MTNR1B), rs7903146(TCF7L2), and rs1801278(IRS1) were significantly associated with the increased GDM risk. The association of rs4402960(IGF2BP2) and rs1800629(TNF-α) was significant only when the studies with control allele frequency deviation and publication bias were excluded. Further subgroup analysis showed the risk alleles of rs7903146(TCF7L2) and rs1801282(PPARG) were significantly associated with the GDM risk only in Asian, but not in Caucasian population. The OGTT test using 100 g, but not 75 g; and genotype detection by other assays, but not Taqman method, were also significantly associated with increased GDM risk in rs1801278(IRS1) and rs7903146(TCF7L2). Overall GDM was associated with rs10830963(MTNR1B), rs7903146(TCF7L2), and rs1801278(IRS1), but only rs7903146(TCF7L2) and rs1801282(PPARG) were significant in Asian populations. While rs1801278(IRS1) and rs7903146(TCF7L2) were significantly affected by OGTT protocol and genotyping methods.Previous studies have demonstrated that gestational diabetes mellitus (GDM) and Type 2 diabetes mellitus (T2D) share common genetic polymorphisms. We conducted meta-analysis and subgroup analysis of all available variants and determined the effects of confounding and experimental components on the genetic association of GDM. Any case-controlled or cohort studies with genotype distribution compared GDM cases with controls were included. In total, 28 articles including 8,204 cases and 15,221 controls for 6 polymorphisms were studied. rs10830963( Gestational diabetes mellitus (GDM), one of the most common pregnancy complications, is defined as the onset or first recognition of glucose intolerance during pregnancyGlobally, the prevalence of GDM varies in population and ethnicity from 1% to 14%GDM and Type 2 diabetes mellitus (T2D) have similar pathogenesis with impaired insulin secretion and increased insulin resistance12All recent genetic association studies published in recent years (2004 to 2015) were searched in Medline, Evidence Based Medicine (EBM), Pubmed and Web of Science (ISI) for studies published in English and in the WanFang and China National Knowledge Infrastructure (CNKI) database for literature published in Chinese. Keywords in the searches included “gestational diabetes mellitus”, “GDM”, and “genetic”. In addition, the references cited by the original studies, reference lists, conference proceedings, and Google scholar were also searched. Articles published in language other than English and Chinese were not included in this analysis.Inclusion criteria included any case-controlled or cohort studies with genotype distribution information in both GDM cases and controls. Exclusion criteria included review papers, commentary articles, publication in other languages, studies of postpartum diabetes mellitus, duplicated reports and case series. Genetic studies with no information on genetic polymorphisms, incomplete genotyping data and family trio studies were also excluded. For meta-analysis, a genetic variant reported by less than 3 independent studies and meta-analysis papers were further excluded.Data extraction was independently completed by two reviewers (L.W. and L.C.) from all eligible publications. If a consensus could not be reached, a third reviewer (C.C.W.) settled the discrepancy. If any outstanding queries remain, the corresponding authors of the publication were contacted for data clarification. When the data were not available in the published articles or a further clarification was needed, we contacted the authors by e-mail.I2 statistic which reflected the heterogeneity proportion in the total variation of effect size. If I2 > 50%, random-effects model (REM) was used. While I2 ≤ 50%, fixed-effects model (FEM) was used to determine the significant heterogeneityStudied variants and its molecular functions in T2D/GDM were recorded. Information was extracted from each selected study, including names of the authors, publication year, study ethnicity, sample size and the definition of cases and controls, the diagnostic criterion for GDM used in the study, the mean age and BMI of cases and controls, genotyping methods, and the frequency of risk alleles were defined according to genotypes. Pooled odds ratio (OR) and 95% confidence intervals (CI) were calculated by allele models of the selected studies on the same variant. Significance levels were determined by Z test. Forest plots were used to demonstrate effect sizes and their confidence intervals (CI)nd trimester vs 3rd trimester) were compared. For the diagnosis of GDM, diagnostic criteria using different approaches (75 g OGTT vs 100 g OGTT) were compared. For study methods, genotyping methods (Taqman vs others), study ethnicity (Asian vs Caucasian) and sample sizes  were also compared. Sample size was defined as small or large according to calculation using an online sample size estimator (OSSE) on the included papers for each variant , previous history of GDM (yes vs. no) and BMI before and during pregnancy (<25 vs ≥25) were compared. For demographic data, parity (nullpara vs multipara) and gestational age , Melatonin receptor 1B (MTNR1B), Transcription factor 7-like 2 (TCF7L2) are involved in insulin secretion19IRS1) and Peroxisome proliferator-activated receptor gamma (PPARG) are involved in insulin resistance22TNF-α) is involved in inflammation in DM and/or GDM pathogenesis  are located at intron regions, these causal variants do modulate gene function and impact on downstream transcriptional machineryIRS1, rs1801282 in PPARG and rs1800629 in TNF-α) are located at exon regions. Study characteristics, detailed genotype information and allele distribution in each included study are summarized in Literature search identified 83 potential articles, including 75 from PubMed and ISI 2004–2015) and 8 from the WanFang database (2004–2015). After abstracts were screened, 18 articles were excluded: 2 published in other languages (Polish and Czech), 2 studies which included postpartum DM, 14 which had no information on genetic polymorphisms. In addition, 37 articles were excluded for the different reasons as listed: 30 articles whereby the reported genetic variants have been studied in less than 3 independent studies for appropriate meta-analysis, 6 which were published meta-analysis and 1 which had doubtful data with potential reversed wild-type allele numbers and risk allele numbers but could not be verified by contacting the author04–2015 aogenesis 24. ThougIGF2BP2 (rs4402960) There were 3 articles which studied the T allele of rs4402960 but meta-analysis did not identify any significant association of the variant with the increased risk of GDM . There was no significant HWE variation . There were not enough studies for subgroup analysis.ariation , but theariation . After tariation  and heteMTNR1B (rs10830963) There were 7 eligible studies which examined the rs10830963 polymorphism. Meta-analysis showed that the G allele was significantly associated with increased risk of GDM  and Caucasian populations  There were 9 published articles which studied the rs7903146 polymorphism. Meta-analysis showed that the T allele was significantly associated with increased risk of GDM , but not in Caucasian population ; 2 6.3%, p = 0.344) and GDM diagnosis using 75 g OGTT  only (91) only . Studies91) only .IRS1 (rs1801278) Five eligible articles studied rs1801278 polymorphism. Meta-analysis showed that the T allele was significantly associated with the increased risk of GDM  There were 10 included articles which studied the rs1801282 polymorphism. Meta-analysis showed that the G allele was not significantly associated with the increased risk of GDM , but not in Caucasian populations  There were 3 included articles which studied the rs1800629 polymorphism. Meta-analysis showed no significant association between rs1800629 and GDM risk ; P = 0.633 IGF2BP2, MTNR1B, TCF7L2, IRS1, TNF-α, and PPARG genes, and showed the risk alleles of MTNR1B, TCF7L2 and IRS1, but not PPARG, were significantly associated with increased risk of GDM with or without study heterogeneity, HWE derivation and publication bias. The results confirmed previous meta-analyses that the risk allele of rs7903146 in TCF7L2IRS1 and rs10830963 in MTNR1B were associated with increased risk of GDMPPARG and GDM riskIGF2BP2 and TNF-α were significantly associated with increased risk of GDM only after studies which failed HWE were excluded, which had not been identified in previous studiesPrevious meta-analysis identified few genetic polymorphism associated with GDM10MTNR1BTCF7L2IRS1TNF-α and PPARG showed direct link to each other under category of gene pathway. It indicates the direct gene-gene interactions between TNF-α and PPARG  and PPARG (rs1801282) were significantly associated with increased/decreased risk of GDM in Asian population, mostly from China, but not in Caucasian population. All 7 previous genetic studies shows the significant association of TCF7L2 (rs7903146) in Caucasian populations were positive in 6 out 7 studies with highest OR as 2.04PPARG (rs1801282) in Caucasian populations but only 1 out of 5 studies in Asian population were positiveTCF7L2 and PPARG in the development of GDM in Asian population only, but larger scale study will be necessary to confirm the results. In addition, larger pre-pregnancy BMI (≥25) has significant association in MTNR1B (rs10830963) with GDM, indicating the potential effects of obesity on the role of MTNR1B mutation in GDM riskTCF7L2 (rs7903146) and IRS1 (rs1801278) were significantly associated with increased risk of GDM in other methods, including PCR-RFLP, rather than Taqman assay. PCR-RFLP is a rapid, simple and inexpensive genotyping technique that exploits variations in homologous DNA sequences but poor in conditions of compound heterozygous mutationPrevalence of GDM in Asian countries is now higher than that in other countries2 rs79031 and PPARMTNR1B rs830963 wiCDKAL1KCNJ11GCK−8), however there is no other genome-wide association study available to extract the variant information for present meta-analysis. The genetic association of these variants with GDM should also be included in future if sufficient association studies become available.Although this present study is comprehensive, included more variants for meta-analysis and carried out subgroup-analysis, there were several limitations. Firstly, more accurate analysis using the adjusted data by age and BMI would be preferable to direct use of unadjusted raw data. Secondly, environmental factors including cigarette smoking, alcohol consumption, and dietary habit are important confounding factors which should preferably be considered and recorded in genetic studies. Thirdly, due to the limitation of included studies with small sample sizes, the odd ratio are small and the results will be seriously affected by any studies removed due to significant heterogeneity, HWE and publication bias. Since a strict minimal number of studies was required for meta-analysis, some of important variants of Overall GDM was associated with rs10830963, rs7903146, and rs1801278, but only rs7903146 and rs1801282 were significant in Asian populations. While rs1801278 and rs7903146 were significantly affected by OGTT protocol and genotyping methods. In summary, the present study dissected the effects of subgroup information on the genetic association of GDM, which not only confirmed the genetic association for some of the variants, but also to explore the effects of ethnicity, diagnosis criteria, genotype methods and BMI on the results. These factors should be considered in the association between the genetic variants and the risk of GDM in future genetic studies.How to cite this article: Wu, L. et al. Genetic variants associated with gestational diabetes mellitus: a meta-analysis and subgroup analysis. Sci. Rep. 6, 30539; doi: 10.1038/srep30539 (2016).


