of TNF. ICAM1 is a transmembrane glycoprotein belonging to the immunoglobulin superfamily of cell adhesion molecules, normally expressed on the surface of various types of cells: leucocytes, endothelial cells and fibroblasts . The ICAM1, located on chromosome 19p13, has at least two functional bi-allelic polymorphisms, one at codon 241 in exon 4 and another one at codon 469  in exon 6. On chromosome 3p25 is located PPAR-γ which is a member of the nuclear hormone receptor super family that plays a pivotal role in regulating adipocyte differentiation, lipid and glucose metabolism, insulin insensitivity and immune response . A common structural polymorphism is 34 C>G (rs1801282) located at codon 12 (Pro12Ala) of PPAR-γ2 specific exon 8. IL-6 is a pleiotropic cytokine located on chromosome 7 p21-24 that plays a central role in haematopoiesis, as well as in the differentiation and growth of a number of cells of different histologic origin such as endothelial cells, keratinocytes, neuronal cells, osteoblasts and osteoclasts . In human IL-6 gene, the polymorphism that change guanine to cytosine at the -174 promoter region  has been reported to increase IL-6 levels . IL-8 (located on chromosome 4q13-q21) is a pro-angiogenic chemokine and one of the major mediators of inflammatory response. Of the several polymorphisms detected in IL-8, a common polymorphism at -251 position  of the promoter region has been associated with transcription activity of the gene . We aimed to investigate the contribution of the polymorphisms of the above mentioned inflammatory response genes as predisposition risk factors for CRC susceptibility in Malaysian population. IL-8-251 T>A polymorphism singly on sporadic CRC susceptibility risk. Variant allele and genotype of IL-8-251 T>A was found to be significantly associated with CRC susceptibility risk . In the light of these results, we extended the case-control study on more number of subjects and investigated the association of few additional polymorphisms of inflammatory response genes with CRC predisposition risk. This report encompasses the genetic association study carried out on the association of inflammatory response genes polymorphisms such as TNF-α -308 G>A, ICAM-1 K469E, ICAM-1 R241G , IL-6 -174 G>C , PPAR-γ 34 C>G, and also including IL-8 -251 T>A, with susceptibility risk in Malaysian CRC patients. The previously reported SNP IL-8-251 T>A  (17) was also considered in the present analysis after adding on more study subjects. As a first step, we conducted a case-control study  to investigate the association of Study setting and study subjectsThis study was carried out in Human Genome Centre, Universiti Sains Malaysia, Malaysia, after getting approval from Research Review Board and Research Ethics Committee (Human) of Universiti Sains Malaysia (Ref. no. USMKK/PPP/JEPeM [(208.4(1.4)]) and Ethical approval from Ministry of Health, Malaysia (Registration ID. NMRR-09-351-4033). For this case control study, CRC patients were recruited from Hospital Universiti Sains Malaysia (HUSM) and few hospitals under the Ministry of Health, Malaysia such as Hospital Sultanah Bahiyah, Alor Setar, Kedah and Hospital Raja Perempuan Zainab II, Kota Bharu, Malaysia.Inclusion criteriaSporadic colorectal cancer cases were identified from the database of pathology laboratories that reviewed all histologies. For inclusion, cases were histo-pathologically confirmed colorectal cases, who did not have previous colon/rectal or other cancers, and were between 30 and 70 years age at diagnosis and who were sufficiently mentally competent to participate in the interview on collection of personal and other epidemiological data. All procedures followed the ethical standards of institutional and national committee on human experimentation and the 2008 revision of 1975 Declaration of Helsinki.Exclusion criteriaCases with known (as indicated in the pathology reports) familial adenomatous polyposis (FAP), Hereditary Nonpolyposis Colorectal Cancer (HNPCC) or any other previous malignancy were excluded. Those patients with a history of systemic diseases of immune-inflammation mechanism were excluded from the study. ControlsControls were normal healthy individuals, volunteers who visited HUSM or other hospitals, for other problems unrelated to colorectal or other cancers. Controls were genetically unrelated to the cases and were without individual history of cancer and inflammatory diseases. DNA extractionoC till use. Genomic DNA was extracted using commercial DNA extraction kit  and the genes of interest were amplified using appropriate primers.Peripheral blood samples of 280 normal controls and 280 clinically diagnosed and histo-pathologically confirmed CRC patients were collected in EDTA tubes, after obtaining written informed consent. The collected samples were stored at -20GenotypingTNF-α -308 G>A, ICAM-1 K469E, IL-6 -174 G>C and PPAR-γ 34 C>G) were genotyped using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique. The other 2 SNPs (IL-8 -251 T>A and ICAM-1 R241G) were genotyped using Allele specific PCR.Out of the six SNPs included in this study, four SNPs , and 100% concordance rate was achieved. Statistical analysis2 test. The associations of polymorphic genotypes with CRC susceptibility risk was determined by using logistic regression analysis deriving odds ratios (ORs) and the corresponding 95% confidence intervals (CI). The ORs of CRC risk associated with the variant allele carrier and homozygous variant genotype for each of the polymorphism was based on the homozygosity of the major allele as the reference group. The base line group was the common major allele homozygote which by definition has an OR of 1. An association with a p-value of less than 0.05 was considered as significant. Statistical analysis was carried out using SPSS version 20. Both cases and controls were analyzed with a Chi square test to determine whether they were in Hardy-Weinberg equilibrium. The differences in distribution of various genotype and allele frequencies of the SNPs studied, gender and age between the cases and controls were calculated using Chi square, χDistribution of study subjects based on gender and ageAltogether 560 study subjects  were recruited in this case-control study. Among the study subjects, cases consisted of histo-pathologically confirmed CRC patients and controls comprised of healthy normal volunteers. Genotypes frequencies of inflammation response genes in study subjectsTNF-α -308G>A, the frequencies of homozygous wild type -308 TT genotype was significantly higher in normal controls (p=0.005), whereas the homozygous variant genotype TNF-α -308 AA was significantly higher (p<0.001) in CRC patients compared to controls. The variant allele frequency was significantly higher among CRC patients (p=0.001). Comparison of the genotype frequencies ICAM-1K469E polymorphism between patients and controls showed no significant difference in the genotype and allele frequencies between them. For ICAM-1 R241G polymorphism, the frequencies of homozygous wild type R241R was significantly higher in controls compared to CRC patients, with p value of 0.045. With regard to allele frequencies among controls, only major allele (R) was observed (100%) and no variant allele was observed. There was no significant difference in the frequencies of alleles and genotypes between cases and controls for IL-6 - 174 G>C single nucleotide polymorphism. In the case of PPAR-γ 34 C>G, the frequency of homozygous wild type CC and wild type allele (C) were higher in controls (p=0.030 and p=0.031 respectively), as shown in IL-8 -251T>A genotypes of patients and controls, the homozygous variant -251AA was significantly higher in CRC patients (p=0.001) and the frequency of variant allele A of IL-8 was also significantly higher in CRC patients (p=0.041). The results of the Hardy Weinberg equilibrium analysis of each SNP for both cases and controls showed values >0.05 (data not shown). This indicated that the cohort was in HWE and suggested that the results were reliable. Risk association of inflammation response gene polymorphisms with CRC susceptibilityTNF-α homozygous variant genotype (TNF-α -308 AA) showed