Periodontitis and osteoporosis: a two-sample Mendelian randomization analysis

Abstract The incidences of periodontitis and osteoporosis are rising worldwide. Observational studies have shown that periodontitis is associated with increased risk of osteoporosis. We performed a Mendelian randomization (MR) study to genetically investigate the causality of periodontitis on osteoporosis. We explored the causal effect of periodontitis on osteoporosis by MR analysis. A total of 9 single nucleotide polymorphisms (SNP) were related to periodontitis. The primary approach in this MR analysis was the inverse variance-weighted (IVW) method. Simple median, weighted median, and penalized weighted median were used to analyze sensitivity. The fixed-effect IVW model and random-effect IVW model showed no significant causal effect of genetically predicted periodontitis on the risk of osteoporosis (OR=1.032; 95%CI: 0.923-1.153; P=0.574; OR=1.032; 95%CI: 0.920-1.158; P=0.588, respectively). Similar results were observed in simple mode (OR=1.031; 95%CI: 0.780-1.361, P=0.835), weighted mode (OR=1.120; 95%CI: 0.944-1.328, P=0.229), simple median (OR=1.003; 95%CI: 0.839-1.197, P=0.977), weighted median (OR=1.078; 95%CI: 0.921-1.262, P=0.346), penalized weight median (OR 1.078; 95%CI: 0.919-1.264, P=0.351), and MR-Egger method (OR=1.360; 95%CI: 0.998-1.853, P=0.092). There was no heterogeneity in the IVW and MR-Egger analyses (Q=7.454, P=0.489 and Q=3.901, P=0.791, respectively). MR-Egger regression revealed no evidence of a pleiotropic influence through genetic variants (intercept: -0.004; P=0.101). The leave-one-out sensitivity analysis indicated no driven influence of any individual SNP on the association between periodontitis and osteoporosis. The Mendelian randomization analysis did not show a significant detrimental effect of periodontitis on the risk of osteoporosis.

Effect of obesity, lipids and adipokines on allergic rhinitis risk: a Mendelian randomization study

Abstract Objectives: Observational studies suggested that obesity may promote the development of allergic rhinitis. The aim of this study was to explore the association of obesity, lipids and adipokines with this allergic disease at the genetic level using Mendelian randomization strategies. Methods: Summary data for three obesity indicators (such as body mass index), eight lipid indicators (such as triglycerides) and six adipokines (such as interleukin-6 and adipocyte fatty acid-binding protein) were collected, and suitable instrumental variables were extracted from these summary data according to the three main assumptions of Mendelian randomization. Three Mendelian randomization methods (such as inverse variance weighted) were used to detect the casual effect of the above indicators on allergic rhinitis risk. Sensitivity analyses were performed to assess heterogeneity and horizontal pleiotropy. Results: After Bonferroni correction, the inverse variance weighted reported that elevated levels of interleukin-6 and adipocyte fatty acid-binding protein were nominally associated with the decreased risk of allergic rhinitis (OR = 0.870, 95% CI 0.765-0.990, p = 0.035; OR = 0.732, 95% CI 0.551-0.973, p = 0.032). The other Mendelian randomization methods supported these results. Obesity, lipids and other adipokines were not related to this allergic disease. Sensitivity analyses found no heterogeneity and horizontal pleiotropy in the study. Conclusion: The study provided some interesting, but not sufficient, evidence to suggest that interleukin-6 and adipocyte fatty acid-binding protein might play a protective role in the development of allergic rhinitis at the genetic level. These findings should be validated by more research. Level of evidence: This was a Mendelian randomized study with a level of evidence second only to clinical randomized trials, and higher than cohort and case-control studies.