MDR1, play a significant role in the transmembrane transport of anti-epileptic agents. Single nucleotide polymorphism C3435T (rs1045642) within MDR1 gene may be associated with an increased expression of P-gp which affects the levels of antiepileptic drugs in plasma. The presented studies analysed the association between C3435T polymorphism of MDR1 gene and the incidence of drug-resistant epilepsy in the population of Polish children.Epilepsy is a disease of neurological character. Approximately one third of epileptic patients demonstrate a drug-resistant phenotype, which is associated with the development of drug-resistant epilepsy. The multidrug resistance protein 1 and glycoprotein P, encoded by MDR1 gene was analysed by the high resolution melting technique in a group of patients with drug-resistant (n = 106) and drug-responsive epilepsy (n = 67), as well as in non-epileptic children (n = 98) hospitalised at the Department of Neurology, Polish Mother’s Memorial Hospital in Lodz. Genotype and allele distributions were evaluated and their compatibility with the Hardy–Weinberg distribution was assessed by means of the χ2 test. Genotype and allele evaluation, regarding their relationship with a given feature, was supported by an analysis of odds ratio and 95 % confidence interval, calculated according to the logistic regression model.C3435T polymorphism of MDR1 gene, which may enhance the risk of the disease. The T allele may then play a protective role. No differences were found in the studied groups, regarding either genotype or allele distribution in reference to patient’s gender or concomitant diseases.An association was observed between the incidence rate of DRE and the presence of C allele in C3435T polymorphism of MDR1 gene may be connected with the incidence of drug-resistant epilepsy in the population of Polish children.Following the obtained results, C3435T polymorphism of ISRCTN ISRCTN73824458. Registered 28th September 2014. Epilepsy is one of the most frequent diseases of the nervous system, with prevalence rate estimated at approx. 1 % of the population in the world. The incidence of epilepsy is slightly higher in men than in women, while presenting significantly higher rates in children and in subjects above 65 years. The average incidence rate in the world population amounts to 50–70/100,000/year. In Poland, the number of affected subjects approaches 400,000 with the incidence of 7/1000 inhabitants .The basic treatment of epilepsy consists of a wide range of pharmacological substances—anticonvulsant medications. However, despite the constant development of new anticonvulsants with various molecular mechanisms of action, the fully effective pharmacological treatment of epilepsy has not yet been reached. In some of the patients, so-called, DRE may occur, as a serious clinical problem.There are two main theories to explain the phenomenon of drug-resistance. The hypothesis of transporters assumes that the expression or function of multidrug transporters gets enhanced in the brain, thus suppressing the access of antiepileptic drugs to the central nervous system. The other hypothesis is based on the assumption that epilepsy-related changes induce lower sensitivity to anticonvulsant .Despite the increasing knowledge of suspected risk factors of DRE, it still unclear why the responsiveness to pharmacological treatment may vary significantly between epilepsy patients with supposedly similar clinical manifestations of the disease. The suggested determinants of DRE include genetic factors and varying pharmacodynamic and pharmacokinetic features of administered drugs –7.MDR1, in the transmembrane transport of anti-epileptic agents [MDR1 gene has been suggested as one of the genetic factors underlying DRE phenomenon [MDR1 gene and thus the activity of P-gp, which plays a significant role in the transmembrane drug transport [The to-date’s literature data indicate a significant role of MDR 1 and P-gp, encoded by c agents –10. The enomenon –13. It hMDR1 gene polymorphism, while structuring the variable expression of P-gp, may then control the efficacy of anti-epileptic therapy. An increased expression of this gene leads to higher volumes of P-gp in the endothelial cells of the blood–brain barrier and in astrocytes. This process results in decreasing the parenchymal concentrations of drugs, despite achieved therapeutic level in blood [The in blood , 13. Impin blood , 13.MDR1 gene C3435T polymorphism in the development of DRE in children [However, the currently available literature data lack an unequivocal response to the question about the exact role of the children –17.MDR1 gene and DRE in the population of Polish children.The goal of the study was to analyse the association between C3435T polymorphism of Whole blood samples 1 ml), used as material for molecular studies, were collected from children with DRE (n = 106) and drug-responsive (n = 67) epilepsy, as well as from non-epileptic children (n = 98), hospitalised at the Department of Neurology, Polish Mother’s Memorial Hospital, Research Institute, in the years 2010–2016. The group of children with DRE included 52 boys and 54 girls and the group of therapy responders included 35 boys and 32 girls, while the group of non-epileptic children comprised 52 boys and 46 girls. The demographic parameters of the study groups were not significantly different . Genetic studies of ® 480 High Resolution Melting Master Kit , according to the manufacturer’s recommendations. A non-template control contained water, instead of genomic DNA, as a negative control. Additionally, positive controls (DNA samples with known genotype) were employed in each run of HRM analysis. PCR amplification was performed in a LightCycler® 96  Thermocycler. The collected data were analysed, using the LightCycler® 96 software version SW 1.1 .Genomic DNA was prepared, using DNeasy Blood & Tissue Kit  according to the manufacturer instruction. PCR products for the analysed variants were analysed by HRM analysis. Real-time PCR cycling and conditions and primers for HRM analysis of all the examined MDR1 SNPs are summarized in Table 2 test. Differences between distributions in particular groups were evaluated also by the χ2 test. All multivariate models were adjusted for age and use of variety of drugs. T test  or Mann–Whitney test  was used to compare each parameter between two groups. An ANOVA test was used to identify parameters that would make significant differences between more than two groups; Scheffe’s test was then used to test the significance of difference in each identified parameter between any two groups. Genotype and allele evaluation, regarding their relationship with a given feature, e.g., a risk for disease, was supported by an analysis of OR and 95 % CI, calculated according to the logistic regression model. The wild type of genotype and allele was a reference group. The Statistica v. 7.0 software package  was used.Genotype and allele distributions were evaluated and their compatibility with HWE distribution was assessed by means of the χMDR1 gene C3435T polymorphism may be associated with the incidence of DRE in Polish children.It was demonstrated that the p < 0.05). The CC genotype occurred in the patients with statistically significantly higher frequency, while the TT homozygote was found with statistically significantly lower frequency vs. the group of healthy controls (p < 0.05). It was demonstrated that the C allele in those children may be a risk factor for DRE, unlike the T allele which, by contrast, may play a protective role .See Table MDR1 C3435T in the controls group were in agreement with HWE (p > 0.05). In case of the C3435T polymorphism of MDR1 gene the distribution of the genotypes in the patients differed significantly from one expected from HWE (p < 0.05). It is caused by the very low abundance of the MDR1 TT genotype in the examined Polish population.The observed genotype frequency of p = 0.014).Similar results were observed when the group of epileptic non-responders was compared with the responders (see Table p > 0.05) .No differences were found in the study groups, either in genotype or allele distribution in reference to patient’s gender or concomitant diseases  changes, leading to modifications in the sequence of amino acids . A consequence of these changes is different stability and activity of this protein [A number of hypotheses try to explain the relationship between the  protein , 23.Since this conjugation is not complete and its degree differs in particular populations, the above-mentioned correlation was not observed in all the reported studies. The presence of other, missense type, polymorphisms, e.g., C1236T, may be an additional worrying factor . AnotherThe obtained results demonstrate a possibility of a relationship between C3435T polymorphism and the incidence rate of DRE in the population of the Polish children. However, it requires further studies on much larger study groups. Still, one cannot exclude a possible influence of the studied polymorphism on epilepsy development in result of combined effects with other factors. For the process of epilepsy development is complicated and demanding a complex participation of multiple factors.MDR1 and P-gp expression has not been stated. Among the abundance of genetic polymorphisms in MDR1 gene only one polymorphism of MDR1 was analysed without respect to linkage disequilibrium, which is a crucial feature of population genetics. A joint analysis of SNP C3435T of MDR1 and other SNPs in MDR1 could shed a new light on the role of SNPs in DRE.Drawing conclusions from obtained data should be done with a substantial level of caution due to the limitations affecting this study: test group and controls may be quantitatively unsatisfactory, SNPs linkage disequilibrium was not considered, circulating P-gp levels in patients were unknown and the relation between SNP C3435T in


The results of epidemiologic studies on the relationship between the coffee consumption and pancreatic cancer risk were inconsistent. Thus, we performed an update meta-analysis of cohort studies to quantitatively summarize the association between coffee consumption and pancreatic cancer risk.We searched CBM (China Biology Medicine disc) and MEDLINE for studies of coffee consumption and pancreatic cancer risk up to June 2015. A total of 20 cohort studies were identified in this meta-analysis, and we analyzed these studies using random effects model. The dose-response analysis was conducted too.versus lowest coffee consumption was 0.75 , 0.63-0.86). Statistic significant heterogeneity was found among these studies . The pooled RR for increment of 1 cup/day of coffee consumption was 0.99  for the nine studies, without statistically significant.The overall relative risk (RR) for highest coffee consumption High coffee consumption is associated with a reduced pancreatic cancer risk. However, the result should be accepted with caution, due to the potential confounder and bias could not be excluded. Further well designed studies are needed to confirm the finding. Pancreatic cancer is the eighth most common cause of death from cancer worldwide.Coffee is one of the most popular beverages over the world. Since the early 1980s, epidemiologic studies on the relationship between the coffee consumption and pancreatic cancer risk have been conducted in different countries,We searched CBM (China Biology Medicine disc) and MEDLINE for studies of coffee consumption and pancreatic cancer risk up to June 2015. Key words searched were as follows: (pancreatic OR pancreas) AND (cancer OR tumor OR carcinoma) AND (coffee OR caffeine OR drinking OR beverages OR diet OR lifestyle). Moreover, we have scan reference lists of retrieved articles to search for additional studies. The language of the studies was limited to English or Chinese.The inclusion criteria for the present meta-analysis were: (1) prospective cohort study design; (2) presented the consumption of coffee; and (3) provided the relative risk (RRs) (or odds rations or hazard ration) with their confidence intervals (CIs) . The exclusion criteria were: (1) case-control design; (2) data about coffee consumption was insufficient; (3) duplicate reports; (4) if multiple articles were from the same study population, only the one with largest sample or most information was included.Two authors (Ran and Wang) independently extracted all data and tabulated them, discrepancies were resolved by discussion. The following data from each eligible study was extracted: first author’s last name, year of publication, country, period of follow-up, number of participants, RRs of pancreatic cancer with corresponding 95% CIs for each level of coffee consumption, and variables adjusted for the statistical analysis.versus lowest level of coffee consumption. Then subgroup analysis to evaluate the influence of geographic areas was performed too.For all the included cohort studies, we computed overall RRs with 95% CIs for the highest Q test and IQ test, P < 0.10 was considered present heterogeneity. If the heterogeneity was statistically significant, a random effects model was conducted. Otherwise, a fixed effects model was used.Statistical heterogeneity was investigated by et al was used to evaluate linear trends (study-specific slopes) from the correlated natural logs of the RRs through categories of coffee consumption.For the dose-response analysis of coffee consumption, the method proposed by Greenland Finally, publication bias was evaluated by the Begg’s and Egger’s tests. Statistical analyses were