Mendelian Randomization Study Research Articles

Reassessing the Association of Sedentary Behavior and Physical Activity with Ischemic Stroke: A Mendelian Randomization Study

ABSTRACT Purpose Findings from previous Mendelian randomization (MR) studies disagreed with the current scientific consensus regarding the role of physical activity (PA) and sedentary behavior in ischemic stroke (IS). We reassessed these associations with a focus on etiological subtypes of IS and the potential mediating roles of cardiometabolic traits and brain imaging-derived phenotypes (IDPs). Methods We performed MR analyses using summary statistics from genome-wide association studies of sedentary behavior and PA (n = 88,411~608,595), cardiometabolic traits (n = 393,193~694,649), brain IDPs (n = 33,224) and the latest IS data (62,100 cases and 1,234,808 controls). Inverse-variance weighted regression was used as the primary method, complemented by several sensitivity analyses. A two-step MR approach was employed to assess the mediating effects of cardiometabolic traits and brain IDPs. Results Genetic liability to leisure-time moderate-to-vigorous PA (LTMVPA) and higher overall PA (OPA) were associated with reduced risks of IS and small vessel stroke (Benjamini–Hochberg adjusted P < 0.05). Suggestive associations were observed between longer leisure-screen time and higher IS risk and between higher OPA and lower cardioembolic stroke risk (P < 0.05). The isotropic volume fraction in the anterior limb of the left internal capsule (ALIC), as well as some cardiometabolic metrics, partially mediated these associations. There was no evidence for causal effects of overall MVPA, overall light-intensity PA or overall sedentary duration on IS. Conclusions Longer LST, less OPA and not engaging in moderate-to-vigorous PA during leisure time were associated with higher risk of ischemic stroke. The associations between PA and ischemic stroke depended on different subtypes and were mediated by changes in ALIC and cardiometabolic biomarkers.

The association between metabolic syndrome and lung cancer risk: a Mendelian randomization study

The association between metabolic syndrome and lung cancer risk: a Mendelian randomization study

Causal associations between gut Bifidobacteriaceae and transplant failure: a Mendelian randomization study

Causal associations between gut <i>Bifidobacteriaceae</i> and transplant failure: a Mendelian randomization study

Correlation between benign prostatic hyperplasia and comorbidities: a systematic analysis integrating global burden of disease and mendelian randomization study

Correlation between benign prostatic hyperplasia and comorbidities: a systematic analysis integrating global burden of disease and mendelian randomization study

Impact of diabetes mellitus on the risk of Alzheimer’s disease: a mendelian randomization study

Impact of diabetes mellitus on the risk of Alzheimer’s disease: a mendelian randomization study

Causal association of obesity-related anthropometric traits with myopia and the mediating role of educational attainment: a Mendelian randomization study

AIM: To study the causal relationship between obesity-related anthropometric traits and myopia and the mediating role of educational attainment (EA). METHODS: Univariable Mendelian randomization (UVMR) was performed to evaluate the causal association between body mass index (BMI), height, waist-hip ratio (WHR, adjusted for BMI), and mean spherical equivalent (MSE). BMI was divided into fat and fat-free mass and included in multivariable Mendelian randomization (MVMR) to explore the roles of different BMI components in the causal relationship between BMI and MSE. A mediation analysis based on two-step Mendelian randomization (MR) was carried out. Specifically, UVMR was conducted to estimate the causal effect of BMI on EA. The direct effect of EA on MSE was estimated from MVMR. The mediation effect of EA in the BMI-EA-MSE model was calculated by the product of coefficients method. Expression quantitative trait loci (eQTL)-MR, reverse MR, and Linkage Disequilibrium Score Regression (LDSC) were performed to assess the robustness. RESULTS: Genetically predicted higher BMI had a positive total effect on MSE (βIVW=0.26 D, 95%CI=0.14 to 0.37 D, P&amp;#x003C;0.001), whereas there was no significant association between height, WHR, and MSE. Fat mass was found to play a significant role in the effect of body mass on MSE (βIVW=0.50 D, 95%CI=0.21 to 0.78 D, P=0.001), but there was no significant association between fat-free mass and MSE. The causal effect of BMI on EA was -0.14 (95%CI=-0.16 to -0.11, P&amp;#x003C;0.001), and the direct effect of EA on MSE was -0.63 D (95%CI=-0.81 to -0.44 D, P&amp;#x003C;0.001). The mediating effect of EA in the BMI-EA-MSE model was 0.09 D (95%CI=0.06 to 0.12 D), with a mediation proportion of 33% (95%CI=22.1% to 44.6%). No reverse causal associations were detected except for BMI on EA. The results of eQTL-MR and LDSC were consistent with each MR analysis. CONCLUSION: Genetically predicted higher BMI decreases the degree of myopia with a 33% mediation proportion by EA, and fat mass provides a dominant protective role in body mass-myopia. As a supplement to previous observational studies, it provides strong evidence for the relationship between anthropometric traits and refractive errors and offers a theoretical basis for future measures to prevent and control myopia.