significantly higher risk for CRC development with OR 5.484 . Allele A of TNF-α -308 was associated with increased risk of CRC, since it was found over-represented among CRC patients . The variant genotypes (heterozygous and homozygous variant) of ICAM-1 K469E did not show significant association for CRC susceptibility risk. Also, the variant allele (G) of ICAM-1 did not show any higher risk for CRC susceptibility. The risk association of ICAM-1 R241G with CRC susceptibility risk could not be evaluated, due to 0% of heterozygous and homozygous variant allele and genotype frequencies, in controls. The heterozygous variant genotype of IL-6 -174 G>C did not show any significant association with CRC susceptibility risk and the risk of homozygous variant genotype could not be evaluated, due to 0% frequency of this genotype in control samples. The variant allele also did not show significant risk for CRC susceptibility. The homozygous variant genotype of PPAR-γ 34GG was not present in any of the CRC patients and controls. In all the normal control samples, only homozygous wild type genotype was observed. So, the risk association of PPAR-γ 34 C>G with CRC susceptibility risk could not be evaluated, due to 0% of heterozygous and homozygous variant genotype frequencies. The risk association of the allele of PPAR-γ polymorphism could not be assessed due to the presence of only wild type alleles in control sample. In the case of IL-8, the homozygous variant genotype (IL-8 -251AA) showed significantly higher risk for CRC susceptibility with OR 4.133 . The variant allele (A) of IL-8 also showed significantly higher risk with OR 1.345, .After determining the frequencies of the different categories of genotypes for each of the 6 SNPs included in the study, the association of the variant genotypes with CRC susceptibility risk was evaluated and the results are shown in Risk association based on gender stratificationTNF-α homozygous variant genotype (TNF-α -308 AA) conferred a higher risk for CRC development in female subjects . Likewise, the homozygous variant genotype of IL-8 -251AA also showed significantly higher risk among females with OR 11.429 . The other variant polymorphisms did not show any significant gender specific association with CRC risk.We stratified our study subjects according to gender and investigated the association of the all candidate polymorphisms with colorectal cancer susceptibility risk and the results are shown in Risk association based on age groupIL-8 was associated with higher risk for CRC development in both age groups – for individuals in the more than 50 years age group  as well as those in less than 50 years age group . However, the variant genotype AA of TNF-α showed higher CRC risk association only in those above 50 years age group . No significant association between age group and CRC risk was observed for other polymorphisms studied. Risk associations based on age groups are shown in Risk association based on smoking status stratificationIL-8 -251AA showed significantly higher risk with OR 3.664  in smokers. In the case of TNF-α -308 G>A polymorphism, the heterozygous genotype  and homozygous variant genotype  showed higher risk in smokers. The other polymorphisms, failed to show any association with CRC risk when stratified based on smoking status of the study subjects. When the results were stratified according to smoking status, . Cytokines play a vital role in the mediation and regulation of immune response including tumour promoting inflammation. Many of these cytokines are pro-inflammatory and anti-inflammatory and have been implicated in tumorigenic process . Genes encoding the cytokines are genetically polymorphic and polymorphisms in inflammatory response genes have been implicated in susceptibility to inflammatory diseases as well as cancers including CRC. TNF-α -308AA homozygous variant genotype was associated with a significantly increased risk of CRC compared with -308GG genotype . The strong association observed suggest that TNF-α -308 G>A polymorphism could be contributing significantly for CRC predisposition risk in Malaysian population and also implicates its role in inflammation mediated colorectal carcinogenesis pathway. Because transcription of TNF-α is regulated by the promoter region of the TNF-α gene, polymorphisms located in this region could regulate TNF-α production and thus affect the risk of cancer. Compared to the common G allele, the A allele has been reported to increase gene transcription and produce a six-to seven fold higher level of TNF-α transcription . So it is presumed that the SNPs within the TNF such as -308 G>A might be causing structural changes within regulatory sites that could affect the function or regulation of TNF alpha production. The uncontrolled excessive production might be contributing to colorectal carcinogenesis. According to Stokker and Hommes (2004), elevated TNF-α play a pivotal role in the pathogenesis of the inflammatory response by interacting with TNF receptors and regulating apoptosis, cell proliferation and differentiation.We observed that TNF-α - 308 G>A was demonstrated to be associated with CRC susceptibility. Moreover they also reported that this polymorphism was associated with severity of CRC. Li et al., (2011) also observed a positive association of this polymorphism with CRC susceptibility in Chinese population. A meta-analysis involving 14 studies with a total number of 2,837 CRC cases and 3,601 controls by Min et al., (2014) also indicated that TNF-α -308 G>A was moderately associated with an increased risk of colon cancer risk in Western population. However, our results are in disagreement with few other studies. A study by Wu et al., (2008) reported that TNF-α -308G>A gene polymorphism was not associated with the development of colorectal cancer, but TNF- α -308 A/A genotype and A allele were related to the progression of colorectal cancer in Chinese population. Jang et al., (2001) in Korean population, Landi et al., (2003) in Spanish population, Toth et al (2007) in Hungarian population and Kapitanovic et al (2014) in Croatian population did not find any association of this polymorphism with CRC risk. Few other earlier studies  and two earlier meta- analyses  also reported no association of TNF-α -308 G>A polymorphism with CRC risk. The results from two recent other studies,  in ethnic Kashmiri (North Indian) population and Hamadien et al., (2016) in Saudi Arabian population)] also indicated that there was no significant association between TNF-α -308G>A promoter SNP and the risk of developing CRC. This could be attributed to the difference in the polymorphic allele frequencies of TNF- α -308G>A in different population ethnic groups. Our results are in agreement with few other studies. In a study by Garrity-Park et al (2008), the heterozygous and homozygous variant at IL-8 -251AA genotype was associated with a significantly increased risk of CRC as compared with homozygous wild type-251TT genotype . Similarly, in case of allele frequency also, such an association was observed. When compared with wild type allele T of SNP IL-8 -251, the variant allele A showed significantly increased risk for CRC predisposition with OR 1.345 . The strong association that was observed in the present study in CRC patients prompts to suggest that IL-8 -251T>A polymorphism could be contributing significantly for CRC risk in Malaysian patients. Disrupted gene expression or altered protein formation of IL-8 gene may contribute positively or negatively to the establishment or progression of CRC. The relevance of IL-8-251 T>A polymorphism in CRC susceptibility could be explained by the functional alteration of gene product. Researchers had suggested that, the properties of IL-8 might be giving pro-angiogenic effect in the tumour and endothelial cells and enhancing the tumour cell proliferation as well as prolonging the survival of human endothelial cells . As suggested by Wei et al., (2007) higher promoter activity of IL-8-251 T>A might increase expression of IL-8, resulting in a high function of IL-8, inducing Th1- predominant immune response and leading to more susceptibility to CRC than a low production