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.

Risk Factors of Depression Screened by Two-Sample Mendelian Randomization Analysis: A Systematic Review / 生物医学与环境科学（英文）

OBJECTIVE@#This study explored the potentially modifiable factors for depression and major depressive disorder (MDD) from the MR-Base database and further evaluated the associations between drug targets with MDD.@*METHODS@#We analyzed two-sample of Mendelian randomization (2SMR) using genetic variant depression ( n = 113,154) and MDD ( n = 208,811) from Genome-Wide Association Studies (GWAS). Separate calculations were performed with modifiable risk factors from MR-Base for 1,001 genomes. The MR analysis was performed by screening drug targets with MDD in the DrugBank database to explore the therapeutic targets for MDD. Inverse variance weighted (IVW), fixed-effect inverse variance weighted (FE-IVW), MR-Egger, weighted median, and weighted mode were used for complementary calculation.@*RESULTS@#The potential causal relationship between modifiable risk factors and depression contained 459 results for depression and 424 for MDD. Also, the associations between drug targets and MDD showed that SLC6A4, GRIN2A, GRIN2C, SCN10A, and IL1B expression are associated with an increased risk of depression. In contrast, ADRB1, CHRNA3, HTR3A, GSTP1, and GABRG2 genes are candidate protective factors against depression.@*CONCLUSION@#This study identified the risk factors causally associated with depression and MDD, and estimated 10 drug targets with significant impact on MDD, providing essential information for formulating strategies to prevent and treat depression.

Application of Mendelian randomization in liver cancer / 临床肝胆病杂志

In recent years， the research method of Mendelian randomization based on genome-wide association studies has been widely used for etiological exploration in the medical field， which can effectively overcome the confounding biases and interference of reverse causalities in traditional observational researches with its unique advantages of the distributive randomness and timing priority of genetic variants. This article reviews the method of Mendelian randomization and its application in liver cancer， in order to provide new ideas for the research on causal association in liver cancer.

Casual Association Between Coffee Intake and Prostate Cancer Based on Two-sample Mendel Randomization / 肿瘤防治研究

Objective To assess the causal relationship between coffee intake and prostate cancer risk by using the two-sample Mendel randomization (MR) method. Methods The genome-wide association study (GWAS) data on coffee intake (exposure) and prostate cancer (outcome) were obtained from two independent data sets in UK Biobank. The inverse variance weighted method (IVW), weighted median estimator method (WME), and MR-Egger method were used for MR analyses. The OR value and 95%CI were used to represent the association between coffee intake and prostate cancer. In addition, the MR-Egger method was performed for pleiotropic and heterogeneity tests, and the leave-one-out method was used for sensitivity analysis. Results A total of 38 SNP were selected as instrumental variables. The IVW method showed that coffee intake might reduce the risk of prostate cancer (OR=0.994; 95%CI: 0.990-0.999; P=0.009). The WME method obtained the same conclusions (OR=0.991; 95%CI: 0.985-0.999; P=0.018), but MR-Egger regression did not find a causal relationship between coffee intake and prostate cancer (OR=0.992; 95%CI: 0.983-1.000; P=0.084). The MR-Egger method showed no pleiotropy (intercept=4.2E-5; P=0.581) or heterogeneity (Q=27.20; P=0.854) among the instrumental variables. The sensitivity analysis indicated that the conclusion was robust. Conclusion Two-sample Mendel randomization analysis reveals that coffee consumption might reduce the risk of prostate cancer.