Powerful Test of Heterogeneity in Two‐Sample Summary‐Data Mendelian Randomization

ABSTRACTBackgroundThe success of a Mendelian randomization (MR) study critically depends on the validity of the assumptions underlying MR. We focus on detecting heterogeneity (also known as horizontal pleiotropy) in two‐sample summary‐data MR. A popular approach is to apply Cochran's statistic method, developed for meta‐analysis. However, Cochran's statistic, including its modifications, is known to lack power when its degrees of freedom are large. Furthermore, there is no theoretical justification for the claimed null distribution of the minimum of the modified Cochran's statistic with exact weighting (), although it seems to perform well in simulation studies.MethodThe principle of our proposed method is straightforward: if a set of variables are valid instruments, then any linear combination of these variables is still a valid instrument. Specifically, this principle holds when these linear combinations are formed using eigenvectors derived from a variance matrix. Each linear combination follows a known normal distribution from which a value can be calculated. We use the minimum value for these eigenvector‐based linear combinations as the test statistic. Additionally, we explore a modification of the modified Cochran's statistic by replacing the weighting matrix with a truncated singular value decomposition.ResultsExtensive simulation studies reveal that the proposed methods outperform Cochran's statistic, including those with modified weights, and MR‐PRESSO, another popular method for detecting heterogeneity, in cases where the number of instruments is not large or the Wald ratios take two values. We also demonstrate these methods using empirical examples. Furthermore, we show that does not follow, but is dominated by, the claimed null chi‐square distribution. The proposed methods are implemented in an R package iGasso.ConclusionsDimension reduction techniques are useful for generating powerful tests of heterogeneity in MR.

Inflammatory bowel disease and risk of ophthalmic inflammation-related diseases: a two-sample Mendelian randomization study

AIM: To investigate the causal effect of inflammatory bowel disease (IBD) on ocular inflammation using Mendelian randomization (MR) analysis. METHODS: Genetic instruments associated with inflammatory bowel disease (IBD), ulcerative colitis (UC), and Crohn's disease (CD) were derived from the largest genome-wide association studies (GWAS) published to date. The FinnGen research project was utilized to identify genetic risk variants associated with conjunctivitis, keratitis, iridocyclitis, chorioretinitis, episcleritis, and optic neuritis. All participants were of European ancestry. Three methods which included inverse variance weighting (IVW), weighted median (WM), and MR-Egger regression were performed to estimate the causal association in this study. IVW took the inverse variance of each study as the weight to calculate the weighted average of effect sizes, to summarize the effect sizes of multiple independent studies, which could provide the most precise estimated results. IVW was used as the primary outcome, while WM and MR-Egger were used to improve the estimation of IVW. RESULTS: A nominal causal effect of genetically predicted IBD on risk of non-infectious conjunctivitis, keratitis, iridocyclitis, and optic neuritis, but not on chorioretinitis or episcleritis. After Bonferroni correction, the results showed that genetically predicted UC was significantly associated with an increased risk of iridocyclitis (IVW: OR, 1.17; 95%CI, 1.10-1.24, P=2.54×10-7). CD was significantly associated with conjunctivitis (IVW: OR, 1.05; 95%CI, 1.03-1.08, P=3.20×10-5), keratitis (IVW: OR, 1.06; 95%CI, 1.02-1.09; P=1.13×10-3), and iridocyclitis (IVW: OR, 1.09; 95%CI, 1.04-1.14; P=1.43×10-4). CONCLUSION: IBD causally poses a risk of inflammation of conjunctiva, cornea, Iris-ciliary body complex, and optic neuritis. CD is more closely associated with the eye inflammation than UC. These impliy that the relationship of IBD and different parts of the eye structure are different, and provide novel evidence linking based on the association of the gut-eye axis.

