Multivariable Mendelian Randomization Analysis Research Articles

Risk Factors for Intracerebral Hemorrhage: Genome-Wide Association Study and Mendelian Randomization Analyses.

The genetic and nongenetic causes of intracerebral hemorrhage (ICH) remain obscure. The present study aimed to uncover the genetic and modifiable risk factors for ICH. We meta-analyzed genome-wide association study data from 3 European biobanks, involving 7605 ICH cases and 711 818 noncases, to identify the genomic loci linked to ICH. To uncover the potential causal associations of cardiometabolic and lifestyle factors with ICH, we performed Mendelian randomization analyses using genetic instruments identified in previous genome-wide association studies of the exposures and ICH data from the present genome-wide association study meta-analysis. We performed multivariable Mendelian randomization analyses to examine the independent associations of the identified risk factors with ICH and evaluate potential mediating pathways. We identified 1 ICH risk locus, located at the APOE genomic region. The lead variant in this locus was rs429358 (chr19:45411941), which was associated with an odds ratio of ICH of 1.17 (95% CI, 1.11-1.20; P=6.01×10-11) per C allele. Genetically predicted higher levels of body mass index, visceral adiposity, diastolic blood pressure, systolic blood pressure, and lifetime smoking index, as well as genetic liability to type 2 diabetes, were associated with higher odds of ICH after multiple testing corrections. Additionally, a genetic increase in waist-to-hip ratio and liability to smoking initiation were consistently associated with ICH, albeit at the nominal significance level (P<0.05). Multivariable Mendelian randomization analysis showed that the association between body mass index and ICH was attenuated on adjustment for type 2 diabetes and further that type 2 diabetes may be a mediator of the body mass index-ICH relationship. Our findings indicate that the APOE locus contributes to ICH genetic susceptibility in European populations. Excess adiposity, elevated blood pressure, type 2 diabetes, and smoking were identified as the chief modifiable cardiometabolic and lifestyle factors for ICH.

A Causal Relationship Between Type 1 Diabetes and Risk of Osteoporosis: A Univariable and Multivariable Mendelian Randomization Study

Objective: This Mendelian randomization (MR) analysis aims to investigate the causal relationship between type 1 diabetes (T1D) and osteoporosis (OP).Methods: Single nucleotide polymorphisms (SNPs) associated with T1D were selected from the summary statistics of the genome-wide association study (GWAS) in European ancestry as instrumental variables (IVs) for univariable MR (UVMR) to explore the causal relationship between T1D and OP. Inverse variance weighting (IVW) was the primary method used to assess possible causality between T1D and OP. MR-PRESSO and MR-Egger intercepts were used to assess the horizontal pleiotropy of the IVs, and Q tests and the “leave-one-out” method were used to test for heterogeneity of MR results. Multivariable MR (MVMR) analysis was used to account for potential confounders such as smoking, obesity, drinking, and serum 25-hydroxyvitamin D (25OHD) concentrations.Result: Inverse variance weighted estimates suggest T1D may increase risk of OP (UVMR: OR=1.06, 95% CI: 1.02–1.10, p=0.002) (MVMR: OR=1.50, 95% CI: 1.07–1.90, p&lt;0.001).Conclusion: Our findings suggest that T1D can increase the risk of OP.

Causality of Helicobacter pylori infection on eosinophilic esophagitis and potential pathogenesis: a Mendelian randomization study

BackgroundObservational studies have indicated a possible connection between Helicobacter pylori (H. pylori) infection and eosinophilic esophagitis (EoE), but their causal relationship has yet to be established. To investigate the causal associations between H. pylori infection and EoE, we performed a Mendelian randomization (MR) analysis.MethodsFirstly, we conducted both univariable and multivariable Mendelian randomization (MR) analyses. Furthermore, a two-step MR was carried out to ascertain the potential underlying pathways of these associations, particularly the involvement of inflammatory cytokines. We employed the inverse-variance weighted (IVW) method as the main analysis in our MR study. To enhance the credibility of the results, we also conducted several sensitivity analyses.ResultsOur study demonstrated a noteworthy correlation between genetically predicted anti-H. pylori IgG antibody levels and a reduced risk of EoE (OR=0.325, 95% CI=0.165–0.643, P value=0.004, adj p value=0.009). No significant causal associations were detected between other H. pylori antibodies and EoE in our study. When it comes to multivariable MR analysis controlling for education attainment, household income, and deprivation individually, the independent causal impact of anti-H. pylori IgG on EoE persisted. Surprisingly, the two-step MR analysis indicated that inflammatory factors (IL-4, IL-5, IL-13, IL-17, and IFN-γ) did not appear to mediate the protective effect of H. pylori infection against EoE.ConclusionFindings suggested that among the range of H. pylori-related antibodies, anti-H. pylori IgG antibody is the sole causal factor associated with protection against EoE. Certain inflammatory factors may not be involved in mediating this association. These findings make a significant contribution to advancing our understanding of the pathogenesis of EoE and its evolving etiology.

