Two-sample Mendelian Randomization Analysis Research Articles

Causal correlations between inflammatory proteins and heart failure: A two-sample Mendelian randomization analysis.

Inflammation plays a critical role in both the development and progression of heart failure (HF), which is a leading cause of morbidity and mortality worldwide. However, the causality between specific inflammation-related proteins and HF risk remains unclear. This study aims to investigate the genetically supported causality between inflammatory proteins and HF using a two-sample Mendelian randomization (MR) analysis. We utilized genome-wide association study (GWAS) data of 91 inflammation-related proteins as exposures from the SCALLOP Consortium (14,824 participants), alongside outcome GWAS summary statistics from FinnGen (29,218 cases/381,838 controls) and HERMES (47,309 cases/930,014 controls) for HF, to conduct a two-sample MR analysis. For each inflammatory protein, instrumental variables (IVs) were chosen following the three foundational assumptions of the MR analysis, requiring a minimum of three qualifying single nucleotide polymorphisms (SNPs) each with a P<5e-8. Associations between inflammatory proteins and HF were assessed through inverse-variance weighted (IVW), MR-Egger regression, weighted median and weighted mode analysis. The reliability and validity of the results were evaluated by examining heterogeneity, horizontal pleiotropy, leave-one-out analysis, meta-analysis and reverse MR analysis. Heterogeneity refers to the variation in results across different genetic variants. Horizontal pleiotropy occurs when a genetic variant influences multiple traits through different biological pathways. Addressing both heterogeneity and horizontal pleiotropy is crucial for ensuring the reliability and interpretability of MR results. Our analysis identified associations between three inflammatory proteins and HF risk. Matrix metalloproteinase-1 (MMP-1) (OR, 1.09; 95% CI, 1.00-1.18; P=0.04) and TNF-beta (OR, 1.05; 95% CI, 1.01-1.09; P=0.01) were positively associated with HF risk in FinnGen. In contrast, urokinase-type plasminogen activator (uPA) was inversely associated with HF risk in both FinnGen (OR, 0.85; 95% CI, 0.78-0.92; P=3.27e-5) and HERMES (OR, 0.93; 95% CI, 0.87-0.99; P=0.03). No evidence of heterogeneity and horizontal pleiotropy was observed in the MR analysis, indicating the robustness of our findings. A meta-analysis further supported this association, indicating a reduced risk (OR, 0.89; 95% CI, 0.81-0.98; P=0.02). No reverse causality was found between HF and these three inflammatory proteins (P>0.05 for all). This study provides genetically supported evidence of the causal association of specific inflammatory proteins with HF risk. The positive association of MMP-1 and TNF-beta with HF suggests their roles in disease pathogenesis, whereas the inverse association of the uPA indicates its potential protective effect. Our findings highlight the potential of targeting specific inflammatory pathways as a therapeutic strategy for HF.

Causal association between allergic diseases and celiac disease: a bidirectional two-sample and multivariable Mendelian-randomization study.

This study aimed to assess the causality of allergic diseases and celiac disease. We collected summary-level data from publicly available genome-wide association studies to conduct our bidirectional two-sample and multivariable Mendelian randomization analysis. Furthermore, a series of sensitivity analyses were applied to validate our findings. In bidirectional two-sample MR analyses, we found a significant causal effect of atopic dermatitis (AD) on CD (Inverse-variance weighted (IVW): odds ratio [OR] = 1.302, 95% confidence interval [CI] = 1.152-1.471, P < 0.001). We also found a significant causal effect of allergic rhinitis (AR) on CD (IVW: OR = 4.181, 95% CI = 1.495-11.697, P = 0.006). However, the MR-Egger method indicated a different causal effect direction compared to the IVW and weighted median method. After Bonferroni correction, the result of asthma on CD is suggestive of a causal effect (IVW: OR = 1.186, 95% CI = 1.021-1.378, P = 0.026). No causal effects were found when CD was considered as an exposure variable. In MVMR analyses, after separately and jointly adjusting for the influence of smoking and BMI, the causal effect of AD on CD remained robust. Our study suggests that AD is a risk factor for CD and it is considered suggestive of a causal relationship between asthma and CD. Further research is needed to explore the potential mechanisms underlying this causal effect.

Obesity and risk for liver disease: a two-sample Mendelian randomisation study.

