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New insights into causal relationship between serum lipids, obesity, and asthma: a Mendelian randomization study.

OBJECTIVE: To identify causal risk factors for asthma using a Mendelian randomization (MR) approach. METHODS: Genetic variants associated with the exposures at the genome-wide significance level (p&#x2009;<&#x2009;5&#x2009;&#xd7;&#x2009;10&#x2009;-&#x2009;8) were obtained from corresponding genome-wide association studies. Summary-level statistical data for asthma were obtained from the UK Biobank (UKB) and the FinnGen Consortia. Univariate and multivariate MR analyses were performed to clarify causal relationships among obesity, serum lipids, and asthma. Meta-analyses were performed to combine UKB and FinnGen results using a fixed-effects model. RESULTS: In FinnGen, the odds for asthma increased for every 1-SD increase in body mass index (BMI; odds ratio [OR] 1.292, p&#x2009;=&#x2009;1.34&#x2009;&#xd7;&#x2009;10-7), together with body fat percentage (BF%; OR 1.449, p&#x2009;=&#x2009;4.90&#xd7;10-3), and total cholesterol level (OR = 0.949, p&#x2009;=&#x2009;0.027). However, higher BMI and BF% were found to increase the risk for asthma in the multivariate MR analysis. In the UKB, the BMI results were replicated. Meta-analysis revealed that high-density lipoprotein cholesterol could also increase the risk for asthma, although there were no associations with other risk factors included in this study. CONCLUSION: This MR study found that genetically predicted higher BF% and BMI could increase the risk for asthma and corroborated some risk factors for asthma from previous MR studies. Moreover, the results suggest that higher BMI and BF% could serve as independent risk factors for asthma.

Humans↗

Uric Acid Levels and Cardiovascular and Cerebrovascular Diseases: A Mendelian Randomization Study.

INTRODUCTION: The relationship between uric acid (UA) levels and cardiovascular and cerebrovascular diseases (CCVD) is controversial. A two-sample Mendelian randomization (MR) study was conducted to explore the causal effects of UA levels on CCVD. METHODS: Genetic variants strongly associated with UA levels were selected as instrumental variables from the Genome-Wide Association Study (GWAS) dataset. The GWAS data, sourced from the Global Urate Genetics Consortium (GUGC), comprised a sample size of 110,347 individuals. The selected CCVD outcomes included stroke, coronary artery disease (CAD), as well as atrial fibrillation and flutter. The primary analytical approach employed the inverse-variance weighted (IVW) method, supplemented by MR-Egger and weighted median as complementary methods. Sensitivity analysis was performed to test heterogeneity and pleiotropy. RESULTS: The MR analysis results indicated a causal association between UA levels and stroke (odds ratio [OR]: 1.002; 95% confidence interval [CI]: 1.000-1.003; p = 0.036), CAD (OR: 1.118; 95% CI: 1.044-1.197; p = 0.001), as well as atrial fibrillation and flutter (OR: 1.141; 95% CI: 1.037-1.256; p = 0.007). The results of MR-Egger and weighted median methods confirmed the direction of the IVW results, enhancing the robustness of the findings. No significant anomalies were detected in the sensitivity analysis. CONCLUSION: The MR study suggests that UA levels exert causal effects on stroke, CAD, as well as atrial fibrillation and flutter.

Humans↗

Dietary antioxidants: a challenge or an opportunity for asthma? Genetic insights from a Two-sample mendelian randomization study.

