Mendelian Randomization Study Research Articles

Helicobacter pylori infection and inflammatory bowel disease: a 2-sample Mendelian randomization study

IntroductionObservational studies have discovered a contradictory phenomenon between Helicobacter pylori (H. pylori) infection and inflammatory bowel disease (IBD). The study aimed to confirm the causal association between H. pylori and IBD, including ulcerative colitis (UC) and Crohn's disease (CD).MethodsWe conducted a Mendelian randomization (MR) study with two sample Genome-Wide Association Studies (GWAS) to determine whether there is a causal relationship between H. pylori infection and IBD, as well as the possible pathogenic factors that may be involved. The reliability of the main MR assumptions was examined through a series of sensitivity analyses.ResultsTwo genetic variants (SNPs) previously identified were employed as instrumental variables (IVs) for H. pylori infection. GWAS data for IBD, UC, and CD were obtained from the recent DF10 release10 of the FinnGen study. Our findings indicated a significant association between H. pylori seropositivity and an increased risk of IBD and UC (IBD: OR: 1.16, 95% CI, 1.03–1.31, P < 0.05; UC: OR: 1.22, 95% CI, 1.08–1.37, P < 0.001) while no causal relationship with CD (P > 0.05). Analysis of the main virulence pathogenic factors revealed a causal relationship between cytotoxin-associated protein A (CagA) and IBD and UC (IBD: OR: 1. 06, 95% CI, 1.001–1.11, P < 0.05; UC: OR: 1.07, 95% CI, 1.004–1.14, P < 0.05), while no correlation was found for vacuolar cytotoxin A (VacA) (P > 0.05). After applying the False Discovery Rate (FDR) correction, the causal relationship between CagA and the risk of IBD or UC was no longer statistically significant.ConclusionThis study suggests a potential causal relationship between H. pylori infection and IBD, particularly UC. The effect may be more pronounced in individuals with previous H. pylori infections.

Hypertensive disorders of pregnancy and stroke: a univariate and multivariate Mendelian randomization study

BackgroundHypertensive disorders of pregnancy (HDP) are associated with an increased risk of stroke later in life in multiparous women. However, causality of these associations remains unclear. This study employed 2-sample univariate and multivariate Mendelian randomization (MR) to assess the causal connection between HDP and stroke.MethodsGenetic variants for HDP and two subtypes were identified from recent large-scale genome-wide association studies and the FinnGen consortium. Stroke summary data were obtained from the MEGASTROKE consortium. The primary analytical approach for univariate MR was the inverse variance weighting method. Sensitivity analyses incorporated methods such as MR-Egger regression, weighted median, and maximum likelihood to ascertain the robustness of the results. Additionally, multivariable MR analyses were conducted to account for potential associative effects of hypertension and type 2 diabetes.ResultsGenetically predicted HDP was associated with a high risk of large artery atherosclerosis (odds ratio [OR]=1.50, 95% confidence interval [CI]: 1.17–1.91, P=1.13×10-3) and small vessel stroke (OR=1.29, 95% CI: 1.20–1.50, P=1.52×10-3). HDP may also correlate with ischemic stroke (OR=1.13, 95% CI: 1.04–1.23, P=4.99×10-3) and stroke (OR=1.11, 95% CI: 1.03–1.20, P=8.85×10-3). An elevated risk of small vessel stroke (OR=1.20, 95% CI: 1.01–1.43, P=3.74×10-2) and large artery atherosclerosis (OR=1.22, 95% CI: 1.01–1.47, P=4.07×10-2) may be related with genetically predicted susceptibility to gestational hypertension. Genetically predicted susceptibility to preeclampsia or eclampsia may be associated with an increased risk of stroke (OR = 1.10, 95% CI: 1.02–1.19, P = 1.16×10-2) and ischemic stroke (OR = 1.10, 95% CI: 1.02–1.20, P = 1.84×10-2). Type 2 diabetes mellitus and hypertension were identified as significant factors contributing to the association between HDP and stroke.ConclusionsThis study provides genetic evidence supporting an association between HDP and increased stroke risk bolstering HDP as a cerebrovascular risk factor.