of IL-8. Thus the variant allele may be playing a facilitative role in the development of CRC.In conformity with our previous report , the homozygous variant IL-8-251 T>A polymorphism in CRC risk in Malaysian patients is in agreement with another case- control study on American population done by Gunter et al., (2006) in which variant genotype IL-8 -251 AA showed significantly higher risk for CRC predisposition. This has been confirmed by a study by Lurje et al., (2008). Another study on interleukin genes and associations with colon and rectal cancer risk and overall survival showed SNPs from genes within the IL-8 pathway  to have significant association with both colon and rectal cancer risk . In contradictory to the present study, Landi et al., (2003) in Spanish population, Theorodopolous et al., (2006) in Greek population and Dumitrescu et al., (2012) in Romanian population reported that, the IL-8 -251 T>A genotypes was not associated with a higher risk for CRC predisposition. Hu et al., (2012) conducted a meta-analysis including 9 case-control studies with 7003 individuals  focusing on this polymorphism and CRC susceptibility. Their results also concluded that IL-8 -251 T>A polymorphism was not associated with CRC risk. However, few other meta-analyses on the association of this polymorphism with other cancers showed a positive association with some of the cancers. An association of this polymorphism was reported by Cheng et al., (2013) for gastric cancer risk in Asian population, for Oral cancer risk in Caucasian population by Wang et al., (2013) and for renal cell cancer risk by Chen et al., (2016) in Chinese Han population. In a meta-analysis on association between IL-8 -251 T>A and risk of lung cancer done by Gao et al., (2014), the results showed that the IL-8– 251A/T polymorphism was associated with lung cancer susceptibility in Asians and the –251 A allele may increase risk of lung cancer in Asians.The present study result on the impact of  ICAM-1 K469E polymorphism, there was no significant difference in the variant allele and genotype frequencies between cases and controls. With regard to ICAM-1 G241R polymorphism, the frequencies of homozygous wild type genotype were significantly higher in controls compared to cases. Surprisingly no heterozygous and homozygous variant genotypes of ICAM-1 G241R were observed in controls whereas cases showed a low frequency of heterozygous and homozygous variant genotypes. It seems that the variant allele is very infrequent in Malaysian population. In a study by Wang et al., (2009), only the GG genotype was observed in the tested Chinese population, which was consistent also with Japanese and Korean populations respectively, which probably reflects a common ancestor in these populations . On examining the associated risk, the variant genotype of ICAM-1 K469E, in the present study did not show any significant association for CRC susceptibility risk. For ICAM-1 G241R, the risk association could not be evaluated in view of the absence of variant allele and genotypes among the controls. Several studies have investigated the relationship between ICAM-1 gene polymorphisms and tumour susceptibility, but results showed inconsistency. Our results are also in agreement with few studies as well as in disagreement with few other studies. Wang et al’s (2014), meta-analysis involving 14 case-control studies  did not support the ICAM-1 K469E polymorphism as a risk factor for cancer. Cheng and Liang (2015) who conducted a meta-analysis  suggested that ICAM-1 G241R polymorphism might be a genetic risk factor for development of cancer in general, especially in European population whereas K469E polymorphism might not act as a cancer risk factor. Another meta-analysis by Tan et al., (2015) showed ICAM-1 K469E polymorphism contributed to decreased susceptibility to cancer in Caucasians, especially for melanoma and CRC, but may be risk factor for oral cancer in Asians. ICAM-1 K469E polymorphism has been associated with increased risk of gastric cancer .The present study results on ICAM-1 K469E polymorphism is in disagreement with another study by Theodoropoulos et al., (2006) in Greek population. Their study showed that variant allele of ICAM-1 K469E was associated with significantly higher risk for CRC predisposition. For theIL-6 -174 G>C in cases and controls, showed no statistically significant difference. The risk was examined for heterozygous variant of IL-6 -174G>C only, as homozygous variant was observed in only two CRC patients and none of the controls. However, heterozygous variant did not show any risk association with CRC susceptibility. With the observed results from the present study, it is reasonable to suggest that polymorphism -174 at IL-6 gene with change of Guanine to Cytosine may be not associated with CRC predisposition risk in Malaysian population. On the contrary, in Landi et al’s., (2003) study on Spanish population, this SNP showed an increased risk for CRC predisposition . Similarly, in the study done by Theodoropoulus et al., (2006), the SNP at promoter region of IL-6 -174 was found to be associated with increased risk of CRC susceptibility with OR 2.10  in Greek population. In the same study, the allele frequency of variant allele of IL-6 -174 G>C also showed significantly higher risk for CRC predisposition risk with OR 1.77 . A meta-analysis by Hu et al (2013) involving 11 populations incorporating 6,481 cases and 7,935 controls, found lack of association between IL-6-174 G<C polymorphism and CRC risk. Another meta-analysis by by Zhou et al (2014) also did not find any significant association of IL-6-174 G>C polymorphism with CRC risk. Our results are in agreement with results from the above two meta-analyses.In this study, comparison of the frequencies of alleles and polymorphic genotypes of PPAR-γ also, none of the patients and controls showed homozygous variant genotype in the present study, while heterozygous variant was observed in 2.2% of CRC patients and none in controls. When the genotype frequencies were compared between cases and controls, the homozygous wild type was significantly higher in controls (0.030). Likewise, the frequencies of major allele was found to be higher in controls (p=031). It seems that the variant allele is infrequent in Malaysian population. Because of this same reason, the risk association of PPAR-γ could not be determined and PPAR-γ polymorphism singly, does not seem to be contributing in CRC susceptibility risk in this population. In a previous study on Greek population, Theorodopoulos et al., (2006) reported that, both variant allele and genotype frequencies of PPAR-γ 34 C>G reduced the risk for CRC susceptibility. Study by Gong et al., (2005) and Landi et al., (2003) also reported that, PPAR-γ was associated with reduced risk of CRC predisposition. Sarraf et al., (1999) reported that PPAR-γ contributed to suppression of colon cancer. A study by Gong et al., (2005) showed that PPAR-γ 34 C>G was associated with reduced risk colorectal adenoma in USA population. Another study by Koh et al (2006) on PPAR-γ 34 C>G polymorphism and CRC risk among Chinese in Singapore also showed lower risk. Lu et al., (2010), in a meta-analysis comprising of 9 studies with a total number of 4,533 cases and 6,483 controls reported that PPAR-γ 34 C>G was associated with colon cancer risk, but not associated with rectal cancer risk. Another recent meta-analysis based on 15 studies including 13,575 cases and 17,085 controls by Wei et al., (2015) also found that PPAR-γ 34 C>G polymorphism was associated with a reduced risk of CRC in Caucasians and no significant association with CRC risk in Asians. For the SNP 34 C>G of IL-8 and TNF-α showed a higher risk for CRC among females. The underlying reason for this gender bias is still unknown. The immune and inflammatory response between males and females might be different. It is presumed that genetic factors may at least, in part account for gender-related differences in immune / inflammation response. Age wise stratification showed that carriers of TNF-α AA genotype with 50 years and above had a significantly higher risk for CRC susceptibility. This is quite expected