Causal relationship between branched-chain amino acids and peripheral atherosclerosis： a Mendelian randomization study / 上海预防医学

ObjectiveWe conducted a two-sample Mendelian randomization （MR） study to assess the causal relationship between circulating isoleucine， leucine and valine levels and the risk of peripheral atherosclerosis. MethodsBased on the large-scale genome-wide association study （GWAS） database， single nucleotide polymorphisms （SNPs） closely related to the circulating levels of isoleucine， leucine and valine were identified as instrumental variables （IVs）. Two-sample MR analysis applying the inverse variance weighted （IVW） method and the weighted median estimator （WME） method were performed to estimate the causal relationship between the risk of peripheral atherosclerosis and the exposure with more than three SNPs that were available as IVs. The pleiotropy was evaluated by using the MR-Egger regression and MR-PRESSO method， and the leave-one-out method was used in sensitivity analysis. ResultsFour， one and one SNPs were identified as IVs for circulating isoleucine， leucine and valine levels， respectively. For isoleucine， the IVW model demonstrated there was no evidence of heterogeneity among the IVs （P=0.715）， and there was a significant causal relationship between the increase of circulating isoleucine level and a higher risk of peripheral atherosclerosis risk. Per every 1 elevated standard deviation （SD） of circulating isoleucine level resulted in increasing 31% of peripheral atherosclerosis risk （OR=1.31， 95%CI： 1.07‒1.61）. Similarly， the OR（95%CI） was 1.33 （1.04‒1.71） in the WME model. The MR-Egger regression and MR-PRESSO analysis indicated no evidence of pleiotropy in IVs （all P>0.05）. The result of the leave-one-out sensitivity analysis was stable. The Wald ratio model displayed that the causal relationship between circulating leucine and valine levels and the risk of peripheral atherosclerosis was not statistically significant. The OR （95%CI） for leucine and valine was 1.13 （0.78‒1.63） and 1.11 （0.82‒1.50）， respectively. ConclusionThere is a significant causal relationship between the increase of circulating isoleucine level and a higher peripheral atherosclerosis risk. The causal relationships between circulating leucine and valine levels and the risk of peripheral atherosclerosis need to be further confirmed in future studies.

Association between neonatal birth weight and maternal type 2 diabetes mellitus: a bidirectional Mendelian randomization study / 预防医学

Objective@#To examine the association between neonatal birth weight and maternal type 2 diabetes (T2DM), so as to provide insights into the formulation of the early T2DM prevention and improvements of maternal and children health.@*Methods@#Single-nucleotide polymorphisms (SNPs) were collected from two genome-wide association studies (GWAS) that examined the association between neonatal birth weight and maternal T2DM. Inverse variance weighted method was employed for forward Mendelian randomization with 26 birth weight-associated SNPs as instrumental variables and maternal T2DM as the study outcome and for reverse Mendelian randomization with 18 maternal T2DM-associated SNPs as instrumental variables and maternal effects of neonatal birth weight as the study outcome. The heterogeneity was examined using Cochran's Q test, and the pleiotropy was evaluated using MR-Egger regression, while the robustness of the results was evaluated using leave-one-out test.@*Results@#Cochran's Q test detected heterogeneity across two studies (P=0.019, 0.038), and random effect models were employed. Mendelian randomization showed that an increase in neonatal birth weight by per standard error (approximately 488 g) resulted a 29.9% reduction in the risk of maternal T2DM (OR=0.701, 95%CI: 0.547-0.899), and maternal T2DM increased the neonatal birth weight by 0.074 standard errors (OR=1.074, 95%CI: 1.043-1.106). No horizontal pleiotropy was seen for instrumental variables (P=0.241, 0.188). With each SNP excluded in turn, the results of Mendelian randomization study were robust. @*Conclusion @#There are bidirectional associations between neonatal birth weight and risk of maternal T2DM.