performed with Stata .A total of 20 cohort studies were identified in this meta-analysis, including 1341876 participants and 2872 cases of pancreatic cancer.As various measurement units for coffee consumption were used in the included studies, we just considered to compare the highest coffee consumption category with lowest coffee consumption category, and take the latter as the reference category.versus lowest coffee consumption was 0.75 . Statistic significant heterogeneity was found among these studies (IP for heterogeneity =0.045) (P for bias =0.436) nor Begg’ test (P for bias =0.078) indicated a significant publication bias  . Neitherion bias .P for heterogeneity =0.738). And similar result was found in the seven studies in Europe . In contrast, when the four studies in Asia were pooled, coffee consumption was associated with a reduced pancreatic cancer risk   .Q = 35.29; p = 0.23).Nine studies were included in the dose-response analysis for the relationship between coffee consumption and pancreatic cancer risk.et al performed another meta-analysis with 37 case-control studies and 17 cohort studies, the result suggested non-significant association between coffee consumption and the risk of pancreatic cancer .Up to now, more and more evidences, which is provided by epidemiological studies have demonstrated the inverse association between coffee consumption and some cancer risk, such as breast cancer, prostate cancer, liver cancer, and colorectal cancer.In our meta-analysis, when the 20 studies were pooled, high coffee consumption was associated with a reduced pancreatic cancer risk, but the results of subgroup, which stratify by geographic area, were diverse. Studies in America and Europe showed a non-significant association between coffee consumption for pancreatic cancer risk. In contrast, studies in Asia revealed a significant inverse association between coffee consumption and pancreatic cancer risk. The diverse results among subgroup analysis may be owing to different race and environment.Coffee interfere the cancerous process with different stage. The molecular mechanisms for anticancer effects of coffee compounds are as follows: (1) The antioxidant of coffee may reduce reactive oxygen species (ROS), that can induce DNA damage provoked.Several limitations of our meta-analysis should be discussed. First, we could not obtain enough information to calculate the adjusted RR in some studies, so we just combined unadjusted RRs. This could have influence on the quality of the meta-analysis. Second, as all cohort studies, the potential bias could not be completely avoided. Third, different classification coffee consumption among studies may contribute to the heterogeneity when pooled analysis. Finally, the different measurement units, brewing method, and coffee type may be the cause of heterogeneity too.In summary, the present meta-analysis suggested that high coffee consumption is associated with a reduced pancreatic cancer risk. However, the result should be accepted with caution, due to the potential confounder and bias could not be completely excluded. Further well designed studies are needed to confirm the finding.


BDNF from the perspective of various aspects of systems biology, including its molecular evolution, genomic studies, protein functions, and pathway analysis.Brain-derived neurotrophic factor (BDNF) plays important roles in neuronal survival and differentiation; however, the effects of BDNF on mood disorders remain unclear. We investigated BDNF and performed pathway-based analysis using large genome-wide association (GWA) datasets obtained for mood disorders.We conducted analyses examining sequences, multiple alignments, phylogenetic trees and positive selection across 12 species and several human populations. We summarized the results of previous genomic and functional studies of pro-BDNF and mature-BDNF (m-BDNF) found in a literature review. We identified proteins that interact with BDNF genes exhibit an average of 75% identity with the human gene, while vertebrate orthologues are 85.9%-100% identical to human BDNF. No signs of recent positive selection were found. Associations between BDNF and mood disorders were not significant in most of the genomic studies , while relationships between serum/plasma BDNF level and mood disorders were consistently reported. Pro-BDNF is important in the response to stress; the literature review suggests the necessity of studying both pro- and m-BDNF with regard to mood disorders. In addition to conventional pathway analysis, we further considered proteins that interact with BDNF (I-Genes) and identified several biological pathways involved with BDNF or I-Genes to be significantly associated with mood disorders.BDNF is encoded by a highly conserved gene. The chordate Systematically examining the features and biological pathways of BDNF may provide opportunities to deepen our understanding of the mechanisms underlying mood disorders. BDNF in brain disorders has been a long-standing focus, especially for mood disorders [Brain-derived neurotrophic factor (BDNF) is a member of the family of neurotrophic factors. It was first explored and purified from pig brain in 1982, and other members of the neurotrophin family were successively discovered . In contisorders .BDNF with mood disorders, such as assessing gene expression or the serum BDNF level, conducting linkage studies, or conducting individual and genome-wide association (GWA) studies. Inconsistent findings are often observed across or even within specific study designs. It is unlikely to achieve a comprehensive evaluation without combining information from different sources. Thus, exploration of the relationships between BDNF and mood disorders could benefit substantially from a systematic review of the currently available evidence from different study designs. Recently, more innovative approaches have been adopted to consider the complexity of molecular actions underlying complex traits, such as considering protein-protein interaction (PPI) or conducting pathway-based analyses. There have been some successful applications to psychiatric traits, such as schizophrenia and major depressive disorder [BDNF in mood disorders.In past decades, various study approaches have been undertaken to explore the functions and associations of disorder –10. For disorder . Thus, iBDNF, other works focusing on its gene features, molecular evolution, and protein interactions with other molecules remain scarce and understudied. The adaptive selection and phylogenesis of the BDNF gene in 35 organisms have been previously examined in vertebrates [BDNF in relation to mood disorders. We first evaluated its sequence conservation among species and the magnitude of positive selection in different human populations. Second, we reviewed curated evidence from a systematic review and meta-analysis of different study designs to evaluate the associations between BDNF and mood disorders, as well as evidence from basic experimental designs for the roles of pro-BDNF in emotion related traits. Finally, we investigated the protein interactome of BDNF and applied pathway-based analysis to examine the enrichment of biological pathways involved with BDNF in major depressive disorder (MDD) and bipolar disorder (BPD) separately, using two large GWA datasets.Although a variety of genetic epidemiology designs have been used to study tebrates . HoweverBDNF gene sequence, coding DNA sequence (CDS), and proteins in the NCBI Entrez Gene and Ensembl databases. For species with multiple transcripts in the database, the longest one was selected to include the most information. We used RepeatMasker , a program to screen interspersed and low complexity DNA sequences, to identify different types of repeat sequence to analyze the underlying structure of the genes. The ABBlast searching engine was applied in this program for the advantages of time-saving and good sensitivity.We compared 12 species in vertebrates, including 8 mammals  and 4 non-mammals . We first searched the To compare the similarity between humans and the other species, we used the Basic Local Alignment Search Tool (BLAST) suites to calculate pairwise sequence identity rate for both the CDS nucleotides (blastn suite) and the amino acids of the protein sequence (blastp suite). BLAST is widely used in the comparison of query nucleotides or amino acid sequences and its sequence database, which calculates the similarity statistical significance by the Expected value . The E value threshold was set to 10 by default, indicating a match number of 10 with a sequence of the same length in the database by chance. When the E value was smaller than 10, the pairwise identity and similarity significance were tested among species in BLAST. Multiple sequence alignment of the protein across species was performed by ClustalX (version 2.0) , illustrBDNF gene has undergone recent positive selection during evolution in humans. This web application uses the HapMap phase II (release 21) allelic frequency data of three populations in its analysis, including Utah residents with northern and western European ancestry from the CEPH collection (CEU), Yoruban in Ibadan, Nigeria (YRI), and East Asians (ASN). The measurements of positive selection are calculated by the Integrated Haplotype Score (iHS), which is based on the difference in linkage disequilibrium between a selected and a background allele at the same position. Positive selection is considered to be significant when the iHS is higher than 2 [The detection of adaptive selection across species was performed by PAL2NAL (version 14) . The BDNr than 2 .BDNF and its protein in the context of mood disorders, a substantial amount of data has been accumulated. We performed a literature review by searching in the PubMed database for two topics: genomic studies of BDNF in humans and biological functions of pro-BDNF regardless of species. For the first topic, a number of meta-analysis and review articles have been published in the past decade. Articles were limited to English-language, full text, publication year between 2003 and 2013, human species, and review or meta-analysis as the article type. We also reviewed some of the references of these original articles when necessary. For the second topic, we focused on the biological functions of pro-BDNF in relation to emotion. Article types and species were not restricted. The search in the literature for mood disorder and emotion-related keywords used several MeSH terms, including mood disorder, major affective disorder, major depressive disorder, depression, bipolar disorder, mania, or stress. All the articles initially found in the systematic literature review process were manually checked for their relevance to our topics.Due to the great interest in studying BDNF in human, and we divided these studies into categories of gene expression, linkage, genetic association and GWA studies, and serum/plasma BDNF level. A special note is for gene expression studies. Gene expression data and analysis results are affected by tissue types, experimental platforms, and characteristics of samples. Some gene expression results are deposited in the SMRI , which collected brain tissues of patients with schizophrenia and bipolar disorder. Detailed experimental data of gene expression from12 studies were obtained from the SMRI database. In addition to literature review, we extracted gene expression data from the SMRI database to perform direct analysis, which provided the consensus fold change by weighted combination of individual probes mapping to genes across studies.There are different designs in genomic studies of To identify proteins that interact with BDNF, we used the STRING database . STRING includes more than 5 million known and predicted PPI from 1,133 organisms. It also provides an evidence score (ranging between 0 and 1) for the prediction of PPI from a variety of data sources, including experimental data on physical PPIs, annotated pathway sources, organism-specific or text-mining databases, and predicted associations via gene neighborhoods, fusion, co-occurrence, and co-expression. The higher the evidence score is, the greater is the confidence that the interaction exists. A molecule with an evidence score greater than 0.4 was considered to have medium confidence of interaction with BDNF, according to the suggestion of this web tool. Genes encoding proteins that interact with BDNF were named I-Genes in our study. Using the prediction results of STRING, we collected a total of 363 I-Genes based on predicted interactions with BDNF. We also plotted the PPI network of I-Genes with evidence scores greater than 0.9 in BDNF gene-involving pathways  for pathway annotation. The MsigDB is a large integrated database from several available pathway sources, in which we focused on two main collections, the manually curated pathways based on expert knowledge and online pathway databases such as the Kyoto Encyclopedia of Genes and Genomes, BioCarta, Reactome, and Gene Ontology. In total, 4726 pathways were annotated. We further selected two sets of pathways to be included in our analysis for BPD and MDD: the The GWA datasets of MDD and BPD for pathway analysis were accessed through the Genetic Association Information Network (GAIN). In brief, the MDD GWA data included 1,738 cases and 1,802 controls of Western European ancestry with 435,291 SNPs (single nucleotide polymorphisms); the BPD GWA data included 1,001 cases and 1,033 controls of European Americans with approximately 724,067 SNPs after data cleaning. More detailed