because CRC is a disease associated with old age. But the variant genotype AA of IL-8 was associated with a higher risk for CRC in both groups aged < 50 years and > 50 years, suggesting its influence on inflammation mediated CRC risk among all age groups. As additional exploratory analysis, the association between genotype frequency and CRC risk was investigated after stratifying the subjects based on gender, age and smoking habits. When stratified according to gender, the variant genotypes of IL-8 and TNF-α polymorphisms. It has been well documented that cigarette smoking is one of the life-style factors that play an important role in the exposure of an individual to the carcinogens present in cigarette smoke. Various carcinogens such as polycyclic aromatic hydrocarbons, heterocyclic amines, nitroso-amines and aromatic amines, present in the cigarette smoke can cause harm to the human colon and rectum through formation of DNA adducts . Studies  have demonstrated that these carcinogens, which can reach the colorectal mucosa through direct ingestion or via the circulatory system induce bulky adducts in cryptic cells and contribute to the formation of mutations in the colon. So, cigarette smoking will have a synergistic effect on the colorectal tissues which also promote colorectal carcinogenesis. The modifying effect of smoking habit on association between inflammatory response gene polymorphisms and CRC risk was evaluated by comparison of results for smokers and non-smokers. A significant interaction was observed between smoking habits and From the results, it is reasonable to presume that SNPs showing higher risk might be promoting CRC susceptibility by altering the properties of cytokines and chemokines they encode and acting as negative regulators of cellular growth. According to Theodoropoulus et al., (2006) inflammation favours tumorigenesis by stimulating angiogenesis, damaging DNA and chronically stimulating DNA proliferation. In a continuous inflammatory condition, the inflammatory cells will produce reactive oxygen species (ROS) and reactive nitrogen species (RNS). Cancer development occur when inflammatory cells initiate the production of ROS and/or RNS in inflamed tissues and will cause DNA damage which will lead to activation of oncogenes and/or inactivation of tumor suppressor genes . Hence, it is reasonable to suggest that, in a continuous inflammatory condition, genetic variation in immune and inflammatory response genes leading to aberrant response of host’s immune system, may be acting as genetic predisposition factors, favouring inflammation mediated colorectal carcinogenesis. Polymorphisms which showed conflicting results in different populations might be attributable to the presence of genetic heterogeneity across ethnic populations, small sample size limitations and difference in methodologies employed. Another reason could be pleiotropic role of the polymorphism in the pathogenesis of CRC, or due to interaction with other genetic and environmental factors. Yet another explanation could be linkage disequilibrium (LD) patterns. A polymorphism may be in LD with another nearby causal variant in one ethnic population but not in another. Some variants may have stronger or weaker effects on disease, depending on environment or genetic background. Since CRC risk is determined by complex interactions between various genetic and lifestyle/dietary risk factors, common genetic variants are likely to interact with these environmental – lifestyle risk factors to modify risk.IL-8-251 T>A and TNF-α-308 G>A polymorphisms and CRC risk in Malaysian patients. These two SNPs in inflammatory response genes which undoubtedly contribute to individual risks to colorectal cancer susceptibility could be considered as potential genetic predisposition factors. Results are also in favour of an inflammation mediated pathway for colorectal carcinogenesis. Although the findings presented here are exploratory, our study is limited by its small sample size. In view of our findings as exploratory, and given the emerging evidence on chronic inflammation and CRC risk, further rigorous studies are necessary to resolve various complications and elucidate missing links between inflammation and colorectal cancer.In conclusion, we observed an association between variant allele and genotypes of


Background: Estrogen replacement therapy (ERT) is a common treatment method for menopausal syndrome; however, its therapeutic value for the treatment of neurological diseases is still unclear. Epidemiological studies were performed, and the effect of postmenopausal ERT on treating neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD), was summarized through a meta-analysis.Methods: Twenty-one articles were selected using a systematic searching of the contents listed on PubMed and Web of Science before June 1, 2019. Epidemiological studies were extracted, and relevant research data were obtained from the original articles based on the predefined inclusion criteria and data screening principles. The Comprehensive Meta-Analysis Version 2 software was used to pool effective size, test heterogeneity, conduct meta-regression and subgroup analysis, and to calculate publication bias.Results: Our results showed that ERT significantly decreased the risk of onset and/or development of AD  and PD  compared with the control group. A subgroup and meta-regression analysis showed that study design and measure of effect were the source of heterogeneity. Age, sample size, hormone therapy ascertainment, duration of the treatment, or route of administration did not play a significant role in affecting the outcome of the meta-analysis.Conclusion: We presented evidence here to support the use of estrogen therapy for the treatment of AD and PD. Neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), are characterized by the sustained cell cycle arrest and production of a continuous senescence-associated secretory phenotype due to structural and functional changes in neurons  and its treatment effect on AD and PD. Several studies demonstrated that AD-related cognitive decline was improved and a lower risk of onset and/or developing AD was observed following the menopausal hormone therapy , no control group (n = 21), meta-analyses studies (n = 13), or repeated analysis with some documents (n = 6). Therefore, a total of 21 studies with 1,266 patient cases and 3,845 control cases were included in this meta-analysis. A flowchart of the selection process was presented in The initial search yielded 3,668 records from PubMed and 3,201 records from Web of Science. After the screening of titles and abstracts, 6,758 records were excluded because they were not related to our present subject. The remaining 111 articles were selected for full-text scrutiny. Ninety studies were excluded due to no usable data  and model, or other covariates.Age was provided in the form of the mean value, unless otherwise stated. Nearly all the studies included adjusted odds ratio (OR)/relative risk (RR)/hazard risk (HR) values because there were some differences in covariates among the studies.The Comprehensive Meta-Analysis Version 2 software  was used for all the statistical analyses. We grouped study findings on the basis of how hormone therapy was categorized  and included a summary for measure of effect and 95% CIs in the tables. These summaries were calculated based on random-effects models which involved a weighting scheme.P < 0.05. I2 index was used to determine the inconsistency across different studies to evaluate the impact of heterogeneity. We used 25, 50, and 75% of I2 to define low, medium, and high levels of heterogeneity. The Egger's test was used to determine the significance of a statistical test for publication bias to assess the degree of asymmetry in the funnel plot.Cochran Q test was applied to evaluate the statistical difference of heterogeneity across different studies. It was considered statistically significant when P < 0.05. Meanwhile, the change in I2 was compared before and after the introduction of covariates into the regression model.Meta regression was conducted among factors that might lead to heterogeneity in order