Association between primary sclerosing cholangitis and the risk of colorectal cancer: A two-sample Mendelian randomization study / 临床肝胆病杂志

Objective To investigate the association between primary sclerosing cholangitis (PSC) and colorectal cancer (CRC) by using two-sample Mendelian randomization (TSMR). Methods The single nucleotide polymorphism (SNP) data associated with PSC and CRC were obtained from Finland Biobank and UK Biobank, respectively. A secondary data analysis was performed for all pooled data based on genome-wide association studies to select the genetic loci closely associated with PSC as instrumental variables, and TSMR was conducted by seven methods, i.e., Egger regression in Mendelian randomization, weighted median, inverse variance weighted (IVW) random effects model, maximum likelihood, linear weighted median, IVW radial method, and IVW fixed effects model. Odds ratio (OR) value was used to evaluate the causal relationship between PSC and the risk of CRC. Results There was a positive causal relationship between gene predicted PSC and CRC, and with the IVW fixed effects model as an example, genetically determined patients with PSC could increase the risk of CRC ( OR =1.002 243, 95% confidence interval: 1.001 319-1.003 167). TSMR results showed no heterogeneity ( P =0.87) or horizontal pleiotropy ( P =0.95). The three instrumental variables selected for PSC were strong instrumental variables ( F =11.86). Conclusion TSMR shows the genetic evidence for the association between PSC and the risk of CRC. Regardless of the presence or absence of inflammatory bowel disease, active enteroscopy screening among patients with PSC may help with the early identification and timely intervention of CRC.

Association between smoking and ankylosing spondylitis: a Mendelian randomization study / 预防医学

Objective@#To evaluate the association of smoking with the risk of ankylosing spondylitis (AS) using a Mendelian randomization (MR) approach.@*Methods@#A total of 16 383 186 AS-associated single nucleotide polymorphisms (SNPs), 378 smoking initiation associated SNPs and 126 lifetime smoking score-associated SNPs were collected from three large-scale genome-wide association studies (GWAS). The association of smoking phenotypes with the risk of AS was examined using inverse-variance weighted (IVW) with AS as a outcome variable, smoking initiation and lifetime smoking score as exposure factors and SNPs with strong associations with smoking as instrumental variables, and sensitivity analyses were performed with maximum likelihood-based method, MR pleiotropy residual sum and outlier (MR-PRESSO) test and MR-Egger regression analysis.@*Results@# A 33.5% increased risk of AS was found among genetically predicted smokers relative to non-smokers (OR=1.335, 95%CI: 1.059-1.682), and an increase in predicted lifetime smoking by per standard deviation resulted in a 101.4% increased risk of AS (OR=2.014, 95%CI: 1.341-3.024). The maximum likelihood-based method and MR-PRESSO test showed consistent correlated effect estimations and MR-Egger regression analysis identified no evidence of pleiotropy.@*Conclusion@#It is genetically predicted that smoking is associated with an increased risk of AS.

Mendelian Randomization Analysis of Research on Risk Factors for Gastric Cancer / 肿瘤防治研究

Objective To understand the application and research progress of Mendelian randomization (MR) studies related to gastric cancer and provide a scientific basis for gastric cancer prevention. Methods Published studies on risk factors of gastric cancer based on MR methods were searched in PubMed, Web of Science, EMBASE, CNKI, and WANFANG DATA from the establishment of each database to November 19th, 2022. Two researchers examined the eligibility of studies, extracted key information, and assessed the research quality independently. Results A total of 30 publications published from 2016 to 2022 were included in the study, and 20 were judged to be of high quality. These studies examined the relationship between behaviors and lifestyle factors, anthropometric characteristics, indicators of biological exposure, and other pathological conditions and gastric cancer, and the results suggest potential causal associations between smoking and other factors and the risk of gastric cancer. Conclusion Previous MR studies extensively investigated the causal association between internal and external exposures or traits and gastric cancer and provided positive evidence of gastric cancer etiology. However, MR studies may be subject to methodological limitations. Interpretation of results needs to be approached with caution, which necessitates the integration with biological plausibility and evidence from observation studies.

