For diabetes, the estimates were positive for all compounds but statistically significant for oxychlordane [OR = 1.96 ]; for trans-nonachlor [OR = 2.43 ] and for heptachlor epoxide [OR = 1.88 ]. Our results support that among adults, the odds of having diabetes significantly increase with increasing levels of chlordanes. The data did not allow to reach a clear conclusion regarding the association with adiposity.Chlordane compounds (CHLs) are components of technical chlordane listed in the Stockholm convention on persistent organic pollutants identified as endocrine disrupting chemicals (EDCs) and may interfere with hormone biosynthesis, metabolism or action resulting in an unbalanced hormonal function. There is increasing scientific evidence showing EDCs as risk factors in the pathogenesis and development of obesity and obesity-related metabolic syndromes such as type 2 diabetes, but there is no systematized information on the effect of CHLs in humans. Our aim is to identify the epidemiological data on the association between CHLs with adiposity and diabetes using a systematic approach to identify the available data and summarizing the results through meta-analysis. We searched PubMed and Web of Science from inception up to 15 February 2021, to retrieve original data on the association between chlordanes, and adiposity or diabetes. For adiposity, regression coefficients and Pearson or Spearman correlation coefficients were extracted and converted into standardized regression coefficients. Data were combined using fixed effects meta-analyses to compute summary regression coefficients and corresponding 95% confidence intervals (95% CI). For the association between chlordanes and diabetes, Odds ratios (ORs) were extracted and the DerSimonian and Laird method was used to compute summary estimates and respective 95% CI. For both, adjusted estimates were preferred, whenever available. Among 31 eligible studies, mostly using a cross-sectional approach, the meta-analysis for adiposity was possible only for oxychlordane and transchlordane, none of them were significantly associated with adiposity [(β = 0.04, 95% CI 0.00; 0.07, I Furthermore, it is expected that the total environmental burden of disease is underestimated2.Environmental chemical exposures have gained great attention in the past decades based on the growing awareness on the role that the environment plays in health. According to a systematic review performed in 2011, the global burden of disease accountable to environmental exposures and management of selected chemicals amounts to at least 4.9 million deaths per year, representing 8.3% of mortality and 5.7% of the total burden of disease in disability-adjusted life years (DALYs) worldwide3. The major components are trans-chlordane (13%), cis-chlordane (11%), trans-nonachlor (5%) and heptachlor (5%) but more thanh 30 less abundant chemicals were also identified4. In humans, the exposure occurs primarily through food intake, but also by inhalation or skin contact5.Chlordane compounds (CHLs) are components of technical chlordane listed in the Stockholm Convention on Persistent Organic Pollutants6. Despite been globally discontinued in 1997, due to their ability to accumulate in the environment and to travel large distances from where they are released, chlordane-related compounds are present in soil, air, and water9. Although exposure levels of chlordane compounds are expected to decrease over time due to the decrease in their use, their harmful consequences may still be felt for very long periods. Moreover, a better understanding of their consequences may be essential to estimate the effect of other endocrine disruptors for which the effects were not know because exposure levels or time of exposure are still not sufficient to quantify their effects.Chlordane is a synthetic organochlorine pesticide used for several decades in agriculture, but also in housing for pest control11. But there is no systematized information about the effect of chlordanes in humans. Since both obesity and diabetes are pathologies which occur progressively and do not have an immediate consequence after exposure, in addition to understanding the effect on disease occurrence, it is also important to understand the association with different levels of adiposity and diabetes-related features such as fasting glucose or insulin resistance. Previous studies preformed in animal models hypothesize that exposure to elevated levels of chlorane compounds increases the risk of adiposity and diabetes. As chlordane compounds are known as endocrine disruptores, it is possible that the exposition to these compounds, could also increase the risk of adiposity and diabetes in humans. However, to our knowledge, no systematic review has been performed regarding the association between the exposure to CHLs and adiposity or diabetes and diabetes-related features in humans.Chlordane compounds are endocrine disrupting chemicals (EDCs), which means that they may affect the natural function of hormones by blocking, mimicking, displacing, or acting to subvert their roles. There is increasing scientific evidence showing EDCs as risk factors in the pathogenesis and development of obesity and obesity-related metabolic syndrome such type 2 diabetesWe hypothesize that exposure to chlordane compounds increases the risk of adiposity and diabetes in humans. Thus, we used a PECO framework  to develop our question. PECO was applied as follows: P, general adult population; E, exposure to chlordane compounds; C, individuals without adiposity and diabetes; O adiposity and diabetes. These PECO statements were used to develop the search terms and inclusion/exclusion criteria for our systematic review in the next step to summarize the epidemiological data on the association between chlordane compounds and adiposity and diabetes using a systematic approach to identify and perform a meta-analysis of available data in order to evaluate our hypothesis.12. This systematic review and meta-analysis was undertaken with a prospective protocol using the PRISMA  guidelines13 but was not registered in the PROSPERO database.In 2016, our group started this work as part of the HEALS  project, producing a report that presents the preliminary results of the association between EDCs (which includes other EDC exposure) and adverse health outcomes related to adiposity and diabetes. The current publication is an update of the preliminary work, focusing specifically on the exposure to chlordane, using the methodology previously describedPubmed and Web of Science were searched without imposing any limitations, from inception up to 15 February 2021, to retrieve original papers reporting data on the association between chlordanes, adiposity and diabetes, using the following search expressions:(("Endocrine disruptor" OR Endocrine disruptor [mh] OR Pesticide OR "Brominated flame retardants" OR organochlorine OR chlordane* OR oxychlordane OR trans-nonachlor OR "heptachlor epoxide" OR trans-nonachlordane OR cis-chlordane OR cis-nonachlor) AND (Diabetes OR Glucose OR Glucose Metabolism Disorders [mh] OR glycemia OR hyperglycemia OR Hypoglycemia OR Hyperinsulinism OR "Insulin resistance" OR obesity OR overweight OR BMI OR "Body fat" OR Adipose tissue [mh] OR Body size [mh] OR "body size" OR "body weight" OR Anthropometry OR "anthropometric measures”)) AND (humans [mh]).Pubmed: ((TS = ”Endocrine disruptor" OR TS = Pesticide OR TS = "Brominated flame retardants" OR TS = organochlorine OR TS = chlordane OR TS = oxychlordane OR TS = trans-nonachlor OR TS = "heptachlor epoxide" OR TS = trans-nonachlordane OR TS = cis-chlordane OR TS = cis-nonachlor) AND (TS = Diabetes OR TS = Glucose OR TS = “Glucose Metabolism Disorders” OR TS = glycemia OR TS = hyperglycemia OR TS = Hypoglycemia OR TS = Hyperinsulinism OR TS = "Insulin resistance" OR TS = obesity OR TS = overweight OR TS = BMI OR TS = "Body fat" OR TS = “Adipose tissue” OR TS = "body size" OR TS = "body weight" OR TS = Anthropometry OR TS = "anthropometric measures”)) AND (TS = humans). The systematic review flowchart is presented in Fig. ISI-Web of Science: 12.References were reviewed independently by two of three researchers  according to the following exclusion criteria: (1) studies not written in English, Portuguese or Spanish, (2) studies not involving adult human subjects, (3) studies not presenting original data , (4) case reports or case series, (5) studies addressing exposures other than chlordanes or outcomes other than adiposity or diabetes-related features and (6) studies not providing association estimates, (7) studies performed in individuals with a diagnosed disease  and (8) samples composed exclusively by individuals with high exposure to chlordanes , since these individuals have presumably been exposed to much higher doses of chlordanes than individuals from other study samples, and therefore, exposure levels may not present enough variability to reflect the real association. When more than one study referred to the same sample, we considered the one presenting data for the largest sample or, if the sample size was equal, we chose the one providing results in more detail. On the other hand, if two publications studying the same sample reported complementary results (i.e. presenting estimates for different outcome measures), that otherwise would be lost if only one was included, both of them were considered eligible for data extraction12. The literature search was then complemented by backward citation tracking of the papers considered for data extraction.In step one, the exclusion criteria were applied to title and/or abstract and in step two, to the full-text. When the abstract of a particular paper was not available, the article was selected for evaluation in step two, except when the title unequivocally presented information for exclusion . Decisions taken independently by the two reviewers were compared in both steps and disagreements were resolved by consensus or after discussion involving a fourth researcher (ER). The agreement between the reviewers was 68.1% in step one and 72.3% in step twoOur search identified 6500 publications of which 31 presented original data on the association between chlordanes and adiposity or diabetes-related features.12. Of the 31 studies evaluated, 18 were considered only for the meta-analysis  have independently extracted information from selected studies: 1) study design (type of study and period of data collection), (2) sample characteristics , (3) exposure characteristics , (4) outcome characteristics , (5) descriptive measures and (6) association measures. Estimates on the association between exposure to chlordanes and adiposity or diabetes-related features were extracted for the whole sample, but when available, age- or sex-stratified estimates were also retrieved study de12.For the 31 papers included in the systematic review, additional exclusion criteria were considered for the meta-analysis in order to improve comparability between studies. Then, we excluded studies performed among pregnant women since pregnancy induces changes in adiposity and/or diabetes measures and may consequently modify the association and studies presenting association measures that were not possible to combine [e.g. odds ratios (ORs) with correlation coefficients]. Regarding the meta-analysis for adiposity, since most studies provided correlation or beta coefficients to estimate the association with chlordanes, we excluded studies presenting incompatible measures, such as ORs, relative risks or hazard ratios. We also excluded studies that provided coefficients for log-transformed variables since they were not comparable with those provided for untransformed variables, which were the most commonly described. Conversely, as the majority of