Bidirectional casual effects between periodontitis and Sjögren's syndrome: a Mendelian randomization study / 口腔疾病防治

Objective@#To evaluate the bidirectional association between periodontitis and Sjögren's syndrome using the Mendelian randomization (MR) method.@*Methods@#Genome-wide association study (GWAS) data of periodontitis (N = 45 563) and Sjögren's syndrome (N = 214 435) were selected to meet the requirements of the same ethnicity and different regions. Inverse variance-weighted (IVW), MR-Egger, and weighted median (WM) tests were used to evaluate the causal effect. Cochran's Q statistics, MR-Egger intercept, MR-PRESSO and leave-one-out analysis were used as sensitivity analyses to assess the stability and reliability of the results.@*Results@#After screening, the GWAS data of Sjögren's syndrome were based on the Finnish region, and the periodontitis GWAS data were based on the UK region, both of which originated from European ancestry. Using IVW (OR = 1.017, 95% CI = 0.956-1.082), MR-Egger (OR = 0.985, 95% CI= 0.956-1.082), and WM (OR =1.021, 95% CI = 0.948-1.099), no causal effect of Sjögren's syndrome on periodontitis was found using any of the three methods. Conversely, no causal effect of periodontitis on Sjögren's syndrome was found (IVW, OR = 1.024, 95% CI = 0.852-1.230; MR-Egger, OR = 0.978, 95% CI = 0.789-1.212; WM, OR = 1.024, 95% CI = 0.846-1.260). The sensitivity analyses indicated that the results were stable and reliable. Cochran's Q test and MR-PRESSO revealed that there was no significant heterogeneity among the instrumental variables, which included single nucleotide polymorphisms (SNPs). The intercept of MR-Egger regression indicated no pleiotropy in the included SNPs. No individual SNP was found that significantly affected the results using the leave-one-out method.@*Conclusion@#This study does not support a bidirectional causal effect between periodontitis and Sjögren's syndrome.

Research progress of Mendelian randomization in ocular diseases / 国际眼科杂志(Guoji Yanke Zazhi)

Etiological research is necessary for understanding the occurrence and epidemiological patterns of diseases, and is also a prerequisite for the diagnosis, prevention and treatment of clinical diseases. Mendelian randomization(MR), a method of research that combines genetics and epidemiology, has the advantage of exploring the causal relationship between exposure and disease genetically as well as avoiding confounding factors and reverse causation. Thus, it has been extensively utilized in the etiological study of diseases. This paper reviews the implementation of MR in the research of ocular diseases and provides ideas and approaches for the investigation of related mechanisms as well as the development of intervention strategies.

Association between ulcerative colitis and pancreatitis: a Mendelian randomization study / 预防医学

Objective @#To examine the causal relationship between ulcerative colitis (UC) and pancreatitis, to provide basis for early screening of pancreatitis among UC patients.@*Methods@#Genomic data of UC were obtained from 47 745 European individuals pooled by the International Inflammatory Bowel Disease Genetics Consortium, including 156 116 single nucleotide polymorphism (SNP), and genomic data of pancreatitis were obtained from 198 166 European individuals pooled from FinnGen, including 16 380 428 SNPs. Mendelian randomization (MR) analysis was performed using the inverse variance weighted (IVW) method with 72 UC-associated SNPs as instrumental variables and pancreatitis as the study outcome. The heterogeneity was assessed using Cochran Q test, the horizontal pleiotropy was assessed using MR-Egger regression, MR-PRESSO was performed with the exclusion of outliers, and effect of individual SNP on the results was tested with the leave-one-out method. @*Results@#MR analysis results showed that patients with genetically predicted UC had an increased risk of pancreatitis relative to those without UC (OR=1.076, 95%CI: 1.019-1.136, P<0.05). Cochran Q test showed no heterogeneity (P>0.05), and MR-Egger regression did not reveal horizontal pleiotropy of instrumental variables (P>0.05). The MR analysis results were robust after removing SNP one by one.@*Conclusions@#Genetically predicted UC is associated with an increased risk of pancreatitis. The screening for pancreatitis risk should be enhanced in patients with UC.

Application of Mendelian randomization analysis in exploring the etiology of nonalcoholic fatty liver disease / 临床肝胆病杂志

Nonalcoholic fatty liver disease （NAFLD） is an abnormal lipid metabolic disorder of the liver characterized by accumulation of a large amount of lipids in the liver， and it is currently the most common liver disease around the world. Mendelian randomization （MR） incorporates genomic data into traditional epidemiological study designs to infer the causal relationship between exposure factors and disease risk. In recent years， MR has been widely used in studies on inference of the etiology of NAFLD. This article systematically summarizes the advances in the application of MR in NAFLD research， so as to provide new ideas for understanding the nature of the disease and scientific interventions.