Association of ticagrelor with risk of infection：a two-sample Mendelian randomization study based on the GWAS database / 中国药房

OBJECTIVE To investigate the causal association between ticagrelor and risk of infection METHODS Two-sample Mendelian randomization was adopted. Genetic instrumental variables were selected based on the results of the largest genome-wide association analysis to in vivo exposure of ticagrelor and its major active metabolite AR-C124910XX. The causal associations of ticagrelor and its major active metabolite AR-C124910XX with drug indications （coronary artery disease， unstable angina pectoris， myocardial infarction， stroke and ischemic stroke）were analyzed by inverse variance weighted Mendelian randomization model as a positive control for genetic instrumental variables. The causal relationship between ticagrelor and bacterial infection， acute lower respiratory infection， bacterial pneumoniae， pneumoniae，acute upper respiratory infection and sepsis were furtheranalyzed by using this method， and the robustness of the results was assessed by using heterogeneity tests and horizontal 202002030415） pleiotropy tests. RESULTS The increase of area under the curve at steady state （AUCss） of the genetic surrogated ticagrelor significantly reduced the risk of coronary artery disease， myocardial infarction and unstable angina pectoris （P＜0.001）. AUCss genetic instrument variables of its main active metabolite AR-C124910XX failed to pass positive control. Further analysis showed that the increase of the genetic surrogated ticagrelor exposure suggestively reduced the risk of bacterial infection [OR（95%CI）＝0.80（0.65，0.99），P＝0.040] and sepsis [OR （95%CI）＝0.84（0.73， 0.98）， P＝0.023]. The results of the heterogeneity tests showed that there was no heterogeneity in the causal association of the genetic surrogated ticagrelor AUCss with bacterial infection and sepsis （P＞0.05）. The results of horizontal pleiotropy tests showed that the causal association of genetic surrogated ticagrelor AUCss with bacterial infection and sepsis had no effects on horizontal pleiotropy （P＞0.05）. CONCLUSIONS Ticagrelor has a potential role in reducing the risk of sepsis and bacterial infections.

Genetically predicted insomnia causally increases the risk of erectile dysfunction / 亚洲男科学杂志(英文版)

Sleep has attracted extensive attention due to its significance in health. However, its association with erectile dysfunction (ED) is insufficiently investigated. To investigate the potential causal links between sleep traits (insomnia, sleep duration, and chronotype) and ED, this study was performed. The single-nucleotide polymorphisms (SNPs) associated with insomnia, sleep duration, and chronotype were retrieved from previous genome-wide association studies (GWAS). A conventional two-sample Mendelian randomization (MR) was used to estimate the causal links between sleep traits and ED. The summary statistics of ED were from individuals of European ancestry (6175 cases vs 217 630 controls). As shown by the random effect inverse-variance-weighting (IVW) estimator, genetically predicted insomnia was causally associated with a 1.15-fold risk of ED (95% confidence interval: 1.07-1.23, P < 0.001). Sleep duration and morningness were not causally associated with ED, as indicated by the IVW (all P > 0.05). These findings were consistent with the results of sensitivity analyses. Based on genetic data, this study provides causal evidence that genetically predicted insomnia increases the risk of ED, whereas sleep duration and chronotype do not.

Análisis mediante variables instrumentales para establecer causalidad en investigaciones observacionales / Analysis through instrumental variables to establish causality in observational research

La identificación de relaciones causales es uno de los problemas fundamentales de la investigación científica en medicina y es necesaria para poder ejercerla en forma efectiva. Sin embargo, desde el punto de vista práctico es difícil establecer la existencia de relaciones causales en estudios de carácter observacional, en gran parte por la presencia de factores de confusión. El análisis a través de variables instrumentales es una de las estrategias que permite controlar el efecto confundidor y documentar la presencia de relaciones causa-efecto en estas situaciones. En este artículo, el autor resume los principales supuestos del análisis a través de variables instrumentales, haciendo foco en la aleatorización mendeliana. (AU)