Genetically mimicked effects of thyroid dysfunction on diabetic retinopathy risk: a 2-sample univariable and multivariable Mendelian randomization study

BackgroundThyroid dysfunction exhibits a heightened prevalence among people with diabetes compared to those without diabetes. Furthermore, TD emerges as a notable correlated risk factor for the onset of diabetic retinopathy.MethodsUsing data from the FinnGen database (R9), we investigated the causal relationship between thyroid dysfunction (TD) and four stages of diabetic retinopathy (DR). A two-sample univariable Mendelian randomization (UVMR) approach was employed to estimate the total causal effect of TD on four stages of DR, while multivariable Mendelian randomization (MVMR) was used to assess the direct causal effect. The meta-analysis was conducted to summarize the collective effect of TD on four stages of DR. The inverse variance weighted (IVW) method was the primary approach for Mendelian randomization analysis, with heterogeneity, horizontal pleiotropy, and leave-one-out sensitivity analyses performed to validate the robustness of the findings.ResultsIn UVMR analysis, thyrotoxicosis (TOS) was significantly associated with an increased risk of diabetic retinopathy across four stages (OR, 1.10–1.19; P<0.025). However, MVMR analysis, after adjusting for Graves’ disease (GD) and/or rheumatoid arthritis (RA), revealed no significant association between TOS and the four stages of diabetic retinopathy. The Meta-analysis demonstrated the collective effect of TOS on diabetic retinopathy across all stages [OR=1.11; 95% CI (1.08–1.15); P<0.01]. In UVMR analysis, the estimates for hypothyroidism (HPT) and GD were similar to those for TOS. In the MVMR analysis, after adjusting for RA, the significant effect of HPT on DR and non-proliferative diabetic retinopathy (NPDR) remained. Additionally, MVMR analysis suggested that the estimates for GD on DR were not affected by TOS, except for GD-proliferative diabetic retinopathy (PDR). However, no significant correlation persisted after adjusting for RA, including for GD-PDR.ConclusionOur study demonstrated a significant association between thyroid dysfunction TD and DR, with the relationship being particularly pronounced in HPT-DR.

Unraveling the causal association between lifestyle and metabolic factors with endometrial cancer: evidence from a Mendelian randomization study

BackgroundEndometrial carcinoma (EC) remain a malignancy with incompletely understood risk factors. To address this knowledge gap, we employed mendelian randomization study to investigate potential protective and risk elements associated with endometrial cancer.MethodsWe conducted a two-sample Mendelian randomization (MR) study using genetic association data for overall EC and its subtypes from a large-scale genome-wide association study (GWAS). This GWAS encompassed 12,906 EC patients and 108,979 healthy controls. The EC cases were further categorized into 8758 endometrioid and 1230 non-endometrioid subtypes. To serve as instrumental variables, we identified independent genetic variants strongly associated with 5 lifestyle factors and 14 metabolic factors from relevant GWASs. Subsequently, we conducted univariable Mendelian randomization (MR) analyses.ResultsOur study revealed the relationship among EC with lifetime smoking index (OR: 1.43; 95% CI 1.05–1.96), frequency of alcohol consumption (OR:1.23; 95% CI 1.04–1.45), body mass index (BMI) (OR:1.82; 95% CI 1.64–2.01), type 2 diabetes mellitus (T2DM) (OR:1.06; 95% CI 1.00–1.12), and fasting insulin (OR:1.97; 95% CI 1.30–2.98). Conversely, inverse associations with EC were observed for education level (OR:0.72, 95% CI 0.62–0.83), moderate-level physical exercise (OR 0.35, 95% CI 0.15–0.84), and low-density lipoproteins (LDL) (OR 0.91, 95% CI 0.84–0.99).ConclusionsOur findings underscore a causal association between genetically predicted lifetime smoking index, alcohol intake frequency, BMI, T2DM, and fasting insulin with EC risk. Furthermore, our study highlights the potential protective effects of a high education level, moderate-intensity physical exercise, and LDL reduction against EC risk. This MR analysis provided valuable insights into underlying EC risk mechanisms and paved new ways for EC prevention strategies.

The mendelian randomized study revealed the association of prostatitis with prostate cancer risk