Genetic insights into the role of cathepsins in cardiovascular diseases: a Mendelian randomization study.

This study aimed to explore the causal relationships between cathepsins and cardiovascular diseases (CVDs) by Mendelian randomization (MR) analysis. Single nucleotide polymorphisms (SNPs) associated with nine cathepsin types (cathepsins B, E, F, G, H, O, S, L2, and Z) were obtained from the INTERVAL study (3301 individuals). CVDs data were acquired from the UK Biobank (coronary atherosclerosis: 14334 cases, 346860 controls) and a genome-wide association study (GWAS) (myocardial infarction: 20917 cases, 440906 controls; myocarditis: 633 cases, 427278 controls; chronic heart failure: 14262 cases, 471898 controls; angina pectoris: 30025 cases, 440906 controls; stable angina pectoris: 17894 cases, 325132 controls; unstable angina pectoris: 9481 cases, 446987 controls; pericarditis: 1795 cases, 453370 controls). Inverse variance weighted (IVW), MR-Egger, weighted median methods were adopted to conduct univariable MR (UVMR), reverse MR, multivariable MR (MVMR) analyses to estimate causality. The UVMR analyses demonstrated significant causal relationships between higher cathepsin E levels and increased risk of coronary atherosclerosis [IVW: P=0.0051, odds ratio (OR)=1.0033, 95% confidence interval (CI)=1.0010-1.0056] and myocardial infarction (IVW: P=0.0097, OR=1.0553, 95% CI=1.0131-1.0993), while elevated cathepsin L2 levels were causally related to reduced risk of myocarditis (IVW: P=0.0120, OR=0.6895, 95% CI=0.5158-0.9216) and chronic heart failure (IVW: P=0.0134, OR=0.9316, 95% CI=0.8807-0.9854). Reverse MR analyses revealed that myocardial infarction increased cathepsin O levels (IVW: P=0.0400, OR=1.0708, 95% CI=1.0031-1.1431). MVMR analyses treating nine cathepsins together revealed that the positive causality between cathepsin E levels and coronary atherosclerosis risk (IVW: P=0.0390, OR=1.0030, 95% CI=1.0000-1.0060), and the protective effect of cathepsin L2 levels on myocarditis (IVW: P=0.0030, OR=0.6610, 95% CI=0.5031-0.8676) and chronic heart failure (IVW: P=0.0090, OR=0.9259, 95% CI=0.8737-0.9812) remained, as higher cathepsin O levels were found to be causally related to increased risks of myocarditis (IVW: P=0.0030, OR=1.6145, 95% CI=1.1829-2.2034) and chronic heart failure (IVW: P=0.0300, OR=1.0779, 95% CI=1.0070-1.1537). The study highlights the causalities of cathepsin E, L2, and O on CVDs, offering insights into their roles in cardiovascular biomarkers and therapeutic targets development. Further research is required to apply these genetic findings clinically.

Lipids, apolipoproteins and gestational diabetes mellitus: a Mendelian randomization study

BackgroundThis study investigates the causal relationship between lipid traits and GDM in an effort to better understand the aetiology of GDM.MethodsEmploying a two-sample Mendelian Randomization (MR) framework, we used Single Nucleotide Polymorphisms (SNPs) as instrumental variables to examine the impact of lipids and apolipoproteins on GDM. The research comprised univariable and multivariable MR analyses, with a prime focus on individual and combined effects of lipid-related traits. Statistical techniques included the fixed-effect inverse variance weighted (IVW) method and supplementary methods such as MR-Egger for comprehensive assessment.ResultsOur findings revealed the following significant associations: apoA-I and HDL cholesterol were inversely correlated with GDM risk, while triglycerides showed a positive correlation. In multivariable analysis, apoA-I consistently exhibited a strong causal link with GDM, even after adjusting for other lipids and Body Mass Index (BMI).ConclusionThe study demonstrates a significant causal relationship between apoA-I and GDM risk.

Exploring Putative Causal Associations between Diet and Periodontal Disease Susceptibility.