to identify the main factors. A predefined subgroup analysis was used to assess the impact of various factors in the study. The following subgroups were defined in the AD group: case >500 vs. case ≤500, case-control study vs. prospective cohort, publishing year ≤1995 vs. 1996–2005 vs. 2006–2019, women age ≤70 vs. 71–79 vs. age ≥80, measure of effect: OR vs. HR vs. RR, hormone therapy ascertainment by interview vs. questionnaires vs. prescription database vs. medical records, duration of the treatment <5 years vs. 5–10 years vs. treatment >10 years. It was considered as statistically significant if We found 111 potentially relevant articles. Among these articles, a total of 21 eligible studies were pooled together for analyses . The NewStratification of the study: 13 were case-control studies, five were prospective cohort studies, and three were cross-sectional studies. Stratification of the location: 15 studies were conducted in America, three in Europe , and two other countries . In the AD group, there were 13 studies in America, two in Europe (one in the UK and one in Netherlands), and one in other countries. Stratification of neurological disorders: five cases evaluated the impact of ERT on PD and 16 cases on AD. All studies were collected on the use of hormone therapy either by self-report  at the start of the study, by electronic prescription database, or by medical records. Furthermore, all studies were included in this review except one reported using standard criteria to diagnose AD and dementia .P < 0.001) and PD  in patients compared with the control , but five studies of PD showed no heterogeneity . Since the data of PD were not enough, we only performed meta-regression analysis on the AD group. Study design (P = 0.01) and effect measure (P = 0.03) might be the sources of heterogeneity in the AD group, but number of cases (P = 0.172), age (P = 0.986), publication year (P = 0.712), hormone therapy ascertainment (P = 0.494), and duration of the treatment (P = 0.217) had no moderating effects on the significant association between hormone replacement therapy (HRT) and AD incidence (P > 0.05 in these studies)  .P = 0.01) and measure of effect (P = 0.03). Estimated pooled differences among each subgroup are presented in P < 0.001), adding more proof that ERT is indeed beneficial for treating AD.Furthermore, according to the results of subgroup analyses in the AD group, heterogeneity came from data measure. Two of the interaction terms of the predefined subgroups showed statistical significance: study design . Pathological cognitive changes had been a big challenge to recall the memory of hormone therapy use. We included several studies with hospital records or multidisciplinary evaluations on top of patient's self-report to reduce the chance of recall bias.P = 0.01). Therefore, we classified the articles into case-control study and prospective cohort study according to different study designs and then re-conducted meta-analysis. When only prospective cohort studies were included, we observed an increased effective size for AD studies , adding more proof that ERT is indeed beneficial for treating AD  showed no statistical significance. According to the subgroup analysis among age ≤70 , age 71–79 , and age ≥80 , there was no evidence indicating that age was associated with the risk of disease development.Some literature suggests that the role of ERT may depend on the age of menopause and the therapeutic intervention used. The time window of estrogen therapy is associated with the risk of onset and/or developing neurodegenerative disease, and early treatment performed 10 years after menopause can decrease the risk , as shown in Through different regulatory mechanisms, estrogen affects the conduction of nerve signals and tissue changes in the brain. At the same time, genes associated with neurodegenerative diseases are also shown to be regulated by estrogen  (Szmuilowicz et al., All datasets generated for this study are included in the article/supplementary material.QL and YC conceived and designed the study. SL and YS collected the data. YS, XC, and XL analyzed and interpreted the data. YS drafted the manuscript with critical revisions from all the authors.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.


ALDH2 rs671 genetic polymorphism has been linked with cardiovascular diseases (CVDs), but comprehensive epidemiological studies are lacking. An observational, retrospective big data study was carried out to evaluate the associations between this polymorphism and clustering cardiovascular risk factors (CRFs) in a Chinese population.The A total of 13,101 individuals  were enrolled. Genetic polymorphism was assessed using gene mutation detection kits, coupled with an automatic fluorescent analyzer. Other data were obtained from the records of the Department of Health Care at Peking Union Medical College Hospital.ALDH2 rs671, we found significant differences in males , but not in females. For males, the frequencies of hypertension, diabetes, and obesity were significantly higher for GG than for GA or AA . However, there was no significant difference for dyslipidemia, and no significant associations were observed for all frequencies in females. The prevalence of individuals with 1–4 CRFs was significantly higher among GG males than those carrying GA or AA, and fewer GG males had non-CRFs .Comparing the concentrations of common biochemical analytes, including BMI, SBP, DBP, ALT, AST, γ-GT, TBil, Cr, Glu, TC, TG, and HDL-C among individuals with the GG, GA, and AA genotypes of ALDH2 rs671 are associated with clustering CRFs, especially hypertension and diabetes in males, but not in females. These associations are likely mediated by alcohol intake, which is also associated with this gene.Polymorphisms of  Cardiovascular diseases (CVDs) is one of the leading causes of mortality worldwide , 2, withAlcohol is one of the most widely used recreational substances worldwide, and its intake is a leading risk factor for global disease burden, including CVDs –7. DespiALDH2 gene, which is commonly polymorphic in East Asian populations , but not in females . However studies , 26, 29. studies , 26, 29.= 0.015) . Interes= 0.015) . This alALDH2 genotype and many diseases including CVDs and their risk factors, most of them were animal experiments. Epidemiological studies did not emerge until recently, and most have focused on the association between ALDH2 and single CRFs, rather than clustering CRFs. In this study, we derived clinical big data from the HIS and LIS of PUMCH, which was simple, cost-efficient and a good reflection of the general population. With all individuals represented in PUMCH being analyzed over a five-year period by the same analytical systems, variation due different methods or facilitates was avoided, and the demographic information and clinical laboratory measurements were thorough. Furthermore, we were able to analyze hypertension, diabetes, obesity, and dyslipidemia simultaneously, while correcting for covariations via multivariate logistic regression analysis.Although there have been many other studies exploring and evaluating the association between However, some limitations of this study are notable. Alcohol intake was not considered in the evaluation, and other important factors such as smoking and socioeconomic situation were also lacking. Also, in this cross-sectional study, the major CRFs, including hypertension, diabetes, obesity, and dyslipidemia, were assessed based only on single test of the corresponding clinical measurements. Casual inferences from this study should therefore be avoided. In the future, long term follow-up cohort studies considering more details, especially the pattern of alcohol consumption, are needed to further explore the causal relationships suggested by our data.ALDH2 gene polymorphism is associated with clustering CRFs, and that the rs671 A allele may be protective against clustering CRFs in males. This is likely mediated by alcohol intake or related lifestyle factors associated with this genetic variant.Our study indicates that the Additional file 1: Supplemental Table 1. The frequency of ALDH2 rs671 genotype by age and sex.