In recent observational studies, a potential link between prostatitis and prostate cancer (PCa) has been hinted at, yet the causality remains ambiguous. In our endeavor to scrutinize the conceivable causal nexus between prostatitis and PCa, we embarked upon a Mendelian randomization (MR) study. MR circumvents arbitrary groupings by employing genetic variations that have a strong association with the exposure as instrumental variables to infer causal relationships between exposures and outcomes. The etiology of PCa remains elusive. Given that prostatitis and prostate cancer occupy the same anatomical region, MR can more effectively delineate their relationship by mitigating confounding variables. This method can indirectly elucidate disease correlations, thereby contributing to cancer prevention strategies. FinnGen Consortium data were used for the prostatitis genome-wide association study (GWAS), including 74,658 participants. UK biobank baseline data (ncase = 3436, ncontrol = 459574), European Bioinformatics Institute Database (ncase = 79148, ncontrol = 61106), and IEU openGWAS database (ncase = 79148, ncontrol = 61106) were used for PCa outcomes, mostly for European population samples. Data from the GWSAs for prostatitis were compared with data from the three GWASs for PCa, respectively, in an analysis of an MR. Utilizing the inverse variance weighting (IVW) methodology as our primary analytical framework, we delved into a meticulous exploration of the conceivable causal association between prostatitis and PCa. Furthermore, we deployed supplementary methodologies, including Maximum Likelihood, MR-Egger, weighted median, and MR-PRESSO, to thoroughly assess and scrutinize the causality aspect comprehensively. Cochran’s Q statistic is employed as a metric to quantify the heterogeneity inherent in instrumental variables. The inverse variance weighted analysis revealed no discernible effect of prostatitis on PCa in the three PCa GWAS databases (odds ratio [OR]: 1.001, 95% Confidence Interval [CI]: 0.999–1.002, p = 0.28), (OR: 1.015, 95% CI: 0.981–1.050, p = 0.40), (OR: 1.015, 95% CI: 0.981–1.050, p = 0.40). Similarly, employing MR-Egger did not yield substantial evidence (OR: 0.999, 95% CI: 0.999–1.002, p = 0.89), (OR: 1.103, 95% CI: 1.006–1.209, p = 0.07), (OR: 1.103, 95% CI: 1.006–1.209, p = 0.07). The weighted median analysis also failed to provide convincing support for the impact of prostatitis on the incidence of PCa (OR: 1.001, 95% CI: 1.000-1.002, p = 0.064), (OR: 0.989, 95% CI: 0.946–1.034, p = 0.64), (OR: 0.989, 95% CI: 0.945–1.036, p = 0.65). The results of the MR showed no causality from prostatitis to PCa.

Dissecting Causal Relationships Between Dietary Habits and Diverse Subtypes of Stroke: Mendelian Randomization Study

Background: Understanding the causal relations between dietary habits and stroke is crucial for prioritizing public health interventions and developing effective health strategies. This study utilized Mendelian randomization (MR) analysis to examine the causal associations between 20 dietary habits and various stroke subtypes, aiming to identify potential mediators and evaluate the proportions of mediation. Methods: A two-sample MR analysis was conducted to examine the causal relationships between dietary habits and stroke incidence. Mediation analysis, two-step MR (TSMR), and multivariable MR (MVMR) were employed to identify potential mediators. Genetic data pertaining to dietary habits and stroke were obtained from extensive genome-wide association study (GWAS) consortia. The inverse variance-weighted (IVW) method served as the primary analytical approach, with the additional scrutiny of significant correlations conducted through the Egger regression, MR-Pleiotropy Residual Sum and Outlier (MR-PRESSO), and weighted median techniques. Results: Our analyses indicated that genetically predicted intakes of dried fruits, cheese, cereal, oily fish, and hot drink temperatures were protective against stroke, whereas higher intakes of lamb/mutton, poultry, and added salt significantly elevated stroke risk. Specifically, dried fruit consumption demonstrated a protective effect against total stroke (β = −0.009, p = 0.013), ischemic stroke (β = −0.475, p = 0.003), and small-vessel ischemic stroke (β = −0.682, p = 0.033) through reductions in BMI levels, accounting for mediated proportions of 3.2%, 17.1%, and 8.5%, respectively. Furthermore, cheese intake provided a protective effect against ischemic stroke (β = −0.275, p = 0.003) by decreasing BMI and increasing HDL-C levels, with mediated proportions of 30.5% and 6.5%. Together, BMI and HDL-C accounted for 34.9% of the beneficial effect of cheese intake on reducing the risk of ischemic stroke. In contrast, an increased salt intake exhibited a positive association with large-artery ischemic stroke (β = 0.432, p = 0.033) through BMI elevation, with a mediated proportion of 10.9%. Conclusions: Our findings provide compelling evidence supporting causal relationships between dietary habits and stroke subtypes, while identifying mediators and evaluating the proportions of mediation. Adhering to a low-calorie, nutrient-dense diet enriched with dried fruits, cheese, and cereal, along with reduced salt and poultry consumption, could potentially mitigate stroke risk.