The associations between obesity and liver diseases are complex and diverse. To explore the causal relationships between obesity and liver diseases, we applied two-sample Mendelian randomisation (MR) and multivariable MR analysis. The data of exposures (BMI and WHRadjBMI) and outcomes (liver diseases and liver function biomarker) were obtained from the open genome-wide association study database. A two-sample MR study revealed that the genetically predicted BMI and WHRadjBMI were associated with non-alcoholic fatty liver disease, liver fibrosis and autoimmune hepatitis. Obesity was not associated with primary biliary cholangitis, liver failure, liver cell carcinoma, viral hepatitis and secondary malignant neoplasm of liver. A higher WHRadjBMI was associated with higher levels of biomarkers of lipid accumulation and metabolic disorders. These findings indicated independent causal roles of obesity in non-alcoholic fatty liver disease, liver fibrosis and impaired liver metabolic function rather than in viral or autoimmune liver disease.

Causal associations of tea consumption on risk of pancreatic adenocarcinoma and the mediating role of vascular endothelial growth factor D levels.

Tea is one of the most widely consumed beverages in the world. However, the association between tea and risk of pancreatic adenocarcinoma remains controversial. This study aimed to investigate the causal relationship between tea consumption and risk of pancreatic adenocarcinoma and to explore their mediating effects. The two-sample Mendelian randomisation (MR) analysis showed an inverse causal relationship between tea intake and pancreatic adenocarcinoma (OR: 0·111 (0·02, 0·85), P < 0·04). To examine the mediating effects, we explored the potential mechanisms by which tea intake reduces the risk of pancreatic adenocarcinoma. Based on the oral bioavailability and drug-like properties in Traditional Chinese Medicine Systems Pharmacology database, we selected the main active ingredients of tea. We screened out the fifteen representative targeted genes by Pharmmapper database, and the gene ontology enrichment analysis showed that these targeted genes were related to vascular endothelial growth factor (VEGF) pathway. The two-step MR analysis of results showed that only VEGF-D played a mediating role, with a mediation ratio of 0·230 (0·066, 0·394). In conclusion, the findings suggest that VEGF-D mediates the effect of tea intake on the risk of pancreatic adenocarcinoma.

Causal association of gut microbes and blood metabolites with acne identified through systematic mendelian randomization.

Acne is a prevalent inflammatory disease in dermatology, and its pathogenesis may be associated with inflammation, immunity, and other mechanisms. It commonly manifests in young individuals and frequently imposes a heavy economic, physical, and psychological burden on patients. Gut microbes and blood metabolites, as significant immune and inflammatory regulators in the body, have been hypothesized to form the "neurocutaneous axis." Nonetheless, the precise causal relationships among the gut microbes, circulating blood metabolites, and acne development have yet to be elucidated. This study employed bidirectional two-sample Mendelian randomization (MR) to probe the causal impacts of 412 distinct gut microbes and 249 blood metabolites on acne. Single nucleotide polymorphisms (SNPs), which are closely associated with gut microbes and blood metabolites, were utilized as instrumental variables. This approach was taken to discern whether these elements serve as pathogenic or protective factors in relation to acne. Furthermore, a mediation analysis encompassing gut microbes, blood metabolites, and acne was conducted to explore potential correlations between gut microbes and blood metabolites, as well as their cumulative effects on acne. This was done to substantiate the notion of causality. Bidirectional two-sample MR analysis revealed 8 gut bacteria, 6 bacterial metabolic abundance pathways determined by birdshot, and 8 blood metabolites significantly associated with acne. The mediation MR analysis revealed 2 potential causal relationships, namely, Bifidobacterium-DHA-Acne and Bifidobacterium-Degree of Unsaturation-Acne. This study identified gut microbes and blood metabolites that are causally associated with acne. A potential causal relationship between gut microbes and blood metabolites was obtained via mediation analysis. These insights pave the way for the identification of new targets and the formulation of innovative approaches for the prevention and treatment of acne.

The relationship between pulmonary ventilation function and bone marrow hematopoietic function: A mendelian randomization analysis