information about the GAIN GWA datasets is available elsewhere , 18. In We conducted pathway analyses using both competitive and self-contained methods. Competitive tests compare the statistics of certain genes in a given pathway with genes not in the pathway, while self-contained methods only compare specific genes in an interested pathway with non-associated background genome. Thus, we applied both the GSEA  and SumStat (sum statistic) methods for pathway analysis. Detailed information on these two statistics can be found elsewhere , 20. In adj-value less than 0.05 was considered significant. All the pathway analyses were performed using R (2.14.2).To further consider the information gathered from PPI, we implemented a weighting scheme to give I-Genes twice the weight of the remaining genes in a given pathway. The significance of each examined pathway was calculated by 15,000 times permutation. The analysis flow chart for pathway analysis is shown in The DNA length of the BDNF gene varies widely across the examined vertebrates , rangingBDNF gene is highly conserved among the vertebrates examined. The high identity rate in amino acid sequences across species suggested that the functions of BDNF originated early in evolutionary history and are not specific to mammals with more complicated and sophisticated emotional expression. Using the human sequence as the reference, the CDS sequence identity rate is high across species. For example, the identity rate is 85.7% between humans and chickens. The identity rate in the amino acid sequence between humans and other species is even higher, with an identity above 90% for chickens and a low in zebrafish of 70%. Except for zebrafish, the The results of multiple alignments are shown in BDNF gene did not experience strong natural selection in these species. BDNF variants in the CEU, YRI and ASN populations. In the BDNF gene region, the selection force was highest in the YRI population, with the highest differential linkage disequilibrium. However, the magnitude of positive selection in all three populations was non-significant (|iHS|<2). Moreover, we applied another program, dbPSHP [BDNF region in all examined populations.Human possess a higher level of emotional expressions and complex cognitional function; thus, we examined adaptive selection across species as well as several human populations. The dN/dS ratios in pairwise comparisons across species were all below one ., indica, dbPSHP , which uBDNF gene across species and human populations suggested that the polymorphisms in this gene are unlikely to have dramatic deleterious impacts on species fitness and survival. Interestingly, a recent study reported high genetic diversity for the Val66Met polymorphism, of which the derived Met allele has frequency ranging from 0–72% in 58 global populations [BDNF gene regions in the database and different analysis algorithms. However, from the evolutionary genetic point of view, mutations in the BDNF gene may still influence adaptions to environmental changes, especially for mental disorders. A polygenic mutation-selection balance theory  has been suggested to explain the development of mood disorders in human [BDNF.The findings of non-significant natural selection in the evolutionary history across species and different human populations were consistent with results reported using the Selectome database . The absulations , suggestin human , furtherBDNF. The results of this literature review of the genomic study designs of the BDNF gene and serum/plasma levels are listed in BDNF mRNA levels in peripheral blood were found between BPD patients and controls [BDNF mRNA level was neither associated with mood disorders nor exhibited substantial fold change between mood disorder patients and healthy controls.A decade ago, the neurotrophin hypothesis was proposed for the etiology of mood disorders, and BDNF is among the most studied neurotrophic factors . A variecontrols . We alsoBDNF gene is located on chromosome 11p. In seven review articles of linkage studies for MDD and BPD, only one study on BPD reported a suggestive linkage region at 11p  [BDNF gene (greater than 130 Mbp). Thus, the results from linkage studies provided negative evidence for mutations of the BDNF gene to have any direct and substantial effect on the familial inheritance of mood disorders, which may be due to the complex genetic etiology underlying MDD and BPD. The effect of the BDNF gene on mood disorder is too weak to be detected by family-based linkage study design.Linkage studies are often adopted to examine susceptible genetic regions and loci for the trait of interest. The 11S1923) . HoweverBDNF gene, the most tested genetic polymorphism is the Val66Met variant (rs6265). A few meta-analysis studies have been conducted for MDD and BPD, and the results are summarized in For genetic association studies, two designs are commonly adopted: the candidate genes approach and the GWA approach. In the BDNF with mood disorders [Large scale GWA studies are expected to have a better chance of finding underlying susceptible genetic variants for mood disorders, especially meta- or mega-analysis of GWA studies that include even larger sample sizes with millions of markers distributed over the genome. Several GWA meta-analyses with thousands of individuals have been conducted for MDD and BPD, however, none of these studies reported suggestive signals for the association of the Val66Met marker or other genetic variants of isorders –42. Thes-8) between serum BDNF and depression status was also reported in Sen et al., (2008) [-4) [Some studies have examined the relationship between BDNF protein level and neuropsychiatric disorders in the hope of identifying useful peripheral biomarkers for predicting the risk of mood disorders. While most of the genomic studies  showed negative or inconsistent results, protein level studies seemed to demonstrate more consistent and positive findings. We systematically reviewed articles and meta-analysis studies for MDD and BPD considering both plasma and serum BDNF expression levels. For MDD, a significant association  . In a me, (2008) . For BPD08) [-4) .In addition to the comparison between the blood level of BDNF in mood disorder patients and healthy controls, several studies further investigate the effect of different disorder statuses. After medication treatment, significantly increased BDNF levels were found in MDD patients , 46. ForBDNF has been widely tested for mood disorders, the evidence was not consistent across different study designs and individual studies. A data integration strategy is necessary to evaluate the role of BDNF in mood disorders. We previously developed a data integration pipeline to combine multiple sources of genomic information  to prioritize candidate loci for MDD [BDNF was identified in the top candidate gene list for BPD [BDNF in mood disorders.Although  for MDD . With a  for MDD . Similar for BPD , 48. TheIt is possible that BDNF interacts with other molecules in specific biological pathways to exert its effect on the trait of interest . We furtBDNF and the underlying mechanism of BPD. For both MDD and BPD, the results were very similar regardless of adding a weighting scheme to I-Genes or not. Adding extra weight to the genes that interact with BDNF in specified pathways seemed to be irrelevant and did not exert substantial influence on the pathway analysis results.BDNF in the two disease categories. Interestingly, the MAPK signaling pathway that included both the BDNF gene and more than 10 percent IGenes showed association with BPD under both the BDNF-pw and IGene-pw categories. The MAPK pathway is activated by BDNF through binding to the TrkB receptor, which further emphasizes the involvement of BDNF in mood disorders.Comparing significant pathways of IGene-pw and BDNF-pw, we found that the results were quite different. The most significant IGene-pw were the calcium signaling pathway, neurological system process, and synaptic transmission for BPD (P<0.001), which were all related to nervous system functions. In contrast, the significant BDNF-pw were related to receptor binding, gene regulations of certain cells or organisms that were involved in cancer or physical health problems. Several previous studies have shown that cancer mortality rates were higher in mood disorder patients than in the general population . The BDNSome of the significant pathways that were identified in MDD and/or BPD in our studies were also reported by previous studies for mood disorders, such as calcium signaling pathway and glutamate receptor activity. Hasbi et al., (2009) reported that calcium mobilization to the plasma membrane was induced by the activation of the dopamine D1-D2 receptor heteromer, and the mobilization triggered the activation of CaMKIIα in the nucleus that enhanced BDNF expression . BDNF alNeurotrophins are first produced and released in a precursor form and then proteolytically cleaved by several enzymes to create a mature form . Like otOn the other hand, the level of BDNF is found to be influenced by adverse environmental stimuli and stress, which is often linked with emotional, physiological and psychological reactions. Acute and chronic stresses are reported to increase the risk of developing mood disorders , 56, andOther observations regarding anti-depression treatment provide additional supporting evidence for the roles of BDNF in mood disorders. Segawa et al., (2013) examined the effects of electroconvulsive seizures (ECS) on the expression of BDNF and other protease enzymes in the hippocampus of rats . The autThe current study had certain limitations. Because most of our analyses relied on data from publicly available and published literature reports, the accuracy of these results is influenced by the completeness of the databases and potential publication bias in the literature. This situation exists in most similar research settings, and we elected to use multiple databases to reduce the potential problems. We selected a so-called integrated database to reduce information bias and restricted our literature review to meta-analysis and review studies. In addition, we collected data from different data sources as completely as possible and developed a weighting system in the hope of obtaining more robust findings.BDNF. Genes that interact with BDNF are evaluated at the pathway level and analyzed using two GWAS datasets of BPD and MDD.From a biological perspective, BDNF proteins participate in neuron development and stress responses, which are considered to play important roles in relation to neuropsychiatric disorders. Many previous studies examined the relationship between BDNF and mood disorders using a variety of study designs and analytical methods. We have systematically reviewed evidence from genomic studies and BDNF protein level studies, including pro-BDNF and m-BDNF. In addition, we performed sequence alignment among different species and tested positive selection to explore the evolutionary history of BDNF with mood disorders, while studies examining serum/plasma levels of BDNF provided more consistent positive findings for its involvement in mood disorders. The lack of evidence from genetic studies may not negate the roles of BDNF in mood disorders. Most of the risk variants in GWA studies often explain very small proportion of heritability in complex disorders, and the negative findings may result from small main effect of BDNF [BDNF with mood disorders may not be through the main effect. BDNF likely acts as a modifier gene or jointly with other genes in the same pathway to contribute to the risk of mood disorders. One example is a study that reported a significant interaction effect between BDNF Val66Met and DRD3 Ser9Gly genotypes, influencing bipolar disorder [To summarize, we observed a general pattern that most linkage and GWA association studies provided negative findings for  of BDNF . In addidisorder . BecauseStress is considered an important environmental stimulus that influences the risk of mood disorders by altering the expression of BDNF. Previous studies have suggested different roles for pro-BDNF and m-BDNF and how these proteins operate in response to stress. Examining the changes in pro-BDNF and m-BDNF blood levels and the pro-BDNF/m-BDNF ratio may be useful and important for the early detection of mood disorders. Moreover, the expression of the proteases that cut pro-BDNF to produce m-BDNF and of the proteins that interact with BDNF may also be important indicators for the risk of developing mood disorders, and further study is warranted to investigate their roles in the underlying mechanisms of mood disorders.S1 Fig(DOCX)Click here for additional data file.S2 FigA. Genes interacts with BDNF by STRING.  B. Map I-Genes to the pathways in MsigDB, select the pathways which overlap rate is more than 10%, and exclude pathways with extreme gene numbers. (#:34) C. All the genes in 34 pathways were included for analysis.  D. Give weights for genes with evidence score provided by STRING. E. Use GSEA and SumStat as statistics.(DOCX)Click here for additional data file.S1 TableSignificant level: dN/dS≧1.(DOCX)Click here for additional data file.S2 Tablea The total number of genes in each pathway annotated by MsigDB. b Pathway was selected since it was related to BDNF. c Pathway was selected since it include more than 10 percent I-Genes. d Pathway was significant in at least one statistical way.—: Did not include in pathway analysis since the extreme pathway gene numbers.(DOCX)Click here for additional data file.