Causal Relationships between Circulating Immune Cell Traits and the Risk of Rheumatoid Arthritis and Osteoarthritis: A Bidirectional Two-Sample Mendelian Randomization Study

Background: Rheumatoid arthritis (RA) and osteoarthritis (OA) are prevalent chronic joint disorders with immunological pathogenesis. However, the causal relationships between circulating immune cells and them remain largely unknown. Therefore, we conducted a bidirectional two-sample Mendelian randomization (MR) study to determine their causal relationship. Methods: Genome-wide association study summary statistics were extracted from publicly available databases regarding immune cell phenotypes, RA, and OA. MR analysis was conducted using five MR methods, with inverse-variance-weighted (IVW) as the primary analysis method. False discovery rate correction (FDR) was used to reduce the likelihood of type 1 errors. We also conducted MR-Egger intercept tests to evaluate horizontal pleiotropy. Results: After FDR adjustment of the P values for the IVW method, the CD27 expression on memory B cells was negatively related to the risk of RA (P < 0.001), and the human leukocyte antigen (HLA)--DR expression on CD14+ monocytes was negatively related to the risk of OA (P < 0.001). We also found that RA was negatively associated with the expression of HLA-DR on myeloid dendritic cells (P < 0.001), but significant horizontal pleiotropy was observed. Conclusion: Our study demonstrates a causal relationship between specific immune cell traits and RA as well as OA, providing further insight into the role of immune cells in the pathogenesis of these disorders.

Association between the composite dietary antioxidant index and risk of infertility: Evidence from NHANES 2013-2020 and a Mendelian randomization study.

The Composite Dietary Antioxidant Index (CDAI) measures the antioxidant capacity of the diet, which is believed to provide protection against various diseases, including depression, osteoporosis, and papillomavirus infection, by neutralizing harmful oxidative stress. However, the relationship between CDAI and infertility is not well understood. This research aims to explore the potential correlations between CDAI and the risk of infertility. This research harnessed data from the National Health and Nutrition Examination Survey (NHANES) to execute a cross-sectional analysis involving 8263 US women aged 20-45. Each participant was subjected to two distinct 24-h dietary recall interviews. We calculated the CDAI using average daily antioxidant intake. Infertility was assessed using a standardized questionnaire. The association between CDAI and infertility was examined using weighted multiple logistic regression models, while nonlinear correlations were explored through restricted cubic splines. To affirm the robustness of our findings, sensitivity and subgroup analyses were performed using unweighted logistic regression. Additionally, to ascertain the causal influence of circulating antioxidant levels on infertility, a two-sample univariable Mendelian randomization (MR) analysis was conducted, using the inverse variance weighted (IVW) method as the primary analytic approach. Participants who were infertile exhibited lower CDAI levels compared to their fertile counterparts. When confounding variables were accounted for in the multivariate weighted logistic regression model, an inverse relationship was observed between CDAI and infertility, with the odds ratio for the highest versus lowest quartile being 0.55 (0.33-0.90, P = 0.02). However, the IVW method indicated that genetically predicted elevated levels of CDAI did not significantly correlate with infertility. Cross-sectional observational studies indicate that antioxidants from diets might diminish infertility risks. However, findings from MR studies do not confirm a causal connection. Additional prospective research is required to elucidate this association further.

PD-1/PD-L1 and coronary heart disease: a mendelian randomization study

IntroductionIt has been found that programmed cell death protein-1 (PD-1) or its ligand PD-L1 may play an important role in the onset and progression of coronary heart disease (CHD). Thus, we conducted this mendelian randomization analysis (MR) to estimate the causal relationship between PD-1/PD-L1 and 5 specific CHDs (chronic ischemic heart disease, acute myocardial infarction, angina pectoris, coronary atherosclerosis, and unstable angina pectoris), complemented by gene set enrichment analysis (GSEA) for further validation.MethodsPublicly available summary-level data were attained from the UK Biobank with genetic instruments obtained from the largest available, nonoverlapping genome-wide association studies (GWAS). Our analysis involved various approaches including inverse variance-weighted meta-analysis, alternative techniques like weighted median, MR-Egger, MR-multipotency residuals and outliers detection (PRESSO), along with multiple sensitivity assessments such as MR-Egger intercept test, Cochran's Q test, and leave-one-out sensitivity analysis to evaluate and exclude any anomalies.ResultsGene expression profile (GSE71226) was obtained from Gene Expression Omnibus (GEO) database for GSEA. IVW analysis showed a causal association between PD-1 and chronic ischemic heart disease (OR, 0.997; 95%CI, 0.995-0.999; P, 0.009), chronic ischemic heart disease and PD-1 (beta, −3.1; 95%CI, −6.017 to −0.183; P, 0.037), chronic ischemic heart disease and PD-L1 (beta, −3.269; 95%CI, −6.197 to −0.341; P, 0.029). No significant causal relationship was found between PD-1/PD-L1 and other 4 CHDs. The accuracy and robustness of these findings were confirmed by sensitivity tests. GSEA found that the KEGG pathway and related core genes of “PD-L1 expression and PD-1 checkpoint pathway in cancer” pathway were downregulated in CHD.DiscussionThis study provided evidence of a bidirectional causal relationship between PD-1 and chronic ischemic heart disease and a protective association between chronic ischemic heart disease and PD-L1.