BACKGROUND: Oxidative stress is crucial in the immune response and airway inflammatory process associated with asthma. While the relationship between dietary antioxidants and asthma remains debated in observational studies, this study uses two-sample Mendelian randomization (MR) to explore a potential causal link. METHODS: We acquired six distinct categories of absolute circulating antioxidants and five different types of metabolic circulating antioxidants from the most recent genome-wide association study data of the European population, including vitamin A (retinol), vitamin C (ascorbic acid), vitamin E (tocopherol), &#x3b2;-carotene, lycopene, and urate. The latest data regarding asthma was obtained from the FinnGen database. We utilized single nucleotide polymorphisms as instrumental variables to conduct five MR methods. To confirm the accuracy of the results, additional sensitivity analyses were performed to eliminate any potential confounding factors, such as heterogeneity and pleiotropy. RESULTS: MR and sensitivity analyses revealed an association between circulating urate and asthma, suggesting a potential increase in asthma risk (OR = 1.090; 95% CI = 1.030-1.150; p&#x2009;=&#x2009;0.004). No causal relationship was found for other antioxidants. CONCLUSIONS: This MR analysis suggested that genetically determined circulating urate may increase asthma risk. Further large-scale randomized controlled trials and mediated MR analysis are needed to explore underlying mechanisms.

Humans↗

Risk relationship between inflammatory bowel disease and urolithiasis: A two-sample Mendelian randomization study.

BACKGROUND: The causal genetic relationship between common parenteral manifestations of inflammatory bowel disease (IBD) and urolithiasis remains unclear because their timing is difficult to determine. This study investigated the causal genetic association between IBD and urolithiasis using Mendelian randomization (MR) based on data from large population-based genome-wide association studies (GWASs). METHODS: A two-sample MR analysis was performed to assess the potential relationship between IBD and urolithiasis. Specific single nucleotide polymorphism data were obtained from GWASs, including IBD (n = 59957) and its main subtypes, Crohn's disease (CD) (n = 40266) and ulcerative colitis (UC) (n = 45975). Summarized data on urolithiasis (n = 218792) were obtained from different GWAS studies. A random-effects model was analyzed using inverse-variance weighting, MR-Egger, and weighted medians. RESULTS: Genetic predisposition to IBD and the risk of urolithiasis were significantly associated [odds ratio (OR), 1.04 (95% confidence interval [CI], 1.00-.08), P = 0.01]. Consistently, the weighted median method yielded similar results [OR, 1.06 (95% CI, 1.00-1.12), P = 0.02]. The MR-Egger method also demonstrated comparable findings [OR, 1.02 (95% CI, 0.96-1.08), P = 0.45]. Both funnel plots and MR-Egger intercepts indicated no directional pleiotropic effects between IBD and urolithiasis. CD was strongly associated with it in its subtype analysis [OR, 1.04 (95% CI, 1.01-1.07), P = 0.01], and UC was also causally associated with urolithiasis, although the association was not significant [OR, 0.99 (95% CI, 0.95-1.03), P = 0.71]. CONCLUSION: A unidirectional positive causal correlation was identified between IBD and urolithiasis, with varying degrees of association observed among the different subtypes of IBD. Recognizing the increased incidence of urolithiasis in patients with IBD is crucial in clinical practice. Early detection and surveillance of IBD, improved patient awareness, adoption of preventive strategies, and promotion of collaborative efforts among healthcare providers regarding treatment methodologies are vital for improving patient outcomes.

Humans↗

Genetic evidence for causal association between migraine and dementia: a mendelian randomization study.