To investigate the clinical effect of preservation or nonpreservation of the left colic artery (LCA) in total mesorectal excision (TME) under laparoscopy.  The words, like “rectal cancer,” “left colonic artery,” and “laparoscopy,” were used as the retrieval terms, and the keyword retrieval method was adopted. The retrieval period was set as from January 1, 2013, to June 1, 2018. We searched databases including PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI) to collect randomized and controlled trials which compared the effect of preservation or nonpreservation of the LCA in TME under laparoscopy. Two researchers independently carried out literature screening, data extraction, and literature quality evaluation; Review Manager 5.3 was used for the meta-analysis. P < 0.0001) and postoperative urinary and sexual dysfunction  and significantly shorter time for intestinal function recovery . There were no significant differences between the two groups in the duration of surgery, blood loss, number of dissected lymph nodes, or postoperative hospital stay.  Seven studies including 1467 cases were identified for the meta-analysis. As showed by the meta-analysis, compared with the LCA nonpreservation group, the LCA preservation group had significantly reduced incidence of anastomotic leakage (OR = 0.44, CI = ,  From the results, the LCA preservation group seems to achieve comparable success with acceptable safety outcomes. Therefore, this surgical method can be recommended in the clinical practice. Colorectal cancer is the third most common malignancy that causes significant morbidity and mortality in the world. More than 1.3 million people are diagnosed with colorectal cancer each year, and more than 600,000 patients die from colorectal cancer or related complications . At presWe search for laparoscopic rectal cancer surgery (using TME with or without the preservation of the LCA)-related articles published from January 01, 2013, to June 1, 2018, from databases including CNKI, PubMed, and Web of Science. Keywords retrieved were laparoscopic, rectal cancer, left colonic artery, rectal, laparoscopy, and left colic artery.Inclusion criteria are the following: (1) literature study of the diagnosis of rectal cancer and laparoscopic TME for the treatment of rectal cancer; (2) literature with integral analytical data and independent studies including at least one control group with consistent purposes; (3) preservation or nonpreservation of the LCA as the only difference between the experimental group and the control group; (4) similar literature research methods; and (5) the combined results expressed by corresponding statistical indicators.Exclusion criteria are the following: (1) duplicate or multiple articles about the same study, which may lead to content bias; (2) abstracts, research protocols, letters, editorials, comments, guidelines, and case reports; (3) and noncomparative studies.Two researchers used a unified retrieval strategy to independently screen and extract data based on the inclusion and exclusion criteria. If there was a discrepancy, the decision shall be made through discussion or consultation with a third researcher. In this study, 37 related articles were obtained, among which 7 articles that met the inclusion criteria were finally included.I2 was performed on the included literature: a fixed effect model was used in the absence of statistical heterogeneity ; otherwise , a random effects model was used. The Z-test was used to test the combined effect. A difference was considered of statistical significance at P < 0.05 and of great statistical significance at P < 0.01. At the same time, the funnel chart was constructed to assess the presence of bias.A statistical analysis was performed on the retrieved domestic and foreign literature for the following: duration of surgery, blood loss, number of dissected lymph nodes, postoperative anastomotic leakage, time for intestinal function recovery, postoperative urinary and sexual dysfunction, two-year recurrence rate, and overall survival. The data from each article was compiled in a table and entered into a computer. The meta-analysis software Review Manager 5.3 was used to calculate and analyze the data. Weighted mean difference (WMD) and binary data were calculated for continuous variables. Odds ratio (OR) and combined values were expressed in 95% confidence interval (CI); the heterogeneity test of The included studies involved a total of 1467 cases, of which 872 had LCA preservation and 595 did not.The literature retrieval and screening process is shown in I2 = 64%, P = 0.010); when combined with WMD using the random effects model, the combined effect of WMD is 3.27 , which is not significantly different. Based on the results of the analysis, it can be concluded that there is no significant difference in the WMD in the duration of surgery between LCA-preserved patients and LCA-nonpreserved ones. Therefore, whether the LCA is preserved during the laparoscopic rectal cancer resection does not affect the duration of surgery. The funnel plot shows a symmetrical shape, indicating that there is no bias.The meta-analysis results are shown in Figures I2 = 0%, P = 0.81); when combined with WMD using the fixed effects model, the combined effect of WMD is 0.16 , which is not significantly different. Based on the results of the analysis, it can be concluded that there is no significant difference in the WMD in the intraoperative blood loss between LCA-preserved patients and LCA-nonpreserved ones. Therefore, whether the LCA is preserved during the laparoscopic rectal cancer resection does not affect the amount of blood loss. The funnel plot shows a symmetrical shape, indicating that there is no bias.The meta-analysis results are shown in Figures I2 = 90%, P ≤ 0.00001); when combined with WMD using the random effects model, the combined effect of WMD is -1.07 , which is not significantly different. Based on the results of the analysis, it can be concluded that there is no significant difference in the WMD in the number of dissected lymph nodes between LCA-preserved patients and LCA-nonpreserved ones. Therefore, whether the LCA is preserved during the laparoscopic rectal cancer resection does not affect the number of dissected lymph nodes. The funnel plot shows a symmetrical shape, indicating that there is no bias.The meta-analysis results are shown in Figures I2 = 0%, P = 0.55); when combined with OR using the fixed effects model, the combined effect of OR is 0.44 , which is significantly different. Based on the results of the analysis, it can be concluded that there is a significant difference in the OR of anastomotic leakage between LCA-preserved patients and LCA-nonpreserved ones. The “diamond” representing the combined effect falls to the left of the ineffective line. The patients with preservation of the LCA had a lower incidence of anastomotic leakage than those without preservation of the LCA. Therefore, preservation of the LCA can reduce the incidence of anastomotic leakage. At the same time, the funnel plot shows a symmetrical shape, indicating that there is no bias.The meta-analysis results are shown in Figures I2 = 0%, P = 0.52); when combined with WMD using the fixed effects model, the combined effect of WMD is -0.26 , which is significantly different. Based on the results of the analysis, it can be concluded that there is a significant difference in the WMD of time for intestinal function recovery between LCA-preserved patients and LCA-nonpreserved ones. The “diamond” representing the combined effect falls to the left of the ineffective line. The patients with preservation of the LCA had shorter time for intestinal function recovery than those without preservation of the LCA. Therefore, preservation of the LCA can help patients in terms of time for intestinal function recovery. At the same time, the funnel plot shows a symmetrical shape, indicating that there is no bias.The meta-analysis results are shown in Figures I2 = 0%, P = 0.61); when combined with OR using the fixed effects model, the combined effect of OR is 0.26 , which is significantly different. Based on the results of the analysis, it can be concluded that there is a significant difference in the OR of postoperative urinary and sexual dysfunction between LCA-preserved patients and LCA-nonpreserved ones. The “diamond” representing the combined effect falls to the left of the invalid line. The patients with preservation of the LCA had a lower incidence of postoperative urinary and sexual dysfunction than those without preservation of the LCA. Therefore, preservation of the LCA can reduce the potential of urinary and sexual dysfunction. At the same time, the funnel plot shows a symmetrical shape, indicating that there is no bias.The meta-analysis results are shown in Figures I2 = 88%, P = 0.004); when combined with WMD using the random effects model, the combined effect of WMD is -1.69 , which is not significantly different. Based on the results of the analysis, it can be concluded that there is no significant difference in the WMD of postoperative hospital stay between LCA-preserved patients and LCA-nonpreserved ones. Therefore, whether the LCA is preserved during the laparoscopic rectal cancer resection does not affect the postoperative hospital stay. The funnel plot shows a symmetrical shape, indicating that there is no bias.The meta-analysis results are shown in Figures There has been a long debate about whether to preserve the left colonic artery in TME under laparoscopy. So far, there is no clear consensus. Anastomotic leakage is one of the most serious complications after rectal cancer surgery. Anastomotic blood supply and tension are two important factors affecting the incidence of anastomotic leakage. Theoretically, preservation of the LCA can improve the blood supply to the colon , 15; theThe evidence from the current study suggests that preservation of the LCA during laparoscopic rectal cancer resection shows a significant effect on reducing the incidence of anastomotic leakage and postoperative urinary and sexual dysfunction, as well as the time for intestinal function recovery, but the effect on reducing duration of surgery, amount of blood loss, number of dissected lymph nodes, and postoperative hospital stay was not significant. Therefore, this surgical method can be recommended in the clinical practice. However, our conclusion still needs to be tested by more data in the future studies.