The identification of causal relationships is one of the fundamental challenges in scientific research in medicine and is necessary for its effective practice. However, from a practical standpoint, establishing the existence of causal relationships in observational studies is difficult, largely due to the presence of confounding factors. Analysis through instrumental variables is one of the strategies that allows to control the confounding effect and documenting the presence of cause-and-effect relationships in these situations. In this article, the author summarizes the main assumptions of analysis through instrumental variables, with a focus on Mendelian randomization. (AU)

Testing relationship between tea intake and the risk of rheumatoid arthritis and systemic lupus erythematosus: a Mendelian randomization study

Abstract Background We performed Mendelian randomization (MR) to assess the causal effect of tea intake on rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Methods Genetic instruments for tea intake were obtained from a large genome-wide association study (GWAS) dataset of the UK Biobank. Genetic association estimates for RA (6236 cases and 147,221 controls) and SLE (538 cases and 213,145 controls) were obtained from the FinnGen study through the IEU GWAS database. Results MR analyses using the inverse-variance weighted method showed that tea intake was not associated with risk of RA [odds ratio (OR) per standard deviation increment in genetically predicted tea intake = 0.997, 95% confidence interval (CI) 0.658-1.511] and SLE (OR per standard deviation increment in genetically predicted tea intake = 0.961, 95% CI 0.299-3.092). Weighted median, weighted mode, MR-Egger, leave-one-out and multivariable MR controlling for several confounding factors including current tobacco smoking, coffee intake, and alcoholic drinks per week yielded completely consistent results. No evidence of heterogeneity and pleiotropy was found. Conclusion Our MR study did not suggest a causal effect of genetically predicted tea intake on RA and SLE.

Risk factors of systemic lupus erythematosus: an overview of systematic reviews and Mendelian randomization studies

Abstract Background The etiology of systemic lupus erythematosus is complex and incurable. A large number of systematic reviews have studied the risk factors of it. Mendelian randomization is an analytical method that uses genetic data as tool variables to evaluate the causal relationship between exposure and outcome. Objective To review the systematic reviews and Mendelian randomization studies that focused on the risk factors of systemic lupus erythematosus and shed light on the development of treatments for its prevention and intervention. Methods From inception to January 2022, we systematically searched MEDLINE (via PubMed) and Embase for related systematic reviews and Mendelian randomization studies. Extract relevant main data for studies that meet inclusion criteria. The quality of systematic reviews was assessed by using Assessment of Multiple Systematic Reviews 2 (AMSTAR-2). Finally, the risk factors are scored comprehensively according to the results' quantity, quality, and consistency. Results Our study involved 64 systematic reviews and 12 Mendelian randomization studies. The results of systematic reviews showed that diseases (endometriosis, atopic dermatitis, allergic rhinitis), lifestyle (smoking, drinking, vaccination), and gene polymorphism influenced the incidence of systemic lupus erythematosus. The results of Mendelian randomization studies identified the role of disease (periodontitis, celiac disease), trace elements (selenium, iron), cytokines (growth differentiation factor 15), and gut microbiome in the pathogenesis of systemic lupus erythematosus. Conclusion We should pay attention to preventing and treating systemic lupus erythematosus in patients with endometriosis, celiac disease, and periodontitis. Take appropriate dietary supplements to increase serum iron and selenium levels to reduce the risk of systemic lupus erythematosus. There should be no excessive intervention in lifestyles such as smoking and drinking.

Causality between type 2 diabetes mellitus and age-related macular degeneration: a Mendelian randomization study / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To analyze the causality between type 2 diabetes mellitus(T2DM)and age-related macular degeneration(ARMD)based on two-sample Mendelian randomization(MR).METHODS: T2DM and ARMD samples were extracted from the FinnGen database. Inverse variance weighted(IVW)was used as the main analysis method, MR-Egger and weighted median(WM)as supplementary methods to analyze the potential relationship between them. In addition, Cochran Q test and MR-Egger intercept were also used to analyze the sensitivity, and the P-value was used as the index of research results.RESULTS: IVW showed that T2DM was associated with the incidence of exudative ARMD(OR=1.14, 95%CI 1.01～1.28, P=0.021), but it was not significantly associated with the incidence of atrophic ARMD(OR=0.96, 95%CI 0.86～1.07, P=0.554). The results of sensitivity analysis confirmed that there was no heterogeneity and pleiotropy in this study, and the results were reliable.CONCLUSION: There is a causal relationship between T2DM and exudative ARMD. Considering the high rate of blindness caused by ARMD, it is of great significance to recognize and control the risk factors of ARMD to reduce its prevalence rate and early diagnosis and treatment.