BACKGROUND: There is an association between migraine and dementia, however, their causal relationship remains unclear. This study employed bidirectional two-sample Mendelian randomization (MR) to investigate the potential causal relationship between migraine and dementia and its subtypes: Alzheimer's disease (AD), vascular dementia (VaD), frontotemporal dementia (FTD), and dementia with Lewy bodies (DLB). METHODS: Summary-level statistics data were obtained from publicly available genome-wide association studies (GWAS) for both migraine and five types of dementia. Single nucleotide polymorphisms (SNPs) associated with migraine and each dementia subtype were selected. MR analysis was conducted using inverse variance weighting (IVW) and weighted median (WM) methods. Sensitivity analyses included Cochran's Q test, MR pleiotropy residual sum and outlier (MR-PRESSO) analysis, the intercept of MR-Egger, and leave-one-out analysis. RESULTS: Migraine showed a significant causal relationship with AD and VaD, whereas no causal relationship was observed with all-cause dementia, FTD, or DLB. Migraine may be a potential risk factor for AD (odds ratio [OR]: 1.09; 95% confidence interval [CI]: 0.02-0.14; P&#x2009;=&#x2009;0.007), while VaD may be a potential risk factor for migraine (OR: 1.04; 95% CI: 0.02-0.06; P&#x2009;=&#x2009;7.760E-5). Sensitivity analyses demonstrated the robustness of our findings. CONCLUSION: Our study suggest that migraine may have potential causal relationships with AD and VaD. Migraine may be a risk factor for AD, and VaD may be a risk factor for migraine. Our study contributes to unraveling the comprehensive genetic associations between migraine and various types of dementia, and our findings will enhance the academic understanding of the comorbidity between migraine and dementia.

Humans↗

The Association of Allergic Rhinitis with Chronic Adenotonsillar Diseases and Chronic Rhinosinusitis: A Mendelian Randomization Study.

INTRODUCTION: Allergic rhinitis (AR) has long been considered to be associated with chronic adenotonsillar disease (CATD). However, their causal relationship remains unclear. This study aims to investigate the causal relationship between AR and CATD and to examine the mediating role of chronic rhinosinusitis (CRS) in this association. METHODS: This study employed a two-sample Mendelian randomization (MR) design using genetic instrumental variable analysis. Data for allergic rhinitis (AR) were obtained from the MRC IEU OpenGWAS data infrastructure, data for chronic adenotonsillar disease (CATD) from the FinnGen biobank, and data for chronic rhinosinusitis (CRS) from the GWAS Catalog. Several MR methods were applied. In addition, a two-step MR approach was used to investigate the mediating role of CRS in the relationship between AR and CATD. RESULTS: MR analysis identified a positive correlation between AR and CATD. IVW and weighted median analyses showed significant causal effects (beta = 0.55, 95% CI: 0.26 to 0.84); p <0.001). No causal association was found between CATD and AR. AR and CRS showed a positive correlation (beta = 1.38, 95% CI: 0.78 to 1.98; p = 6.5 &#xd7; 10-6). CRS had a beta value of 0.15 (95% CI: 0.06 to 0.24; p = 0.001) for CATD. CRS mediates 37.6% of the AR to CATD pathway (mediation effect = 0.20, 95% CI: 0.04 to 0.37; p = 0.013). DISCUSSION: These findings indicate that AR may contribute to CATD risk through CRS, highlighting the need for further research to explore underlying biological mechanisms and validate these findings. CONCLUSIONS: This study suggests a positive causal relationship between AR and CATD, with CRS acting as a mediator.

Mendelian Randomization Analysis↗

Aerobic Fitness and Health-Related Phenotypes: A Two-Stage Phenome-Wide Mendelian Randomization Study.

PURPOSE: We investigated potentially causal associations between genetically predicted aerobic fitness and multiple health phenotypes using a two-stage phenome-wide Mendelian randomization (MR) study. METHODS: Genetically determined aerobic fitness, as operationalized by Cai et al., served as the exposure instrument. We screened 712 health-related phenotypes as outcomes using publicly available European-ancestry genome-wide association studies (GWAS) summary statistics from OpenGWAS (Discovery GWAS n > 5000), prioritizing non-UK Biobank/non-FinnGen datasets for Discovery when available and selecting an independent GWAS for validation. Associations were estimated using the MR-Robust Adjusted Profile Score method, controlled for multiple testing (5% false discovery rate) and unaffected by violations of MR assumptions (directional concordance between discovery and validation; no evidence of horizontal pleiotropy across inverse-variance weighted, MR-Egger, weighted-median, and weighted-mode methods; negative control analysis on hair color). RESULTS: We identified 108 discovery associations, of which 34 remained valid and statistically significant after validation. Higher genetically determined aerobic fitness was associated with lower lacunar stroke risk, lower arterial stiffness, higher heart rate variability, lower diastolic blood pressure, more favorable anthropometric measures, lower use of antidiabetic drugs, lower asthma risk, lower C-reactive protein, higher bone mineral density, favorable liver function biomarkers, favorable platelet-related traits, multiple blood count-derived hematological cell indices and counts, as well as higher years of schooling. Adverse associations were confined to atrial fibrillation, valvular heart disease, and systolic blood pressure. CONCLUSIONS: Genetically determined aerobic fitness is linked to a broad pattern of favorable cardiometabolic, inflammatory, musculoskeletal, respiratory, hepatic, and hematological phenotypes, alongside a narrow set of potential cardiovascular hazards.