Dietary factors may play an important role in periodontal health. However, current evidence from observational studies remains inconclusive. This study aimed to investigate the causal relationships between dietary exposures and periodontal disease risks using Mendelian randomization analysis. Large-scale genome-wide association study summary statistics for 20 dietary factors were obtained from the MRC-IEU consortium. Multivariable and univariable 2-sample Mendelian randomization analyses were performed to assess the causal effects of each dietary exposure on 6 periodontal outcomes, including gingivitis and periodontitis. Genetically predicted higher dried fruit intake was significantly associated with reduced risks of acute gingivitis (odds ratio [OR]: 0.02; 95% confidence interval [CI]: 0.00-0.42; P = 0.01) and bleeding gums (OR: 0.96; 95% CI: 0.93-0.99; P = 0.01). Higher fresh fruit and water intake showed protective effects against chronic gingivitis (OR: 0.18; 95% CI: 0.04-0.91; P = 0.04 and OR: 0.15; 95% CI: 0.04-0.53; P = 0.00) and bleeding gums (OR: 0.95; 95% CI: 0.92-0.981; P = 0.00 and OR: 0.98; 95% CI: 0.96-0.99; P = 0.02). Alcohol intake frequency and processed meat intake were risk factors for bleeding gums (OR: 1.01; 95% CI: 1.00-1.02; P = 0.01 and OR: 1.05; 95% CI: 1.01-1.08; P = 0.00) and painful gums (OR: 1.01; 95% CI: 1.00-1.01; P = 0.00 and OR: 1.02; 95% CI: 1.01-1.03; P = 0.00). Most of the causal relationships between genetic predisposition to the specified dietary factors and periodontal diseases remained statistically significant (P < 0.05) after adjusting for genetic risks associated with dentures, smoking, and type 2 diabetes in multivariable Mendelian randomization models. The findings suggest potential protective effects of higher fruit and water intake against gingivitis and other periodontal problems, while alcohol and processed meat intake may increase the risks of periodontal disease. Our study provides preliminary causal evidence on the effects of diet on periodontal health and could inform prevention strategies targeting dietary habits to improve oral health. This study suggests that fruit and water intake may protect against periodontal disease, while alcohol and processed meats increase risk, informing dietary guidelines to improve oral health.

Association Between Neuroinflammation and Parkinson's Disease: A Comprehensive Mendelian Randomization Study.

The objective of the study is to determine the causal relationship and potential mechanisms between Parkinson's disease (PD) and neuroinflammatory and neurotoxic mediators. We conducted two-sample Mendelian randomization (2SMR) study and multivariable Mendelian randomization (MVMR) analysis to investigate the causality between PD and neuroinflammatory and neurotoxic mediators. The mediation analysis with MR was also conducted to determine the potential mediating effect of neuroinflammatory and neurotoxic mediators between asthma and PD. Genetically predicted levels of nine neuroinflammation were associated with changes in PD risk. The associations of PD with CCL24, galectin-3 levels, haptoglobin, and Holo-Transcobalamin-2 remained significant in multivariable analyses. The mediation analysis with MR revealed that asthma affects PD through CCL24 and galectin-3. The results showed neuroinflammation could affect the pathogenesis of PD. In the combined analysis of these nine variables, CCL24, galectin-3 levels, HP, and Holo-Transcobalamin-2 alone were found to be significant. Asthma plays an intermediary role through CCL24 and galectin-3 levels.

Association between autoimmune liver diseases and chronic hepatitis B: A multivariable Mendelian randomization study in European population

BackgroundObservational studies have indicated a link between autoimmune liver diseases (AILD) and chronic hepatitis B (CHB) through observational studies. The association between AILD and CHB remains indeterminate. MethodsA two-sample Mendelian randomization (MR) analysis was conducted to scrutinize the causal nexus between AILD and CHB utilizing summary statistics derived from extensive genome-wide association studies (GWASs) in European populations. The primary statistical methodology employed was the inverse variance-weighted (IVW) method to deduce the causal connection of AILD on CHB. This study incorporated primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and autoimmune hepatitis (AIH) as subtypes of AILD. Additionally, we conducted a multivariable MR (MVMR) analysis to account for the potential confounding effects of smoking, alcohol consumption, body mass index (BMI), and some autoimmune diseases. ResultsOur MR investigation encompassed a cohort of 725,816 individuals. The MR analysis revealed that genetically predicted PSC significantly correlated with a reduced risk of CHB (IVW OR = 0.857; 95%CI: 0.770–0.953, P = 0.005). Conversely, the reverse MR analysis suggested that genetic susceptibility to PSC might not modify the risk of CHB (IVW OR = 1.004; 95% CI: 0.958–1.053, P = 0.866). Genetically proxied PBC and AIH exhibited no discernible causal association with CHB in the MR analysis using the IVW method (P = 0.583; P = 0.425). The MVMR analysis still indicated a decreased risk of CHB associated with PSC (OR = 0.853, P = 0.003). ConclusionOur study elucidates a causal relationship between PSC and a diminished risk of CHB.