papers on the association between chlordanes and diabetes-related features presented results using ORs, studies that provided beta or correlation coefficients were excluded from the meta-analyses. When the exposure was analyzed as a categorical variable, only the estimate concerning the highest exposure category in comparison with the lowest was includedMeta-analyses were performed whenever three or more eligible estimates evaluating the effect on adiposity measures and diabetes-related features were suitable to be combined. Therefore, meta-analyses were performed for the association of oxychlordane and trans-nonachlor with both adiposity and diabetes and for heptachlor epoxide exclusively with diabetes.14. When necessary, regression coefficients and Pearson or Spearman correlation coefficients were converted and used for meta-analyses. We used the standard errors to compute the weight of each individual study. When comparing the standard errors obtained from beta coefficients to those calculated for correlation coefficients, minor differences were found (0.02 units on average). This contributes to the robustness of the results reported by our systematic review and meta-analysis. Appropriately converted data from studies were combined using fixed effects meta-analyses to compute summary regression coefficients and corresponding 95% confidence intervals (95% CI)15. In order to compute summary estimates (ORs) and respective 95% CIs for the available data on the association between chlordanes and diabetes-related features, the DerSimonian and Laird computational method was used. Heterogeneity between studies was assessed by the I2 statistic16. Visual inspection of the funnel plots and the Egger’s regression asymmetry test were used for assessment of publication bias17. We also performed sensitivity analysis in order to explore remaining confounding.The statistical analysis was performed with STATA®, version 11.2 12.For meta-analyses on the association between chlordanes and adiposity, standardized regression coefficients and its standard error were calculated in different research approaches of the original studies19.For the assessment of methodological quality of the studies included, we used the “Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: Guidelines for Reporting Observational Studies”. The STROBE statement presents a checklist of items that tought to be addressed when observational studies are reported. The STROBE Statement was used to evaluate the quality of reporting of included observational studies and their scores were assessed  were performed using NHANES 1999–2000 and 2001–2002 combined datasets. The paper by Lee et al.25 was included in the meta-analysis since Lee et al.26 and Cho et al.23 did not assess BMI as the adiposity measure. Bjerregaard-Olsen40 has evaluated the association among pregnant women using pre-pregnancy BMI as outcome, and was thus excluded from the meta-analysis. We have included a total of seven publications in the meta-analysis41, all of them presenting cross-sectional data on the association between oxychlordane and BMI, with a sample size ranging from 42 to 2016 individuals. The overall beta coefficient was 0.04  (Table I2 = 89.7%). However, with the exception of Rosenbaum et al.39, all included estimates have shown positive associations. Visual inspection of the funnel plot  showed no statistically significant publication bias.Table I2 = 91.9%] was found, while more recently published studies did not find an association between oxychlordane and BMI .We have also performed a sensitivity analysis by stratifying data according to the year of publication. Considering studies published before 2006, a positive and statistically significant association between oxychlordane and BMI , we decided to maintain a conservative approach and keep both studies in the analysis. Visual inspection of the funnel plot  showed no statistically significant publication bias.The description of studies selected for the systematic review on the association between oxychlordane and diabetes-related features is found in Table 43 . Similarly, in order to avoid the overrepresentation of this population, only Everett, CJ and Matheson34 was included in the meta-analysis for being the one with the largest sample size. This study presented data for two outcome categories (diabetes and pre-diabetes), but only the estimate for diabetes was included. Park et al.50 was not selected for inclusion in the meta-analysis since estimates were presented only as correlation coefficients, thus ineligible. Lee et al.23 presented both cross-sectional and prospective results, but only cross-sectional estimates were considered for analysis since it was the most comparable estimate with the ones provided in other studies. Ten studies were then considered for the meta-analysis46, resulting in a positive and statistically significant overall estimate   which may occur long time before the study. As the number of included studies was very low, we were not able to perform sensitivitvy analyses, but despite the above mentioned study differences, heterogeneity was null (I2 = 0.0%). Visual inspection of the funnel plot  showed no statistically significant publication bias.Five publications evaluated the association between heptachlor epoxide and diabetes-related features Table 34,35,50.9)] Fig. . However48 was performed among spouses of pesticide applicators and has shown an inverse association with diabetes .Only one paper provided estimates on the exposure to technical chlordane and have evaluated its association with diabetes-related features Table . The stu13 in order to minimize possible bias. The overall results suggest no association between chlordane compounds and adiposity but show higher odds of having diabetes-related features with increasing levels of all the chlordane compounds evaluated. Although these results may seem contradictory, it is necessary to emphasize that unlike results that we found in the case of diabetes, most studies assessing adiposity measures were not specifically designed to study the effect of chlordanes on adiposity, rather, they used adiposity measures as a covariate to test other hypothesis. In addition, most of the results studying the association between chlordanes and adiposity are based on continuous variables, using betas or correlation coefficients, while diabetes and its related features were mostly classified as categorical variables and the association quantified by ORs. Stronger associations were found in studies where the exposition variable is categorical rather than continuous, indicating that the observed differences in results between diabetes and adiposity may be related to the level of exposure. Even among studies addressing diabetes, the strength of association was stronger among those for which the exposure is analyzed as a categorical variable. The differences on identified studies estimating the association between chlordane compounds, adiposity and diabetes, are also reflected in the levels of heterogeneity observed across summary estimates, which are substancially higher for adiposity and therefore should be read with caution.We have conducted a systematic review and meta-analysis presenting the most updated epidemiological evidence on the association between chlordanes, adiposity and diabetes-related features in adults. This systematic review was not registered a priori in the International Prospective Register of Systematic Reviews (PROSPERO). This is a limitation since it could introduce potential bias to the review. However our results were reported according PRISMA statement.25 and Hue et al.22 did not present the mean values for oxychlordane nor for trans-nonachlor concentration levels, while Magnusdottir et al.21 and Pelletier et al.20 presented geometric and arithmetic means, respectively, and therefore we are not able to accurately evaluate the comparability between studies and the impact of different exposure levels on our results. Additionally, some confounders were recognized for the association between chlordanes and obesity and diabetes, being sex, age, race/ethnicity or dietary habits considering among the most important ones51. Although several publications presented adjusted estimates, which allow to assume that the observed associations are independent of these variables, some studies failed to take them into account.Since the identified studies used different measures of association to quantify the relationship between chlordanes and both adiposity and diabetes, it was not possible to include all the identified estimates in meta-analyses, which also impacts the robustness of our results. The small number of studies also limits the possibility to perform sensitivity analyses and to adequatly identify possible sources of variance between studies. Although we are not able to fully address the possible impact of these variables on our results, we can speculate on some of the potential sources of variance. Assay methodologies used for exposure assessment were quite diverse, which may lead to differences on the validity and precision of exposure assessments and increase heterogeneity between studies. The choice of different methods to measure adiposity and diabetes related features may also have implications for the overall estimates. Another aspect possibly conditioning the high heterogeneity observed is linked to different exposure levels between study samples, which is difficult to evaluate if the information is missing or presented in different formats. For instance, regarding adiposity, Lee et alIn addition, it is also important to highlight that people with higher exposure levels to chlordane compounds may also be exposed to olther organochlorine substances, which makes it difficult to disentangle the specific effect of each chlordane compound. Since included studies did not presented the effect for each compound independently of other compounds, our meta-analyses will be not able to quantify the specific effect of each compound. Thus, it is not possible to ensure that at least some of the effect observed are not due exposure to EDCs other than chlordanes.Despite these limitations, reliable conclusions can be drawn from the analyses summarizing the association between chlordane compounds and diabetes, which presented low heterogeneity levels and showed a consistent positive association through all the compounds evaluated. Although no statistical evidence of publication bias was observed, overall our results are suggestive of the existence of an underrepresentation of small studies.52. The lack of association evidenced in more recent studies may not mean that these compounds have no impact on obesity, but rather be a consequence of control measures regarding chlordane that have been implemented and that have neutralized the levels of chlordanes in the population.In order to gain a comprehensive perspective regarding the effect of chlordanes on adiposity, all the identified adiposity measures were considered eligible for analysis. We found estimates for BMI, fat mass, waist circumference, visceral and subcutaneous adipose tissue but meta-analyses were only possible using BMI. Nevertheless, neither oxychlordane nor trans-nonachlor showed a statistical significant positive association with BMI. As described above most studies assessing BMI were not specifically designed to study the effect of chlordanes on adiposity but presented this association as adiposity is a potential confounder for its specific aim. Also, for BMI, some studies used self-reported antropometric measures (height and weight). It is knonw that self-reported data are often not reliable, perhaps due to lack of recall or a desire to conform to aspired norms, which may increases heterogeneity and