Humans↗

Blood Pressure Lowering and Risk of Cancer: Individual Participant-Level Data Meta-Analysis and Mendelian Randomization Studies.

BACKGROUND: Pharmacologic blood pressure (BP) lowering is typically a lifelong treatment, and both clinicians and patients may have concerns about the long-term use of antihypertensive agents and the risk for cancer. However, evidence from randomized controlled trials (RCTs) regarding the effect of long-term pharmacologic BP lowering on the risk for new-onset cancer is limited, with most knowledge derived from observational studies. OBJECTIVES: The aim of this study was to assess whether long-term BP lowering affects the risk for new-onset cancer, cause-specific cancer death, and selected site-specific cancers. METHODS: Individual-level data from 42 RCTs were pooled using a one-stage individual participant data meta-analysis. The primary outcome was incident cancer of all types, and secondary outcomes were cause-specific cancer death and selected site-specific cancers. Prespecified subgroup analyses were conducted to assess the heterogeneity of the BP-lowering effect by baseline variables and over follow-up time. Cox proportional hazards regression, stratified by trial, was used for the statistical analysis. For site-specific cancers, analyses were complemented with Mendelian randomization, using naturally randomized genetic variants associated with BP lowering to mimic the design of a long-term RCT. RESULTS: Data from 314,016 randomly allocated participants without known cancer at baseline were analyzed. Over a median follow-up of 4 years (Q1-Q3: 3-5 years), 17,954 participants (5.7%) developed cancer, and 4,878 (1.5%) died of cancer. In the individual participant data meta-analysis, no associations were found between reductions in systolic or diastolic BP and cancer risk (HR per 5 mm Hg reduction in systolic BP: 1.03 [95% CI: 0.99-1.06]; HR per 3 mm Hg reduction in diastolic BP: 1.03 [95% CI: 0.98-1.07]). No changes in relative risk for incident cancer were observed over follow-up time, nor was there evidence of heterogeneity in treatment effects across baseline subgroups. No effect on cause-specific cancer death was found. For site-specific cancers, no evidence of an effect was observed, except a possible link with lung cancer risk (HR for systolic BP reduction: 1.17; 99.5% CI: 1.02-1.32). Mendelian randomization studies showed no association between systolic or diastolic BP reduction and site-specific cancers, including overall lung cancer and its subtypes. CONCLUSIONS: Randomized data analysis provided no evidence to indicate that pharmacologic BP lowering has a substantial impact, either increasing or decreasing, on the risk for incident cancer, cause-specific cancer death, or selected site-specific cancers.

epidemiology↗

Is there a genetic correlation between tinnitus and temporomandibular joint disorder?: A two-sample Mendelian randomization study.