However, this association remains ambiguous. Thus, we performed a meta-analysis to provide more precise conclusion on this issue. Odds ratios (OR) with corresponding 95% confidence intervals (CI) were applied to assess the strength of the relationships. There was a protective association between HIF1A Pro582Ser polymorphism and diabetes under the heterozygous genetic model . Similar associations were observed in diabetic complications risk under the allelic , homozygous , recessive  and dominant  genetic models. No effects of the HIF1A Ala588Thr polymorphism were found in risk of diabetes and diabetic complications. Taken together, these findings revealed the protective effect of HIF1A Pro582Ser polymorphism against diabetes and diabetic complications.Diabetes is an age-related chronic disease associated with a number of complications, emerging as one of the major causes of morbidity and mortality worldwide. Several studies indicated that hypoxia-inducible factor 1-alpha  Diabetes is an age-related chronic disease and has already become one of the major causes of mortality and morbidity worldwide . The proHypoxia-inducible factor-1(HIF-1), a master regulator of oxygen homeostasis, allows the adaptive responses to the hypoxic environment . HIF-1 aClinical and experimental studies indicate that hyperglycemia suggests a state of pseudohypoxia and activates HIF-1α activity for adaptation of hypoxia , 16. In HIF1A (for HIF-1α) carries two common nonsynonymous single nucleotide polymorphisms (SNP) in exon 12, Pro582Ser (rs11549465) and Ala588Thr (rs11549467), which both exhibit higher transcriptional activity of HIF1A [HIF1A Pro582Ser and Ala588Thr may be associated with diabetes and diabetic complications. Yamada et al. [HIF1A Pro582Ser polymorphism exerted a protective effect in the occurrence of diabetes, but no correlation with diabetic complications in a Japanese population. While Ekberg et al. [HIF1A Pro582Ser on the development of severe diabetic retinopathy with risk reduction of 95%. Several other studies also focused on the associations of HIF1A Pro582Ser and Ala588Thr polymorphisms with diabetes and diabetic complications, including type 1 and type 2 diabetes, diabetic nephropathy, diabetic retinopathy and diabetic foot ulcers [The gene of HIF1A , 25. Prea et al.  firstly g et al.  identifit ulcers –33. NeveHIF1A Pro582Ser and Ala588Thr polymorphisms with diabetes and diabetic complications were included in our meta-analysis. All the included articles were all conducted with case-control design and the sample sizes varied from 145 to 1165. A total of 5 and 6 eligible studies were identified for diabetes and diabetic complications, respectively. The general characteristics of the studies included in the meta-analysis were presented in The current meta-analysis was conducted according to the guidelines of the “Preferred Reporting Items for Systematic reviews and Meta-Analyses’’ (PRISMA) statement. As depicted in the flow diagram , the iniHIF1A Pro582Ser polymorphism and the risk of diabetes were summarized in detail in P = 0.007). Furthermore, both the Cochran’s Q test and estimate of I2 showed no significant between-study heterogeneity under the heterozygous genetic model . In contrast, no significant association was found between HIF1A Pro582Ser polymorphism and diabetes under the allelic , homozygous , recessive  and dominant  genetic models. However, significant heterogeneity among the constituent studies was found under the allelic , homozygous , recessive  and dominant  genetic models.The results of meta-analysis and heterogeneity test between Pheterogeneity = 0.579, I2 = 0%), homozygous , recessive  and dominant  genetic models , homozygous , recessive  and dominant  genetic models.In addition, as shown in the HIF1A Pro582Ser polymorphism and the risk of diabetic complications were summarized in detail in HIF1A Pro582Ser polymorphism was also significantly associated with a decreased risk of diabetic complications under the allelic , homozygous , recessive  and dominant  genetic models. Both the Cochran’s Q test and estimate of I2 showed no significant heterogeneity among the constituent studies under the allelic , homozygous , recessive  and dominant  genetic models. In contrast, no significant association was found under the heterozygous genetic model . However, significant between-study heterogeneity was found under the heterozygous genetic model .The results of meta-analysis and heterogeneity test between Pheterogeneity = 0.423, I2 = 0%)  .HIF1A Pro582Ser polymorphism and a decreased risk of diabetic complications under the heterozygous genetic model   .HIF1A Ala588Thr polymorphism and the risk of diabetes were summarized in detail in HIF1A Ala588Thr polymorphism with diabetes risk under all genetic models, including the allelic , homozygous , heterozygous , dominant  and recessive  genetic models.The results of meta-analysis and heterogeneity test between HIF1A Ala588Thr polymorphism and the risk of diabetic complications were summarized in detail in HIF1A Pro582Ser polymorphism were also found in risk of diabetic complications under the allelic , homozygous , heterozygous , dominant  and recessive  genetic models.The results of meta-analysis and heterogeneity test between HIF1A Pro582Ser polymorphism and the risk of diabetes, no evidence of significant publication bias was detected by the Begg’s test . The P-values for Begg’s test also demonstrated that there was no publication bias of meta-analysis of the association between HIF1A Pro582Ser polymorphism and the risk of diabetic complications .Publication bias of the included studies was assessed by using the Begg’s funnel plot . For theHIF1A polymorphisms (Pro582Ser and Ala588Thr) and the occurrence of diabetes and diabetic complications. The results indicated HIF1A Pro582Ser polymorphism was significantly associated with reduced risk of diabetes under the heterozygous genetic model. Furthermore, after excluding the outlier study that deviated from Hardy-Weinberg equilibrium (HWE) in controls and contributed to between-study heterogeneity, the corrected ORs demonstrated that HIF1A Pro582Ser polymorphism could perform a protective effect on the risk of diabetes under all other genetic models. For the meta-analysis of diabetic complications, the findings provided evidence for the protective associations between HIF1A Pro582Ser polymorphism and diabetic complications under all genetic models except the heterozygous genetic model. Similarly, when the outlier study was removed, the corrected ORs also showed a protective association under the heterozygous genetic model. However, no significant effects of the HIF1A Ala588Thr polymorphism were found in the risk of diabetes and diabetic complications.To our knowledge, this is the first meta-analysis to explore the genetic associations between HIF1A Pro582Ser polymorphism was a stable variant and showed increased transcriptional activity, which may offer enhanced HIF-1α activity under normoxic conditions [HIF1A Pro582Ser mutation on the risk of diabetes and diabetic complications.As a key oxygen sensor mediating cellular adaptive responses to hypoxia, HIF-1α plays a pivotal role in cellular and systemic homeostatic. The stabilization of HIF-1α is regulated by oxygen-dependent prolyl hydroxylation of proline domains located in Pro402 and Pro564, which is significant for the effect of hyperglycemia on HIF-1α , 34. Hownditions , 39. It nditions , 19, 40.HIF1A Pro582Ser polymorphism in the risk of diabetic complications, one of the strengths was lack of obvious heterogeneity in all genetic models except the heterozygous genetic model. In contrast, for the meta-analysis of the HIF1A Pro582Ser polymorphism in the risk of diabetes, significant heterogeneity was found in all genetic models except the heterozygous genetic model. Heterogeneity may result from the potential differences