Association between the risk of increase in total cholesterol and the risk of cholelithiasis： A bidirectional Mendelian randomization study / 临床肝胆病杂志

ObjectiveTo investigate the association between the risk of increase in total cholesterol （TC） and the risk of cholelithiasis by using bidirectional Mendelian randomization （MR）. MethodsThe open gwas public database was used to obtain the single nucleotide polymorphism data associated with TC and cholelithiasis， and a secondary data analysis was performed for all summary data of genome-wide association studies. The genetic loci closely associated with TC or cholelithiasis were selected as exposure or outcome variables， and the bidirectional MR analysis was performed using the methods such as Egger regression， Weighted median， IVW random effects model， and IVW fixed effects model， with odds ratio （OR） values for evaluating the causal relationship between TC and cholelithiasis. ResultsWith TC as the exposure and cholelithiasis as the outcome， TC-cholelithiasis had an overall OR value of 0.91 （95% confidence interval ［CI］： 0.85‍ ‍—‍ ‍0.97） before elimination of heterogeneity and 0.93 （95%CI： 0.89‍ ‍—‍ ‍0.97） after elimination of heterogeneity. With cholelithiasis as the exposure and TC as the outcome， TC-cholelithiasis had an overall OR value of 0.20 （95%CI： 0.06‍ ‍—‍ ‍0.65） before elimination of heterogeneity and 0.28 （95%CI： 0.10‍ ‍—‍ ‍0.83） after elimination of heterogeneity. There was a bidirectional causal relationship between genetically predicted TC and cholelithiasis. ConclusionThis study confirms the bidirectional causal relationship between TC and cholelithiasis. The risk of cholelithiasis decreases with the increase in alleles associated with the elevation of TC level； on the contrary， the risk of elevated TC level decreases with the increase in alleles associated with the onset of cholelithiasis.

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.

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.

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.

Causal Association Between Unsaturated Fatty Acids and Inflammatory Bowel Disease: A Mendelian Randomization Analysis / 胃肠病学

Background: Inflammatory bowel disease (IBD) is a chronic recurrent inflammatory disease of gastrointestinal tract including ulcerative colitis (UC) and Crohn's disease (CD). It is unclear whether there is a causal association between unsaturated fatty acids and IBD. Aims: A two⁃sample Mendelian randomization analysis was used to explore the causal association between unsaturated fatty acids and IBD. Methods: The data of the genome⁃wide association study (GWAS) of unsaturated fatty acids and IBD were obtained from web⁃based public databases. Two⁃sample Mendelian randomization analysis was performed by using inverse⁃variance weighted analysis, and weight median estimator and MR⁃Egger regression were conducted to validate the association of the causal effect. The causality of unsaturated fatty acids on the risk of IBD was evaluated by OR and 95% CI. Results: No direct causal association was found between ω⁃6 fatty acids and CD, and a direct causal association was found with UC. Inverse⁃variance weighted analysis showed a 16% increase in the risk of UC for each standard deviation increase in ω⁃6 fatty acid gene levels (OR=1.16, 95% CI: 1.00⁃1.36, P=0.04). However, no causal association was found between ω⁃3 fatty acids, monounsaturated fatty acids and IBD. Conclusions: ω⁃6 fatty acids may be only causally associated with UC, and no causal association is found between ω⁃3 fatty acids, monounsaturated fatty acids and IBD.