Causal association between interleukin and constipation: A Mendelian randomization analysis / 西安交通大学学报(医学版)

【Objective】 To explore the causal association between interleukin (IL) level and constipation by using two-sample Mendelian randomization. 【Methods】 Analyses were performed based on the data from gene-wide association studies (GWAS). Both interleukin and constipation data were obtained from European populations. IL as an exposure variable was obtained from two GWAS data sets: ⅰ. from a genetic map of the human plasma proteome containing 3 301 samples; ⅱ. from a GWAS data set on 90 circulating proteins, containing 30 931 samples. Constipation as an outcome variable was obtained from two GWAS data sets: ⅰ. from Finngene, containing 26919 cases and 282235 controls; ⅱ. from UKBiobank, containing a total of 3 328 cases and 459682 controls. Single nucleotide polymorphisms strongly associated with exposure variables were used as instrumental variables, with inverse variance weighted (IVW) as the main analysis method, MR-egger regression and weighted median method as supplementary evidence for IVW results, and horizontal pleiotropy and heterogeneity were tested to ensure the stability of the results. 【Results】 In both of the two different outcome variables GWAS data, IVW analysis results showed that decreased level of IL-17 receptor C was associated with an increased risk of constipation, with ORs of 0.956 (95% CI: 0.916-0.997, P=0.036‖Finngene) and 0.998 (95% CI: 0.997-0.999, P=0.040‖ukb). Increased level of IL-18 was associated with an increased risk of constipation, with ORs of 1.055 (95% CI: 1.008-1.104, P=0.022‖Finngene) and 1.001 (95% CI: 1.000-1.002, P=0.044‖ukb); while in the Finngene data, the IVW results also suggested that increased levels of IL-2 receptor alpha subunit α and decreased levels of IL-10 and IL-17 were associated with an increased risk of constipation, with ORs of 1.054 (95% CI: 1.001-1.110, P=0.049), 0.945 (95% CI: 0.896-0.996, P=0.035) and 0.934 (95% CI: 0.896-0.997, P=0.040). 【Conclusion】 IL-17 receptor C, IL-18, IL-2 receptor alpha subunit α, IL-10, and IL-17 were causally associated with the risk of constipation.

Causal Relationship Between Acromegaly and Colon Cancer: A Two-sample Mendelian Randomization Study / 肿瘤防治研究

Objective To determine the causal relationship between acromegaly and colon cancer by using two-sample Mendelian randomization. Methods Genetic loci closely related to acromegaly in the whole genome-wide association study (GWAS) were selected as tool variables, and the genetic data of colon cancer from different GWASs were analyzed by two-sample Mendelian randomization (MR).The inverse variance weighting method (IVW) of the random effect model was used for analysis, and MR-weighted median and MR-Egger methods were used to supplement the analysis. Results were presented as OR values. Results Four SNPs closely related to acromegaly were obtained as tool variables, and the multiplicity test of tool variables showed that P=0.59.Three methods were used to estimate causal effects.The IVW analysis were OR=1.00(0.99-1.001) and P=0.42;the MR-Egger analysis results were OR=1.00(0.99-1.001) and P=0.42;and the Weighted median analysis results were OR=1.00(1.00-1.001) and P=0.03.The sensitivity test showed that the confidence interval of the tool variable SNP passed through 0, indicating the robustness of the MR results. Conclusion Acromegaly is not an independent risk factor for colon cancer.