Tinnitus and temporomandibular disorder (TMD) are frequent coexistence of clinical symptoms caused by some systemic diseases in all humans. The observational research results on the correlation between tinnitus and TMD are inconsistent with the reported findings. The purpose of the study was to explore the bidirectional causal relationship between tinnitus and TMD. This study adopts a two-sample Mendelian randomization (MR) methodology. Single-nucleotide polymorphisms from the genome-wide association study were used as instrumental variables to elucidate the bidirectional causal relationship between tinnitus and TMD. The quality of our study was evaluated in accordance with the STROBE-MR guidelines. The MR analysis results showed that tinnitus (yes, most or all of the time now) could be significantly reduced TMD muscular pain linked with fibromyalgia (OR&#x2005;=&#x2005;0.239, 95% CI: 0.087-0.66, P&#x2005;=&#x2005;.0057), but there was no correlation between other frequencies of tinnitus and the increased risk of TMD in genetic predisposition (all P&#x2005;>&#x2005;.05). The reverse MR analysis revealed no causal relationship and correlation between TMD exposure and increased risk of tinnitus. Sensitivity analysis indicated no horizontal pleiotropy and insignificant heterogeneity. This MR study supports evidence of a correlation between high-frequency tinnitus and reduced risk of TMD muscle pain associated with fibromyalgia. Further research on disease mechanisms are needed to explore the correlation between tinnitus and TMD.

Humans↗

Causal effect of chloride intracellular channel protein 5 on chronic periodontitis: A Mendelian randomization study.

This study aimed to evaluate the potential causal effect of chloride intracellular channel protein 5 (CLIC5) on the risk of chronic periodontitis (CP) using a Mendelian randomization (MR) approach. MR analysis was conducted utilizing publicly available summary statistics from genome-wide association studies summary statistics for CLIC5 and CP. Multiple MR methods, including inverse variance weighted, MR Egger, weighted median and weighted mode, were employed to estimate the causal effects. Sensitivity analyses, comprising leave-one-out and heterogeneity assessments were performed to evaluate the robustness of our findings. This MR analysis consistently revealed a negative association between CLIC5 and CP, with statistical significance achieved using the inverse variance weighted and weighted median methods. The concordant effect estimates obtained from all methodological approaches collectively indicated a potential protective effect of CLIC5 against CP. The sensitivity analyses further confirmed the robustness of these findings. This study provides genetic evidence suggesting a potential causal association between increased CLIC5 levels and decreased risk of CP. These findings augment the existing literature implicating chloride channel proteins in modulating the inflammatory processes pertinent to periodontal health. Further investigation is warranted to decipher the underlying biological mechanisms and to explore the potential of CLIC5 as a therapeutic target for CP.

Chloride Channels↗

Exploring Causal Links Between 91 Circulating Inflammatory Proteins and Hashimoto's Thyroiditis: A Bidirectional Mendelian Randomization Study.

BACKGROUND: Increasing evidence has linked inflammation to Hashimoto's thyroiditis (HT) etiology. However, the causal role of circulating inflammatory proteins in HT remains uncertain. To investigate this, we conducted a bidirectional Mendelian randomization (MR) study. METHODS: Genetic data for 91 inflammatory proteins and HT were sourced from publicly available GWAS databases. The PhenoScanner database was then searched for pleiotropic SNPs associated with potential confounders. Inverse variance weighted (IVW) analysis was used as the primary analysis, simultaneously supplemented by five sensitivity analyses to strengthen the results. RESULTS: The results revealed that, after false discovery rate (FDR) correction, interleukin (IL)-12p40 was causally associated with increased risk of HT (OR [95% CI]&#x2009;=&#x2009;1.295 [1.172, 1.431], p = 3.66 &#xd7; 10-7, PFDR&#x2009;=&#x2009;3.33&#xd7;10-5). Conversely, none of the inflammatory proteins was a consequence of HT. CONCLUSION: This study suggests that IL-12p40 is probably one of the factors correlated with HT etiology, contributing to a better understanding of the pathogenesis of HT and underscoring the potential for therapeutic interventions targeting inflammatory proteins.

Humans↗

Genetically Predicted Muscle Mass and Function in Relation to Deep Vein Thrombosis: A Two-step Mendelian Randomization Study Highlighting the Mediating Role of BMI.