Causal Link between Gut Microbiota and Infertility: A Two-sample Bidirectional Mendelian Randomization Study

Causal Link between Gut Microbiota and Infertility: A Two-sample Bidirectional Mendelian Randomization Study

Rumen microbiome and fat deposition in sheep: insights from a bidirectional mendelian randomization study

Rumen microbiome and fat deposition in sheep: insights from a bidirectional mendelian randomization study

Causality between autoimmune diseases and schizophrenia: a bidirectional Mendelian randomization study.

Observational studies have shown a link between autoimmune diseases and schizophrenia, with conflicting conclusions. Due to the existence of confounding factors, the causal link between autoimmune diseases and schizophrenia is still unknown. We conducted a comprehensive Mendelian randomization (MR) analysis of schizophrenia and ten common autoimmune diseases in individuals of European descent using genome-wide association studies (GWASs). To evaluate the relationships between autoimmune diseases and schizophrenia, inverse variance weighted, MR-RAPS, Bayesian weighted MR, constrained maximum likelihood, debiased IVW, MR-Egger, and weighted median were utilized. Several sensitivity analyses were performed to ensure the reliability of the study's results. Our findings reveal that genetically predicted ankylosing spondylitis is related to an increased risk of schizophrenia, whereas celiac disease, type 1 diabetes, and systemic lupus erythematosus are associated with a lower risk of schizophrenia. In the reverse MR analysis, our study indicated that genetically predicted schizophrenia is linked to higher risks of ankylosing spondylitis, Crohn's disease, ulcerative colitis, inflammatory bowel disease, and psoriasis. Neither multiple sclerosis nor rheumatoid arthritis have been linked to schizophrenia, and vice versa. Despite contradicting some other observational reports, this study showed support for a causal link between autoimmune diseases and schizophrenia. To gain a better understanding of the mechanisms underlying the development of immune-mediated schizophrenia, additional research is required to identify potential mechanisms identified in observational studies.

Association of B cells and the risk of Esophageal cancer: a bidirectional two-sample mendelian randomization study.

Currently, research on the role of B cells in esophageal cancer (EC) is limited, and existing studies on their impact are controversial. Therefore, this study was conducted to elucidate the complex causal relationship between B cells and EC, expand the understanding of esophageal cancer immunology. Bidirectional two-sample Mendelian randomization (MR) was performed to assess the causal relationships between 190 B cell phenotypes and EC. To complement the MR analysis, Bayesian Weighted Mendelian Randomization (BWMR) was employed, and sensitivity analyses were conducted to evaluate the robustness of the findings. Positive results were further validated in independent cohorts of esophageal cancer studies. In addition, RNA sequencing (RNA-seq) data from The Cancer Genome Atlas (TCGA) were utilized for validation, incorporating B cell-related gene expression analysis and functional enrichment analysis to support the MR findings. In the primary analysis, significant causal relationships were observed between 5 B cell types and the risk of EC; the onset of EC was causally linked to 3 B cell phenotypes. Validation in other cohorts revealed that 4 outcomes aligned with the primary analysis, included were CD19 on IgD + CD38-, CD20 on IgD- CD27-, CD20 on IgD- CD38br, and CD38 on PB/PC. Further validation using RNA-seq data showed that CD38 mRNA was significantly overexpressed in EC tissues, whereas CD19 and MS4A1 mRNA levels did not differ significantly between tumor and normal tissues. Functional enrichment analysis revealed that CD19, MS4A1, and CD38 are involved in multiple tumor-related immune pathways, suggesting their pivotal role in regulating the tumor immune microenvironment. Our study suggests a potential connection between B cell phenotypes and EC through bidirectional two-sample MR combined with BWMR analysis, providing a preliminary basis for future research.

Mendelian randomization analyses support causal relationships between gut microbiome and longevity.

Gut microbiome plays a significant role in longevity, and dysbiosis is indeed one of the hallmarks of aging. However, the causal relationship between gut microbiota and human longevity or aging remains elusive. Our study assessed the causal relationships between gut microbiome and longevity using Mendelian Randomization (MR). Summary statistics for the gut microbiome were obtained from four genome-wide association study (GWAS) meta-analysis of the MiBioGen consortium (N = 18,340), Dutch Microbiome Project (N = 7738), German individuals (N = 8956), and Finland individuals (N = 5959). Summary statistics for Longevity were obtained from Five GWAS meta-analysis, including Human healthspan (N = 300,447), Longevity (N = 36,745), Lifespans (N = 1,012,240), Parental longevity (N = 389,166), and Frailty (one of the primary aging-linked physiological hallmarks, N = 175,226). Our findings reveal several noteworthy associations, including a negative correlation between Bacteroides massiliensis and longevity, whereas the genus Subdoligranulum and Alistipes, as well as species Alistipes senegalensis and Alistipes shahii, exhibited positive associations with specific longevity traits. Moreover, the microbial pathway of coenzyme A biosynthesis I, pyruvate fermentation to acetate and lactate II, and pentose phosphate pathway exhibited positive associations with two or more traits linked to longevity. Conversely, the TCA cycle VIII (helicobacter) pathway consistently demonstrated a negative correlation with lifespan and parental longevity. Our findings of this MR study indicated many significant associations between gut microbiome and longevity. These microbial taxa and pathways may potentially play a protective role in promoting longevity or have a suppressive effect on lifespan.

