Mendelian Randomization: Concepts and Scope

Novel therapeutic targets uncovered by genome-wide integrative analysis in bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the most common chronic respiratory disease in extremely premature infants. This study aims to identify gene expression dysregulation and explore various molecular pathways implicated in BPD.

METHODS

This study integrated BPD genome-wide association study (GWAS), single-cell transcriptomics (scRNA-seq), and Mendelian randomization (MR) analysis to investigate the causal relationship between gene expression and BPD.

RESULTS

Cell annotation and ligand-receptor analysis highlighted myofibroblasts as the most interactive cell type. Key genes, including CDH4, ENC1, and PAM, were identified as protective factors against BPD, while GRB10 was associated with increased disease risk. Immune metabolism-related pathways showed elevated activity of PAM, GRB10, and ENC1 in epithelial-mesenchymal transition. The Drug-Gene Interaction Database (DGIdb) predicted three drugs-LM10, navoximod, and ziprasidone-that potentially interact with these key genes.

CONCLUSION

This integrative genome-wide analysis provides valuable insights into the genetic mechanisms underlying BPD. The findings facilitate the identification of novel therapeutic targets and pave the way for personalized treatment strategies for affected neonates.

Combining mitochondrial proteomes and Mendelian randomization to identify novel therapeutic targets for diabetic nephropathy

Diabetic nephropathy (DN) is a common microvascular complication of diabetes. Mitochondrial dysfunction in the kidney caused by diabetes has previously been linked to the pathogenesis of DN. By mass spectrometry, we identified characteristic proteins of DN from the renal mitochondria in mouse model. To identify the core proteins among them, Mendelian randomization (MR) analysis, microarray data validation, and drug-target interaction analysis were employed. MR analysis found that 189 candidate targets had a causal link with DN risk factors (estimated glomerular filtration rate (eGFR), urinary albumin excretion, and serum creatinine). After systematic analysis, we validated that SLC25A16, CTNND1, C2CD2L, ALDH3A2, NEU1, APEH, CORO1A, NUDT19, and NDUFA4L2 are the core proteins with promising druggability in DN. This study suggests the feasibility of using MR analysis for DN drug target screening, and provides potential insights into mitochondrial dysfunction research, which may contribute to further DN pathogenesis exploration.

Bidirectional Mendelian randomization and colocalization analysis of gut microbiota on lipid profile

The gut microbiota plays a crucial role in human health, but its impact on lipid metabolism remains unclear. Understanding the causal relationship between gut bacteria and lipid profiles is essential for developing strategies to prevent and treat dyslipidemia and cardiovascular diseases. This study aimed to assess this relationship using two-sample Mendelian randomization (MR). Data for both exposure and outcomes were obtained from the IEU-GWAS database, with lipid profile data sourced from a publication. Genome-wide significant single nucleotide polymorphisms (SNPs), which were independent of outcome factors but correlated with exposure variables, were identified as instrumental variables. Several MR methods, including weighted analysis, maximum likelihood, inverse variance weighting (IVW), MR-Egger, and weighted median, were applied. Colocalization analysis further validated the findings. The analysis revealed microbial groups with causal relationships to ApoA1, ApoB, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, total cholesterol, and triglycerides. Reverse MR and colocalization analysis provided additional confirmation of these results. This study offers new evidence of the causal link between gut microbiota and lipid profiles, providing insights for improving lipid profiles and reducing cardiovascular disease risk.

Autoimmune thyroid disease is a risk factor for mood disorders, a Mendelian randomization study

BACKGROUND

Observational studies have demonstrated associations between autoimmune thyroid disease and both mood disorders and dementia, but the direction of causality has not been established.

METHODS

We employed bidirectional, two-sample Mendelian randomization analyses to assess the causal links between autoimmune thyroid disease (Graves' disease and autoimmune thyroiditis), and mood disorders (major depressive disorder and bipolar disorder) as well as dementia (Alzheimer's disease and dementia with Lewy bodies). We obtained Genome-Wide Association Study data from the Finngen database and IEU Open GWAS. For statistical analysis, we utilized several robust methods inverse variance weighted, MR-Egger, weighted median, simple mode and weighted mode. Sensitivity analyses are performed to detect potential horizontal pleiotropy, and to exclude any outlier data points that could skew our results.