Exploring the causal pathway from gut microbiota to polycystic ovary syndrome: A network Mendelian randomization study.

Polycystic ovary syndrome (PCOS) is a complicated endocrine and metabolic syndrome with unclear pathogenesis. The gut microbiota sheds light on the etiology and pathophysiology of PCOS. We used Mendelian randomization (MR) studies to systematically evaluate the pathological mechanism gut microbiota causally associated with PCOS risk. A network MR analysis was performed to estimate the causal effects of gut microbiota and risk factors on PCOS, as well as the mediation effect of risk factors linking gut microbiota to PCOS. The investigation of side effects for the important gut microbiota was subsequently broadened to include phenotypes by performing Phenowide-MR analysis for a range of diseases. Genus Sellimonas id.14369 were causally associated with reduced PCOS risk (odds ratio [OR] = 0.69, 95% confidence interval [CI]: 0.58-0.84, P = 1.22 × 10-4) after multiple testing correction. And Sellimonas retained consistent causal effect estimates after a series of sensitivity analyses. In addition, we observed an indirect effect of Sellimonas on PCOS through body mass index (BMI) using network MR (b = -0.05, 95% CI: -0.09 to -0.01), with a mediated proportion of 12.82% of the total effect. Further, Phenowide-MR analyses showed that the protective effects of Sellimonas on type 2 diabetes and depression (for type 2 diabetes: OR = 0.95, 95% CI: 0.90-0.99, P = .0366; for depression: OR = 0.99, 95% CI: 0.98-1.00, P = .0210). We summarized that the causal path between gut microbiota and type 2 diabetes are also jointly mediated by BMI. Sellimonas may be a protective factor of PCOS, which can affect the occurrence of PCOS through BMI, supporting future studies on the importance of addressing obesity and metabolic issues in preventing and managing PCOS.

Relationships between heart failure, depression, and anxiety: A Mendelian randomization study.

Growing evidence suggests that heart failure (HF) is associated with an increased risk of depressive disorders and anxiety. However, the existing studies were observational and may have confounded and not reflected true causal relationships. This study collected genetic instruments about HF, depression, and anxiety from publicly available genetic summary data. Two-sample Mendelian randomization (MR) analysis was performed, with inverse-variance weighted designated as the primary approach for determining causal effects. Secondary analyses included MR-Egger regression and the weighted media method. Additionally, we conducted MR pleiotropy residual sum and outlier to address horizontal pleiotropy. Cochran Q test, MR-Egger intercept test, and leave-one-out analysis were used to assess the robustness of the findings. The significance is determined by a P-value below .05. Gene prediction result revealed that HF did not exhibit a significant association with elevated incidence of depression by inverse-variance weighted method no matter HF from the Heart Failure Molecular Epidemiology for Therapeutic Targets Consortium (odds ratio [OR] = 1.05, 95% confidence interval [CI] = 0.93-1.18, P = .424 for major depressive disorder, MDD; OR = 1.01, 95% CI = 0.94-1.09, P = .782 for major depression) or the FinnGen Consortium (OR = 1.03, 95% CI = 0.92-1.15, P = .644 for MDD; OR = 1.00, 95% CI = 0.94-1.07, P = .962 for major depression). In contrast, the results of HF on anxiety exhibited inconsistency (OR = 1.60, 95% CI = 1.10-2.31, P = .013 for Heart Failure Molecular Epidemiology for Therapeutic Targets Consortium; OR = 1.42, 95% CI = 0.91-2.21, P = .123 for FinnGen Consortium); however, a combined effect analysis indicated support causal relationship between HF and the risk of anxiety (OR = 1.52, 95% CI = 1.07-2.00, P < .001). Our findings did not reveal evidence to confirm a causal association between HF and depression. However, our results provide support for a causal effect of HF on the risk of anxiety.