Periodontal disease increases the severity of chronic obstructive pulmonary disease: a Mendelian randomization study

BackgroundRecent research suggests that periodontitis can increase the risk of chronic obstructive pulmonary disease (COPD). In this study, we performed two-sample Mendelian randomization (MR) and investigated the causal effect of periodontitis (PD) on the genetic prediction of COPD. The study aimed to estimate how exposures affected outcomes.MethodsPublished data from the Gene-Lifestyle Interaction in the Dental Endpoints (GLIDE) Consortium’s genome-wide association studies (GWAS) for periodontitis (17,353 cases and 28,210 controls) and COPD (16,488 cases and 169,688 controls) from European ancestry were utilized. This study employed a two-sample MR analysis approach and applied several complementary methods, including weighted median, inverse variance weighted (IVW), and MR-Egger regression. Multivariable Mendelian randomization (MVMR) analysis was further conducted to mitigate the influence of smoking on COPD.ResultsWe chose five single-nucleotide polymorphisms (SNPs) as instrumental variables for periodontitis. A strong genetically predicted causal link between periodontitis and COPD, that is, periodontitis as an independent risk factor for COPD was detected. PD (OR = 1.102951, 95% CI: 1.005–1.211, p = 0.039) MR-Egger regression and weighted median analysis results were coincident with those of the IVW method. According to the sensitivity analysis, horizontal pleiotropy’s effect on causal estimations seemed unlikely. However, reverse MR analysis revealed no significant genetic causal association between COPD and periodontitis. IVW (OR = 1.048 > 1, 95%CI: 0.973–1.128, p = 0.2082) MR Egger (OR = 0.826, 95%CI:0.658–1.037, p = 0.1104) and weighted median (OR = 1.043, 95%CI: 0.941–1.156, p = 0.4239). The results of multivariable Mendelian randomization (MVMR) analysis, after adjusting for the confounding effect of smoking, suggest a potential causal relationship between periodontitis and COPD (P = 0.035).ConclusionIn this study, periodontitis was found to be independent of COPD and a significant risk factor, providing new insights into periodontitis-mediated mechanisms underlying COPD development.

The possible causal relationship between COVID-19 and imaging markers of cerebral small vessel disease: a Mendelian randomization study

ABSTRACT Objectives Observational studies have suggested that SARS-CoV-2 infection may increase the burden of cerebral small vessel disease (CSVD). This study aims to explore the causal correlation between COVID-19 and the imaging markers of CSVD using Mendelian randomization (MR) methods. Methods Summary-level genome-wide association study (GWAS) statistics for COVID-19 susceptibility, hospitalization, and severity were utilized as proxies for exposure. Large-scale meta-analysis GWAS data on three neuroimaging markers of white matter hyperintensity, lacunar stroke, and brain microbleeds, were employed as outcomes. Our primary MR analysis employed the inverse variance weighted (IVW) approach, supplemented by MR-Egger, weighted median, and MR-PRESSO methods. We also conducted multivariable MR analysis to address confounding bias and validate the robustness of the established causal estimates. Comprehensive sensitivity analyses included Cochran’s Q test, Egger-intercept analysis, MR-PRESSO, and leave-one-out analysis. Results The MR analysis revealed a significant causal correlation between the severity of COVID-19 and an increased risk of lacunar stroke, as demonstrated by the IVW method (ORivw = 1.08, 95% CI: 1.03–1.16, pivw = 0.005, FDR = 0.047). Nevertheless, no causal correlations were observed between COVID-19 susceptibility or hospitalization and any CSVD imaging markers. The robustness and stability of these findings were further confirmed by multivariable MR analysis and comprehensive sensitivity analyses. Discussion This study provides compelling evidence of a potential causal effect of severe COVID-19 on the incidence of lacunar stroke, which may bring fresh insights into the understanding of the comorbidity between COVID-19 and CSVD.

Causal relationship between air pollution, lung function, gastroesophageal reflux disease, and non-alcoholic fatty liver disease: univariate and multivariate Mendelian randomization study.