Background: In recent years, the comorbidity between respiratory and hematopoietic system diseases has emerged as a new challenge. However, the potential genetic link between the ventilatory function of the respiratory system and the hematopoietic function of the bone marrow remains unclear. In this study, we conducted a comprehensive investigation into the possible genetic connection between lung ventilatory function and bone marrow hematopoietic function. Methods: We selected two exposure factors, Forced Expiratory Volume in 1 second (FEV1) and Forced Vital Capacity (FVC), which represent pulmonary ventilation function, and two outcome indicators, Immature Fraction of Reticulocytes (IFR) and Reticulocyte Count (RC), which represent bone marrow hematopoiesis function, from published genome-wide association studies. Based on the three core assumptions of Mendelian randomization analysis, we extracted Single Nucleotide Polymorphism (SNPs) associated with FEV1 and FVC as instrumental variables for the exposure factors. We then conducted two-sample Mendelian randomization analyses using inverse variance weighted (IVW), weighted median, and MR-Egger regression methods. Lastly, we assessed the reliability of the testing results through MR-Egger, Cochran’s Q test, and the leave-one-out test. Through these steps, we aimed to explore the causal relationship between pulmonary ventilation function and the outcome of bone marrow hematopoiesis function and evaluated the reliability of the testing results using methods such as MR-Egger, Cochran’s Q test, and the leave-one-out test. Results: The IVW method revealed that a decrease in FEV1 is associated with an increase in IFR (β = −0.072, 95% CI: −0.131 to −0.014, p = 0.01), and the results from MR-Egger regression showed a similar association (β = −0.169, 95% CI: −0.342 to −0.004, p = 0.05). Furthermore, a decrease in FEV1 is associated with an increase in RC (β = −0.143, 95% CI: −0.198 to −0.087, p =4.00E-07), and MR-Egger regression yielded consistent results (β = −0.216, 95% CI: −0.381 to −0.541, p=1.07E-02). Similarly, a decrease in FVC is associated with an increase in IFR (β = −0.073, 95% CI: −0.116 to −0.031, p = 6.17E-04), and MR-Egger regression showed a similar trend (β = −0.046, 95% CI: −0.160 to −0.067, p=0.42). Additionally, a decrease in FVC is associated with an increase in RC (β = −0.173, 95% CI: −0.221 to −0.125, p = 2.33E-12), and MR-Egger regression yielded consistent results (β = −0.142, 95% CI: −0.272 to −0.012, p = 3.32E-02). The reliability tests indicated heterogeneity in the above MR analyses but no evidence of horizontal pleiotropy. Therefore, a fixed-effect model IVW was used to explore the causal relationships, which were found to be robust and reliable with no outliers or significant bias in this study. Conclusion: This study indicates that there is a negative causal relationship between pulmonary ventilation function and bone marrow hematopoietic function. A decrease in pulmonary ventilation function stimulates bone marrow hematopoiesis. However, further research is needed to elucidate this mechanism.

Mendelian Randomization Estimates the Effects of Plasma and Cerebrospinal Fluid Proteins on Intelligence, Fluid Intelligence Score, and Cognitive Performance.

Observational studies have revealed associations between levels of plasma and cerebrospinal fluid (CSF) proteins and cognition-related traits. However, these associations may be influenced by confounding factors inherent in observational research. This study aims to identify plasma and CSF proteins associated with intelligence, fluid intelligence score, and cognitive performance through the application of Mendelian randomization (MR). Proteomic quantitative trait locus (pQTL) data for plasma and CSF proteins were sourced from existing genome-wide association study (GWAS). Intelligence, fluid intelligence score, and cognitive performance GWAS summary statistics provided comprehensive data for two-sample MR analysis. Extensive sensitivity analyses, including Steiger testing, reverse MR analysis, and Bayesian co-localization, were conducted to validate associations and identify shared genetic variants. Phenotype scanning explored potential pleiotropic effects. MR analysis identified several proteins in plasma and CSF significantly associated with intelligence, fluid intelligence scores, and cognitive performance. For intelligence, negatively associated proteins in plasma include endoplasmic reticulum aminopeptidase 2 (ERAP2) and secretogranin III (SCG3), while positively associated proteins are myeloperoxidase (MPO), signal regulatory protein alpha (SIRPA), regulator of microtubule dynamics 1 (RMDN1), and endoplasmic reticulum lectin 1 (ERLEC1). In CSF, C1-esterase inhibitor and carboxypeptidase E (CBPE) both exhibited positive associations with intelligence. For fluid intelligence scores, negatively associated proteins in plasma are copine 1 (CPNE1) and SCG3, while positively associated proteins are nudix hydrolase 12 (NUDT12) and RMDN1.In CSF, Macrophage Stimulating Protein (MSP) demonstrated a significant negative impact. For cognitive performance, negatively associated proteins in plasma include ERAP2, tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (TIE1), and SCG3, while positively associated proteins are NUDT12, RMDN1, ERLEC1, and ectonucleotide pyrophosphatase/phosphodiesterase family member 5 (ENPP5). In CSF, C1-esterase inhibitor was positively associated, while MSP and soluble tyrosine kinase with immunoglobulin-like and EGF-like domains 1(sTie-1) showed a negative association. Bayesian co-localization analysis revealed significant genetic overlaps between SIRPA, RMDN1, and ERLEC1 in plasma with intelligence; NUDT12 and SCG3 in plasma with fluid intelligence scores; and TIE1, NUDT12, RMDN1, ERLEC1, and ENPP5 in plasma with cognitive performance. Additionally, significant co-localization was identified between C1-esterase inhibitor and CBPE in CSF with intelligence, as well as between C1-esterase inhibitor and sTie-1 in CSF with cognitive performance. Reverse causality analysis confirmed the causal direction from proteins to cognitive traits. This study identifies specific plasma and CSF proteins that significantly impact intelligence, fluid intelligence scores, and cognitive performance. These proteins could serve as biomarkers and targets for future research and therapeutic interventions aimed at sustaining cognitive abilities and reducing impairment risks.