RESULTS

Gene-proxy for Graves' disease was associated with an increased risk of major depressive disorder (P-value = 0.02), whereas gene-proxy for autoimmune thyroiditis was linked to a greater risk of bipolar disorder (P-value = 0.043). The levels of pleiotropy and heterogeneity among genetic variants suggest bias is unlikely, leave-one-out test confirmed a robust correlation. No indication that mood disorders influence the risk of autoimmune thyroid disease, and no evidence of a causal relationship between autoimmune thyroid disease and dementia.

CONCLUSIONS

Graves' disease is associated with heightened risk of major depressive disorder, and autoimmune thyroiditis is correlated with increased risk of bipolar disorder.

Effects of obesity on aging brain and cognitive decline: A cohort study from the UK Biobank

Objective

To investigate the impact of obesity on brain structure and cognition using large neuroimaging and genetic data.

Methods

Associations between body mass index (BMI), gray matter volume (GMV), whiter matter hyper-intensities (WMH), and fluid intelligence score (FIS) were estimated in 30283 participants from the UK Biobank. Longitudinal data analysis was conducted. Genome-wide association studies were applied to explore the genetic loci associations among BMI, GMV, WMH, and FIS. Mendelian Randomization analyses were applied to further estimate the effects of obesity on changes in the brain and cognition.

Results

The observational analysis revealed that BMI was negatively associated with GMV (r = -0.15, p < 1 × 10-24) and positively associated with WMH (r = 0.08, p < 1 × 10-16). The change in BMI was negatively associated with the change in GMV (r = -0.04, p < 5 × 10-5). Genetic overlap was observed among BMI, GMV, and FIS at SBK1 (rs2726032), SGF29 (rs17707300), TUFM (rs3088215), AKAP6 (rs1051695), IL27 (rs4788084), and SPI1 (rs3740689 and rs935914). The MR analysis provided evidence that higher BMI was associated with lower GMV (β=-1119.12, p = 5.77 ×10-6), higher WMH (β=42.76, p = 6.37 ×10-4), and lower FIS (β=-0.081, p = 1.92 ×10-23).

Conclusions

The phenotypic and genetic association between obesity and aging brain and cognitive decline suggested that weight control could be a promising strategy for slowing the aging brain.

Epigenome-wide DNA methylation association study of CHIP provides insight into perturbed gene regulation

With age, hematopoietic stem cells can acquire somatic mutations in leukemogenic genes that confer a proliferative advantage in a phenomenon termed CHIP. How these mutations result in increased risk for numerous age-related diseases remains poorly understood. We conduct a multiracial meta-analysis of EWAS of CHIP in the Framingham Heart Study, Jackson Heart Study, Cardiovascular Health Study, and Atherosclerosis Risk in Communities cohorts (N = 8196) to elucidate the molecular mechanisms underlying CHIP and illuminate how these changes influence cardiovascular disease risk. We functionally validate the EWAS findings using human hematopoietic stem cell models of CHIP. We then use expression quantitative trait methylation analysis to identify transcriptomic changes associated with CHIP-associated CpGs. Causal inference analyses reveal 261 CHIP-associated CpGs associated with cardiovascular traits and all-cause mortality (FDR adjusted p-value < 0.05). Taken together, our study reports the epigenetic changes impacted by CHIP and their associations with age-related disease outcomes.

Detection of the genetic association of circulating Helicobacter pylori antibodies with atrial fibrillation

Helicobacter pylori (H pylori) infection and H pylori antibodies have been reported to be associated with an increased risk of atrial fibrillation (AF) in several observational studies. However, whether this relationship is causal and which H pylori antibodies serve as the determinant of AF remains largely unclear. Recently published Genome-wide association studies on 7 different antibodies of H pylori-specific proteins and AF (2 correction methods) were included in this study. A two-sample Mendelian randomization study was employed to investigate the causal effects of circulating H pylori antibodies on the risk of AF. Genetically predicted serum H pylori Catalase antibody level was associated with an increased risk of AF (Firth correction) (odds ratio = 1.137, 95% confidence interval: 1.008-1.282, P = .037) and AF (saddlepoint approximation correction) (odds ratio = 1.139, 95% confidence interval: 1.010-1.284, P = .034). No significant causal correlations were found between other H pylori antibodies and AF. This Mendelian randomization study demonstrates that H pylori Catalase antibody is the only causal determinant associated with the risk of AF in terms of H pylori-related antibodies.