contribut to underestimated a possible association. In addition to the limitations described above, we would like to further emphasize two aspects. Firstly, chlordanes are lipophilic substances and may therefore accumulate in the adipose tissue. In cross-sectional studies whith exposure assessed using a blood sample, as in most of the studies identified by the systematic review, it is possible that individuals with higher percentage of body fat may present lower levels of exposure concentration, which will in turn decrease the magnitude of the association between the concentration of chlordanes and adiposity. Secondly, after stratifying our results according to the year of publication, we observed that older studies presented a positive and statistically significant association between oxychlordane and BMI, unlike more recent studies. This can be explained due to the progressive control of chlordane use over time. Chlordane started to be used in agriculture, then restricted for termite control and finally banned, based on concerns regarding its potential to cause cancer and its slow breakdown in the environmentThe molecular mechanisms linking chlordanes and diabetes or diabetes-related features are currently poorly understood and only a few studies have addressed these effects. In vitro studies showed that members of the chlordane family may act via multiple signaling pathways, which icludes the activation of several nuclear receptors. Data based on laboratory studies investigating the potential mechanisms of action of chlordane effects on diabetes or diabetes-related features are presented in Supplementary data In our study, we found a positive and statistically significant association for chlordane compounds and diabetes-related features. However, and particulalrly for oxychlordane and trans-nonachlor, moderate levels of heterogeneity were observed . Possible reasons for these inconsistencies are explored below.53. However, the current available information regarding chlordanes does not allow to understand if the association with diabetes is dependent on the exposure level. Another limitation of our results pertains to the fact that a significant number of included studies presented cross-sectional data, making it difficult to understand the temporal relationship between the exposure and the outcome. Type 2 diabetes may alter the metabolism of EDCs, either by slowing their excretion rate or by increasing the release of these substances from adipose tissue into the blood stream, by inducing lipolysis. In any case, the presence of glucose metabolism disorders may affect the measured levels of chemicals and not the other way around, as it would be intended to investigate in this study. However, this effect tends to decrease the strength of the association, and thus, the positive association observed in our results may be underestimated. In addtion, there were some inconsistencies observed regarding the adjustment for confounding effects across studies, particularly concerning oxychlordane and trans-nonachlor. Three of the included studies did not provide adjusted estimates for the association between these compounds and diabetes and although the majority has taken into account factors like age and BMI among their estimates, many failed to adjust for other potential variables of interest such as sex, race or lipidic profile. The adjustment for blood lipids is however a controversial issue, considering that on the one hand, chlordanes are lipophilic substances and higher lipid blood levels may lead to a higher chemical concentration, which would in turn lead to overestimated associations if this is not properly taken into account in regression models. On the other hand, it is also known that the exposure to these POPs may lead to higher lipid levels which are also associated with diabetes. This would mean that lipids could be a mediator on the association between EDCs and diabetes and thus lipid-adjusted models would not be recommended. However, and despite these limitations, the consistency found for a positive association between the exposure to chlordanes and diabetes across all the compounds identified allows us to be confident in our results.The outcomes used to assess diabetes included self-reported diagnosis of diabetes, anti-diabetic medication use, medical records, the assessment of fasting and non-fasting blood glucose, oral glucose tolerance test, HbA1c levels and insulin resistance (HOMA-IR) or the combination of more than one of these indicators. The lack of a consistent standardized approach to measure the outcome may contribute to the observed heterogeneity between studies. The use of ORs to estimate the association between chlordanes and diabetes has the disadvantage of requiring the comparison with a reference group, which is usually the one corresponding to the lowest category of exposure. By following this approach, estimates provided in different study populations may be difficult to compare since different populations may have different exposure levels and present a different risk in the reference category, even if the same measure of diabetes is being used. The impact of these differences on overall estimates was difficult to take into account since most studies did not provide descriptive data on exposure levels. In order to minimize the possible impact of this effect, we have excluded publications performed among individuals that were expected to have particularly high chlordane exposure levels, such as occupationally exposed populations. In addition, whenever a study presented estimates for categorized exposure levels, e.g. quantiles, we have chosen to include in the analysis the result for the highest category of exposure. This may be a relevant issue for our results since it has been suggested that for some EDCs, lower exposures may have stronger adverse effects on diabetes or diabetes-related features29, while three longitudinal studies have assessed diabetes48. As future perspectives, we propose that more studies need to be conducted following a longitudinal approach and including large, and representative samples. New evidence should also include the evaluation of dose–response relationships and the role of joint exposures. Exposure to chlordanes should be directly measured in appropriate biological samples at multiple time points throughout follow-up and according to standardized procedures. Information on key confounders should also be systematically collected and accounted for in future research.One of the major literature gaps identified is the lack of longitudinal data evaluating the association between chlordanes and both adiposity and diabetes/diabetes-related features. Only two papers with a longitudinal approach have measured the association between chlordanes and adiposity In conclusion, this revision for the first time allow us to have data that support that odds of having diabetes significantly increase with increase levels of chlordanes but the data did not allow to reach a clear conclusion regarding association with adiposity in humans. For most of the analyzed compounds, the other studies identified in the systematic review also showed results in accordance with those found in meta-analyses. Although our overall estimates do not reveal a strong association between these compounds and adiposity or diabetes, considering the ubiquitous use of these chemicals, even if the increased risk is small, its impact on public health will still be relevant. The consistency of results across the assessed compounds gives us confidence in our meta-analyses results, although, in general, evidence is still scarce to draw firm conclusions. Another general comment is linked to the difficulty of establishing comparisons between studies due to unstandardized methodological choices. An international agreement on methods to measure both exposure and outcome variables and to conduct epidemiological studies could increase the knowledge on how adverse effects of exposure to various stressors (exposome) can influence human health.Supplementary Information.


Insulin resistance is a metabolic disorder that occurs in type 2 diabetes mellitus and obesity. Genetic factors such as β3-adrenoceptor polymorphism (Trp64Arg) may be involved in IR and insulin secretion. However, their association is controversial. Therefore, the current meta-analysis was conducted to clarify the relationship between the Trp64Arg and IR.The literature search was performed in PubMed, Embase, and Web of Science using the keywords “Receptors, Adrenergic, beta-3, Receptors, Adrenergic, Insulin Resistance, Protein-Coupled Receptor Kinase 3” from 2005 to February 7, 2021. We used a random-effects model to calculate the pooled effect size. We conducted subgroup analysis and regression analysis to identify sources of heterogeneity; and Egger’s test and funnel plot were used to test publication bias. Finally, we conducted a sensitivity analysis.I2 = 57.6%, p = 0.016). However, there was no association between Trp64Arg and the homeostasis model (HOMA-IR) assessment. Egger’s tests showed no publication bias; the sensitivity analysis showed that our results were stable. Regression analysis revealed no source of heterogeneity.We included eight papers with 1,586 subjects. There was a positive correlation between Trp64Arg mutation and insulin level (standardized mean difference = 0.20, 95% confidence intervals: 0.00 to 0.39, Trp64Arg may be associated with IR. European ancestry, obesity, plasma insulin level, and test status may be potential factors affecting the relationship between Trp64Arg and IR. Insulin resistance (IR) is a metabolic disorder that can lead to type 2 diabetes and obesity . It can β-Adrenoceptors are the targets of endogenous catecholamines noradrenaline and adrenaline . β3-Adre(BMI); Trp64Arg mutation had a specific effect on BMI –15. SimiTherefore, to help resolve the discrepancies among these studies, we analyzed the association between Trp64Arg and IR or its related indices in this meta-analysis.We performed the meta-analysis based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines . A literThe inclusion criteria were as follows: 1) studies of humans; 2) inclusion of means, the standard deviation (SD) of related indices of IR, including insulin level and HOMA-IR by genotypes and by subgroups; 3) publication in English; and 4) observational studies with subjects ≥10. The exclusion criteria were as follows: 1) case reports, reviews, comments, protocols, meeting abstracts, and meta-analyses; 2) no study of the correlation between Trp64Arg and IR; 3) other interventions; and 4) inability to assess the full text.For data extraction, two independent reviewers reviewed all studies and extracted the data in a standardized format. The data were collected after all the disagreements were resolved. The collected information included the first author of the studies, the year of publication, country, sample size, the number of men and women, and the effect value. Subjects’ characteristics such as age, BMI, health condition, and test status of insulin were also extracted as potential variables for further subgroup analysis. To unify the units of insulin, the conversion factor 6.945 (1 mU/L = 6.945 pM) was applied to transform insulin concentration from picomolar into milliunits per liter . The quaI2 was used to show the heterogeneity; I2 ≥50% and p-value <0.05 indicated significant heterogeneity . In the influence analysis, we found that Erhardt’s study (p = 0.796)  (= 0.431) . HoweverI2 = 0%, p = 0.431), and not for other test status. We also found a positive relationship only in plasma blood samples , obese populations , and European ethnicity   were significantly lower . FurtherIn summary, our study further clarified the relationship between Trp64Arg and IR and explained it at the gene level. It provides a direction for genetic research on the identification of therapeutic targets for clinical treatment of IR. However, the included studies are all case–control studies and cross-sectional studies; therefore, it is difficult to draw causal inferences. There may be selection bias in population selection, in either case–control studies or cross-sectional studies. And, measurement error may also exist. Finally, the number of articles included in our study is small, so more studies need to be included for further analysis.Our meta-analysis suggested that the Trp64Arg mutation in the beta-adrenergic receptor had a positive correlation with IR. Ethnicity, obesity status, blood sample source, and test status may be the potential factors affecting the relationship between Trp64Arg and IR.The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/HW and CZ had the same contribution to the literature. HW and CZ designed the work, collected the data, conducted data analysis, and wrote the manuscript. ML, QL, QZ, DL, and Z-YM reviewed and edited the manuscript. JD had full access over all data in the study and is ultimately responsible for the decision to submit and publish the final version. All authors contributed to the article and approved the submitted version.This work was supported by two grants (to JD) from the National Natural Science Foundation of China (No. 31872791) and Natural Science Foundation of Shandong Province of China (No. ZR2019MC046).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