XRCC3) protein plays an important role in the repair of DNA double-strand breaks. The relationship between XRCC3 polymorphisms and the risk of radiation-induced adverse effects on normal tissue remains inconclusive. Thus, we performed a meta-analysis to elucidate the association between XRCC3 polymorphisms and radiation-induced adverse effects on normal tissue. All eligible studies up to December 2014 were identified through a search of the PubMed, Embase and Web of Science databases. Seventeen studies involving 656 cases and 2193 controls were ultimately included in this meta-analysis. The pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated to evaluate the association between XRCC3 polymorphisms and the risk of radiation-induced normal tissue adverse effects. We found that the XRCC3 p.Thr241Met (rs861539) polymorphism was significantly associated with early adverse effects induced by radiotherapy . A positive association lacking statistical significance with late adverse effects was also identified . In addition, the rs861539 polymorphism was significantly correlated with a higher risk of adverse effects induced by head and neck area irradiation  and breast irradiation , whereas the correlation was not significant for lung irradiation or pelvic irradiation. Furthermore, XRCC3 rs1799794 polymorphism may have a protective effect against late adverse effects induced by radiotherapy . Well-designed large-scale clinical studies are required to further validate our results.The X-ray repair cross-complementing group 3 ( Radiotherapy is an important and commonly used modality in cancer treatment, but normal tissues both in the vicinity of the target area and the pathway of the radiation beam are inevitably irradiated, which may result in a spectrum of normal tissue adverse effects . The preIn recent years, accumulating evidence has supported the hypothesis that the risk of radiotoxicity correlates with genetic susceptibility ,7. SinglXRCC3), a member of the RAD51-related protein family [XRCC3 polymorphisms and radiation-induced adverse effects have reported inconclusive results. Thus, we reviewed this controversial evidence and performed a meta-analysis to evaluate the association between XRCC3 polymorphisms and the risk of radiation-induced adverse effects.DNA is widely considered the main target of radiotherapy, which causes cell death by inducing both single-strand breaks (SSBs) and double-strand breaks (DSBs) . DSBs arn family , particin family  and playn family –19. Seven family –22. PrevXRCC3” or “X-ray repair cross-complementing group 3,” “radiotherapy” or “radiation,” and “injury” or “toxicity” or “adverse effect” or “complication.” Studies satisfying the following criteria were eligible for inclusion: (1) case-control study or cohort study; (2) evaluated the effect of SNPs in XRCC3 on radiation-induced adverse effects on normal tissue; (3) adequate information provided to calculate the odds ratio (OR) and the corresponding 95% confidence interval (95%CI). There were no limitations on the language of publication. To avoid exaggerating the effects of certain studies, the patient cohorts of the included studies were verified to ensure that only one appropriate comparison from each cohort was included for the calculation of the pooled statistic.Two investigators (Y.Z. Song and C.C. Xia) independently searched the PubMed, Embase and Web of Science databases using the terms “polymorphism” or “SNP,” “XRCC3, and numbers of cases and controls who possessed the major allele homozygote, heterozygote and minor allele homozygote genotypes.Two investigators (Y.Z. Song and W.Y. Shi) independently extracted data from each included study. Disagreements were resolved by discussion among all investigators. The following data were extracted: first author, year of publication, ethnicity, cancer type, normal tissue toxicity, subtype of SNP in XRCC3 polymorphisms and the risk of adverse effects induced by radiotherapy under a dominance model . The heterogeneity between studies was assessed with the chi-squared based Q-test and I2 statistics [P was <0.10 or the I2 statistic was ≥50%, the heterogeneity was considered statistically significant, and a random-effects model (DerSimonian-Laird method) was used [P <0.05 was considered significant for all of the analyses except the heterogeneity tests. Statistical analyses were performed using Review Manager  and STATA .The pooled OR and 95%CI were calculated to assess the association strength between atistics –24. Whenwas used ; otherwiwas used . If morewas used –28. If pwas used . A two-sXRCC3 were included in this meta-analysis. Fifteen studies were identified for rs861539, five studies for rs1799794 and two studies for rs1799796. For rs861539, six studies evaluated the early adverse effects induced by radiotherapy, while nine studies focused on late adverse effects.A flow diagram summarizing the literature review process and reasons for exclusion is presented in P = 0.001) (P = 0.01) and mucositis    . Subgrou = 0.01) . For rs1 = 0.19) .P = 0.05) (P = 0.01) (P = 0.01)  . Further = 0.05) . For rs1 = 0.01) . For rs1 = 0.01) .P = 0.0003) and breast irradiation , while no significant association was observed for lung irradiation  or pelvic irradiation   .I² = 89%, chi-squared P = 0.003). The pooled results were stable in the sensitivity analysis.The heterogeneities between studies of all analyses were not significant except the analysis for the early effect of rs1799794  from the initial results . The direction of the effect and the significant association were both constant, which indicates that the pooled result was stable and representative.The number of included studies for rs861539 was sufficient to evaluate the publication bias. The distribution of included studies in Begg’s funnel plot was visually symmetrical . However” method , three mXRCC3 on early and late effects previously reported and the possibility of different molecular mechanisms [XRCC3 polymorphisms to the risk of adverse effects on normal tissue induced by radiotherapy. Three SNPs of XRCC3 were included in our meta-analysis: XRCC3 NM_005432.3:c.722C>T, NP_005423.1:p.Thr241Met (rs861539); XRCC3 NM_005432.3:c.-316A>G (rs1799794); and XRCC3 NM_005432.3:c.562-14A>G (rs1799796). XRCC3 p.Thr241Met is the most commonly reported polymorphism of XRCC3. Our meta-analysis indicated that the XRCC3 p.Thr241Met polymorphism is significantly associated with an elevated risk of radiation-induced early adverse effect.Radiation-induced adverse effects are commonly classified as early or late effects, depending on the time before manifestation of relevant clinical symptoms. Early effects occur during radiotherapy or within a few weeks after radiotherapy, while late effects emerge months to years after radiotherapy . Early echanisms , we analXRCC3. Due to obvious heterogeneity, no meta-analysis was undertaken. A positive association between SNPs in DNA repair genes and acute radiotoxicity events has been reported [XRCC3 polymorphisms and the risk of radiation-induced adverse effects in head and neck cancer (HNC) patients have been published, and they were included in the present meta-analysis. Our meta-analysis focused on XRCC3 and provided more specific evidence. Subgroup analysis according to irradiated area revealed that rs861539 significantly correlates with an elevated risk of adverse effects induced by head and neck irradiation, with similar results observed for breast irradiation.A systematic review aimed to explore the association between 14 SNPs in 9 genes and radiotoxicity in normal tissues of the head and neck . Of the reported . Since tXRCC3 did not reach genome-wide significance in these studies. In the present meta-analysis, the pooled OR of pelvic irradiation was also not significant   have been published on normal tissue radiobiology –51. Most = 0.81) , althougP = 0.01), which indicates that rs1799794 polymorphism may have a protective effect against late adverse effects. Further studies are needed to confirm this conclusion. The analysis evaluating the effect of rs1799794 on early adverse effects yielded a significant heterogeneity, because the only two identified studies reached opposing conclusions. For rs1799796, only one study for each early and late effect was identified, and thus heterogeneity was not applicable. No definite conclusion can be made for rs1799794 and rs1799796, due to the relatively small number of identified studies.For rs1799794, a significant association with late adverse effects was revealed  [P = 0.39) [Although accumulating studies have evaluated the association between SNPs and radiation-induced adverse effects, no SNPs have been identified that can indicate which patients are at higher risk of normal tissue injury following radiotherapy . Barnett= 0.003) . Similar = 0.39) . However = 0.39) .As a meta-analysis, heterogeneity among included studies should be considered. One of the most important potential sources of heterogeneity is the evaluation of miscellaneous cancer types together. However, the irradiated area, not the cancer type, is directly related to the occurrence of adverse effects induced by radiotherapy. Radiosensitivity varies according to anatomical site, but a common biological mechanism may occur in different irradiated organs. Hence, it is rational to include different cancer types when evaluating the adverse effects induced by radiotherapy on normal tissue . Some ofIn addition to heterogeneity, other limitations of the present meta-analysis should be noted when interpreting the results. First, publication bias may exist for rs861539; however, after adjustment using the “trim and fill” method , the resXRCC3 polymorphisms and the risk of radiation-induced adverse effects. In conclusion, the meta-analysis suggests that the XRCC3 p.Thr241Met polymorphism is significantly associated with a higher risk of radiation-induced early adverse effects such as acute skin toxicity and mucositis. Although the association between rs861539 and late adverse effects was not significant, rs861539 was significantly correlated with a higher risk of fibrosis. In patients who received head and neck irradiation and breast irradiation, rs861539 was significantly correlated with a higher risk of adverse effects. Our results need to be further confirmed in well-designed large-scale clinical studies assessing the value of XRCC3 polymorphisms in identifying patients at higher risk of radiation-induced adverse effect. These patients might benefit from individual radiotherapy regimens and early intervention for adverse effects accordingly.To the best of our knowledge, the present meta-analysis is the first meta-analysis focusing on the association between S1 PRISMA Checklist(DOC)Click here for additional data file.S1 FigA fixed-effects model was used. The square with the corresponding horizontal line represents the OR and 95%CI of each study. The area of the square reflects the weight of the study. The diamond represents the pooled OR and 95%CI.(TIF)Click here for additional data file.S1 TablePZ-test: P value of Z-test for overall effect. Phet: P value of chi-squared based Q-test for heterogeneity. NA: not available.(DOCX)Click here for additional data file.S2 Table(XLSX)Click here for additional data file.S3 Table(DOCX)Click here for additional data file.