Exploring estrogen-related mechanisms in ovarian carcinogenesis: association between bone mineral density and ovarian cancer risk in a multivariable Mendelian randomization study.

Estrogen may play a role in epithelial ovarian cancer (EOC) carcinogenesis, with effects varying by EOC histotype. Measuring women's long-term exposure to estrogen is difficult, but bone mineral density (BMD) may be a reasonable proxy of longer-term exposure. We examined this relationship by assessing the association between genetic predisposition for higher BMD and risk of EOC by histotype. We used Mendelian randomization (MR) to assess associations between genetic markers for femoral neck and lumbar spine BMD and each EOC histotype. We used multivariable MR (MVMR) to adjust for probable pleiotropic traits, including body mass index, height, menarcheal age, menopausal age, smoking, alcohol intake, and vitamin D. Univariable analyses suggested greater BMD was associated with increased risk of endometrioid EOC (per standard deviation increase; lumbar spine OR = 1.21; 95% CI 0.93,1.57, femoral neck: OR = 1.25; 0.99,1.57), but sensitivity analyses indicated that pleiotropy was likely. Adjustment using MVMR reduced the magnitude of estimates slightly (lumbar spine: OR = 1.13; 95% CI 1.00,1.28, femoral neck: OR = 1.18; 1.03,1.36). Results for lumbar spine BMD and high-grade serous EOC were also suggestive of an association (univariable MR: OR = 1.16; 95% CI 1.03,1.30; MVMR: OR = 1.06; 0.99,1.14). Our study found associations between genetic predisposition to higher BMD, a proxy for long-term estrogen exposure, and risk of developing endometroid and high-grade serous EOC cancers. These findings add to existing evidence of the relationship between estrogen and increased risk of EOC for certain histotypes.

Atopic disease and inflammatory bowel disease: A bidirectional Mendelian randomization study.

Observational studies have reported associations between atopic diseases, including allergic rhinitis (AR), asthma, atopic dermatitis (AD), and inflammatory bowel disease (IBD), but the causal relationship remains unknown. We utilized pooled data from genome-wide association studies, qualified instrumental variables were screened according to the 3 hypotheses of MR, and bidirectional causality between atopic diseases and IBD was assessed using 2-sample Mendelian randomization analysis (2SMR). The results of our study suggest that AR increased the risk of Crohn disease (CD) (IVW OR = 1.19, 95% CI = 1.02-1.39, P = .026), ulcerative colitis (UC) (IVW OR = 1.14, 95% CI = 1.01-1.29, P = .031) and overall IBD (IVW OR = 1.15, 95% CI = 1.03-1.28, P = .015); Asthma increased the risk of CD (IVW OR = 7.66, 95% CI = 1.58-37.20, P = .012), UC (IVW OR = 3.81, 95% CI = 1.09-13.32, P = .036) and overall IBD (IVW OR = 5.13, 95% CI = 1.48-17.70, P = .010); AD increased the risk of CD (IVW OR = 1.19, 95% CI = 1.02-1.39, P = .023) and overall IBD (IVW OR = 1.14, 95% CI = 1.03-1.28, P = .015) risk. In reverse causality, only CD increased the risk of AR (IVW OR = 1.02, 95% CI = 1.00-1.05, P = .031). This study shows that atopic diseases of AR and asthma are causally related to IBD and its subtypes, and AD is causally related to IBD (which may be attributed to CD). Of the reverse causality, only CD was causally related to AR.

Investigating the genetic causal relationship between breast cancer and endometrial cancer: A two-sample Mendelian randomization study.

Observational studies have consistently shown a correlation between breast cancer (BC) and endometrial cancer (EC). Despite these findings, the causal relationship between these cancers has not been clearly defined. This research employed a bidirectional two-sample Mendelian randomization to explore the genetic causality between BC and EC. Genetic instruments for BC were derived from the Breast Cancer Association Consortium genome-wide association studies summary statistics, while for EC, data were sourced from the Endometrial Cancer Association Consortium, the Epidemiology of Endometrial Cancer Consortium, and the UK Biobank. The primary analytical method was inverse-variance weighted. Additional analyses, such as MR-Egger and weighted median, were conducted to validate the robustness of our findings from multiple perspectives. The MR-Egger intercept test was conducted to examine potential pleiotropy, whereas Cochrane Q test was implemented to assess heterogeneity. A leave-one-out analysis was conducted to assess the sensitivity of the observed association. Our analysis identified a bidirectional genetic causal relationship between estrogen receptor-positive breast cancer (ER+BC) and EC. Inverse-variance weighted analysis indicated an odds ratio of 1.0686 (95% confidence interval: 1.0029-1.1386, P = .0403) from ER+BC to EC and an odds ratio of 1.0692 (95% confidence interval: 1.0183-1.1225, P = .0071) from EC to ER+BC. No significant horizontal pleiotropy was detected. This study confirms a bidirectional genetic link between ER+BC and EC, suggesting shared genetic etiologies and possibly linked pathophysiological pathways. Understanding the genetic interplay between ER+BC and EC can enhance strategies for the precise prevention and screening of these prevalent cancers, potentially leading to improved clinical outcomes and management of secondary primary malignancies.