PRS differences were investigated for binary traits and the quantitative Positive and Negative Syndrome Scale. Both BD-PRS and SZ-PRS significantly differentiated controls from at-risk and clinical groups (Nagelkerke’s pseudo-R2: 1.3–7.7%), except for BD type-II for SZ-PRS. Out of 28 pairwise comparisons for SZ-PRS and BD-PRS, 9 and 12, respectively, reached the Bonferroni-corrected significance. BD-PRS differed between control and at-risk groups, but not between at-risk and BD type-I groups. There was no difference between controls and schizotypy. SZ-PRSs, but not BD-PRSs, were positively associated with transdiagnostic symptomology. Overall, PRSs support the continuum model across the psychosis spectrum at the genomic level with possible irregularities for schizotypy. The at-risk state demands heightened clinical attention and research addressing symptom course specifiers. Continued efforts are needed to refine the diagnostic and prognostic accuracy of PRSs in mental healthcare.As early detection of symptoms in the subclinical to clinical psychosis spectrum may improve health outcomes, knowing the probabilistic susceptibility of developing a disorder could guide mitigation measures and clinical intervention. In this context, polygenic risk scores (PRSs) quantifying the additive effects of multiple common genetic variants hold the potential to predict complex diseases and index severity gradients. PRSs for schizophrenia (SZ) and bipolar disorder (BD) were computed using Bayesian regression and continuous shrinkage priors based on the latest SZ and BD genome-wide association studies . Eight well-phenotyped groups ( Psychosis is a mental condition characterized by disturbed contact with reality, affecting cognition, feelings, and behavior. It manifests primarily as sensory experiences in the absence of physical stimuli  and holding bizarre, irrational, or false beliefs (delusions) . While pOvert psychosis in SZ is often preceded by early signs and mild symptoms developing 2–5 years before a formal diagnosis . Newer dThis work investigates the associations and between-group differences of PRS computed for SZ and BD across the extended psychosis spectrum. In an early study utilizing PRS , SZ-PRS www.psycourse.de] provided in the Supplementary Methods and Materials) and conducted in compliance with the Declaration of Helsinki. Table Data included in this work come from three main projects, two completed in Switzerland , 39, thep < 0.001), or minor allele frequency (MAF) < 0.1%. In the individual-level QC, data were removed to eliminate duplicates, sex mismatches, cryptic relatives (PI-HAT > 0.125), samples with an individual genotyping rate >98%, or heterozygosity rate exceeding 3 SD from the mean. Population stratification was assessed using a principal component analysis on the pairwise genomic relationship matrix. Individuals with genotypes not clustered with 1000 Genomes Project EUR super-populations were removed from the analyses (n = 47). After QC, pre-phasing was performed using SHAPEIT [Genomic DNA was isolated from venous whole blood or saliva  and genotyped using Illumina Infinium Psych-Array BeadChips . SNP-level quality control (QC) included the removal of variants with a call rate <98%, significant deviations from Hardy–Weinberg equilibrium (HWE) ( SHAPEIT  and impu SHAPEIT . The pha SHAPEIT  was usedφ) [φ1/2 ~ C+, where C+ denotes the half-Cauchy distribution). In our study, the automatically estimated global shrinkage parameter was φ = 1.8E−04 for SZ and φ = 1.3E−04 for BD. PRS-CS allowed us to use a single polygenic score for each discovery trait  that considers the polygenicity of the disorder and appropriately models the genetic architecture of SZ and BD. The PRSs were standardized using z-score transformation to facilitate interpretation.The PRS calculations for each individual were based on the risk alleles and the corresponding odds ratios (ORs) from the most recent GWAS of the Psychiatric Genomics Consortium (PGC3) on SZ  and BD . The SZ φ)  was autoR2 value as the difference in Nagelkerke’s pseudo-R2 [An analysis of variance (ANOVA) was conducted to assess between-group differences in SZ-PRS and BD-PRS (with group as predictor and PRS as outcome variable), using subject age, sex, and first five genetic ancestry principal components (PCs) to account for population stratification. Pairwise comparisons were corrected per analysis using a Bonferroni correction for 28 tests performed . Additionally, to assess the associations with group/diagnosis and variance explained by PRS, block-wise binary logistic regressions with healthy controls were conducted. For each PRS, two statistical models with case/control status as outcome were compared, one testing the covariates alone  and the other testing the covariates with the added PRS (full model). We report the seudo-R2  between To examine the effects of PRS predicting the symptom PANSS scores  across low, medium, and high symptom score distributions, quantile regressions using three tau (τ) values  and accounting for age, sex, and the five ancestry-specific PCs were conducted. The quantiles indicate that 25%, 50%, and 75% of the scores, respectively, fall below each corresponding point in the distribution of scores. Quantile regression  was chosStatistical analyses were performed using the R statistical computing environment (version 4.0.5). Nominal significance was assessed at an α < 0.05 threshold.After QC, 1580 samples  from the initial pool of 1752 genotyped samples, with complete information for study group, sex, and age, were available for analysis, including 6,600,214 genetic markers. PANSS data were accessible for 1134 individuals . The characteristics and symptom scores of participants are summarized in Table F7,1565 = 9.30, p = 2.52 × 10−11) and BD-PRS . Out of 28 pairwise Bonferroni-corrected tests for SZ-PRS and for BD-PRS, 9 and 12 were significant, respectively. Figure ANOVA revealed significant among-group differences for both SZ-PRS (p = 6.88 × 10−9), SZA , BD I , and RISK  groups with the controls . BD-PRS was also significantly associated with the case–control status for contrasts involving the BD I , BD II , SZA , SZ , and RISK  groups and the control group, resulting in a slightly higher Nagelkerke’s pseudo-R2 change range, 4.0–7.7%  = 1.62, 95% CI = 1.37–1.93, t = 3.86, p = 1.18 × 10−4), 50th , and 75th  percentiles. Significant effects were also found for Positive Symptoms at the 50th  and 75th  percentiles and for General Psychopathology at the 25th  and 50th  percentiles, while Negative Symptoms were significant only at the 50th percentile . In contrast, no significant effects were observed for BD-PRS across any of the PANSS measures. Figure SZ-PRS was found to be a significant predictor of PANSS Total Score at the 25th . In the binary logistic regressions, neither high nor low schizotypy was significantly associated with either of the two PRSs. It should be emphasized that this sample in our study was composed of healthy participants by excluding individuals with clinical diagnoses. Drawing participants without restriction from a general population could lead to different results. Previously, findings indicating high overlaps between schizotypy and SZ have been made for single candidate genes , 85. OurOur findings also contribute to the ongoing discussion of the symptom- and function-level correlates of PRS in support of the continuum model. To the best of our knowledge, this study is the largest to investigate relations between PRS and the gold standard PANSS and is also unique in its transdiagnostic approach. We observed significant associations with SZ-PRS across all symptom measures. However, we were unable to detect any effect whatsoever using BD-PRS, suggesting its lack of specificity in this application and/or its limited power. Previous studies varied in their capacity to find associations with continuous symptom measures. These earlier results included no significant effects , links wThis study has two particularly promising clinical applications of PRSs in the context of psychotic disorders and their antecedents: as potential support or a stratification tool in early diagnostic decision-making; in informing pre-emptive or full treatment strategies. Substantial clinical and research-based evidence demonstrates the utility of early interventions in reducing the highly debilitating character of psychotic disorders . Indeed,We acknowledge some limitations of this work. The numbers of participants varied substantially among groups. Inclusion of more polarized schizotypy groups  might also have been better suited to the goals of this study. The cross-sectional nature of these findings implies the possibility of a progression across the phenotypic spectrum, development of comorbidities, or dampening of genetic liability later in life. Indeed, the at-risk group had the lowest mean age. We also did not consider the role of medication. Finally, as GWASs exclude rare variants, we only investigated the effects of common variants with population frequencies of 1% or more. There are also more general limitations to polygenic risk profiling discussed in the current scientific debate on PRS, which has included articles covering its potential clinical utility  and bioeWhile PRS is certainly not immediately ready for routine clinical application, this study highlights the value of PRS for SZ and BD in elucidating the genetic architecture of psychosis and identifying vulnerable individuals who may benefit from early attention and monitoring. Future research should focus on possible differential developmental trajectories and factors precipitating or mitigating pre-existing genetic liability.Supplementary Information