A mendelian randomization study of the causal association between gastroesophageal reflux and atrial fibrillation / 公共卫生与预防医学

Objective In this study，we performed two sampie Mendelian Randomization to infer a causal association between Gastroesophageal reflux(GERD) and Atrial fibrillation(AF)，it can effectively avoid the problems such as reverse causation and confounds in traditional epidemiology. Methods We used the Summary data of GERD and AF from published Genome wide association study(GWAS) of European Individuals. Single Nucleotide Polymorphisms (SNPs) were extracted as Instrumental Variables (IVs).The main MR methods include Inverse Variance [] Weighted(IVW)，Weighted Median(WME)，MR-Egger，Simple Mode，and Weighted Mode.In addition，we used the sensitivity analysis such as MR-PRESSO，Cochran's Q test etc. Results The IVW shows a causal association between GERD and AF(P<0.0001，OR=1.16，95%CI:1.10-1.23).The WME shows P＜0.0001，OR=1.20，95%CI:1.11-1.30；Simple Mode shows P=0.01，OR=1.34，95%CI:1.07-1.69；Weighted Mode shows P=0.02，OR=1.33，95%CI:1.06-1.66. Conclusion This study based on genetic data supports the causal association between GERD and AF. The occurrence of GERD could increase the risk of AF.

Mendelian randomization study to investigate the causal relationship between plasma homocysteine and chronic obstructive pulmonary disease / 世界急诊医学杂志（英文）

@#BACKGROUND: Several observational studies have shown an association between homocysteine (Hcy) levels and chronic obstructive pulmonary disease (COPD), but causal relationships are not clear. Our study aimed to explore the causal relationship between plasma Hcy and COPD by two-sample Mendelian randomization (MR). METHODS: A two-sample MR study was performed to infer the causal link. Genetically predicted plasma Hcy was selected as an instrumental variable (IV) from published genome-wide association study (GWAS) meta-analyses. COPD with different etiologies was extracted as outcome variables from other GWAS meta-analyses. The main MR analysis was performed using the inverse-variance weighted (IVW) method. Additional analyses were further performed using Cochran's Q-test and MR-Egger regression to evaluate the heterogeneity or horizontal pleiotropy of our findings. RESULTS: MR analysis showed no significant association between plasma Hcy and COPD. The results of the groups were consistent with the sensitivity analysis and repeated analysis, without heterogeneity or horizontal pleiotropy. The IVW results showed COPD hospital admissions (odds ratio [OR] 1.06, 95% confidence interval [CI] 0.91-1.24, P=0.42), asthma/COPD (OR 0.97, 95% CI 0.89-1.06, P=0.55), COPD-related chronic infection (OR 1.50, 95% CI 0.57-3.99, P=0.41), COPD/asthma/interstitial lung disease (ILD)-related pneumonia or pneumonia-derived septicemia (OR 0.93, 95% CI 0.86-1.02, P=0.13), and COPD-related respiratory insufficiency (OR 1.00, 95% CI 0.7-1.44, P=0.99). CONCLUSION: There is no direct causal relationship between plasma Hcy and COPD in our study. As Hcy is known to have deleterious effects on endothelial function and vascular homeostasis, further studies are needed to investigate whether additional factors mediate the association between Hcy and COPD.