Causal Effects of Gastroesophageal Reflux on Chronic Rhinosinusitis: A Bidirectional Two-Sample Mendelian Randomization Study.

Observational studies have shown a bidirectional association between gastroesophageal reflux (GER) and chronic rhinosinusitis (CRS) or chronic rhinitis (CR), but it is not clear whether this association is causal. This study was to investigate the causality between GER and CRS or CR using bidirectional two-sample Mendelian randomization (MR) analysis. Using pooled data from large genome-wide association studies (GWAS), genetic loci independently associated with GER, CRS and CR in populations of European and American ancestry were selected as instrumental variables (IVs). The inverse variance weighted (IVW) method was used to analyse the random effects model of MR, and the odds ratio (OR) was used as the evaluation index to explore the bidirectional causality between GER and CRS or CR. Single nucleotide polymorphism (SNP) outliers were detected using MR-pleiotropy Residual Sum and Outliers (MR-PRESSO). The MR-Egger intercept test examined the horizontal pleiotropy of SNPs. The "leave-one-out" sensitivity analysis examined whether MR results were affected by a single SNP. The main results of IVW showed that GER increased the risk of CRS (OR = 1.3795, 95% CI = 1.188-1.603, p < 0.0500) and CR (OR = 1.3941, 95% CI = 1.1671-1.6652, p < 0.0500). The obtained SNPs as IVs for GER, CRS and CR had no significant horizontal pleiotropy, heterogeneity or bias. Regarding the reverse directions, no notable associations could be found. This MR analysis revealed that genetically predicted GER had a causal effect on an increased risk of CRS or CR, but not vice versa. These results have great implications for the management of CRS (especially for refractory CRS) or CR in clinical practice.

Skimmed milk intake reduces the risk of ER− breast cancer: a Mendelian randomization analysis

BackgroundIn prior observational investigations, it has been demonstrated that the consumption of milk is associated with the incidence of breast cancer (BC). Despite the existence of a two-sample Mendelian randomization (MR) that suggests a causal relationship between milk intake and breast cancer risk, the outcomes still lack a definitive conclusion. This ambiguity may be attributed to variables such as the variety of milk ingested, estrogen levels, the specific type of BC, and potential confounding factors. Therefore, our principal objective is to establish the causal association between the consumption of skimmed milk and full cream milk and the risk of different types of BC through the utilization of two-sample and two-step MR analyses.MethodsIn this study, we analyzed single nucleotide polymorphisms associated with skimmed and full-cream milk consumption in a cohort of 360,806 individuals from European populations through genome-wide association studies. We conducted a two-sample MR analysis using three different methods: inverse variance weighting (IVW) was used as the main analysis, and MR-Egger and Weighted median were used as supplementary analyses to IVW. We also performed sensitivity analysis, which included leave-one-out analysis, Cochran's Q test to detect heterogeneity, and MR-Egger intercept analysis to detect potential biases caused by pleiotropy. We used two-step MR analysis to evaluate potential mediators of associations.ResultsIn the two-sample MR analysis, IVW analysis suggests a potential inverse causal relationship between skimmed milk and BC [OR 0.34, 95% CI (0.12–1.00), P = 0.05]. Subgroup analysis revealed that skimmed milk reduces the risk of estrogen receptor-negative (ER−) breast cancer [OR 0.18, 95% CI (0.04–0.90), P = 0.04], but not estrogen receptor-positive (ER+) breast cancer [OR 0.42, 95% CI (0.15–1.22), P = 0.11]. MR Egger reached similar results, that is, skimmed milk reduces the risk of ER− breast cancer [OR 0.006, 95% CI (0.00–0.70), P = 0.04], but not BC [OR 0.16, 95% CI (0.01–4.66), P = 0.30] and ER+ breast cancer [OR 0.50, 95% CI (0.02–12.61), P = 0.65]. Additionally, we found no causal relationship between full cream milk and BC (P > 0.05). In two-step MR analysis, we found evidence for a mediating role of BMI in the relationship between skimmed milk intake and ER-breast cancer risk.ConclusionOur findings strengthen the evidence for a protective effect of skimmed milk consumption on ER-breast cancer risk. Further two-step MR analyses suggest that this protective effect may partly result from body mass index (BMI). There is no evidence that full cream milk consumption affects the risk of BC.