Collagens are important structural components of intervertebral disc. A number of studies have been performed for association between polymorphisms of collagen genes and risk of intervertebral disc degeneration (IVDD) but yielded inconsistent results. Here, we performed a meta-analysis to investigate the association of collagen IX alpha 2 (COL9A2) Trp2, collagen IX alpha 3 (COL9A3) Trp3, collagen I alpha 1 (COL1A1) Sp1 and collagen XI alpha 1 (COL11A1) C4603T polymorphisms with susceptibility to IVDD.Eligible studies were retrieved by searching MEDLINE, EMBASE, Web of Science prior to 31 March, 2021. Odds ratio (OR) and corresponding 95% confidence interval (CI) were calculated for association strength.P = 0.058), which did not reach statistical significance. However, Trp2 carriers had 2.62-fold  risk than non-carriers in Caucasians. COL9A3 Trp3 was not associated with IVDD risk . T allele and TT genotype of COL1A1 Sp1 (+ 1245G > T) were correlated with increased risk of IVDD. Significant associations were found between COL11A1 C4603T and IVDD risk under allelic , dominant , recessive  and homozygote model .A total of 28 eligible studies (31 datasets comprising 5497 cases and 5335 controls) were included. COL9A2 Trp2 carriers had an increased risk of IVDD than non-carriers in overall population (OR = 1.43, 95% CI 0.99–2.06, COL1A1 Sp1 and COL11A1 C4603T polymorphism are associated with IVDD risk while the predictive roles of collagen IX gene Trp2/3 need verification in more large-scale studies.The online version contains supplementary material available at 10.1186/s13018-021-02724-8. Intervertebral disc degeneration (IVDD) is a prevalent health problem worldwide and mainly contributes to neck and low back pain, disc herniation and sciatica . The aetrd residue  of COL9A3 was found associated with an increased risk of IVDD [Intervertebral disc is composed of the outer annulus fibrosis region (AF) and the central nucleus pulposus (NP). Collagens are important components of extracellular matrix (ECM) of intervertebral disc and are detected in AF and NP in large amounts . Specifi of IVDD . Collage of IVDD . A commo of IVDD , 22. TheHowever, more recent studies found a lack of association in independent populations, implying the association between these polymorphisms  and IVDD predisposition was still in controversy –26. HereWe performed the present meta-analysis in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The PRISMA checklist can be found in Additional file P < 0.05), the study was also excluded. For repeated publications, only the most complete or recent one was included.Eligible studies should follow these criteria: (1) investigated the relationships of COL9A2 Trp2 , COL9A3 Trp3 , COL1A1 Sp1 (rs1800012) or COL11A1 C4603T  with disc degeneration, (2) was a case–control or cohort study, (3) provided distributions of genotype and/or allele in both case and control groups. Case reports, reviews, meta-analyses and studies without full-text or available genotype data were excluded. If the genotype frequency of control group was not in Hardy–Weinberg Equilibrium . The total score of NOS ranged from 0 to 9, and ≥ 7 scores indicated high quality. The literature search, selection of eligible studies, data extraction and quality assessment were performed by two independent investigators, and discrepancies were resolved by discussion with a third investigator.I2 and Q test. I2 < 50% and P value for Q test > 0.10 indicated no obvious heterogeneity, and then, a fixed effect model was used for pooled analysis. Otherwise, there was significant heterogeneity and a random effect model was used. Since the homozygous variants of COL9A2 Trp2 and COL9A3 Trp3 were both in low frequency, we only compared the risk of Trp2 or Trp3 carriers to that of non-carriers. For COL1A1 and COL11A1 polymorphisms, the associations were analysed under four genetic models: allelic model, dominant model, recessive model and homozygote model. Sensitivity analysis was performed to evaluate the robustness of meta-analysis and potential source of heterogeneity by excluding one study at a time. Funnel plot and Egger’s test were conducted for publication bias assessment. STATA 12.0  was used for statistical analysis. A P value < 0.05 indicated statistical significance.Pooled odds ratio (OR) and corresponding 95% confidence interval (95% CI) were calculated for the association strength between polymorphism and risk of disc degeneration. The between-study heterogeneity was assessed by P > 0.05, Table A total of 31 relevant publications investigating the correlation between collagen polymorphisms and disc degeneration susceptibility were obtained by literature search and selection. We furtherly excluded 3 studies because of unavailable genotype data –29. Mio’I2 = 64.1%, Fig. P = 0.058). Subgroup analysis in Caucasian population showed that Trp2 carriers had a significantly higher risk compared to non-carriers . In the subgroups of Asian population and mixed ethnical population, no significant association was found between Trp2 and IVDD predisposition. Three studies provided genotype data of male subgroup [We excluded Kales SN’s study  since nosubgroup , 42, 45,P = 0.299, Fig. The Trp3 variant was not found in two studies with 548 cases and 310 controls from Asian populations , 45. ThuP = 0.047, Fig. P < 0.001, Fig. P < 0.001, Fig. We included 4 eligible studies comprising 310 cases and 812 controls in the meta-analysis and used the fixed effect model because of no between-study heterogeneity Table . Sp1 polP < 0.001, Fig. P < 0.001, Fig. P = 0.001, Fig. P < 0.001, Fig. Eight datasets with 1817 cases and 1728 controls were included. There was no obvious between-study heterogeneity, and a fixed effect model was used Table . T allelP = 0.317). The funnel plots were all symmetric  . The T aThe present meta-analysis, having a larger sample size than the previous one , demonstBesides collagens, many factors also contribute to ECM structure feature and mechanical load distribution in intervertebral discs. Fibronectin, a core component of ECM with special spatial expression pattern in intervertebral discs, may help to organize the structure of discs . TREK-1,Our study has some limitations. Firstly, there was substantial heterogeneity for COL9A2 Trp2 and COL9A3 Trp3, which may be resulted from the difference in genetic background, definition of cases and controls, or occupations of participants. Thus, the results should be interpreted cautiously. Secondly, we failed to performed subgroup analyses stratified by age and occupations for all polymorphisms, and by gender and ethnicity for COL1A1 Sp1 and COL11A1 C4603T polymorphisms, to eliminate the influence of these confounders. Thirdly, the number of included studies and sample size for COL1A1 Sp1 was relatively small. Future studies with large sample sizes are warranted.In conclusion, COL1A1 Sp1 polymorphism and COL11A1 C4603T are markers of IVDD susceptibility, and interventions targeting these loci or modulating gene expression may help to prevent development and progression of IVDD. In addition, COL9A2 Trp2 is a risk factor of IVDD in Caucasian population but COL9A3 Trp3 was not correlated with IVDD susceptibility. More well-designed clinical trials with large sample size and performed in different ethnic populations are warranted in the future.Additional file 1. PRISMA 2020 checklist.


ADAMTS5) is one gene that is most frequently implicated. Many recent studies have examined the relationship between a polymorphism in the ADAMTS5 gene (rs226794) and the risk for developing osteoarthritis without definitive results. Objective: In this case-control study, we examined the correlation between the ADAMTS5 gene polymorphism, rs226794, and knee osteoarthritis. We used a meta-analysis and trial sequential analysis to determine whether ADAMTS5 rs226794 expression increases susceptibility to osteoarthritis. Methods: This study consisted of two parts: a case-control study and a meta-analysis. The case-control study included subjects who underwent knee radiography at the Health Examination Center of the Tri Service General Hospital from 2015 to 2019. The Kellgren–Lawrence (KL) grading system was used as diagnostic criteria. Patients with unsuccessful gene sequencing were excluded. There were 606 subjects in the knee osteoarthritis group (KL ≥ 2) and 564 in the control group (KL < 2). Gene sequencing was performed using iPLEX Gold to determine the association between the gene polymorphism of ADAMTS5 rs226794 and knee osteoarthritis. For the meta-analysis, databases such as PubMed, Embase, and Cochrane were queried to identify studies that examined the relationship between ADAMTS5 rs226794 and osteoarthritis. Next, the findings of the meta-analysis were incorporated with the results of the case-control study and samples from the published studies to estimate the association between the genetic polymorphism and osteoarthritis using an odds ratio and a 95% confidence interval. Results: We found a non-significant association between the G allele and knee OA (crude-OR: 0.93 (95% CI: 0.79–1.10) and adjusted-OR: 1.02 (95% CI: 0.76–1.36) in the allele model) in the present study, and the analysis of other genetic models revealed a similar trend. After including five published studies and our case-control study, the results with 2866 Asians indicated a conclusively null association between ADAMTS5 rs226794 and knee OA) OR: 1.09 (95% CI: 0.93–1.26). The results for Caucasians also revealed a null association (OR: 1.21 (95% CI: 0.81–1.82)). Conclusions: This study indicates that the gene polymorphism, ADAMTS5 rs226794, is not significantly associated with knee osteoarthritis. Additionally, assuming that the cumulative sample size in the allele model is sufficient, we confirmed that the G allele is not a risk factor for osteoarthritis. This study integrated all available evidence to arrive at this conclusion, and it suggests that no additional studies are necessary.Background: Osteoarthritis is an important health issue for the elderly. Many studies indicate that genetics is an important risk factor for osteoarthritis, and a disintegrin and metalloproteinase with thrombospondin motifs 5 ( Osteoarthritis (OA) is the most common joint disease occurring globally and is the primary cause of disability in the elderly . Among aADAMTS5 gene, one of the disintegrins and metalloproteinases with thrombospondin motifs (ADAMTS), is located on the long arm of chromosome 21 (21q.21). In mouse experiments, ADAMTS5 expression causes cartilage destruction in OA models [ADAMTS5 may be a risk factor for OA using bioinformatics methods. However, the study did not find any significant association between ADAMTS5 rs226794 and OA. The results indicated that it is necessary to further explore the function of this aggrecanase in human OA to determine whether it has a similar role as that observed in mouse studies [The A models . RodriguADAMTS5 rs226794 polymorphism and knee OA [ADAMTS5 rs226794 polymorphism and knee OA in Taiwan. We also performed a meta-analysis to increase the amount of evidence and evaluate whether the latest conclusions are supported by the current cumulative sample data using trial sequential analysis (TSA).To date, five studies have examined the association between the rs226794 polymorphism and knee OA ,9,10,11; knee OA ,9,10,11. knee OA . However knee OA ,9,10,11,This study was approved by the Institutional Review Board (TSGH-2-102-05-028) of the Tri Service General Hospital (TSGH). Volunteers signed the consent form after the investigators had provided an explanation of the study.A total of 1170 participants (606 case and 564 control) consisting of controls and patients ≥65 years of age were enrolled in this study. All received Taipei City senior medical check-ups between January 2015 and December 2019 at the TSGH, a teaching hospital at the National Defense Medical Center . The check-up is a government-driven welfare program for individuals ≥65 years of age who have been registered as Taipei City residents for >1 year.We examined patients’ information, while the participants underwent check-ups. All participants received study information, understood the process, and provided written consent upon enrollment. Participants