BSD method for three treatments randomly allocated with equal proportion in clinical trials / 中国临床药理学与治疗学

AIM: Previous studies have suggested that big stick design (BSD) method can only be used in clinical trials of two treatments with equal proportion, which has good statistical performance and has become the recommended choice of randomized methods. This study expands BSD method, so that it can be applied to three groups, and provides more randomized methods for clinical trials. METHODS: On the basis of BSD method used in two treatments with equal proportion, the derivation conditional allocation probability of BSD method used in three treatments with equal proportion was carried out. BSD method was compared with simple randomization (SR) method, permuted block design (PBD) method and block urn design (BUD) method by Monte-Carlo simulation in balance and randomness. RESULTS: In terms of balance, PBD method was the best, followed by BUD method, BSD method, and SR method was the worst. In terms of randomness, SR method was the best, followed by BSD method, BUD method and PBD method. The comprehensive performance showed that BSD method was better than BUD method, PBD method and SR method. CONCLUSION: The expanded BSD method used in three treatments with equal proportion has good comprehensive performance, and it can be the recommended randomization method for clinical trials of three treatments with equal proportion.

Association between Crohn's disease and frailty: a bidirectional Mendelian randomization study / 预防医学

Objective @#o evaluate the association between Crohn's disease (CD) and frailty using a Mendelian randomization (MR) approach, so as to provide the evidence for prevention and control strategies.@*Methods@#Genetic association data for CD were collected through the International Inflammatory Bowel Disease Genetics Consortium, with 20 883 samples and 12 276 506 single nucleotide polymorphism (SNP), and genetic association data for frailty were collected through a meta-analysis including 175 226 samples and 7 589 717 SNPs. A forward MR analysis was performed using the inverse-variance weighted (IVW) method with 37 CD-associated SNPs as instrumental variables, and frailty as the study outcome, and a reverse MR analysis was performed with 13 frailty-associated SNPs as instrumental variables and CD as the study outcome. The heterogeneity was assessed using the Cochran's Q test, and the horizontal pleiotropy was assessed using the MR-PRESSO global test and MR-Egger regression. In addition, the robustness of the results was verified with the leave-one-out. @*Results@#Forward MR analysis results showed that patients with genetically predicted CD had an increased risk of frailty index relative to those without CD (β=0.018, 95%CI: 0.011-0.026, P<0.05). Cochran's Q test detected no heterogeneity (P>0.05), and neither the MR-PRESSO test nor the MR-Egger regression revealed horizontal pleiotropy of instrumental variables (both P>0.05). Leave-one-out analysis showed robustness of the MR analysis results. Reverse MR analysis showed no association between frailty index and the risk of CD (OR=0.740, 95%CI: 0.206-2.661, P>0.05). @*Conclusions@#Genetically predicted CD is associated with an increased risk of frailty. It is suggested that screening and prevention of frailty should be reinforced among CD patients.

Association between gut microbiome and intracerebral hemorrhage based on genome-wide association study data / 中南大学学报(医学版)

OBJECTIVES@#Intracerebral hemorrhage (ICH) has the highest mortality and disability rates among various subtypes of stroke. Previous studies have shown that the gut microbiome (GM) is closely related to the risk factors and pathological basis of ICH. This study aims to explore the causal effect of GM on ICH and the potential mechanisms.@*METHODS@#Genome wide association study (GWAS) data on GM and ICH were obtained from Microbiome Genome and International Stroke Genetics Consortium. Based on the GWAS data, we first performed Mendelian randomization (MR) analysis to evaluate the causal association between GM and ICH. Then, a conditional false discovery rate (cFDR) method was conducted to identify the pleiotropic variants.@*RESULTS@#MR analysis showed that Pasteurellales, Pasteurellaceae, and Haemophilus were negatively correlated with the risk of ICH, whileVerrucomicrobiae, Verrucomicrobiales, Verrucomicrobiaceae, Akkermansia, Holdemanella, and LachnospiraceaeUCG010 were positively correlated with ICH. By applying the cFDR method, 3 pleiotropic loci (rs331083, rs4315115, and rs12553325) were found to be associated with both GM and ICH.@*CONCLUSIONS@#There is a causal association and pleiotropic variants between GM and ICH.

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 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 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.