The Gut Microbiota and Its Metabolites and Their Association with the Risk of Autoimmune Thyroid Disease: A Mendelian Randomization Study

Objectives: Observational research shows associations of the gut microbiota and its metabolites with autoimmune thyroid disease (AITD), but the causality is undetermined. Methods: Two-sample Mendelian randomization (MR) was employed to analyze the association of the gut microbiota and its metabolites with AITD. A total of 119 gut microbiotas and nine fecal/circulating metabolites were the exposures. AITD, Graves’ disease (GD), and Hashimoto’s thyroiditis (HT) were the outcomes. Inverse-variance weighting (IVW) was primarily used to assess causality; Cochran’s Q was used to assess heterogeneity. Sensitivity analyses (weighted median, MRPRESSO regression, MRPRESSO intercept, MRPRESSO global, Steiger filtering, leave-one-out) were conducted to assess causal estimate robustness. Multivariable MR (MVMR) was used to estimate the effects of body mass index (BMI) and alcohol consumption frequency on causality. Results: The outcomes were potentially causally associated with 22 gut microbiotas and three metabolites. After multiple-test correction, 3-indoleglyoxylic acid retained significant causality with AITD (IVW: odds ratio [OR] = 1.09, 95% confidence interval [CI] = 1.05–1.14, p = 2.43 × 10−5, FDR = 0.009). The sensitivity analyses were confirmatory (weighted median: OR = 1.06, 95% CI = 1.01–1.12, p = 0.025; MRPRESSO: OR = 1.09, 95% CI = 1.15–1.14, p = 0.001). MVMR revealed no confounding effects on this association (BMI: OR = 1.21, 95% CI =1.08–1.35, p = 0.001; drinks/week: OR = 1.22, 95% CI = 1.04–1.43, p = 0.014). Conclusions: MR revealed no significant causal effects of the gut microbiota on the outcomes. However, MR revealed the causal effects of 3-indoleglyoxylic acid on the risk of AITD.

The association between plasma lipidome and diabetic microangiopathy: a mendelian randomization study.

Current studies have identified severe lipid metabolism diseases in diabetic microangiopathy patients, especially in diabetic kidney disease (DKD), diabetic retinopathy (DR) and diabetic neuropathy (DN), with unclear causal relationships. We employed a large-scale dataset containing 179 lipid species as the exposure and large-scale public summary-level datasets of DKD, DR and DN as the outcome. We applied Mendelian randomization (MR) approach to explore causal associations between circulating liposomes and diabetic microangiopathy. A sequence of sensitivity tests was conducted to verify the stability of the MR analysis. We manifest that diacylglycerol (18:1_18:3) (OR = 0.716, 95%CI = 0.559-0.917, P = 0.008), triacylglycerol (OR:0.741-0.763, P < 0.05) and phosphatidylcholine (OR:0.620-1.247, P < 0.05) have a potential association with DKD. And there is a nominal causal effect of phosphatidylinositol (16:0_18:2) (OR = 0.617, 95%CI = 0.401-0.948, P = 0.028), phosphatidylcholine (OR:0.499-0.672, P < 0.05) and sphingomyelin (OR:0.652-1.850, P < 0.05) to DR. In addition, phosphatidylethanolamine (18:1_0:0) (OR = 0.616, 95%CI = 0.405-0.935, P = 0.023), diacylglycerol (16:0_18:1) (OR = 0.675, 95%CI = 0.463-0.984, P = 0.041) and phosphatidylcholine (OR = 0.720-1.619, P < 0.05) nominally associate with DN. It is noteworthy that plasma lipidome of different structures show different effects. We establish a possible causal connection between certain plasma lipidome and major diabetic microangiopathies. Implementing intervention strategies targeting different lipid molecules may provide novel approaches for preventing and treating diabetic microangiopathies.