were excluded if a sufficient blood sample could not be obtained. The exclusion criteria included patients who had no knee X-ray data and for whom gene sequencing was unsuccessful. A total of 25 samples could not be genotyped by our genotyping method, so there were only 1170 (97.9%) samples included in the final genetic analyses.All participants underwent a radiographic examination of both knees with anterior–posterior and lateral views analyzed, as well as weight bearing and foot-map positioning. Knee radiographs were read and scored by a radiologist using the Kellgren–Lawrence (KL) grading system . In the Approximately 10 mL of peripheral blood were intravenously extracted from participants by a physician or nurse. Genomic DNA was isolated using standard procedures including proteinase K  digestion and phenol/chloroform extraction. The rs226794 SNP was genotyped using the Massarray iPLEX Gold SNP genotyping method. Genotyping was performed under blind conditions. To validate the results, at least 10% of the samples were randomly selected for repeated genotyping, and the concordance rate was 97.2%.t test. Differences in genotype and allele frequencies between knee OA patients and healthy controls were tested using a χ2 test. Odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of knee OA were calculated using logistic regression. Calculation of the genetic polymorphism and knee OA risk was expressed using the allele type, the genotype, and dominant/recessive models. A p-value of <0.05 was considered statistically significant. R 3.4.4 software was used for the statistical analyses.Continuous variables for the general demographic data were expressed as the mean and standard deviation using a Student’s ADAMTS5 rs226794 and OA risk. PubMed, EMBASE, and Cochrane were searched using "ADAMTS5 rs226794,” "Osteoarthritis,” and their synonyms as queries for studies only in English up to 19 November 2020 , and the average age of the case group was higher compared with that in the control group (p < 0.001). ADAMTS5 rs226794 and knee OA in the case and control groups. The distribution of the G allele in the control group and the case group was not significantly different (p = 0.890), and there was no significant correlation with OA (OR: 1.02 (95% CI: 0.76–1.36)). To further verify the results, a dominant model and a recessive model were used in which no significant difference was found after correcting for covariates. Therefore, our study found that ADAMTS5 rs226794 was not significantly correlated with OA. To increase the level of evidence for the meta-analysis, the samples in the case-control study were added to the meta-analysis. TSA was then performed to identify whether or not the same can be concluded for the Asian population.The flow chart for the literature search of this study is shown in A funnel plot was used to demonstrate the association between ORs and standard error in the allele model, with each point representing a study. No significant asymmetry was discovered between the articles. It is worth mentioning that only two Caucasian studies could not be tested by Egger’s regression. The other analyses based on a dominant and recessive model showed similar results as the allele model.ADAMTS5 rs226794 and knee OA. The top left subplot is a forest plot based on an allele model assumption , and the top right subplot is a funnel plot based on the allele model assumption. The results obtained with the dominant (AA +AG vs. GG) and recessive (AA vs. AG+ GG) models are presented in the middle and bottom. All results were insignificant.Selected results from the meta-analysis of ADAMTS5 rs226794 and knee OA is not significantly associated with Asians, and a decisive conclusion was confirmed. Our case-control study was the critical information for this meta-analysis. The cumulative sample size for the Asian population was only 1,697 before adding our case-control study samples, which could not establish a decisive conclusion. Our case-control study provided 1170 samples to enhance the information, and a total of 2867 allowed the Z curve to exceed the sample size required . This reADAMTS5 rs226794 gene polymorphism is not significantly associated with OA, which is consistent with the results of previous studies. Compared with the previous studies published for Caucasians, we found that the gene polymorphism of ADAMTS5 rs226794 was not significantly associated with OA, which was similar to the results of Rodriguez et al. and Canbek et al. [ADAMTS5 rs226794 was not significantly associated with OA [ADAMTS5 rs226794 is not associated with OA, which is consistent with the results of the meta-analysis by Huo et al. showing that the gene polymorphism of ADAMTS5 rs226794 is not significantly associated with OA [The results of this study show that the k et al. . Compare with OA ,18, whic with OA .ADAMTS5 and used bioinformatics methods to successfully identify a single nucleotide polymorphism (SNP) in ADAMTS5 that may promote OA, in addition to discovering rs226794 in exon 7. However, the study found that there was no significant association between ADAMTS5 rs226794 and OA [In mouse experiments, ADAMTS5 expression leads to cartilage destruction in OA models . BecauseADAMTS5 rs226794 and knee OA in the Asian population. (3) The results of the two parts were incorporated by using a random-effects model, which can avoid serious errors that may be caused by model selection based on the level of heterogeneity [Our study has three strengths: (1) Estimation of the sample size by TSA: In the past, no meta-analysis has employed a method to estimate whether its sample size reached the benchmark for a conclusion. This study, after TSA evaluation, indicated that the sample sizes were insufficient in both studies of Caucasians and Asians. (2) In general, epidemiological studies only use their own samples for analysis, whereas meta-analysis studies only analyze published articles. This study combined the methods used in traditional observational studies and meta-analysis techniques to further increase the sample size to improve the level of evidence. Next, TSA was used to examine the sample size and confirmed that there was no significant association between the genetic polymorphism of ogeneity .This study has two limitations. First, only English articles were included, thus articles published in other languages were not included in the meta-analysis, which may cause bias in the results obtained after incorporation. Second, the high heterogeneity could not be explained, which implies potential gene–gene and gene–environment interactions. Our previous study developed a revised version of meta-regression, known as case-weighted meta-regression, to analyze the gene–gene and gene–environment interactions using average population information . We suggThe definitive null relationship between ADAMTS5 rs226794 and knee OA was validated in this study. The information regarding Caucasian studies was insufficient before this study; however, our case–control study provided the critical evidence to elaborate on this phenomenon in Asians. Our study integrated all of the current evidence to confirm this null relationship between ADAMTS5 rs226794 and knee OA and suggests that there is a need for future studies.


An increasing number of studies have reported a significant association between long non-coding RNAs (lncRNAs) dysregulation and pancreatic cancers. In the present study, we aimed to gather articles to evaluate the prognostic value of long non coding RNA in pancreatic cancer.We systematically searched all eligible articles from databases of PubMed, Web of Science, and Scopus to meta-analysis of published articles and screen association of multiple lncRNAs expression with clinicopathology and/or survival of pancreatic cancer. The pooled hazard ratios (HRs) and their 95% confidence intervals (95% CIs) were used to analysis of overall survival, disease-free survival and progression-free survival were measured with a fixed or random effects model.A total of 39 articles were included in the present meta-analysis. Our results showed that dysregulation of lncRNAs were linked to overall survival  and disease-free survival . In addition, our findings revealed the association between dysregulated RNAs and clinicopathological features in this type of cancer.In conclusion, dysregulated lncRNAs could be served as promising biomarkers for diagnosis and prognosis of pancreatic cancer. Pancreatic cancer (PC) is a worldwide challenging cancer characterized by poor prognosis, ranking as one of the most lethal human malignancy. The 5‐year overall survival (OS) of PC patients is less than 5%, with median survival time between 3–6 months. However, progresses in early detection, surgical techniques and treatments strategies including chemotherapy and targeted therapy have resulted in better improvements in management of PC patients, dismal prognosis of the disease has not improved over years .So, it is an urgent need to identify novel diagnostic and prognostic biomarkers associated with pancreatic cancer. In recently decades Long noncoding RNAs (lncRNAs) as type of RNA that do not encode proteins with a length of > 200 nt and crucial role in several different biological processes in diverse human diseases such as development and progression of various cancers . Also LnPrevious meta-analysis has showed that high lncRNAs expression could be used as potential prognostic markers among Asian bladder cancer patients . Also dyThis systematic review and meta-analysis was done based on the standard guidelines of Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) (S1 Checklist) , 17.A comprehensive literature search was performed by three independent reviewers  through the PubMed, Web of Science, and Scopus for relevant papers published up to November 2020. The following search terms were used:  AND  AND ). Moreover, relevant articles were also reviewed manually in order to identify potentially eligible literature. No restrictions by the publication date or language were done.Articles with the following criteria were included in the current meta-analysis: (1) original study conducted on human beings, (2) literature measured the relationship between expression level of lncRNAs with clinicopathological symptom and survival rate in patients with pancreatic cancer, (3) studies which reported sufficient data to estimate hazard ratios (HRs) and their 95% confidence interval (95% CI), and (4) literature published in English. Studies were excluded if they had the following criteria: (1) insufficient data for HR and 95% CI estimation, (2) reviews, letters, laboratory articles and animal studies, (3) reported HRs for a combination of multiple lncRNAs. In addition, if a study had reported final results in different models, we included only the full-adjusted one.Data extraction was done independently by three investigators to rule out any discrepancy. The following data were extracted from each study: (1) basic information including first author’s name, year of publication and country of origin, (2) patients’ characteristic information: ethnicity, study population, sample size and follow-up duration (3) lncRNA information: names of lncRNAs, expression status, detection methods, survival results, and cut-off definition, and analysis method for survival (4) relationship between expression level of lncRNAs and survival outcome or clinicopathological characteristics (5) HRs and their 95% CIs for survival analysis. Any disagreements were resolved by discussion and consensus. The study quality was assessed via the Newcastle–Ottawa Scale (NOS) . The NOS2 statistic. Heterogeneity was considered significant as P < 0.1 or I2 ≥ 50%. Due to high heterogeneity in results, we also were done subgroup analysis