The association between air pollution, lung function, gastroesophageal reflux disease, and Non-alcoholic fatty liver disease (NAFLD) remains inconclusive. Previous studies were not convincing due to confounding factors and reverse causality. We aim to investigate the causal relationship between air pollution, lung function, gastroesophageal reflux disease, and NAFLD using Mendelian randomization analysis. In this study, univariate Mendelian randomization analysis was conducted first. Subsequently, Steiger testing was performed to exclude the possibility of reverse association. Finally, significant risk factors identified from the univariate Mendelian analysis, as well as important factors affecting NAFLD from previous observational studies (type 2 diabetes and body mass index), were included in the multivariable Mendelian randomization analysis. The results of the univariable Mendelian randomization analysis showed a positive correlation between particulate matter 2.5, gastroesophageal reflux disease, and NAFLD. There was a negative correlation between forced expiratory volume in 1 s, forced vital capacity, and NAFLD. The multivariable Mendelian randomization analysis indicated a direct causal relationship between gastroesophageal reflux disease (OR = 1.537, p = 0.011), type 2 diabetes (OR = 1.261, p < 0.001), and NAFLD. This Mendelian randomization study confirmed the causal relationships between air pollution, lung function, gastroesophageal reflux, and NAFLD. Furthermore, gastroesophageal reflux and type 2 diabetes were identified as independent risk factors for NAFLD, having a direct causal connection with the occurrence of NAFLD.

Large-scale genome-wide association studies reveal the genetic causal etiology between air pollutants and autoimmune diseases

BackgroundEpidemiological evidence links a close correlation between long-term exposure to air pollutants and autoimmune diseases, while the causality remained unknown.MethodsTwo-sample Mendelian randomization (TSMR) was used to investigate the role of PM10, PM2.5, NO2, and NOX (N = 423,796–456,380) in 15 autoimmune diseases (N = 14,890–314,995) using data from large European GWASs including UKB, FINNGEN, IMSGC, and IPSCSG. Multivariable Mendelian randomization (MVMR) was conducted to investigate the direct effect of each air pollutant and the mediating role of common factors, including body mass index (BMI), alcohol consumption, smoking status, and household income. Transcriptome-wide association studies (TWAS), two-step MR, and colocalization analyses were performed to explore underlying mechanisms between air pollution and autoimmune diseases.ResultsIn TSMR, after correction of multiple testing, hypothyroidism was causally associated with higher exposure to NO2 [odds ratio (OR): 1.37, p = 9.08 × 10–4] and NOX [OR: 1.34, p = 2.86 × 10–3], ulcerative colitis (UC) was causally associated with higher exposure to NOX [OR: 2.24, p = 1.23 × 10–2] and PM2.5 [OR: 2.60, p = 5.96 × 10–3], rheumatoid arthritis was causally associated with higher exposure to NOX [OR: 1.72, p = 1.50 × 10–2], systemic lupus erythematosus was causally associated with higher exposure to NOX [OR: 4.92, p = 6.89 × 10–3], celiac disease was causally associated with lower exposure to NOX [OR: 0.14, p = 6.74 × 10–4] and PM2.5 [OR: 0.17, p = 3.18 × 10–3]. The risky effects of PM2.5 on UC remained significant in MVMR analyses after adjusting for other air pollutants. MVMR revealed several common mediators between air pollutants and autoimmune diseases. Transcriptional analysis identified specific gene transcripts and pathways interconnecting air pollutants and autoimmune diseases. Two-step MR revealed that POR, HSPA1B, and BRD2 might mediate from air pollutants to autoimmune diseases. POR pQTL (rs59882870, PPH4=1.00) strongly colocalized with autoimmune diseases.ConclusionThis research underscores the necessity of rigorous air pollutant surveillance within public health studies to curb the prevalence of autoimmune diseases.Graphical abstract (Built by the Biorender)

Dissecting the genetic and causal relationship between sleep-related traits and common brain disorders

BackgroundThere is a profound connection between abnormal sleep patterns and brain disorders, suggesting a shared influential association. However, the shared genetic basis and potential causal relationships between sleep-related traits and brain disorders are yet to be fully elucidated. MethodsUtilizing linkage disequilibrium score regression (LDSC) and bidirectional two-sample univariable Mendelian Randomization (UVMR) analyses with large-scale GWAS datasets, we investigated the genetic correlations and causal associations across six sleep traits and 24 prevalent brain disorders. Additionally, a multivariable Mendelian Randomization (MVMR) analysis evaluated the cumulative effects of various sleep traits on each brain disorder, complemented by genetic loci characterization to pinpoint pertinent genes and pathways. ResultsLDSC analysis identified significant genetic correlations in 66 out of 144 (45.8 %) pairs between sleep-related traits and brain disorders, with the most pronounced correlations observed in psychiatric disorders (66 %, 48/72). UVMR analysis identified 29 causal relationships (FDR<0.05) between sleep traits and brain disorders, with 19 associations newly discovered according to our knowledge. Notably, major depression, attention-deficit/hyperactivity disorder, bipolar disorder, cannabis use disorder, and anorexia nervosa showed bidirectional causal relations with sleep traits, especially insomnia's marked influence on major depression (IVW beta 0.468, FDR = 5.24E-09). MVMR analysis revealed a nuanced interplay among various sleep traits and their impact on brain disorders. Genetic loci characterization underscored potential genes, such as HOXB2, while further enrichment analyses illuminated the importance of synaptic processes in these relationships. ConclusionsThis study provides compelling evidence for the causal relationships and shared genetic backgrounds between common sleep-related traits and brain disorders.