Evaluating the relationship between standing height, body mass index, body fat percentage with risk of inguinal hernia: a Mendelian randomization study

Observational studies have suggested links between standing height, BMI, body fat percentage, and inguinal hernia risk, but with inconsistent results. We conducted Mendelian randomization (MR) method to investigate their causal relationships. Independent SNPs associated with standing height, BMI, and body fat percentage were extracted from GWAS data as instrumental variables (IVs). Two-sample MR initially explored causal relationships between these factors and inguinal hernia risk. Multivariable Mendelian randomization (MVMR) assessed the direct causal effects of exposures on inguinal hernia. Positive findings from the MVMR analysis were independently validated. The inverse-variance weighted Methods (IVW), weighted median(WM), and MR-Egger were used for the MR estimates. Sensitivity analyses were used to examine the stability and reliability of the results. Two-sample MR analysis revealed a suggestive causal association between height and inguinal hernia (OR = 1.091, 95% CI = 1.003–1.186, P = 0.042). BMI (OR = 0.846, 95% CI = 0.774–0.924, P < 0.001) and body fat percentage (OR = 0.793, 95% CI = 0.690–0.911, P = 0.001) were significantly protective factors. After MVMR adjustment, BMI (OR = 0.746,95%CI = 0.638–0.872, P < 0.001) remained protective. Independent validation yielded consistent result. Genetically predicted BMI is a significant protective factor for inguinal hernia, providing valuable guidance for individualized prevention strategies.

The causal relationship between anti-CD20 antibodies and endometrial cancer: a Mendelian randomization study

PurposeTo determine the effects of anti-B cell surface marker CD20 antibody on the occurrence and progression of endometrial cancer to provide insights into clinical treatment in the future.MethodsWe performed a two-sample Mendelian randomization analysis (MR) to analyze the causal relationship between EC and immune cell markers. The genome-wide association study (GWAS) data of MS4A1 single nucleotide polymorphism encoding gene of CD20 were collected, and a drug target MR analysis was performed to detect the causal relationship between anti-CD20 antibody and the risk of EC. The risk of follicular lymphoma was used as a positive control, and EC was used as the outcome.ResultsEC exerted an effect on 28 immunophenotypes, predominantly on CD20. CD20 in immunoglobulin D+ CD38− B cells, memory B cells, and unsw memory B cells increased after EC onset. In addition, we detected one immunophenotype that exerted a dangerous effect on EC, i.e., CD3/TD CD4+ (mature stage of the T cell group). Simultaneously, CD20 could be used as both a risk factor and a protective factor for EC (P > 0.05). Anti-CD20 antibodies significantly reduced the risk of follicular lymphoma, including two GWAS pooled datasets. In addition, anti-CD20 antibodies exerted a protective effect on EC in two GWAS pooled datasets (P > 0.05).ConclusionOur study confirms the close relationship between CD20 and EC. Anti-CD20 antibodies may exert a protective effect on EC and reduce the risk of EC morbidity, providing a reference for future clinical diagnosis and treatment. However, further clinical verification of our results is warranted.

Gastroesophageal reflux disease, mood swings, and frozen shoulder: A two-sample, two-step Mendelian randomization study.

A Mendelian randomization (MR) study was undertaken to establish a causal link between gastroesophageal reflux disease (GERD) and frozen shoulder (FS), examining whether the risk of GERD with FS is mediated through mood fluctuations. Genetic loci from populations of independent European ancestry were selected as instrumental variables for GERD, FS, and mood swings. The primary analysis employed the inverse-variance weighted method supplemented by 3 additional analytical methods. This was conducted using two-sample and two-step MR analyses. This study explored the correlation and mediating effects of mood swings between GERD and FS. Our study employed heterogeneity and horizontal diversity, and sensitivity analysis was conducted using the leave-one-out method to explore the robustness of the results. In the two-sample MR analysis, for every 1-unit increase in the log-transformed odds ratio (OR) of GERD, the corresponding OR increased to 1.844 (inverse-variance weighting: OR = 1.844, 95% confidence interval: 1.47-2.30, P < .001). In the two-step MR analysis, we found that mood swings played a mediating role in the association between GERD and FS. We assessed this mediating effect using the delta method (b = 0.181, SE = 0.059, OR = 1.199, 95% confidence interval: 1.072-1.349). Analysis of the data using the above methods indicated that GERD is a risk factor for FS, and mood swings mediate between the 2. Therefore, GERD and mood swings should be included in the health management of patients with FS.

Genetically Predicted Sleep Traits and Sensorineural Hearing Loss: A Mendelian Randomization Study.