Rheumatoid Arthritis, Circulating Inflammatory Proteins, and Hypertension: A Mendelian Randomization Study.

Observational studies have indicated that there is an association between rheumatoid arthritis (RA) and an elevated risk of hypertension. However, a definitive causal relationship between the two conditions has not been established. The objective of this study was to investigate the causal link between RA and hypertension, as well as the potential mediating role of circulating inflammatory proteins in this relationship. We utilized Mendelian randomization (MR) to examine the causal relationship between RA and hypertension. The study data were obtained from publicly accessible genome-wide association study (GWAS) databases and meta-aggregates of large GWAS studies. The primary statistical method for determining causal effects was the inverse variance weighted (IVW) method, which was supplemented by a variety of sensitivity analyses. The results of the IVW method suggest a causal relationship between RA and an increased risk of hypertension (OR = 1.03, 95% CI = 1.01-1.04, p = 3.32×10-5). This association remained statistically significant even after adjusting for multiple confounding factors. Furthermore, MR analyses also revealed causal links between 10 circulating inflammatory proteins and the risk of hypertension, with TNF-related activation-induced cytokine partially mediating RA-induced hypertension at a mediator ratio of 11.17% (0.27%-22.08%). Our study identifies causal relationships between several genetically determined inflammatory proteins and hypertension, establishing that RA increases hypertension risk, with inflammation partially mediating this effect. These findings provide new evidence supporting the inflammatory hypothesis in the mechanism of hypertension. Inflammatory factors may serve as potential targets for antihypertensive therapy.

Exploring genetic associations between immune cells and hypertensive disorder of pregnancy using Mendelian randomization.

Observational epidemiological studies suggested that immunological dysregulation and inflammation play a significant role in the placental and renal dysfunction that leads to maternal hypertension. The immunophenotypes' possible causalities with hypertensive disease of pregnancy remain ambiguous. We performed two-sample Mendelian randomization (MR) analyses to comprehensively investigate the causal effect of immunophenotypes on hypertensive disorder of pregnancy (HDP). The large-scale genome-wide association studies (GWASs) data on immunological traits was taken from public catalog for 731 immunophenotypes. The summarized GWAS data in 4 types of HDP were retrieved from FinnGen database, including 811,605 Finnish individuals. The primary analysis was the inverse variance weighted (IVW) method, supplemented by conducting sensitivity analysis. To confirm whether cardiovascular proteins mediated the causal effect of immune cells on HDP, we additionally executed a mediation MR study. After looking into genetically predicted immunophenotype biomarkers, we discovered 14 highly correlative immunophenotypes and 104 suggestive possible factors. The IVW analysis indicated that HLA DR on myeloid DC, HLA DR on plasmacytoid DC, and HLA DR on DC had a significant association with pre-eclampsia/eclampsia (PE), whereas CD4+ CD8dim AC and CD4+ CD8dim % leukocyte were protective against gestational hypertension (GH). All of HDP in our study had no statistically significant impact on immune cells, according to reverse MR analysis. The mediating role of LOX-1between HLA DR on plasmacytoid DC and chronic hypertension prior to pregnancy was validated. This study showed that many immunophenotypes are implicated in HDP. Furthermore, the level of LOX-1 mediated the pathophysiology relationship between HLA DR on plasmacytoid dendritic cells and chronic hypertension prior to pregnancy.

Allergic Diseases and T2DM:A Bidirectional Multivariable Mendelian Randomization Study and Mediation Analysis

Background Clinical studies involving observation have uncovered a mutual relationship between allergic disorders and diabetes, yet the precise causal link remains undetermined. Methods We conducted two-sample bidirectional Mendelian randomization analyses using single nucleotide polymorphisms (SNPs) associated with allergic conditions (asthma, allergic rhinitis, atopic dermatitis) from genome-wide studies and SNPs related to type 2 diabetes from FinnGen. Initially, we evaluated the causal link between allergic disorders and type 2 diabetes through a univariate Mendelian randomization study, incorporating inverse variance weighting, MR-Egger, and the weighted median estimator. To address potential confounding, we employed multivariate Mendelian randomization. Finally, we validated mediators influencing the correlation between asthma and type 2 diabetes. Results The Inverse variance weighte method showed that asthma genetically increased the risk of type 2 diabetes (Asthma- type 2 diabetes: β(95%CI)＝0.892(0.152～1.632), P = 0.018). Allergic rhinitis and type 2 diabetes exhibit a mutual protective effect: β(95% CI)＝-1.333(-2.617 to -0.049), P = 0.042；type 2 diabetes - Allergic rhinitis: β(95%CI)＝-0.002(-0.004 to -0.000), P = 0.018). The Multivariable Mendelian randomization study results showed that after after excluding confounding factors, asthma still demonstrates statistical significance in relation to type 2 diabetes. Through mediation analysis, it was discovered that lung function and the percentage of monocytes in leukocytes exert an inhibitory effect on the mediation between asthma and type 2 diabetes. Conclusion The Multivariable Mendelian randomization study indicates asthma as a risk factor for type 2 diabetes.Lung function, and the percentage of monocytes in leukocytes, play an inhibitory role in asthma and type 2 diabetes mediating effects.