BackgroundSarcopenia is observationally linked to venous thromboembolism, but the causal architecture and underlying biological pathways remain largely unclear. This study investigated the causal effects of sarcopenia-related traits on lower extremity deep vein thrombosis (DVT) and quantified potential mediating mechanisms.MethodsWe performed two-sample bidirectional Mendelian randomization (MR) and two-step mediation MR using large-scale GWAS data from UK Biobank, EMBL-EBI, and FinnGen. Exposures included appendicular lean mass (ALM), leg fat-free mass (LFM), hand grip strength, and walking pace. Eighteen candidate mediators were screened for indirect pathways.ResultsGenetically predicted higher ALM was significantly associated with increased DVT risk (FinnGen: OR = 1.288, 95% CI: 1.215-1.365, P < 0.001). Similar positive associations were observed for LFM (OR = 1.920-1.954, P < 0.001). By contrast, muscle functional traits - grip strength and walking pace - demonstrated no consistent causal effects. Reverse MR confirmed a unidirectional relationship. Body mass index (BMI) emerged as a pivotal mediator, accounting for 7.58% - 10.50% of the ALM-DVT effect and 52.74% - 62.73% of the LFM-DVT effect. Notably, the independent effect of ALM was largely attenuated after adjusting for metabolic confounders in multivariable MR.ConclusionGenetic predisposition to high muscle mass, rather than functional strength, increases DVT risk. This relationship appears to be significantly driven by metabolic adiposity, suggesting that the "muscle-vascular-coagulation" interaction is partly explained by body-size-related metabolic burden. Risk stratification should integrate muscle mass evaluation with comprehensive metabolic health assessments.

Humans↗

Bidirectional association between abnormal cardiac conditions and epilepsy: A two-sample Mendelian randomization study.

BACKGROUND: Observational studies have consistently indicated a significant correlation between abnormal cardiac conditions and epilepsy. However, the association and direction of this relationship remain a subject of debate. This study employs a two-sample bidirectional Mendelian randomization (MR) approach to investigate the association between abnormal cardiac conditions and epilepsy. METHODS: Instrumental variables, represented by single nucleotide polymorphisms (SNPs) associated with epilepsy and various abnormal cardiac conditions, were derived from large-scale genome-wide association studies databases, including FinnGen and UK Biobank. Bidirectional MR analysis was conducted to estimate the association between epilepsy and abnormal cardiac conditions. Sensitivity analyses were performed using MR-Egger, weighted median, Inverse Variance Weighted, and MR pleiotropy residual sum and outlier methods. RESULTS: The forward MR analysis suggested a potential positive effect of atrial fibrillation and flutter (AF) and valvular heart diseases (VHD) on the risk of epilepsy. Conversely, the reverse MR analysis indicated that epilepsy might increase the susceptibility to AF, VHD, and heart failure. CONCLUSION: The findings support a bidirectional relationship between AF, VHD, and epilepsy, indicating that AF and VHD can elevate the risk of developing epilepsy, while epilepsy, in turn, can also increase the risk of developing AF and VHD. Furthermore, the study suggest that epilepsy may contribute to the development of heart failure. These results underscore the importance of screening for cardiac abnormalities in patients with epilepsy and vice versa, to better understand their clinical significance and potential as modifiable risk factors.

Humans↗

Association between Branched-Chain amino acids and Epilepsy: A Mendelian randomized study.