across the included studies, such as the definition of disease, ethnicity, genotyping methods, sample size. To detect the potential sources of heterogeneity, Galbraith plot analysis was firstly used to explore whether there was outlier study. Then, sensitivity analysis by omitting one individual study each time was further performed to identify the possible source of heterogeneity [HIF1A Pro582Ser genotype frequencies showed significant departure of HWE in the health control group of Pichu’s study (P = 9.34*10-7). In population study, migration, selection, mutation, and absence of random mating may exist when the genotype distribution of controls (disease-free subjects) deviates from HWE. Consequently, the Pichu’s study departure from HWE may bias the meta-analysis results, and can explain the between-study heterogeneity. After excluding the outlier study, the between-study heterogeneity can be effectively eliminated. What's more, the meta-analysis based on the corrected ORs also revealed that the HIF1A Pro582Ser polymorphism played a protective role in the risk of diabetes and diabetic complications.Heterogeneity among constituent studies is common in the meta-analysis of genetic association study and may affect the interpretation of the meta-analysis results , 42. ForHIF1A gene [HIF1A Ala588Thr polymorphism with the risk of diabetes and its complications, the findings should be interpreted with caution. The small sample size may be responsible for the negative relationship between the HIF1A Ala588Thr polymorphism and diabetes and diabetic complications.Some limitations of the current meta-analysis should be admitted. Firstly, the development of diabetes and diabetic complications is affected not only by environmental factors but also multiple genetic factors, the effect of gene-to-gene interactions should be taken into account. For example, vascular endothelial growth factor, another susceptibility gene for diabetes, may interact with F1A gene . Then, bHIF1A Pro582Ser polymorphism against diabetes and diabetic complications. However, there was no significant association of HIF1A Ala588Thr polymorphism with the risk of diabetes and its complications. Owing to the limitations mentioned above, further studies, with larger sample sizes on the association of HIF1A genetic polymorphisms  with the risk of diabetes and its complications, should be performed to confirm our findings in the future.In conclusion, our meta-analysis revealed the protective role of the HIF1A) or variations  in combination with diabetes and diabetic complications . Additionally, other possible original publications were identified by manually searching the reference lists of the selected reviews and articles.A systematical literature search was conducted in the following electronic databases: PubMed, Embase, WanFang Data, and China National Knowledge Infrastructure (CNKI) from their starting dates to December 2019. The following keywords used for the search strategy were hypoxia-inducible factor-1α gene (HIF1A gene and risk of diabetes and diabetic complications was explored. (3) published in English or Chinese. (4) detailed HIF1A genotyping data were offered in case and control groups. If the two reviewers disagreed about the inclusion of a study, it was resolved by group discussion or consensus with a third reviewer.All the identified studies were independently evaluated by two investigators according to the inclusion criteria. The included studies met the criteria as follows: (1) studies were conducted in humans and assessed with a case-control design. (2) the association between Pro582Ser and Ala588Thr of For the included articles in this study, data were collected by two reviewers independently. The following information was extracted from each publication: last name of the first author, year of publication, country of the study, ethnicity of the population, mean age, gender distribution of cases and controls, allele and genetic distributions in case and control groups, total number of cases and controls.HIF1A Pro582Ser gene polymorphism; A vs. G of HIF1A Ala588Thr gene polymorphism), homozygous , heterozygous , dominant  and recessive .In this meta-analysis, five genetic models were performed including the allelic  with 95% confidence intervals (CIs) according to the alleles and genotypes in case and control groups. The pooled estimates of the OR were calculated from a combination of studies in the allelic, homozygous, heterozygous, recessive and dominant models, respectively. The Z test was applied to determine the statistical significance of the pooled OR. The I2 metric and Cochran’s Q test were conducted to check the possibility of heterogeneity among the included studies. Between-study heterogeneity was considered as a statistic significance at I2 > 50% for the I2 test and P < 0.05 for the Q statistics [The strength of the association between atistics . If signatistics . All sta


However we have surprisingly found that our genetic association study (PLoS One (2017), https://doi.org/10.1371/journal.pone.0169781) was included in this meta-analysis, but with mistakenly calculated odds ratios (OR). Therefore we would suggest to use the correct OR values based on our original publication that were already indicating a high genetic effect size for the MTNR1B rs10830963 risk variant on GDM development.We do agree with the authors’ final conclusion that such a meta-analysis should eventually confirm that the  Dear Editor,−4 value to characterize the association of the MTNR1B rs10830963 G allele and GDM diagnosis using the IADPSG criteria under the dominant genetic model and in addition the OR and p values were also reported for the genetic association using the modified 1999’ WHO GDM diagnostic criteria and also under the additive model [We have published the OR = 1.84 (95% CI:1.54±2.21), p = 7x10CG vs. CC” and “GG vs CC” and “C vs G”, respectively). Despite that we did specifically report the minor (G) allele frequencies (MAF) in our study as 0.36 in the GDM group and 0.28 in the control group, these MAF data were apparently also wrongly indicated in the meta-analysis .Conflictingly, the authors reported “0.99-0.99-0.99” as OR values  - of unkG) OR value. Our published data were sufficient to make accurate further OR estimations and calculating the number of individuals with the MTNR1B rs10830963 CC, CG and GG genotypes in both the GDM and control study groups. We directly reported 8 distinct OR values for all the 77 gene variants - including the MTNR1B rs10830963 - assessed in our study  MAF values could have been directly used to calculate the allelic :CC vs CG: OR = 1.85 (95%CI: 1.06-2.37) p = 0.001CC vs GG: OR = 1.81 (95%: 0.72- 3.09) p = 0.05C vs G: OR = 1.44 (95%CI: 0.79 - 1.26) p = 0.026In order to help the meta-analysis of Huang et al. hereby we report the correct results for those comparisons that should have been used in this meta-analysis regarding our study, i.e. the valid OR and crude p for the MTNR1B rs10830963 variant under the IADPSG criteria (as published): 284/485.with the case/control numbers for the There are further points  that would require an update due to that the copy (MAF) and calculation (OR) errors as described above may affect the overall result (for the Caucasian populations) of the meta-analysis.Such an extensive update might provide the authors with a very welcome opportunity to correct the other mistakes in the article, such as the clinical table, where they inaccurately characterized our control pregnant population, despite all participants were assessed with a 75g OGTT in both countries and the controls were defined as those pregnants who did not merit the studied GDM diagnostic criteria as we have described. In addition the weighted mean pre-pregnancy BMI and age values of the Hungarian and Austrian pregnant populations could also be calculated from the original publication .