Identifying the genetic association between rheumatoid arthritis and the risk of infectious diseases

BACKGROUND

Previous evidence suggests an association between rheumatoid arthritis (RA) and infectious diseases, but the causal relationship remains unclear. This study sought to explore causal associations between RA and five common infections: pneumonia, sepsis, urinary tract infections (UTI), skin and subcutaneous tissue infections (SSTI), and bacterial intestinal infections (BII).

METHODS

To identify the causal links, we adopted a Mendelian randomization (MR) design utilizing the inverse variance weighted (IVW), weighted median (WM), and MR-Egger approaches. Univariable MR (UVMR) and multivariable MR (MVMR) analyses were performed using pooled genome-wide association studies (GWAS) data. Additionally, various sensitivity analyses were conducted to ensure the reliability of the results.

RESULTS

In the UVMR analysis, RA was potentially associated with elevated risks of pneumonia (OR = 1.034, 95% CI: 1.016-1.052, P < 0.001) and sepsis (OR = 1.079, 95% CI: 1.048-1.110, P = 3.507E-07). This association remained significant after adjusting for smoking, alcohol consumption, or type 2 diabetes mellitus (T2DM) in the MVMR analysis. However, no causal links were found between RA and UTI, SSTI, and BII. Sensitivity analyses showed no detectable heterogeneity or pleiotropy, strengthening the causal inference of results.

CONCLUSION

Our study provides strong evidence of the association between RA and increased risks of pneumonia and sepsis. Further research is required to validate these findings and elucidate the underlying mechanisms. Key Points • It remains unclear whether the increased susceptibility to infections in RA stems from a genetic predisposition or results from immunosuppressive treatments. • The MR method is employed to assess the relationship between RA and common infectious diseases. • Our MR study supports a potential causal relationship between RA and elevated risks of pneumonia and sepsis.

Schizophrenia, bipolar disorder and major depressive disorder are probably not risk factors for cardiovascular disease: A Mendelian randomized study

BACKGROUND

Individuals with severe mental illnesses (SMI) like schizophrenia, bipolar disorder (BD), and major depressive disorder (MDD) have an increased risk for cardiovascular diseases (CVD), but the causal relationship remains unclear.

METHODS

Mendelian randomization (MR) was used to investigate the potential causal relationship between SMI and CVD and its five subtypes of disease, coronary heart disease, myocardial infarction, stroke, heart failure, and atrial fibrillation. Subsequently, the MR results of SMI with CVD and its subtypes were meta-analyzed separately. To assess the robustness of the findings, Cochran's Q test, MR-Egger intercept test, MR-PRESSO, and leave-one-out analysis were used. Select single nucleotide polymorphisms (SNPs) related to SMI and CVD and their five subtypes (coronary heart disease, myocardial infarction, stroke, heart failure, and atrial fibrillation). Use univariable Mendelian randomization (UVMR) and multivariate Mendelian randomization (MVMR) to assess the causal relationship between these conditions. Conduct a meta-analysis of the MR results of SMI and CVD and their subtypes. Use MR mediation analysis to evaluate the mediating effect of BMI between BD and CVD. Use Cochran's Q test, MR-Egger intercept test, MR-PRESSO, and leave-one-out analysis to enhance the robustness of the study.

RESULTS

MR analyses have revealed correlations between schizophrenia and BD with CVD and their subtypes in certain datasets. No significant evidence of an association between MDD and CVD or its subtypes was observed in our MR analyses. After MVMR and MR meta-analysis, no basis for genetically predicted SMI increasing CVD and their subtypes was found. The MR mediation analysis showed that the reduced risk of certain CVDs in BD was partially related to BMI to some extent.

CONCLUSION

Our MR study did not provide conclusive evidence for a causal association between genetic predisposition to SMI and CVD. Based on the available evidence, it would be more appropriate to consider SMI as potential risk markers for CVD and its subtypes rather than definitive risk factors.