BACKGROUND: Branched-chain amino acids (BCAAs) have been affected epilepsy, yet conclusions remain inconclusive, lacking causal evidence regarding whether BCAAs affect epilepsy. Systematic exploration of the causal relationship between BCAAs and epilepsy could hand out new ideas for the treatment of epilepsy. METHODS: Utilizing bidirectional Mendelian randomization (MR) study, we investigated the causal relationship between BCAA levels and epilepsy. BCAA levels from genome-wide association studies (GWAS), including total BCAAs, leucine levels, isoleucine levels, and valine levels, were employed. Causal relationships were explored applying the method of inverse variance-weighted (IVW) and MR-Egger, followed by sensitivity analyses of the results to evaluate heterogeneity and pleiotropy. RESULTS: Through strict genetic variant selection, we find some related SNPs, total BCAA levels (9), leucine levels (11), isoleucine levels (7), and valine levels (6) as instrumental variables for our MR analysis. Following IVW and sensitivity analysis, total BCAAs levels (OR&#xa0;=&#xa0;1.14, 95&#xa0;% CI&#xa0;=&#xa0;1.019&#xa0;&#x223c;&#xa0;1.285, P&#xa0;=&#xa0;0.022) and leucine levels (OR&#xa0;=&#xa0;1.15, 95&#xa0;% CI&#xa0;=&#xa0;1.018&#xa0;&#x223c;&#xa0;1.304, P&#xa0;=&#xa0;0.025) had significant correlation with epilepsy. CONCLUSIONS: There exists a causal relationship between the levels of total BCAAs and leucine with epilepsy, offering the new ideas into epilepsy potential mechanisms, holding significant implications for its prevention and treatment.

Humans↗

Causal Relationship Between Ischemic Stroke and Vascular Dementia: A Mendelian Randomization Study.

Ischemic stroke (IS) is a major cause of disability and mortality worldwide, and vascular dementia (VaD) is a common dementia subtype associated with cerebrovascular injury. Observational studies have suggested a relationship between IS and VaD, but these studies are vulnerable to confounding and reverse causality. This protocol describes a reproducible two-sample Mendelian randomization (MR) workflow for evaluating the potential causal association between IS and VaD using publicly available genome-wide association study (GWAS) summary statistics. Genetic instruments associated with IS were extracted from a public GWAS dataset, and outcome associations for VaD were obtained from a public VaD GWAS dataset. The corresponding dataset IDs are provided in the Protocol section. After outcome matching and allele harmonization, 51 single-nucleotide polymorphisms (SNPs) were retained for the final MR analysis. The workflow includes instrumental variable selection, linkage disequilibrium clumping, allele harmonization, instrument strength assessment, inverse variance weighted (IVW) analysis, weighted median analysis, MR-Egger analysis, heterogeneity testing, horizontal pleiotropy assessment, and leave-one-out sensitivity analysis. In the representative analysis, the IVW method showed a positive association between genetically predicted IS and VaD risk, and the weighted median method yielded a directionally concordant result. The MR-Egger estimate was directionally consistent but did not reach statistical significance. Therefore, these findings should be interpreted as suggestive evidence of a possible causal effect, rather than definitive proof of causality. This protocol may help researchers apply a transparent and reproducible MR workflow to investigate cerebrovascular disease-related outcomes using public GWAS data.

Humans↗

Dietary patterns and risk of ischemic stroke: A two-sample Mendelian randomization study.

Diet and nutrition critically influence the development and outcomes of ischemic stroke (IS). However, observational studies often yield inconsistent findings due to confounding and measurement error. Mendelian randomization (MR) provides an alternative approach to strengthen causal inference. We conducted a 2-sample MR analysis to evaluate the causal associations between 22 dietary factors and IS risk. Genetic instruments for dietary exposures were derived from the UK Biobank genome-wide association study, and outcome data were obtained from the MEGASTROKE consortium. Inverse-variance weighted analysis served as the primary method, complemented by sensitivity analyses. Consumption of oily fish (&#x3b2;&#x2005;=&#x2005;-0.402, P&#x2005;=&#x2005;.022), cheese (&#x3b2;&#x2005;=&#x2005;-0.364, P&#x2005;=&#x2005;.001), dried fruit (&#x3b2;&#x2005;=&#x2005;-0.710, P&#x2005;=&#x2005;.0002), weekly red wine (&#x3b2;&#x2005;=&#x2005;-0.507, P&#x2005;=&#x2005;.024), and calcium supplements (&#x3b2;&#x2005;=&#x2005;-3.994, P&#x2005;=&#x2005;.015) was associated with reduced risk of IS. Conversely, dietary patterns characterized by high-sugar or high-protein intake showed suggestive associations with increased IS risk, although these did not remain significant after multiple-comparison correction. This 2-sample MR study provides evidence that specific dietary factors, including oily fish, cheese, dried fruit, red wine, and calcium, may reduce IS risk, while high-sugar and high-protein diets may confer increased risk. These findings underscore the importance of dietary management in stroke prevention and highlight the need for further studies to validate the role of potentially harmful dietary patterns.