Multiple sclerosis and COVID-19: a bidirectional Mendelian randomization study

Multiple sclerosis and COVID-19: a bidirectional Mendelian randomization study

Causal effect of vascular endothelial growth factor on the risk of atrial fibrillation: a two-sample Mendelian randomization study

Causal effect of vascular endothelial growth factor on the risk of atrial fibrillation: a two-sample Mendelian randomization study

Causal Relationship Between Sjögren's Syndrome and Gut Microbiota: A Two-Sample Mendelian Randomization Study.

Background: Gut microbiota have been previously reported to be related to a variety of immune diseases. However, the causal connection between Sjögren's syndrome (SS) and gut microbiota has yet to be clarified. Methods: We employed a two-sample Mendelian randomization (MR) analysis to evaluate the causal connection between gut microbiota and SS, utilizing summary statistics from genome-wide association studies (GWASs) obtained from the MiBioGen and FinnGen consortia. The inverse variance weighted (IVW) approach represents the primary method of Mendelian randomization (MR) analysis. Sensitivity analysis was used to eliminate instrumental variables heterogeneity and horizontal pleiotropy. In addition, we performed an analysis using independent GWAS summary statistics for SS from the European Bioinformatics Institute (EBI) dataset for further verify our results. Results: IVW results demonstrated that the phylum Lentisphaerae (OR = 0.79, 95% CI: 0.63-0.99, p = 0.037), class Deltaproteobacteria (OR = 0.67, 95% CI: 0.47-0.96, p = 0.030), family Porphyromonadaceae (OR = 0.60, 95% CI: 0.38-0.94, p = 0.026), genus Eubacterium coprostanoligenes group (OR = 0.61, 95% CI: 0.4-0.93, p = 0.021), genus Blautia (OR = 0.62, 95% CI: 0.43-0.90, p = 0.012), genus Butyricicoccus (OR = 0.61, 95% CI: 0.42-0.90, p = 0.012), genus Escherichia.Shigella (OR = 0.7, 95% CI: 0.49-0.99, p = 0.045) and genus Subdoligranulum (OR = 0.61, 95% CI: 0.44-0.86, p = 0.005) exhibited protective effects on SS. Relevant heterogeneity of horizontal pleiotropy or instrumental variables was not detected. Furthermore, repeating our results with an independent cohort provided by the EBI dataset, only the genus Eubacterium coprostanoligenes group remained significantly associated with the protective effect on SS (OR = 0.41, 95% CI: 0.18-0.91, p = 0.029). Two-step MR analysis further revealed that genus Eubacterium coprostanoligenes group exerts its protective effect by reducing CXCL6 levels in SS (OR, 0.87; 95% CI = 0.76-0.99, p = 0.033). Conclusions: Our study using two-sample MR analysis identified a causal association between multiple genera and SS. A two-step MR result calculated that genus Eubacterium coprostanoligenes group mediated its protective effect by reducing CXCL6 levels in SS. However, the datasets available from the MiBioGen and FinnGen consortia do not provide sufficient information or comprehensive demographic data for subgroup analyses. Additional validation using various omics technologies is necessary to comprehend the development of SS in the intricate interplay between genes and the environment over a period of time.

Association of gut microbiota with critical pneumonia: A two-sample Mendelian randomization study.