Causal associations between estradiol and mouth ulcers: A Mendelian randomization study.

People have difficulty in eating and speaking when they are suffering from mouth ulcers. Some studies suggest that estradiol is associated with the development and treatment of mouth ulcers, while some do not. To clarify the effect of estradiol on mouth ulcers, we performed 2-sample Mendelian randomization and multivariable Mendelian randomization (MVMR) analysis to evaluate their relationship. Data were obtained from the IEU OpenGWAS project and UK biobank, including male estradiol dataset (case/controls = 13,367/134,323), female estradiol dataset (case/controls = 37,461/126,524), mouth ulcers dataset (case/controls = 47,102/414,011). The causal associations were estimated by MR-Egger, weighted median, inverse-variance weighted (IVW) method, simple mode, and weighted mode. Cochran Q test, MR-Egger intercept test, MR-PRESSO tests, and leave-one-out analysis were used to examine sensitivity analyses. The MVMR controlling for depression, anxiety or panic attacks, severe stress and adjustment disorders was used to assess the effect of estradiol on mouth ulcers. Through screening, 13 single nucleotide polymorphisms (SNPs) of males and 2 SNPs of females in estradiol were used for harmonizing and MR analysis. The 2-sample MR analysis showed no causal association between estradiol of males and mouth ulcers (IVW, OR: 0.998, 95% confidence interval [95% CI]: 0.995-1.001, P = .18). Similar results were obtained between estradiol of females and mouth ulcers (IVW, OR: 1.000, 95% CI: 0.988-1.012, P = .97). No pleiotropy and heterogeneity were found and the results were robust (P > .05). After adjusting for the potential effects of confounders, estradiol of males and mouth ulcers still showed no causal association through MVMR analysis (P = .081). While MVMR analysis showed that the causal relationship between estradiol and mouth ulcers in women could not be statistical for the small number of SNPs. There was no evidence of a causal relationship between estradiol and mouth ulcers. The strategy of treating mouth ulcers with estradiol still needs to be confirmed by more studies.

Aminotransferases as causal factors for metabolic syndrome: A bidirectional Mendelian randomization study.

Circulating aminotransferases (ALT and AST) have been used as biomarkers for liver injury. The causal relationships between aminotransferases and metabolic syndrome remain ambiguous. We conducted bidirectional and multivariable Mendelian randomization (MR) analyses between aminotransferases and traits related to metabolic syndrome using genetic variants obtained from genome-wide association studies (GWASs). MR-PRESSO tests were adopted to remove outliers and eliminate pleiotropy. MR steiger tests were conducted to ensure the correct direction of the causal effects. Both aminotransferases were risk factors for essential hypertension. ALT is a risk factor for type 2 diabetes. The bidirectional causal relationship between ALT and hyperglycemia, serum lipids, and obesity was demonstrated. The effect of fasting glucose on AST was demonstrated, while type 2 diabetes did not affect AST. The effect of HDL-C on ALT and the effect of triglycerides on AST were found in multivariable MR analyses. Our bidirectional MR analyses suggest that ALT and AST are causally associated with several metabolic syndrome-related traits, especially hypertension and type 2 diabetes. These findings highlight the potential role of aminotransferases as biomarkers and therapeutic targets for metabolic syndrome.

Causal associations of cognition, intelligence, education, health and lifestyle factors with cervical spondylosis: a mendelian randomization study.