Observational studies suggest a potential association between sleep characteristics, sensorineural hearing loss (SNHL), and sudden SNHL (SSNHL), but causal evidence is scarce. We sought to clarify this issue using two-sample Mendelian randomization analysis. The inverse-variance weighted (IVW) method was performed as primary analysis to assess bidirectional causal associations between sleep traits (chronotype, sleep duration, insomnia, daytime sleepiness, and snoring) and SNHL/SSNHL using publicly available Genome-Wide Association Studies summary data from two large consortia (UK Biobank and FinnGen). Sensitivity analyses, including Mendelian randomization (MR)-Egger, Mendelian randomization pleiotropy residual sum and outlier, weight median, Cochran's Q test, leave-one-out analysis, and potential pleiotropy analysis, were conducted to ensure robustness. IVW analysis found suggestive associations of morning chronotype (odds ratio [OR] = 1.08, 95% confidence interval [CI] = 1.01-1.16, p = 0.031) and daytime sleepiness (OR = 1.88, 95% CI = 1.24-2.87, p = 0.003) with SNHL onset. Additionally, morning chronotype was nominally associated with SSNHL onset using IVW method (OR = 1.37, 95% CI = 1.10-1.71, p = 0.006). However, there was no evidence for the causal effect of SNHL and SSNHL on different sleep traits (all p > 0.05). Sensitivity analysis showed that the results were stable. Within the MR limitations, morning chronotype and daytime sleepiness were underlying causal contributors to the burden of SNHL, indicating that optimal sleep might facilitate the prevention and development of SNHL. 3 Laryngoscope, 134:4723-4729, 2024.

Association between cholelithiasis, cholecystectomy, and risk of breast and gynecological cancers: Evidence from meta-analysis and Mendelian randomization study.

Observational studies have shown that cholelithiasis and cholecystectomy are associated with the risk of breast cancer (BC) and gynecological cancers, but whether these relationships are causal has not been established and remains controversial. Our study began with a meta-analysis that synthesized data from prior observational studies to examine the association between cholelithiasis, cholecystectomy, and the risk of BC and gynecological cancers. Subsequently, a two-sample Mendelian randomization (MR) analysis was conducted utilizing genetic variant data to investigate the potential causal relationship between cholelithiasis, cholecystectomy, and the aforementioned cancers. The results of the meta-analysis demonstrated a significant association between cholecystectomy and the risk of BC (risk ratio [RR]=1.04, 95% confidence interval [CI]: 1.01-1.06, p=0.002) and endometrial cancer (EC) (RR=1.26, 95% CI: 1.02-1.56, p=0.031). Conversely, no significant association was observed between cholelithiasis and the risk of BC, EC, and ovarian cancer. The MR analysis revealed no discernible causal connection between cholelithiasis and overall BC (p=0.053), as well as BC subtypes (including estrogen receptor-positive/negative). Similarly, there was no causal effect of cholecystectomy on BC risk (p=0.399) and its subtypes. Furthermore, no causal associations were identified between cholelithiasis, cholecystectomy, and the risk of gynecological cancers (ovarian, endometrial, and cervical cancer [CC]) (all p>0.05). This study does not support a causal link between cholelithiasis and cholecystectomy and an increased risk of female cancers such as breast, endometrial, ovarian, and CC.

Genetic associations of metabolic factors and therapeutic drug targets with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is frequently accompanied with metabolic dysfunctions, yet the causal relationships between metabolic factors and PCOS remain to be conclusively established and etiology-based therapies are lacking. To comprehensively identify the metabolic causal factors and potential drug targets for PCOS. This genetic association study was conducted using bidirectional two-sample Mendelian Randomization (MR), multivariable MR (MVMR) and drug-target MR. Considering metabolic sexual dimorphism, female-specific genome-wide association studies (GWASs) for metabolic factors were obtained. To ensure the robustness of the findings, an additional independent PCOS GWAS dataset was utilized for replication. The PCOS cohort included 10,074 PCOS cases (mean age 28 to 45 years) and 103,164 controls (mean age 27 to 60 years) of European ancestry. All participants were female. Employing two-sample MR analysis, we found that genetically proxied body mass index (BMI) (OR = 3.40 [95 % CI, 2.65-4.36]), triglyceride (TG) (OR = 1.54 [95 % CI, 1.17-2.04]), low-density lipoprotein cholesterol (LDL-c) (OR = 1.37 [95 % CI, 1.07-1.76]), and type 2 diabetes (T2D) (OR = 1.24 [95 % CI, 1.09-1.41]) were significantly associated with an increased risk of PCOS, whereas genetically predicted high-density lipoprotein cholesterol (HDL-c) (OR = 0.61 [95 % CI, 0.47-0.80]) decreased the odds of PCOS. Stepwise MVMR established a hierarchy of interactions among these metabolic factors, identifying BMI and HDL-c as the most prominent causal factors. Notably, drug-target MR analysis identified incretin-based therapeutics, PCSK9 inhibitors, LPL gene therapy, sulfonylureas, and thiazolidinediones as potential therapeutics for PCOS. All these findings were validated in an independent dataset. This study offered insights into the roles of obesity, diabetes, and dyslipidemia in PCOS etiology and therapeutics, underscoring the necessity for managing metabolic health in women and paving the way for tailored therapeutic strategies for PCOS based on its metabolic underpinnings.