Previous studies have mostly focused on the effects of specific constituents of beverages and foods on the risk of esophageal cancer (EC). An increasing number of studies are now emerging examining the health consequences of the high temperature of beverages and foods. We conducted a meta-analysis to summarize the evidence and clarify the association between hot beverages and foods consumption and EC risk.We searched the PubMed, Embase, and Web of Science databases for relevant studies, published before May 1, 2014, with the aim to estimate the association between hot beverage and food consumption and EC risk. A random-effect model was used to pool the results from the included studies. Publication bias was assessed by using the Begg test, the Egger test, and funnel plot.Thirty-nine studies satisfied the inclusion criteria, giving a total of 42,475 non-overlapping participants and 13,811 EC cases. Hot beverage and food consumption was significantly associated with EC risk, with an odds ratio (OR) of 1.82 . The risk was higher for esophageal squamous cell carcinoma, with a pooled OR of 1.60 , and was insignificant for esophageal adenocarcinoma . Subgroup analyses suggests that the association between hot beverage and food consumption and EC risk were significant in Asian population  and South American population , but not significant in European population .Hot beverage and food consumption is associated with a significantly increased risk of EC, especially in Asian and South American populations, indicating the importance in changing people’s dietary habits to prevent EC. Esophageal cancer (EC) is the eighth most common cancer in the world and ranks six among all cancers in mortality . Many stHot beverage consumption could substantially increase the intraesophageal temperature, depending on the initial drinking temperature. An animal study showed that the structure and the function of the esophageal epithelium were damaged by heat stress even . HoweverIn 2009, Islami and colleagues [This meta-analysis was conducted according to the checklist of the Meta-Analysis of Observational Studies in Epidemiology Guideline . We searStudies were considered eligible for inclusion if they met the following criteria: (1) the study was a case–control or cohort study design, (2) it was published in English, (3) the exposure was hot beverage or food consumption, (4) the outcome of interest was EC, and (5) the study reported the odds ratio (OR) or relative risk (RR) with 95% confidence intervals (CIs) for the association between hot beverages or foods and EC risk or provided sufficient data to calculate them.We extracted the following data from each retrieved article: name of first author, publication year and country of study, study design, specific outcomes, characteristics of study population, number of cases and participants, exposure type, exposure measurement, outcome assessment, comparison categories, OR or RR and corresponding 95% CI, and confounding factors adjusted in the analyses. Data from included studies were independently extracted by two authors (Y.W.C and Y.C), and disagreements were resolved through discussion with the third reviewer (Z.X.L).Two independent reviewers (Y.W.C and C.Y) evaluated the quality of the included studies by the Newcastle-Ottawa Scale , which wRandom-effects model was used to estimate the summary ORs or RRs for the association between hot beverage and food consumption and EC risk. Taking the subjectivity of differentiating between hot and very hot into account, we used the specific OR for standardized category (hot and very hot) versus reference category (cold and warm) of beverage and food consumption. We defined exposure as hot beverages and foods  versus non-hot beverages and foods . If studies had partly overlapped subjects, only the one with a larger sample size was selected for the analysis. If a study reported results for different beverages and foods separately, those beverage/food specific results were regarded as separate reports on the relationship between temperature and EC risk. One study  containeI2 statistic, where values of 25%, 50% and 75% represent cut-off points for low, moderate and high degrees of heterogeneity, respectively [Statistical heterogeneity among studies was evaluated using the ectively . To asseectively  for eachectively , the Eggectively  and funnThe search identified a total of 3780 unique articles from PubMed, Google scholar, and Web of Science databases, of which 189 articles were identified as potentially relevant. After retrieving and reviewing the full text, we determined that 39 studies met our inclusion criteria. The process of study selection is shown in Figure Table I2 = 92.8%, p = 0.001); the pooled OR was 2.09; and the pooled OR of EC risk in relation to hot beverage and food consumption was 1.73.The results from the random-effects meta-analysis of hot beverage and food consumption and the risk of EC were shown in Figure I2 = 50.30%, P = 0.110) and European population .Table P = 0.001) to 1.87, which indicates that the overall result was not significantly influenced by any individual studies.We excluded each study in turn and pooled the results of the remaining included studies. The positive association was not materially changed upon the exclusions, with a pooled OR range from 1.75 , the type of EC (P = 0.047) and sample size (P = 0.033) were significant sources of heterogeneity. Study location alone explained 34.39% of the τ2 in the meta-regression; type of EC explained 12.97%; and sample size explained 8.99%. The results were shown in Table Our meta-regression analysis reveals that the study location .Visual inspection of funnel plot did not identify substantial asymmetry  from 39 case–control studies, we confirmed a positive association between hot beverage and food consumption and EC risk. Individuals who usually have beverages and food served very hot or hot were almost twice likely to develop EC than individuals who usually have beverages and foods served warm or cold. Our subgroup analyses show that the results held true across various populations despite significant heterogeneity.Our meta-analysis shows that the consumption of hot beverages and foods are significantly associated with ESCC  but not with EAC . A large body of observational evidence suggests that the risk factors for ESCC and EAC may be different. For example, alcohol intake is a strong and well established risk factor for ESCC but it is not associated with EAC ; a high Another notable finding is that hot beverage and food consumption appears not to be a risk factor for EC in European population . The result might be ascribed to the small sample size  or the unique dietary habits of Europeans. A previous study noted that Europeans tend to add cold milk to the exposure beverages, tea or coffee before consumption , which mTP53 gene in esophageal tumor samples from geographical areas in which drinking hot beverages is considered an important risk factor for EC [2 and leukotriene B4 as well as overexpression of their receptors are major factors in exacerbating inflammation and oxidative stress, which is the main pathogenesis associated with EAC [It is conceivable that hot beverages and foods may cause thermal injury to the esophageal mucosa, and there are several biological mechanisms through which thermal injury in general could increase the risk of EC. Inflammatory processes associated with chronic irritation of the esophageal mucosa caused by local hyperthermia could stimulate the endogenous formation of reactive nitrogen species and nitrosamines . This hyr for EC -62; thesr for EC . The barr for EC , such asr for EC . In factr for EC -67. In ar for EC . It has r for EC . One revwith EAC . The resAll the original studies used in our meta-analysis are of case–control study design, which is particularly vulnerable to potential biases (both selection bias and information bias). The included studies were conducted among different populations, mostly along with various categorizations of beverages and foods, which could confound our analysis on the specific link between the temperature of beverages and foods and the risk of EC. Lastly, the study relied on self-reported consumption of hot beverages and foods; as a result, the categorization of “hot or very hot” versus “cold or warm” is subject to reporting bias. In addition, the limited information provided in the included studies ruled out the possibility of conducting a dose–response analysis. Nonetheless, this is the first meta-analysis to systematically quantify the association between hot beverage and food consumption and EC risk, and the results of our study are of broad interest to medical science and the public since consumption of beverages such as tea, coffee, and maté are prevalent worldwide ,69,70 anIn the light of our findings, certain factors should be considered in future studies. Large prospective studies are needed to investigate the association of hot beverage and food consumption with both EC risk and the type of EC, not only because of the different ESCC and EAC risk factors but also the rapid changes in incidence of EAC . In addiIn summary, our meta-analysis shows that hot beverage and food consumption is associated with a significantly increase in the risk of EC, especially in Asian and South American populations. Given that hot beverages and foods are prevalent in modern society, the results of our meta-analysis have important implications for cancer etiology research as well as applications in health education and clinical practice.Ethical approval is not required for this review.