based on molecular mechanisms, ethnicity and the expression level of lncRNAs in PC. The funnel plot asymmetry test as well as the Eggers’ regression test were used to assess publication bias. Stata version 13.0  was applied for the whole meta-analysis.HRs and 95% CIs were obtained from studies or calculated from Kaplan–Meier survival curves using Engauge Digitizer version 4.1  to calcuAs shown in Fig. A total of 39 eligible studies involving 4736 patients diagnosed with pancreatic cancer were included in this meta-analysis. These studies were published between 2014 and 2020. Of these, 38 studies were conducted in China , and onlWe assessed quality of included studies using the NOS tool. Given values ranged from 4 to 8 stars based of the number of parameter that analyzed in articles: 3 study was poor quality score and awarded 4 stars , 57, 58,2 = 80.5%, P = 0.000, random-effects) as well as this effect in these studies analyzed by univariate analysis  and multivariate analysis  . Due to the presence of obvious heterogeneity, we performed subgroup analyses based on the ethnicity, molecular mechanisms and the expression level of lncRNAs in PC patients but similarly, heterogeneity was also assessed in our stratified analyses and there did not significant changes in heterogeneity after our subgrouping , Distance metastasis  Node metastasis  and other clinicopathologic factors demonstrated in Table The Funnel plot analysis was used to display asymmetry among the OS, DFS, distant metastasis, differentiation, gender, neural and prineural invasion, LNM, TNM and Stage Fig. . BesidesSensitivity analysis was performed to discover the influence of the individual study on the pooled results by removing one single study from the overall pooled analysis. The results depicted that no individual study significantly changed the pooled HRs Fig.  demonstrDespite many advances in cancer research and treatment, the insidious onset of symptoms and extremely poor diagnosis of PC has still remained a controversial issue. The 5-year survival rate was estimated lower than 25% resulting in worse clinical outcomes in PC . ImagingOver two past decades, numerous studies have focused on the potential roles of lncRNAs as contributors in various cell biological processes including gene and protein expression patterns. A growing body of evidence has verified the association between aberrant expressions of multiple lncRNAs with clinical outcomes for cancer patients. Notably, diagnostic significance of different lncRNAs profiling in digestive system tumors has been proved in numerous publications , 68. So,In the current study, we assessed the prognostic role of different lncRNAs and their association with clinicopathological characteristics of PC. We found significant relation between altered expression of lncRNAs with poor OS period of PC , suggesting that lncRNAs expression profile can be a prognostic biomarker of PC , 63, 69.Moreover, large degree of heterogeneities among included studies were observed inspiring us to search its main causes from different aspects . In thisTotally it could be concluded that lncRNAs expression profiling may serve as a helpful diagnostic and prognostic biomarker in of PC. So investigating the suitable single or panel of lncRNAs should be the focus of future studies –73.However, it should be noted that there are several limitations in our meta-analysis including (1) The small sample sizes of the diagnostic meta-analysis as well as the limited clinical relevance of our results; (2) large heterogeneity in our analyses; (3) The HRs and 95% CIs from some of articles could not be directly obtained and were estimated by software, which may decline the overall accuracy of the pooled effects. Totally, results from our study did not fully show the real clinical significance of lncRNA signature in PC, and in order to obtain a decisive conclusion, further comprehensive meta-analyses are needed to confirm the strong association between the expression pattern of lncRNAs and outcome of PC patients.Altogether, our meta-analysis was updated and completed pervious reports to survey the prognostic value of lncRNAs and their association with clinical features of PC patients. Despite some above mentioned limitations, the present study revealed that lncRNAs could be used as potential prognostic markers for PC. However, more high quality and large-scale studies are still needed to validate the clinical utilities of lncRNAs in management of PC.


Extremely low frequency magnetic fields (ELF-MFs) are classified as a possible carcinogenic factor (Group 2B). This study assessed the association between ELF-MFs and childhood cancer through a systematic review and meta-analysis.Three databases were searched in January 2020. We conducted a meta-analysis for the association between the ELF-MFs exposure level and childhood cancer.A total of 33 studies were identified. Thirty studies with 186,223 participants were included in the meta-analysis. Children exposed to 0.2-, 0.3-, and 0.4-μT ELF-MFs had a 1.26 , 1.22 (95% CI 0.93–1.61), and 1.72 (95% CI 1.25–2.35) times higher odds of childhood leukemia. In childhood brain tumors, children exposed to 0.2-μT had a 0.95 (95% CI 0.59–1.56) times higher odds, and those exposed to 0.4-μT ELF-MFs had a 1.25 (95% CI 0.93–1.61). Children exposed to 0.2- and 0.4-μT ELF-MFs had a 1.10 (95% CI 0.70–1.75) and 2.01 (95% CI 0.89–4.52) times higher odds of any childhood cancers.Significant associations were observed between exposure to ELF-MFs and childhood leukemia. Furthermore, a possible dose-response effect was also observed. The debate on the effect of electromagnetic fields (EMFs) on the human body still continues, and several studies have investigated the effect of magnetic fields that are not well shielded by objects –3. The qThe WHO International Advisory Committee presented a Research Agenda for ELF-MFs whereby they indicated that epidemiological studies are of primary importance in health risk assessment, and that high-priority research needs to conduct pooled analyses of existing childhood cancer studies . Until 2The first epidemiological study of the association between the exposure to ELF-MFs and childhood cancer was published in 1979 . Over thTherefore, it is necessary to comprehensively search and review the literature with an appropriate methodology, and to carry out a meta-analysis to confirm the association between exposure to ELF-MFs and childhood cancer.We aimed to assess the association between ELF-MFs and childhood cancer through a systematic review and meta-analysis of relevant studies.The procedure adopted in this study followed the guidelines of the Cochrane Collaboration . MoreoveUsing the search strategy recommended by Cochrane , the seaStudies were searched, reviewed, and selected by two authors independently (J. P. and G. S.), using predefined criteria. Full texts for studies that met the inclusion criteria were identified and reviewed. In cases where no consensus could be reached, the issue was resolved through either further discussion or a separate examination by another author (J.L.), who is a statistical expert. However, there were no notable inconsistencies with the initial selection.The inclusion criteria were: (1) epidemiologic studies (cohort or case-control design); (2) studies on exposure of ELF-MF; (3) studies with childhood cancer; (4) studies indicating subject number by each group exposure level; (5) based on magnetic field measurements or the calculated field; and (6) the article written in English. Abstracts presented at congresses, reviews, letters, editorials, and unpublished data were excluded.The Newcastle–Ottawa Scale (NOS) was used to determine the risk of bias in the studies that were included  in the sJ.P. and G.S. independently extracted the relevant data from each study, and discussed and resolved any issues that emerged. The data that were abstracted included information on: the first author, publication year, study design, country of origin, eligible population size, study population characteristics, registry group, exposure measurement, and matching variables.I2 statistic [p-value of less than 0.1 was used as an indicator of the presence of heterogeneity, the I2 statistic provides a measure for quantifying the heterogeneity with regard to the proportion of between-study variation based on the total variation in the estimates. In this study, an I2 value of greater than 50% was considered to denote the existence of substantial heterogeneity among the study results. We conducted analyses that were stratified by the level of exposure of EMF, and further evaluated the dose–response effect of EMF exposure. Moreover, the sensitivity analysis was performed by individually excluding each study to assess its influence of each study on the overall result of the meta-analysis.We analyzed the data by using Review Manager (version 5.3) for the association between exposure to EMF and childhood cancer. Meta-analyses of the risk of childhood cancer outcomes were conducted to obtain pooled odds ratios (ORs) with the 95% confidence intervals (CIs) in a random effects model in case-control studies. The cohort studies were excluded in meta-analysis due to its differences in EMF exposure levels and outcome variables between studies. The heterogeneity among studies was estimated by using the tatistic , 32 as wp-value of less than 0.05 was considered to be statistically significant.The publication bias was examined graphically by using a funnel plot of a study’s effect size against the standard error. A two-tailed Our systematic search found a total of 3,933 studies. After removing duplicate articles, a total of 3,250 studies were excluded for lack of eligibility for study inclusion on a review of the study title and abstract. A full-text review of the remaining 186 studies was undertaken, and a further 153 studies were excluded. Finally, 33 studies were included in the systematic review for the association of ELF-MFs and childhood cancer , 33–56, The included three cohort studies were unable to perform meta-analysis due to differences in exposure levels and outcomes between studies. In a cohort study investigating the risk of cancer in children living close to overhead power lines with a magnetic field of 0.01-uT, the standardized incidence ratio was 0.97 , with no statistically significant increases in all cancers . Two of The study characteristics included the year of diagnosis and the registry group . The metThe absolute numbers of childhood cancer cases and controls for the exposure level of the ELF-MFs were presented in The risk of bias in the studies was evaluated by the NOS for all 30 articles included in the meta-analysis. A total of 30 articles that met all of the selection criteria were assessed for their quality. The results associated with the quality ratings of the retrieved studies are shown in We identified 30 studies with 186,233 subjects that report results on the association between ELF-MFs and childhood cancer. Meta-analyses were conducted for pediatric leukemia, brain tumors, and any childhood cancers by level of exposure to ELF-MFS.2 = 0%). For the 0.3-μT exposure level of ELF-MFs, the pooled summary OR was 1.22 (0.93–1.61) without any significant heterogeneity , and there was evidence of publication bias (The results of six study were used to examine an association of exposure to ELF-MFs with any childhood cancers. The pooled summary OR of the 0.2-μT exposure level of ELF-MFs was 1.10 (0.70–1.75) , whereasion bias .The sensitivity analysis was performed after excluding either studies that used calculated fields measurement method or studies that identified very small cases even though many participants were examined and, hence, affected to pooled estimate of meta-analysis