Background: Education, cognition, and intelligence are phenotypically and genetically related. Education has been shown to have a protective effect on the risk of developing cervical spondylosis. However, it is unclear whether cognition and intelligence have independent causal effects on cervical spondylosis, and whether health and lifestyle factors influence this association. Methods: We first assessed the independent effects of education, cognition, and intelligence on cervical spondylosis by two-sample Mendelian randomization and multivariable Mendelian randomization analysis, and evaluated 26 potential association mediators using two-step Mendelian randomization, and calculated the median proportion. Results: The results showed that only education had an independent causal effect on cervical spondylosis, and had a protective effect on the risk of cervical spondylosis (β: 0.3395; se: 0.166; p < 0.05; OR:0.71; [95%CI: 0.481-0.943]. Of the 26 potential associated mediators, a factor was identified: SHBG (mediated proportion: 2.5%). Univariable Mendelian randomization results showed that the risk factors for cervical spondylosis were time spent watching TV (OR:1.96; [95%CI: 1.39-2.76]), smoking (OR:2.56; [95%CI: 1.061-1.486]), body mass index (OR:1.26; [95%CI: 1.124-1.418]), percentage of body fat (OR:1.32; [95%CI: 1.097-1.593]), major depression (OR:1.27; [95%CI: 1.017-1.587]) and sitting height (OR:1.15; [95%CI: 1.025-1.291]). Protective factors include computer using (OR:0.65; [95%CI: 0.418-0.995]), sex hormone binding globulin (OR:0.87; [95%CI: 0.7955-0.951]) and high-density lipoprotein (OR:0.90; [95%CI: 0.826-0.990]). Conclusion: Our findings demonstrate the causal and independent effects of education on cervical spondylosis and suggest that lifestyle media may be a priority target for the prevention of cervical spondylosis due to low educational attainment.

An exploration of causal relationships between nine neurological diseases and the risk of breast cancer: a Mendelian randomization study.

Some preceding researches have observed that certain neurological disorders, such as Alzheimer's disease and multiple sclerosis, may affect breast cancer risk. However, whether there are causal relationships between these neurological conditions and breast cancer is inconclusive. This study was designed to explore whether neurological disorders affected the risks of breast cancer overall and of the two subtypes (ER+ and ER-). In the course of this study, genome-wide association study (GWAS) data for nine neurological diseases (Alzheimer's disease, multiple sclerosis, Parkinson's disease, myasthenia gravis, generalized epilepsy, intracerebral haemorrhage, cerebral atherosclerosis, brain glioblastoma, and benign meningeal tumour) were collected from the Complex Trait Genetics lab and the MRC Integrative Epidemiology Unit, and single-nucleotide polymorphisms (SNPs) extensively associated with these neurological ailments had been recognized as instrumental variables (IVs). GWAS data on breast cancer were collected from the Breast Cancer Association Consortium (BCAC). Two-sample Mendelian randomization (MR) analyses as well as multivariable MR analyses were performed to determine whether these SNPs contributed to breast cancer risk. Additionally, the accuracy of the results was evaluated using the false discovery rate (FDR) multiple correction method. Both heterogeneity and pleiotropy were evaluated by analyzing sensitivities. According to the results of two-sample MR analyses, Alzheimer's disease significantly reduced the risks of overall (OR 0.925, 95% CI [0.871-0.982], P = 0.011) and ER+ (OR 0.912, 95% CI [0.853-0.975], P = 0.007) breast cancer, but there was a negative result in ER- breast cancer. However, after multiple FDR corrections, the effect of Alzheimer's disease on overall breast cancer was not statistically significant. In contrast, multiple sclerosis significantly increased ER+ breast cancer risk (OR 1.007, 95% CI [1.003-1.011], P = 0.001). In addition, the multivariable MR analyses showed that Alzheimer's disease significantly reduced the risk of ER+ breast cancer (IVW: OR 0.929, 95% CI [0.864-0.999], P=0.047; MR-Egger: OR 0.916, 95% CI [0.846-0.992], P=0.031); however, multiple sclerosis significantly increased the risk of ER+ breast cancer (IVW: OR 1.008, 95% CI [1.003-1.012], P=4.35×10-4; MR-Egger: OR 1.008, 95% CI [1.003-1.012], P=5.96×10-4). There were no significant associations between the remainder of the neurological diseases and breast cancer. This study found the trends towards a decreased risk of ER+ breast cancer in patients with Alzheimer's disease and an increased risk in patients with multiple sclerosis. However, due to the limitations of Mendelian randomization, we cannot determine whether there are definite causal relationships between neurological diseases and breast cancer risk. For conclusive evidences, more prospective randomized controlled trials will be needed in the future.

Metabolome-wide Mendelian randomization reveals causal effects of betaine and N-acetylornithine on impairment of renal function.