MTHFR) gene with risk of cardiovascular disease (CVD) in patients with end-stage renal disease (ESRD).This meta-analysis was conducted to evaluate the correlations of a common polymorphism (677C>T) in the methylenetetrahydrofolate reductase (The following electronic databases were searched without language restrictions: Web of Science (1945∼2013), the Cochrane Library Database , MEDLINE (1966∼2013), EMBASE (1980∼2013), CINAHL (1982∼2013) and the Chinese Biomedical Database (CBM) (1982∼2013). Meta-analysis was performed using STATA statistical software. Odds ratios (ORs) with their 95% confidence intervals (95%CIs) were calculated.MTHFR 677C>T polymorphism might increase the risk of CVD in ESRD patients . Further subgroup analysis by ethnicity suggested that the MTHFR 677C>T polymorphism was associated with an elevated risk for CVD in ESRD patients among Asians , but not among Africans or Caucasians .Eight cohort studies met all inclusion criteria and were included in this meta-analysis. A total of 2,292 ESRD patients with CVD were involved in this meta-analysis. Our meta-analysis results revealed that the MTHFR 677C>T polymorphism may be associated with an elevated risk for CVD in ESRD patients, especially among Asians.Our findings indicate that the  Hemodialysis (HD) is a common form of dialysis therapy for kidney disease by achieving the extracorporeal removal of waste products such as creatinine, urea and free water from the blood MTHFR gene, is a key enzyme in folate metabolism which plays a critical role in the synthesis and methylation of DNA encoding for an enzyme responsible for re-methylation of homocysteine (Hcy) to methionine MTHFR gene is located on the short arm of chromosome 1 (1p36.3), is comprised of 11 exons and 10 introns, and is 19.3 kb in length MTHFR gene might alter its production and function, thereby affecting individual prevalence rates of some diseases and even cancers MTHFR promoter region have been reported in previous studies, of which 677C>T has been suggested to be implicated in the susceptibility to CVD in ESRD patients MTHFR genetic polymorphisms contribute to the pathogenesis of CVD in ESRD patients.Methylene tetrahydrofolate reductase (MTHFR), encoded by the The following electronic databases were searched without language restrictions: Web of Science (1945∼2013), the Cochrane Library Database , MEDLINE (1966∼2013), EMBASE (1980∼2013), CINAHL (1982∼2013) and the Chinese Biomedical Database (CBM) (1982∼2013). We used the following keywords and MeSH terms in conjunction with a highly sensitive search strategy: [“SNP” or “mutation” or “genetic polymorphism” or “variation” or “polymorphism” or “single nucleotide polymorphism” or “variant”] and [“cardiovascular disease” or “CVD” or “cardiovascular risk” or “Hemodialysis” or “HD”] and . We also conducted a manual search to find other potential articles based on references identified in retrieved articles.MTHFR 677C>T polymorphisms with the risk of CVD in ESRD patients; (3) all patients met the diagnostic criteria for HD; (4) the study must provide sufficient information about the frequencies of the MTHFR 677C>T polymorphism. If a study could not meet the inclusion criteria, it was excluded. The most recent or the largest sample size publication was included when the authors published several studies using the same subjects. The supporting PRISMA checklist is available as The following criteria were used to determine the eligibility of included studies: (1) the study design must be a clinical cohort study; (2) the study must relate to the relationships of Data were systematically extracted by two authors from each included study using a standardized form. The form used for data extraction documented the most relevant items including publication year, language of publication, the first author's surname, geographical location, sample size, design of study, the source of the subjects, source of samples, allele frequencies, genotyping method of SNP, evidence of HWE in healthy controls, etc.Methodological quality was independently assessed by two observers according to the Newcastle-Ottawa Scale (NOS) criteria Z test was used to estimate the statistical significance of pooled ORs. Heterogeneity among studies was estimated by the Cochran's Q-statistic and 2I tests Q-test shows a P<0.05 or 2I>50%, indicating significant heterogeneity, the random-effects model was conducted; otherwise the fixed-effects model was used. We also explored reasons for heterogeneity using meta-regression and subgroup analyses. In order to evaluate the influence of single studies on the overall estimate, a sensitivity analysis was performed. Funnel plots and Egger's linear regression test were applied to investigate publication bias Meta-analysis was performed with the use of the STATA statistical software . Odds ratios (ORs) with their 95% confidence intervals (95%CIs) were calculated as estimates of relative risk for CVD in ESRD patients. The P>0.05). The NOS scores of all included studies were ≥6. The main characteristics of all eligible studies are listed in Initially, the highly sensitive search strategy identified 156 articles. After screening the titles and abstracts of all retrieved articles, 78 articles were excluded. Then full texts were reviewed and 65 articles were further excluded. Another 5 studies were also excluded due to lack of data integrity . FinallyMTHFR 677C>T polymorphism and susceptibility to CVD in ESRD patients is shown in MTHFR 677C>T polymorphism might increase the risk of CVD in ESRD patients   .MTHFR 677C>T polymorphism was associated with the incidence of CVD in ESRD patients among Asians , but not among Africans or Caucasians . Further subgroup analyses based on genotyping method suggested that the MTHFR 677C>T polymorphism was closely linked to an increased risk of CVD in the majority of subgroups .Meta-regression analysis confirmed that none of the considered factors was the main source of heterogeneity  in exon 4 may influence the plasma Hcy in ESRD patients. Abundant evidence has supported the view that a half reduction in enzymatic capability might lead to a mild Hcy, as well as total elevation of plasma Hcy concentrations in individuals, both of which might contribute to the genetic predisposition to CVD MTHFR can catalyze a rate-limiting reaction in the transformation of methionine into Hcy and back exclusively through the transfer of the methyl group to and from methyl-tetrahydrofolate, separately MTHFR gene with the incidence of CVD in ESRD patients. Our meta-analysis results showed that the MTHFR 677C>T polymorphism was associated with an increased risk of CVD in ESRD patients, indicating that variants in the MTHFR gene may play a pivotal role in the pathology of CVD in ESRD patients. Although the mechanism by which MTHFR genetic polymorphisms lead to the development of CVD in ESRD patients still remains partially understood, a possible explanation is that the MTHFR 677C>T polymorphism may lead to a mild decrease in MTHFR activity which plays a crucial role in the remethylation of Hcy to methionine, resulting in elevated total plasma Hcy levels which may contribute independently to the excess incidence of fatal and nonfatal CVD. Haviv YS et al. have suggested a major role for plasma Hcy level as a determinant of CVD in ESRD patients, whereby the MTHFR variants and low serum folate are important determinants of plasma Hcy level and therefore may also have an indirect impact on the cardiovascular status MTHFR 677C>T polymorphism and an increased risk of CVD in ESRD patients among Asians. In short, our findings were in accordance with previous studies that found that the MTHFR 677C>T polymorphism may alter the risk of developing CVD in ESRD patients, suggesting that these polymorphisms may be useful as biomarkers for the early diagnosis of CVD in ESRD patients.We undertook the present meta-analysis to elucidate the association of genetic mutations in the MTHFR 677C>T polymorphism and the risk of CVD in ESRD patients, our study has some limitations. First, our results lacked sufficient statistical power to assess correlations between the MTHFR 677C>T polymorphism and susceptibility to CVD in ESRD patients due to a relatively small sample size. Second, as a retrospective study, our meta-analysis may have been influenced by subject selection bias, thereby affecting the reliability of our results. Third, our meta-analysis failed to obtain original data from the included studies, which may have limited further evaluation of the potential roles of the MTHFR 677C>T polymorphism in the development and progression of CVD in ESRD patients. Importantly, the inclusion criteria of cases and controls were not well defined in all included studies, which might also have influenced our results.As the first meta-analysis focused on the relationships between the MTHFR 677C>T polymorphism may contribute to increased CVD risk in ESRD patients. Thus, the MTHFR 677C>T polymorphism may be a useful and promising biomarker for the early detection and prognosis of CVD in ESRD patients. However, due to the limitations mentioned above, more research studies with larger sample sizes are still needed to provide a more representative statistical analysis.In conclusion, our findings indicate that the Checklist S1The PRISMA 2009 checklist.(DOC)Click here for additional data file.Supplement S1The Newcastle-Ottawa Scale for assessing methodological quality.(DOC)Click here for additional data file.