significantly , 22. TheWe conducted a meta-analysis on each type of cancer to derive the large-scale integrated values for the association between ELF-MFs exposure and childhood cancer among more than 85,000 children diagnosed with childhood cancer in 15 countries. In this study, based on the systematic review methodology, all articles that presented pediatric cancer, including leukemia, lymphoma, and brain tumor, were included in a comprehensive search. Pooled analysis studies have been conducted on the association between childhood cancer and ELF-MFs exposure , 59. HowThe existence of between-study heterogeneity can generate a statistical problem when attempting to interpret the results of the meta-analysis. Ideally, the studies, whose results are being combined in the meta-analysis, should all be undertaken in the same way and with the same experimental protocols: study heterogeneity is a term used to indicate that this ideal is not fully met . Meta-an2 = 0%) as well as an absence of any evidence for publication bias. In addition, this study derived a large-scale integrated value using larger number of included studies than previous studies. Our results showed slightly higher pooled estimates than previous results, which are 1.07–1.08, 1.11–1.16, and 1.44–2.00 times higher odds for exposures to 0.2-, 0.3-, and 0.4-μT, respectively [This study showed that children exposed to 0.2-μT ELF-MFs had a 1.26 (95% CI 1.06–1.49) times higher odds of child leukemia, those exposed to 0.3-μT had a 1.22 (0.93–1.61) times higher odds, and those exposed to 0.4-μT had a 1.72 (1.25–2.35) times higher odds. These results are based on statistical homogeneity  times higher odds of childhood brain tumors, and children exposed to 0.4-μT ELF-MFs had a 1.25 (0.93–1.61) times higher odds. However, the estimates were not statistically significant. Based on previous pooled analysis, studies showed a 0.95 times on exposure to 0.2-μT and 1.14-times higher odds on exposure to 0.4-μT ELF-MFs, and similar results were found in this study [According to the pooled OR value of four studies, children exposed to 0.2-μT ELF-MFs had a 1.10 (0.70–1.75), and those exposed to 0.4-μT ELF-MFs had a 2.01 (0.89–4.52) times higher odds of any childhood cancer, However, it did not show a high-intensity relation. There have been no pooled analysis studies of any childhood cancer conducted thus far.Public concern about EMFs is considerably high, and many countries have implemented a lot of policies related to EMFs , 62. AnyAlthough we identified three cohort studies that met the study eligibility criteria, these studies were not able to include in the meta-analysis. In the cohort study, the incident ratio of childhood leukemia was 1.6 and any childhood cancer was 1.5 in the group exposed to 0.2-μT, however, it was not statistically significant . In the The ELF-MFs measurement variation was not considered in our meta-analysis. Although some studies used a long-term measurement, others used a spot measurement; however, no distinction has been made in our meta-analysis because of the limited number of studies. Nonetheless, our pooled results showed a non-significant heterogeneity among studies.Another limitation is that all studies included in our study were case-control studies, which reduces the strength of the obtained results because case–control studies are subject to selection bias and other methodological problems. However, all studies that were included in this meta-analysis were the matched case-control studies except one, which had the case and control groups from the same registry. Therefore, it can be seen that the bias shown in case-control studies has diminished.In this large pooled analysis of more than 36,000 children diagnosed with childhood leukemia, statistically significant associations were observed between exposure to ELF-MF and childhood leukemia. Furthermore, the intensity of the association between exposure to ELF-MFs and childhood leukemia was high, as indicated by the dose–response effect.The risk of ELF-MFs, which have been classified as a possibly carcinogenic (Group 2B) factor based on limited evidence in humans, can be ascertained through precise evidence from the integrated results of this study.S1 TableSearch strategies and search results for each database .(DOCX)Click here for additional data file.S1 Checklist(DOC)Click here for additional data file.


Previous studies evaluating the influences of maternal fish oil supplementation on the risk of asthma or wheeze in children showed inconsistent results. We performed a meta-analysis or randomized controlled trials (RCTs) to systematically evaluate the efficacy of maternal fish oil supplementation for asthma or wheeze.Relevant RCTs were obtained by search of PubMed, Embase, and Cochrane's Library databases. A random-effects model incorporating the potential publication bias was used to pool the results.P = 0.40] with mild heterogeneity (I2 = 28%). Subgroup analyses showed that maternal fish oil supplementation significantly reduced the risk of asthma , but not the risk of wheeze . In addition, maternal fish oil supplementation was associated with reduced risk of asthma or wheeze in high-dose studies , but not in low-dose studies . Study characteristics such as the risk of the infants, timing of supplementation, and follow-up duration did not significantly affect the results.Ten RCTs with 3,676 infants were included. Compared to control, maternal supplementation with fish oil was not associated with a reduced risk of asthma or wheeze [odds ratio (OR): 0.91, 95% confidence interval (CI): 0.72–1.14, Maternal fish oil supplementation may reduce the risk of clinically diagnosed asthma in children, particularly with high-dose fish oil. Asthma and wheeze (asthma/wheeze) is a respiratory syndrome which mainly occurs in early childhood –3. The pWe followed the instructions of the PRISMA  statement  and the PubMed, Embase, and the Cochrane Library  databases were searched for relevant studies with a combined strategy of: (1) “omega-3 fatty acids” OR “fish oil” OR fish-oil OR “polyunsaturated fatty acids” OR “marine oil” OR “eicosapentaenoic acid” OR “docosahexaenoic acid” OR “DHA” OR “EPA”; (2) “asthma” OR “wheeze” OR “wheezing” OR “pulmonary” OR “lung” OR “allergy” OR “allergic”; (3) “child” OR “children” OR “adolescent” OR “pediatric” OR “pediatric” OR “infant” OR “neonate” OR “newborn” OR “toddler”; and (4) “random” OR “randomly” OR “randomized” OR “randomized”. Only clinical studies were considered. The references of related reviews and original articles were also searched as a complementation. The latest database search was conducted on April 5th, 2021.Inclusion criteria were: (1) peer-reviewed articles in English; (2) designed as parallel-group RCTs; (3) included infants who were randomly allocated to an intervention group of maternal fish oil supplementation or a control group of placebo or blank treatment; prenatal supplementation of fish oil was achieved by maternal intake during gestational periods and postnatal supplementation was achieved by maternal intake during breast feeding; and (4) reported the incidence of asthma and/or the symptom of wheeze of the offspring during follow-up. If studies with overlapped population were retrieved, the one with the longest follow-up duration was included. Diagnosis and definition of asthma/wheeze were in accordance with those applied among the original studies. Reviews, preclinical studies, observational studies, crossover RCTs, studies with overlapped population, and studies that did not report related outcomes were excluded.Study search, data extraction, and quality evaluation were achieved by two independent authors. If disagreement occurred, it was resolved by consensus between the two authors. We extracted data regarding study information , study design (blind or open-label), maternal or birth information, intervention of fish oil supplementation , regimen of controls, number of children followed, and outcomes reported. Quality evaluation was achieved using the Cochrane's Risk of Bias Tool  accordinvia odds ratio (OR) and its 95% confidence intervals (CIs). We used the Cochrane's Q test to detect the heterogeneity, and significant heterogeneity was suggested if P < 0.10  and Stata software  were applied for statistical analyses.Incidence of asthma in each arm was evaluated P < 0.10 . The I2 d result . Sensitid result . P < 0.0via full-text review based on reasons listed in In summary, 751 articles were obtained through the database search. After exclusion of duplicate studies, 620 articles were screened. Among them, 589 articles were subsequently excluded based on titles and abstracts primarily because these studies were irrelevant. Among the 31 potentially relevant articles, 21 were further excluded P = 0.40; I2 = 28%). Further sensitivity analysis by excluding one dataset at a time showed consistent results . Subgroup analyses showed that maternal fish oil supplementation may reduce the risk of clinically diagnosed asthma , but not the risk of wheeze .The funnel plots were symmetrical for the overall meta-analysis, suggesting low risk of publication bias . Egger'sIn this meta-analysis of RCTs, we found that maternal fish oil supplementation was not associated with an overall reduced risk of asthma/wheeze in children. However, subgroup analysis suggested that maternal fish oil supplementation may reduce the risk of clinically diagnosed asthma, but not for the overall wheeze symptoms. Besides, maternal fish oil supplementation reduced the risk of asthma/wheeze in studies with high-dose fish oil , but not in those with low-dose fish oil . Characteristics of infants  and timing of supplementation  did not seem to significantly affect the results. Taken together, results of the meta-analysis indicated that maternal fish oil supplementation may reduce the risk of clinically diagnosed asthma in children, particularly with high-dose fish oil.Several systematic reviews and meta-analyses have been published previously to evaluate the association between maternal fish oil supplementation and risk of allergic diseases, including asthma and wheeze. Early meta-analyses mainly included observational studies, which suggested that fish or fish oil intake may be beneficial to prevent asthma in children , 8. HoweCompared to the previous meta-analyses, our study has multiple methodological strengths. Firstly, by including the most up-to-date studies, our meta-analysis is comprised of the largest datasets and sample size  which could provide an updated view regarding the role of maternal fish oil supplementation on the risk of asthma/wheeze in childhood. As an update, a study of the same population as the previous two studies , 30 but Our study also has limitations. Firstly, according to the Global Initiative for Asthma Strategy 2021, it may be challenging to make a confident diagnosis of asthma under 5 years old . For theIn conclusion, results of this updated meta-analysis showed that maternal fish oil supplementation may reduce the risk of clinically diagnosed asthma in children, particularly with high-dose fish oil. These findings should be validated in future clinical trials, and the safety of maternal high-dose fish oil supplementation should also be assessed.The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.SW and CL designed the study, performed literature search, data extract, and statistical analyses. SW drafted the manuscript. CL revised the manuscript. All authors approved the submission. All authors contributed to the article and approved the submitted version.This study was supported by Hainan Provincial Natural Science Foundation of China (821QN1002) and Hainan Province Clinical Medical Center.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.