Chronic kidney disease (CKD) is a common public health problem, which is characterized as impairment of renal function. The associations between blood metabolites and renal function remained unclear. This study aimed to assess the causal effect of various circulation metabolites on renal function based on metabolomics. We performed a two-sample Mendelian randomization (MR) analysis to estimate the causality of genetically determined metabolites on renal function. A genome-wide association study (GWAS) of 486 metabolites was used as the exposure, while summary-level data for creatinine-based estimated glomerular filtration rate (eGFR) or CKD occurrence were set the outcomes. Inverse variance weighted (IVW) was used for primary causality analysis and other methods including weight median, MR-egger, and MR-PRESSO were applied as complementary analysis. Cochran Q test, MR-Egger intercept test, MR-PRESSO global test and leave-one-out analysis were used for sensitivity analysis. For the identified metabolites, reverse MR analysis, linkage disequilibrium score (LDSC) regression and multivariable MR (MVMR) analysis were performed for further evaluation. The causality of the identified metabolites on renal function was further validated using GWAS data for cystatin-C-based eGFR. All statistical analyses were performed in R software. In this MR analysis, a total of 44 suggestive associations corresponding to 34 known metabolites were observed. After complementary analysis and sensitivity analysis, robust causative associations between two metabolites (betaine and N-acetylornithine) and renal function were identified. Reverse MR analysis showed no causal effects of renal function on betaine and N-acetylornithine. MVMR analysis revealed that genetically predicted betaine and N-acetylornithine could directly influence independently of each other. The causal effects of betaine and N-acetylornithine were also found on cystatin-C-based eGFR. Our study provided evidence to support the causal effects of betaine and N-acetylornithine on renal function. These findings required further investigations to conduct mechanism exploration and drug target selection of these identified metabolites.

Genetic correlation and causal associations between psychiatric disorders and lung cancer risk

BackgroundPatients with certain psychiatric disorders have increased lung cancer incidence. However, establishing a causal relationship through traditional epidemiological methods poses challenges. MethodsAvailable summary statistics of genome-wide association studies of cigarette smoking, lung cancer, and eight psychiatric disorders, including attention deficit/hyperactivity disorder (ADHD), autism, depression, major depressive disorder, bipolar disorder, insomnia, neuroticism, and schizophrenia (range N: 46,350-1,331,010) were leveraged to estimate genetic correlations using Linkage Disequilibrium Score Regression and assess causal effect of each psychiatric disorder on lung cancer using two-sample Mendelian randomization (MR) models, comprising inverse-variance weighted (IVW), weighted median, MR-Egger, pleiotropy residual sum and outlier testing (MR-PRESSO), and a constrained maximum likelihood approach (cML-MR). ResultsSignificant positive correlations were observed between each psychiatric disorder and both smoking and lung cancer (all FDR < 0.05), except for the correlation between autism and lung cancer. Both univariable and the cML-MA MR analyses demonstrated that liability to schizophrenia, depression, ADHD, or insomnia was associated with an increased risk of overall lung cancer. Genetic liability to insomnia was linked specifically to squamous cell carcinoma (SCC), while genetic liability to ADHD was associated with an elevated risk of both SCC and small cell lung cancer (all P < 0.05). The later was further supported by multivariable MR analyses, which accounted for smoking. LimitationsParticipants were constrained to European ancestry populations. Causal estimates from binary psychiatric disorders may be biased. ConclusionOur findings suggest appropriate management of several psychiatric disorders, particularly ADHD, may potentially reduce the risk of developing lung cancer.

Mendelian randomization of circulating proteome identifies IFN-γ as a druggable target in aplastic anemia.

Aplastic anemia (AA) is a kind of bone marrow failure (BMF) characterized by pancytopenia with hypoplasia/aplasia of bone marrow. Immunosuppressive therapy and bone marrow transplantation are effective methods to treat severe aplastic anemia. However, the efficacy is limited by complications and the availability of suitable donors. This study aimed to determine whether any circulating druggable protein levels may have causal effects on AA and provide potential novel drug targets for AA. Genetic variants strongly associated with circulating druggable protein levels to perform Mendelian randomization (MR) analyses were used. The effect of these druggable protein levels on AA risk was measured using the summary statistics from a large-scale proteomic genome-wide association study (GWAS) and FinnGen database ( https://www.finngen.fi/en/access_results ). Multivariable MR analyses were performed to statistically adjust for potential confounders, including platelet counts, reticulocyte counts, neutrophil counts, and proportions of hematopoietic stem cells. The data showed that higher level of circulating IFN-γ levels was causally associated with AA susceptibility. The causal effects of circulating IFN-γ levels on the AA were broadly consistent, when adjusted for platelet counts, reticulocyte counts, neutrophil counts and proportions of hematopoietic stem cells. High levels of circulating IFN-γ levels might increase the risk of AA and might provide a potential novel target for AA.