RSV) is the most frequent cause of hospitalization in infants worldwide. It is recognized by Toll‐like receptor 4 (TLR 4) and cluster of differentiation 14 (CD14) in the innate immune response. Previous case–control studies reported the influence of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms on the risk of severe RSV infection. However, a decisive conclusion has not been achieved. Therefore, we performed this meta‐analysis to examine the association between these three polymorphisms and the development of RSV bronchiolitis. A systematic literature search was performed using the PubMed, EMbase, Google Scholar Search, China National Knowledge Infrastructure, China Biological Medicine, and Wanfang Databases. The data were extracted and pooled odds ratios with 95% confidence intervals were calculated under six genetic models. A total of six studies with 1009 cases and 1348 controls, three studies with 473 cases and 481 controls, or four studies with 325 cases and 650 controls relating to each of the three polymorphisms were included in this meta‐analysis. The analyzed data indicated that all of these polymorphisms were not associated with the risk of severe RSV infection. This is the first meta‐analysis to investigate the relationship of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms with the risk of severe RSV infection. Although the results of this retrospective analysis indicated a lack of the association, more extensive multicentric studies with large sample sizes are necessary to provide a more reliable estimation of the association between these three polymorphisms and RSV bronchiolitis susceptibility.Respiratory syncytial virus ( Respiratory syncytial virus (RSV) is a member of paramyxoviridae family. It is an RNA virus which could cause serious lower respiratory tract infection in children.Whether individuals are susceptible to RSV and how they respond to RSV are determined by the comprehensive factors rather than a single factor. Environmental factors, such as PM10 (particular matter less than 10 μm in aerodynamic diameter) exposure or cigarette smoke exposure, contribute to susceptibility and response to RSV infection.It has been reported that genetic factors might influence the susceptibility to RSV infection in early life.Several publications have reported the association of single‐nucleotide polymorphisms (SNPs) of Asp299Gly, Thr399Ile in TLR4 and C‐159T in CD14 with the risk of RSV infection, but the conclusions were inconsistent. What is more, no meta‐analysis has been conducted to investigate the association between these three polymorphisms and the risk of RSV infection so far. Therefore, we performed this meta‐analysis to estimate the potential relevance of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms with the susceptibility of severe RSV infection.The present meta‐analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) statement,We carried out a comprehensive and systematic literature search based on the PubMed, EMbase, Google Scholar Search, China National Knowledge Infrastructure (CNKI), China Biological Medicine (CBM), and Wanfang Databases. In order to identify the related articles as many as possible, we used the keywords including ‘RSV or respiratory syncytial virus and TLR4 or Toll‐like receptor 4 or CD14 and polymorphism or polymorphisms or variant or mutation’ to obtain all genetic studies on the relationship of single‐nucleotide polymorphisms (SNPs) in the TLR4 and CD14 genes with severe RSV infection. We also conducted a manual search of references of original or reviewed articles on this subject to identify additional studies. The searches were last updated on June 23, 2015.Eligible studies were selected according to the following inclusion criteria: (i) on the association of TLR4 Asp299Gly (rs4986790), TLR4 Thr399Ile (rs4986791), or CD14 C‐159T (rs2569190) polymorphisms with severe RSV infection; (ii) in a case–control design; (iii) with useful genotype frequencies. The exclusion criteria were (i) animal studies; (ii) abstracts, editorials, and review articles; (iii) studies without sufficient genotype data. The included studies were restricted to English and Chinese. Only one could be accepted if the publications were duplicated. Two reviewers extracted eligible studies independently according to the inclusion and exclusion criteria, and any disagreement was resolved by discussion among the authors.One author extracted the following information from each eligible study: name of the first author, year of publication, the country and ethnicity of the participants, the number of RSV cases and controls, the number of genotypes of TLR4 (Asp299Gly and Thr399Ile) and CD14 (C‐159T) polymorphism in RSV cases and controls, Hardy–Weinberg equilibrium (HWE), and genotyping method. Then, another author checked the data carefully to ensure that they are complete and correct. We did not define a minimum number of patients to be included in our meta‐analysis.P ≤ 0·05 was considered as statistically significant. We performed I2 test to evaluate between‐study heterogeneity according to the criteria from the Cochrane Handbook,2 statistics was presented together with its 95% confidence intervals.2 < 50%); otherwise, random‐effect model was selected. Both the Begg and Egger tests were used to assess the publication bias, and a P value of less than 0·05 indicated the presence of publication bias. The trim and fill method was also employed to identify and correct funnel plot asymmetry arising from publication bias.P < 0·05 was considered statistically significant. A high‐quality study was said that its control group was in HWE. A study without HWE in controls was defined as a low‐quality one. Low‐quality studies were excluded in the sensitivity analysis. Newcastle–Ottawa Scale (NOS) criteria http://ims.cochrane.org/revman).In this meta‐analysis, the pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the association of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphism with the risk of severe RSV infection. Six genetic models, namely the allelic, homozygous, heterozygous, dominant, recessive, and overdominant models, were performed, respectively. Z‐test was used to assess the significance of the pooled ORs, and et al.A flow diagram describing the selection procedure of the eligible studies included in this meta‐analysis is shown in Figure 2 < 50%); thus, the fixed‐effect model was used to calculate the pooled ORs of these models. Combined data revealed that TLR4 Asp299Gly polymorphism was not associated with the risk of severe RSV infection in any genetic model  , the fixed‐effect model was used to calculate the pooled ORs in all genetic models. The results showed that no association of TLR4 Thr399Ile polymorphism was observed with the risk of severe RSV infection in five genetic models  ; thus, the random‐effect model was used for this model, while the fixed‐effect model was selected for the rest models. Our meta‐analysis did not reveal any significant association between CD14 C‐159T polymorphism and risk of severe RSV infection in all genetic models   on TLR4 Thr399Ile polymorphism. On TLR4 Asp299Gly polymorphism, the absence of heterogeneity was also found between studies in the homozygous and recessive model (I2 = 0%), but moderate heterogeneity was observed in the other three genetic models . Finally, the degree of the between‐study heterogeneity of CD14 C‐159T polymorphism varied in the different genetic models. An unobserved heterogeneity was detected in the homozygous (I2 = 15%), heterozygous (I2 = 0%), and dominant (I2 = 0%) models, while moderate heterogeneity and moderate‐to‐substantial heterogeneity were discovered in the allelic/overdominant model (I2 = 30%/31%) and recessive model (I2 = 53%), respectively. Therefore, the fixed‐effect model was used to calculate the pooled ORs in all genetic models except for the one with a moderate‐to‐substantial heterogeneity, in which the random‐effect model was applied. We also used the fixed‐effect model to evaluate the association between CD14 C‐159T polymorphism and RSV infection risk in the recessive model, but the result showed little difference from that using the random‐effect model. Furthermore, we performed the sensitive analysis by deleting one single study from overall pooled analysis each time to check the influence of the removed data. The results of sensitivity analysis based on this leave‐one‐out approach indicated that no single study altered the pooled ORs qualitatively.Our meta‐analysis showed little evidence of genetic heterogeneity in all the genetic models of the three SNPs except for CD14 C‐159T polymorphism in the recessive model (as shown in Table We further performed Begg's test and Egger's test to assess the publication bias. As shown in the Table et al.et al.et al.et al.Up to now, seven case–control studies have reported the association of TLR4 Asp299Gly polymorphism with the risk of RSV infection, but the conclusions were inconsistent. Tal et al.To date, only four case–control studies investigate the influence of TLR4 Thr399Ile polymorphism on the risk of severe RSV infection. Although Tal et al.CD14 is considered to be linked to asthma and atopy. Therefore, most of the CD14 studies focused more on the relationship of the polymorphisms in this gene with the development of asthma rather than severe RSV bronchiolitis.Human severe RSV infection is the most common cause of bronchiolitis and pneumonia in infants and elderly. It is associated with significant morbidity and mortality.Our meta‐analysis had four advantages. Firstly, this study is the first meta‐analysis on the association of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms with the risk of severe RSV infection. Secondly, we performed six genetic models including the least frequently used overdominant model to help evaluate the association between these three SNPs and the development of RSV bronchiolitis. Thirdly, heterogeneity is generally a potential problem when interpreting the results of all meta‐analyses, but such is not in our case. In fact, no substantial heterogeneity was observed among the studies under all the genetic models except for CD14 C‐159T polymorphism in the recessive model in this meta‐analysis. Fourthly, both Begg's and Egger's test results showed low risk of publication bias in our meta‐analysis. In addition, although there may be some unpublished studies excluded in this review, those studies are more likely to have found no association according to the principle of publication bias, which might strengthen rather than weaken the overall finding of this work.Some limitations should be also recognized in our meta‐analysis. Firstly, the relatively small sample size of each study resulted in limited statistical power to detect a potential association in this meta‐analysis. Secondly, the included studies were restricted to just English and Chinese literature, which might bias the results. Thirdly, severe RSV infection is a multifactorial disease that results from complex interactions between many genetic, demographic, and environmental factors such as gestational age, breastfeeding, tobacco smoke exposure, viral stain variation.In conclusion, this meta‐analysis indicated that TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms might not be related to genetic susceptibility of severe RSV infection on existing studies. More extensive multicentric studies with large sample sizes, gene–gene, gene–demographic, and gene–environment interactions are necessary to provide a more reliable estimation of these associations in general population.


Stata software was used to analyze all the statistical data.p53 Arg72Pro polymorphism under the genetic model of Arg/Pro vs. Pro/Pro without heterogeneity . A similar trend was seen in subgroups of hospital-based studies and population-based studies.The pooled data by a fixed-effects model suggested an increased risk of CM associated with p53 Arg72Pro polymorphism may increase individual susceptibility to CM, particularly in Caucasians and could serve as a biomarker to predict the population at high risk of CM.Our meta-analysis based on all studies shows that the  Cutaneous melanoma (CM) representing one of the most malignant skin cancers has caused a large number of skin cancer-related deaths, approximately 8,700 deaths in 2010 . More imp53 involved in a variety of biological activities, such as UV-induced DNA damage, regulates numerous downstream genes to induce cell-cycle arrest, DNA repair or apoptosis [p53 is a most frequently mutated gene that has been described in various cancers [The tumor suppressor poptosis ,7. p53 i cancers ,9 and th cancers . Among tp53 plays a pivotal role in the defence against DNA damage and breakage arsing from UV exposure [p53 in the development of skin cancer, an increasing number of investigators have directed their attention to the effects of p53 Arg72Pro polymorphism on CM risk [p53 Arg72Pro polymorphism may contribute to an increased risk of CM.Previous reports suggest that exposure ,12. Due  CM risk –20. But p53 Arg72Pro polymorphism and CM risk by using the following search terms: “p53 codon 72” or “p53 Arg72Pro”, “polymorphism” or “variants”, and “melanoma” or “cutaneous melanoma”. There was no language restriction. References of the original articles and systematic reviews were manually screened for additional usable data.We searched the databases of PubMed, EMBASE, and Web of Science for case-control studies on the association between p53 Arg72Pro polymorphism and CM risk must be examined, (2) designed as case-control study, (3) detailed genotype frequency in cases and controls to estimate odds ratios (ORs) along with 95% confidence intervals (CIs), and (4) there was no departure from Hardy-Weinberg equilibrium (HWE) in genotype distribution of the control group. Abstracts, editorials, and review articles were not considered in the final analysis.The inclusion criteria included: (1) the association of p53 Arg72Pro polymorphism in cases and controls, and genotyping assays. Disagreement was resolved by discussion between the two reviewers or consulting the third reviewer.On the basis of a consensus on all items, two reviewers independently collected the following characteristics from each study: first author’s name, publication year, study country, ethnicity, total numbers of genotyped cases and controls, genotype counts of p53 Arg72Pro polymorphism and CM risk was assessed by pooled ORs with 95% CIs under five genetic comparisons . HWE of the control groups was determined by the χ2 test. Between-study heterogeneity was estimated by chi-square based Q test [P < 0.05 indicated significant heterogeneity. I2 index was also used to quantify the heterogeneity and we considered the value >50% as statistically significant. When no heterogeneity was observed across studies, the fixed-effects model was used [In this meta-analysis, association of d Q test  and P < was used  to calcuwas used  was perfIn addition, sensitivity analyses were applied to detect the individual influence from the single studies on the pooled ORs. Publication bias was tested by performing Begg’s funnel plots and Egger’s test . All staAs graphically depicted in p53 Arg72Pro polymorphism and CM susceptibility under all genetic models with the exception of Arg/Pro vs. Pro/Pro  as well as population-based studies .Since the test for heterogeneity did not suggest substantial heterogeneity across studies, the fixed-effects model was performed to pool the ORs, as shown in We conducted leave-one-out sensitivity analyses with an aim to determine the effects of the independent studies on the overall results. The analysis did not indicate any significant alteration when the single studies was excluded from the pooling data. Thus our results are stable and credible.p53 Arg72Pro polymorphism and CM susceptibility Click here for additional data file.