Is there a genetic relationship between blood glucose and osteoarthritis? A mendelian randomization study.

The relationship between blood glucose levels and osteoarthritis (OA) is unclear. This study aimed to investigate the genetic causal relationship between blood glucose-related traits and OA. We first performed univariate Mendelian randomization (UVMR) analyses using published genome-wide association study (GWAS) datasets with fasting glucose (FG), 2h-glucose post-challenge glucose (2hGlu), and glycosylated hemoglobin (HbA1c) as exposures, and hip osteoarthritis (HOA) and knee osteoarthritis (KOA) as outcomes; then, we performed inverse analyses of them. We used Inverse-variance weighted (IVW) analysis as the primary analysis, and sensitivity analyses were performed. Moreover, we performed multivariate Mendelian randomization (MVMR) to estimate the independent effect of exposure on outcome after adjusting for body mass index (BMI). Summarized data for blood glucose-related traits were obtained from the MAGIC Consortium study of the glucose trait genome and for OA from the UK Biobank and arcOGEN. Summarized data for BMI were obtained from the GIANT Consortium meta-analysis of individuals of European ancestry. A two-sided p value < 0.05 in UVMR was considered suggestive of significance when p < 0.0167 (Bonferroni correction p = 0.05/3 exposures) was considered statistically significant. We found significant negative genetic causality of FG for HOA and KOA, and these associations remained significant after we adjusted for the effect of BMI [odds ratios (ORs) of 0.829 (0.687-0.999, p = 0.049) and 0.741 (0.570-0.964, p = 0.025)]. HbA1c also had an independent negative genetic causal effect on HOA after adjustment for BMI [0.665 (0.463-0.954, p = 0.027)]. At the same time, there was no evidence of reverse genetic causality of OA on blood glucose-related traits. We further elucidated the relationship between blood glucose-related traits and OA by adjusting for the effect of BMI from a genetic causal perspective. This study provides new insights to further clarify the relationship between blood glucose levels and OA, as well as the pathogenesis, etiology and genetics of OA.

Genetically Predicted Immune Cell-Mediated Effect of Lipid Metabolism on Allergic Diseases: A Two-Step, Mediation Mendelian Randomization Study.

An increasing number of studies have demonstrated that dynamic changes in lipid species can affect allergic diseases; however, the causal relationship and mediating role of immune cells remain unclear. We conducted a bidirectional two-sample mendelian randomization (MR) analysis using genome-wide association study (GWAS) data on 179 lipid species (n = 7,174) and three types of allergic diseases including allergic rhinitis (AR) (n = 370,158), allergic asthma (n = 219,753), and allergic conjunctivitis (n = 377,277). The principal model used was the inverse variance-weighted approach, and a series of sensitivity analyses were conducted to ensure the robustness of the results. We used a two-step MR approach to assess whether the causal effect was mediated by immune cells (n = 3,757). Sterol ester and sphingomyelin played pathogenic roles in allergic asthma, AR, and allergic conjunctivitis; however, the effective subtypes differed. Among them, CD45RA- CD4+ mature T cells and CCR2 on CD14+ CD16+ monocytes affected the promoting impact of sterol ester's metabolism on allergic asthma and AR with different mediating proportions, while the role of sphingomyelin may not involve the immune cells. Moreover, we observed that HLA-DR on CD33- HLA DR+ myeloid cells, CD11b on CD66b++ myeloid cells, and IgD+ CD38- B cells played the most mediating effect of phosphatidylethanolamine (O-18:2_20:4) in allergic asthma, phosphatidylinositol (16:0_18:1) in AR, and phosphatidylethanolamine (18:0_18:2) in allergic conjunctivitis. This MR study provides evidence for specific lipid species associated with the risk of allergic diseases, especially sterol esters, and identifies the immune cells that mediate this causal relationship.