Investigating the causal association between heme oxygenase-1 and asthma: A bidirectional two-sample Mendelian randomization analysis in a European population

BackgroundThe association between heme oxygenase-1 (HO-1) and asthma has been a subject of debate in both observational and experimental studies. We aimed to evaluate the potential causal relationship between HO-1 and asthma. Materials and methodsA bidirectional two-sample Mendelian randomization (TSMR) study was conducted to examine the causal relationship between HO-1 and asthma. In the forward Mendelian randomization (MR) analyses, HO-1 was considered as the exposure, while asthma as the outcome. Conversely, in the reverse MR analyses, asthma was regarded as the exposure, and HO-1 as the outcome. Data for HO-1 and asthma were obtained from publicly accessible genome-wide association studies (GWAS). These causal relationships were identified through 5 MR methods, namely MR-Egger, weighted median, inverse-variance weighted (IVW), simple mode, and weighted mode. Additionally, sensitivity tests were conducted to assess the robustness of MR study. Finally, additional asthma datasets and childhood asthma were selected to validate the findings. ResultsIn the forward MR analyses, according to the IVW method, genetically predicted HO-1 displays a negative correlation with the risk of asthma (OR 0.947, 95% CI 0.905–0.990). It was not found any SNP overly sensitive or disproportionately responsible for the outcome. No evidence of heterogeneity and pleiotropy between SNPs was observed. Genetically predicted asthma was not associated with HO-1 in reverse MR analyses using the IVW method. The same results were validated in additional asthma datasets and in childhood asthma. ConclusionThe results of MR analysis revealed heme oxygenase-1 as a protective factor for asthma.

Coffee and Risk of Pancreatic Cancer: Insights from Two-Sample and Multivariable Mendelian Randomization Analyses

Background: The association between coffee and pancreatic cancer risk has reported inconsistent results. Therefore, a Mendelian randomization (MR) study was undertaken to investigate the association between coffee and pancreatic cancer from a genetic perspective. Methods: In East Asian and European populations, independent genetic variants strongly associated with coffee were chosen as instrumental variables (IVs) from relevant genome-wide association studies (GWASs). GWAS data for pancreatic cancer were obtained from the JENGER (Japanese Encyclopedia of Genetic Associations by Riken) project and GWAS catalog database. Two-sample (TSMR) and multivariable Mendelian randomization (MVMR) analyses were conducted to investigate the genetically predicted causal relationship between coffee consumption and pancreatic cancer. A fixed-effect meta-analysis was employed to aggregate estimates from the two populations to reveal the overall association. Results: Both in East Asian and European populations, an increase in coffee intake of a cup per day was not associated with pancreatic cancer risk, regardless of coffee type (including caffeine drinks, instant coffee, decaffeinated coffee, ground coffee, etc.). The results aligned with the findings of the meta-analysis (OR = 1.100, 95%CI = 0.862–1.403, p = 0.450). Also, for coffee intake with positive results in the TSMR analysis (OR = 1.739, 95%CI 1.104–2.739, p = 0.017), consistent negative results were observed after adjusting for potential confounders (smoking traits, drinking, type 2 diabetes, body mass index) in the MVMR analyses. Conclusions: This study found no genetically predicted causal relationship between coffee consumption and pancreatic cancer risk.