Humans↗

Myeloid Dendritic Cell Counts and Coronary Heart Disease: a Bidirectional Mendelian Randomization Study.

BACKGROUND: Coronary heart disease (CHD) remains a leading cause of morbidity and mortality worldwide, with immune and inflammatory mechanisms playing important roles in its pathogenesis. Dendritic cells (DCs) are key regulators of immune responses; however, the relationship between specific DC subsets and CHD risk remains incompletely understood. METHODS: This study conducted a bidirectional two-sample Mendelian randomization (MR) analysis using publicly available genome-wide association study (GWAS) summary statistics to investigate the potential associations between circulating dendritic cell traits and CHD. Genetic instruments for myeloid dendritic cells (Myeloid DCs) and plasmacytoid dendritic cells (Plasmacytoid DCs), including both absolute counts and relative proportions, were obtained from immune cell GWAS datasets. Summary statistics for CHD were derived from a large European-ancestry population. Multiple MR methods were applied, and sensitivity analyses were performed to assess the robustness of the findings and potential pleiotropic effects. RESULTS: Nominal associations between genetically predicted Myeloid DC counts and CHD risk were observed in the MR-Egger and weighted median analyses, whereas the inverse variance weighted analysis demonstrated no significant association. These nominal associations did not remain statistically significant after correction for multiple testing. No significant associations were observed for Plasmacytoid DC counts or for the relative proportions of either DC subset. Reverse MR analyses were inconclusive due to wide confidence intervals, precluding meaningful inference regarding a causal effect of CHD on DC-related traits. Sensitivity analyses revealed no substantial heterogeneity or horizontal pleiotropy. CONCLUSIONS: This bidirectional MR study explored the potential relationships between circulating dendritic cell traits and CHD risk. Although nominal associations involving Myeloid DC counts were observed in secondary MR analyses, no robust evidence supporting an association remained after correction for multiple testing. Further studies using larger datasets and functional approaches are warranted to clarify the role of dendritic cells in CHD.

Humans↗

The causal relationship between antihypertensive drugs and knee osteoarthritis: A drug target Mendelian randomization study.

Recently studies have revealed a robust association between hypertension and knee osteoarthritis (KOA), with patients likely to suffer from both conditions. We employed Mendelian randomization (MR) analysis to assess the impact of antihypertensive medications on KOA, aiming to offer clinical guidance for concomitant drug therapy and identify potential therapeutic targets for KOA. We obtained exposure instruments (instrumental variables) by locating Single-nucleotide polymorphisms related to systolic blood pressure near drug target genes. We then conducted Mendelian randomization analyses between the exposure data and genome-wide association studies data on KOA to evaluate the impact of antihypertensive drugs on KOA. We observed a significant association between decreased expression of the SLC12A2 target gene and a reduced risk of KOA (odds ratio: 0.915, 95% confidence interval: 0.869-0.964, P&#x2005;<&#x2005;.001). In this study, we find that SLC12A2 inhibitors can have a beneficial effect on KOA, and that the SLC12A2 gene may be a potential therapeutic target for KOA. These findings suggest that when treating patients with both hypertension and KOA, clinicians may consider prioritizing the use of SLC12A2 inhibitors.

Humans↗