Blood pressure phenotype, lipid fractions and type 2 diabetes: a trans-ethnic mendelian randomization study / 中华内分泌代谢杂志

Objective:To explore the causal associations of two blood pressure phenotype and four lipid fractions with type 2 diabetes mellitus(T2DM) in European and East Asian populations using Two-Sample Mendelian randomization analysis.Methods:Blood pressure phenotype, lipid fractions and T2DM genetic loci from two ethnics were matched and combined according to single nucleotide polymorphisms(SNPs) numbering. With SNPs closely related to the exposure phenotype as instrumental variables, the inverse variance weighting method was used to analyze the causal effects of blood pressure phenotype and lipid fractions on T2DM in different ethnic groups. The sensitivity analysis was conducted using MR-Egger regression model, Weighted Median method, MR-PRESSO, MR-robust Adjusted Profile Score, and leave-one-out method.Results:Among European populations, systolic blood pressure( OR=1.40, 95% CI 1.23-1.59, P<0.001) and diastolic blood pressure( OR =1.24, 95% CI 1.08-1.42, P=0.002)were associated with increased risk of T2DM while high density lipoprotein-cholesterol( OR=0.68, 95% CI 0.62-0.76, P<0.001) reduced the risk of T2DM. In East Asian ethnicity, elevated diastolic blood pressure( OR=0.75, 95% CI 0.59-0.95, P=0.007) reduced the risk of T2DM. Sensitivity analysis confirmed the results. Conclusion:There are differences in the effects of blood pressure phenotype and lipid composition on T2DM in different ethnic groups, which may be related to population heterogeneity and exposure sensitivity. It should be taken into consideration in extrapolation.

Mental illness and risk of developing obstructive sleep apnea: a two-sample Mendelian randomization study / 中华老年医学杂志

Objective:A two-sample Mendelian randomized study was used to investigate the relationship between psychiatric disorders and the risk of developing obstructive sleep apnea(OSA).Methods:Genetic variations in bipolar disorder, depression, Alzheimer's disease and schizophrenia were used as instrumental variables and data from genome-wide association studies of OSA patients from the Finngen Consortium were used.In this study, inverse variance weighted method was used as the main analysis method, and three sensitivity analyses including weighted median analysis, MR-Egger regression analysis and MR-PRESSO analysis were jointly applied.Results:Higher genetic predisposition for depression and bipolar disorder increased the risk of developing OSA, the odds ratio is 1.18(95% CI: 1.02-1.37, P=0.026)and 1.06(95% CI: 1.01-1.12, P=0.038)for each unit increase with log-transformed odds ratios of depression and bipolar disorder, respectively.Genetic susceptibility to Alzheimer's disease and schizophrenia was not associated with the risk of developing OSA. Conclusions:This study suggests that a higher genetic predisposition for depression and bipolar disorder may lead to a higher risk of developing OSA.OSA and psychiatric disorders such as depression and bipolar disorder have a high incidence in the elderly, however, their causal effects still need to be studied.

Association of C-reactive Protein with Cardiovascular Outcomes: A Mendelian Randomization Study in the Japanese Population / 生物医学与环境科学（英文）

OBJECTIVE@#Traditional epidemiological studies have shown that C-reactive protein (CRP) is associated with the risk of cardiovascular diseases (CVDs). However, whether this association is causal remains unclear. Therefore, Mendelian randomization (MR) was used to explore the causal relationship of CRP with cardiovascular outcomes including ischemic stroke, atrial fibrillation, arrhythmia and congestive heart failure.@*METHODS@#We performed two-sample MR by using summary-level data obtained from Japanese Encyclopedia of Genetic association by Riken (JENGER), and we selected four single-nucleotide polymorphisms associated with CRP level as instrumental variables. MR estimates were calculated with the inverse-variance weighted (IVW), penalized weighted median and weighted median. MR-Egger regression was used to explore pleiotropy.@*RESULTS@#No significant causal association of genetically determined CRP level with ischemic stroke, atrial fibrillation or arrhythmia was found with all four MR methods (all Ps > 0.05). The IVW method indicated suggestive evidence of a causal association between CRP and congestive heart failure ( OR: 1.337, 95% CI: 1.005-1.780, P = 0.046), whereas the other three methods did not. No clear pleiotropy or heterogeneity were observed.@*CONCLUSIONS@#Suggestive evidence was found only in analysis of congestive heart failure; therefore, further studies are necessary. Furthermore, no causal association was found between CRP and the other three cardiovascular outcomes.