Two-Sample Mendelian Randomization Study Identifies Tissue-Dependent Risk Genes in Autoimmune Diseases

Autoimmune diseases are among the most prevalent diseases across the world with genetic and environmental factors that contribute to their etiology. Because the exact causes of autoimmune diseases are largely unknown, a Mendelian randomization (MR) approach is used here to examine the potential causal association between gene expression levels and disease risk across various tissues. Specifically, this study focuses on six autoimmune diseases including Crohn’s disease, ulcerative colitis, rheumatoid arthritis, multiple sclerosis, type 1 diabetes mellitus, and systemic lupus erythematosus. Several of these diseases are currently treatable with immunosuppressants that target specific genes, such as TNF-alpha, IL-23, CD20, and more. In this study, a two-sample MR analysis is performed with multitissue expression quantitative trait loci (eQTLs) and large-scale genome-wide association studies to investigate how gene expression can influence the risk of developing these diseases. Our results show that genes HLA-DQA1/2, HLA-DRB1/6, HLA-DQB2, C4A, CYP21A2, and HLA-DQB1-AS1 have a high causal effect across several diseases and tissues, and almost all of these findings originate from the major histocompatibility complex (MHC) region on Chromosome 6. Our findings support the current knowledge of genes associated with these diseases while also revealing novel genes that can be used for drug therapies in the future. Although several drug therapies currently exist to treat this selection of autoimmune diseases, we provide further insights into the main, common pathways responsible for autoimmune disease pathogenesis and discuss novel genes that lack research focus.

Associations between T-cell traits and narcolepsy type 1: new insights from a Mendelian randomization study

BackgroundNarcolepsy type 1 (NT1) is primarily caused by a malfunctioning immune system in which T-cells damage the hypothalamus. To elucidate the causal relationships between biomarkers in T-cells and NT1, we employed Mendelian randomization (MR) analysis.MethodsWe conducted a two-sample MR analysis utilizing genetically predicted T-cell traits to examine their effects on NT1. Genome-wide association study summary data were extracted from studies by Valeria (3,757 participants) for 211 T-cell traits, Ollila (6,073 cases and 84,856 controls) for NT1. The MR analysis was executed at two threshold levels. Inverse variance weighted, Wald ratio, weighted median, and MR-Egger regression methods were used for the MR analysis. Odds ratios (ORs) were calculated, and heterogeneity tests, as well as pleiotropy tests, were conducted.ResultsAfter Bonferroni correction at the significant level (p &amp;lt; 1.18 × 10−4), a higher ratio of naive CD4− CD8− T-cells was identified as a risk factor for NT1 (OR = 10.50; 95% CI: 6.98, 15.90, p = 3.89 ×10−29). Conversely, CD4 on HLA DR+ CD4+ T cells (mean fluorescence intensity, MFI) exhibited a negative correlation with NT1. At nominally significant levels (p &amp;lt; 0.05) for both threshold levels, HVEM (herpesvirus entry mediator) on naive CD8+ T cells (MFI) was suggested as a protective factor for NT1. Additionally, a higher ratio of CD25++ CD45RA− CD4 not regulatory T cells, CD127 on CD45RA− CD4 not regulatory T cells (MFI), CD127 on CD28+ CD4+ T cells (MFI), CD3 on HLA DR+ T cells (MFI), and CD3 on HLA DR+ CD4+ T cells (MFI) were suggested as risk factors for NT1.ConclusionThis study confirmed the causal effects of CD4+ and CD8+ T-cells on NT1 and found several novel T-cell-related characteristics.

Effect of tea consumption on the development of hypertension, diabetes, and obesity: a bidirectional two-sample Mendelian randomization analysis

BackgroundThe effect of tea consumption on conditions such as hypertension, diabetes, and obesity has attracted significant global interest. However, the results of various studies on this topic have been mixed and somewhat contentious. Therefore, we conducted a Mendelian randomization (MR) analysis to investigate the causal relationships between tea consumption and the aforementioned health conditions.MethodsA bidirectional two-sample MR analysis was used to systematically explores the associations between tea consumption and hypertension, diabetes, and obesity. MR-Egger regression, weighted median, inverse variance weighted, and weighted mode methods were used to evaluate the potential causal associations. Leave-one-out sensitivity test was used to check the robustness of the IVW estimates.ResultsMR analysis indicated that genetically predicted tea consumption is associated with a protective effect against hypertension, with an odds ratio (OR) of 0.78 and a 95% confidence interval (CI) ranging from 0.64 to 0.95. Additionally, tea consumption appeared to have a potential protective effect on type 2 diabetes and obesity related to excessive calorie intake, influenced by specific single nucleotide polymorphisms (SNPs), namely “rs57462170” and “rs17685.” No causal link was observed between the consumption of green or herbal tea and hypertension, diabetes, or obesity. However, there was a marginal negative association between type 2 diabetes and tea consumption and (OR = 0.99; 95% CI: 0.97–1.00) and a significant negative correlation between obesity due to excessive calorie intake and green tea consumption (OR = 0.35; 95% CI: 0.16–0.78).ConclusionThis study demonstrates a protective causal relationship between the consumption of tea (including black and green teas) and reduced risk of hypertension. Furthermore, our results suggest that tea intake may also have a protective effect on type 2 diabetes and obesity. The results recommend further research to verify or refine these findings.