This study investigated the causal effect of gut microbiota on critical pneumonia. Data came from a large-scale gut microbiota data set (n = 18,340) and the critical pneumonia genome-wide genotyping array (cases n = 2758 and controls n = 42,8607). Inverse variance weighting was used as the primary Mendelian randomization (MR) analysis method. Weighted median, MR-Egger, simple model, weighted model, and MR-Egger, were used to evaluate robustness. Sensitivity analysis used Cochran Q test, MR-Egger intercept test, and MR-PRESSO. For critical pneumonia, inverse variance weighting estimates suggested that Class Verrucomicrobiae (OR = 0.415; 95% CI: 0.207, 0.833; P = .013), Family Verrucomicrobiaceae (OR = 0.415; 95% CI: 0.207, 0.833; P = .013), Genus Akkermansia (OR = 0.415; 95% CI: 0.207, 0.833; P = .013), Genus LachnospiraceaeFCS020group (OR = 0.449; 95% CI: 0.230, 0.890; P = .021), Genus Parasutterella (OR = 0.466; 95% CI: 0.233, 0.929; P = .030), Genus Prevotella7 (OR = 0.645; 95% CI: 0.432, 0.960; P = .031), Order Verrucomicrobiales (OR = 0.415; 95% CI: 0.207, 0.833; P = .013), and Phylum Cyanobacteria (OR = 0.510; 95% CI: 0.272, 0.956; P = .036) had a reduced risk, while Family Enterobacteriaceae (OR = 2.746; 95% CI: 1.008, 7.474; P = .048), Genus RuminococcaceaeUCG003 (OR = 2.811; 95% CI: 1.349, 5.851; P = .006) and Order Enterobacteriales (OR = 2.746; 95% CI: 1.008, 7.474; P = .048) were associated with an increased risk. Sensitivity analyses confirmed that the aforementioned correlations were robust.

The causal association between immune cells and gout: A bidirectional two-sample Mendelian randomization study.

Gout, a metabolic disorder, is increasingly being linked to immune cells. However, the causal relationships between these factors remain unclear. Our study aimed to elucidate the causal relationship between immune cells and gout. Our study used 2-sample Mendelian randomization (MR) to explore the causal relationship between immune cells and gout. It is noteworthy that we utilized 5 methods MR-Egger, weighted median, inverse variance weighted, weighted mode, and simple mode to ensure the reliability of the results. Comprehensive sensitivity analyses were performed to verify the robustness, heterogeneity, and horizontal pleiotropy of the results. After false discovery rate correction (PFDR <0.20), 3 immunophenotypes were identified: one in the B cell panel, one in the regulatory T cells panel, and another in the T lymphocytes, B lymphocytes, Natural Killer cells panel. Among them, 2 immunophenotypes (CD4-CD8-T cell absolute count and CD25 on IgD + CD24 + B cell) increased the risk of developing gout, whereas the other one immunophenotype (CD45RA + CD28- CD8 + T cell %T cell) decreased the risk of gout. Subsequently, we did not observe heterogeneity and horizontal pleiotropy stable in these data through comprehensive sensitivity analyses. Furthermore, we identified some positive results in reverse MR analysis, but after false discovery rate correction (PFDR <0.20), no significant results were detected. Our study revealed causal relationships between immune cells and gout, providing novel insights into the prevention and treatment of gout.

Causal relationship between uric acid and stroke: a two-sample mendelian randomization study.

Many previous observational studies have disputed whether there is a link between uric acid and stroke. And the causal relationship between uric acid and stroke is unclear. To determine whether there is a causal relationship between uric acid and stroke by using mendelian randomization (MR). Uric acid dataset was obtained from Anna Kottgen et al, with a sample size of 110,347 people, including 2450,548 single nucleotide polymorphisms (SNPs). Stroke pooled data from Malik R et al, publicly available in MEGASTROKE genome-wide association study, included meta-analysis data from 40,585 stroke patients and 406,111 control patients, totaling 8211,693 SNPs. The summary data of genome-wide association study of uric acid and stroke were collected from publicly available online databases. Inverse variance weighting was used to determine the causal relationship between uric acid and stroke. MR-Egger and weighted median model were used for supplementary analysis. Results were then analyzed for heterogeneity, pleiotropy, and sensitivity to ensure no statistical pleiotropy and to reduce bias. A total of 27 SNPs were included in this study after the disequilibrium instrumental variables were excluded. Check the PhenoScanner database for SNPs associated with confounders. In the end, a total of 8 SNPs were excluded. Two SNPs were excluded because the correction direction was the same. Since the F statistic is >10, rs10761587 and rs1825043 are excluded. Finally, 15 SNPs were selected as uric acid instrumental variables. Inverse variance weighting-fixed effect model suggested that there was no causal relationship between uric acid and stroke (odds ratio = 1.004, 95% confidence interval = 0.940, 1.072). MR-Egger and weighted median model also showed the same result. In addition, the results of this study were robust without heterogeneity and pleiotropy. This MR study suggests no support of a causal relationship between uric acid and stroke.