Causal relationship between molecular markers of biological aging and orthopedic diseases: A two-sample bidirectional Mendelian randomization study

BACKGROUND

Studies indicate an association between biological aging and orthopedic diseases, but the causality remains unclear.

AIMS

This study aims to investigate the bidirectional causal relationship between molecular markers of biological aging age and orthopedic conditions.

METHODS

A two-sample Mendelian randomization (MR) analysis based on a genome-wide association study (GWAS) was conducted to explore these causal relationships. Analysis methods included inverse variance weighted (IVW), MR-Egger, weighted median, and weighted mode. Sensitivity analyses involved Cochran's Q, MR-Egger, leave-one-out, and MR pleiotropy residual sum and outlier (MR-PRESSO) tests.

RESULTS

The forward MR analysis identified several causal relationships: granulocyte proportions influenced intervertebral disc degeneration (IVDD) (OR 0.2316, P = 0.0101) and low back pain (LBP) (OR 0.2624, P = 0.007); telomere length (TL) affected cervical spondylosis (C/S) (OR 0.8759, P = 0.0167) and IVDD (OR 0.9184, P = 0.023); fibroblast growth factor-23 (FGF-23) impacted frozen shoulder (FS) (OR 1.2424, P = 0.0316); and HannumAge influenced C/S (OR 0.9518, P = 0.0233). The reverse MR analysis found that FS influenced TL (OR 0.9582, P = 0.0002) and α-Klotho (OR 0.7592, P = 0.0256), while sciatica affected TL (OR 0.9344, P = 0.0055) and C/S impacted PhenoAge (OR 1.6583, P = 0.0131) after outlier exclusion. Cochran's Q indicated heterogeneity in certain analyses, and MR-Egger showed no horizontal pleiotropy in significant causal associations.

CONCLUSIONS

This study suggests a potential causal associations between molecular markers of biological aging and orthopedic diseases, suggesting avenues for future research into the underlying mechanisms.

Exploring the role of CD13 and inflammatory factors in radiation enteritis: insights from high-throughput proteomics and Mendelian randomization analysis

BACKGROUND

Radiation enteritis (RE) is an unavoidable complication during radiotherapy for pelvic malignancies, characterized by chronic inflammation, fibrosis, and vascular injury in the intestinal tissue. Currently, there is a lack of research that delves into the relationship between inflammatory factors and key proteins in RE.

METHODS

This study employed high-throughput proteomics to analyze intestinal tissues from RE rats and healthy controls, identifying differentially expressed key proteins. The degree of intestinal damage was validated through HE staining. Furthermore, five Mendelian randomization methods were used to analyze the causal relationship between 70 serum circulating inflammatory factors and CD13 levels. Sensitivity analyses, including heterogeneity tests, leave-one-out tests, and horizontal pleiotropy tests, were performed to ensure the robustness and reliability of the results.

RESULTS

CD13 was identified as a key differentially expressed protein, with its expression significantly upregulated in RE rats and positively correlated with disease severity. Bidirectional Mendelian randomization analysis revealed causal relationships between CD13 and four inflammatory factors: increased levels of CCL28 and EN-RAGE may promote the rise in CD13, while increased levels of TAM-binding protein may be associated with decreased CD13 levels. Additionally, higher CD13 levels were found to be associated with increased levels of interleukin-12. Sensitivity analyses indicated good consistency and reliability in terms of heterogeneity and pleiotropy for these exposure variables.

CONCLUSION

This study reveals the potential mechanistic role of CD13 in RE. Moreover, the identified CD13-associated inflammatory factors offer potential targets for the development of new prevention and treatment strategies, with significant clinical implications.

Plasma lipidome and intracranial aneurysms: A univariable and multivariable Mendelian randomization study

BACKGROUND

Recent studies suggest that plasma lipids, including lipoproteins and fatty acids, may contribute to the pathogenesis of intracranial aneurysms (IAs). However, the relationship between a broader range of plasma lipids and IA risk remains unclear. This study uses the Mendelian randomization (MR) approach to explore the causal relationships between 179 plasma lipids and the risk of IAs.

METHODS

We used summary statistics from a study of 7174 individuals to examine 179 plasma lipids. Data on IAs and aneurysmal subarachnoid hemorrhage (aSAH) were drawn from a study by Bakker MK et al., which included 2070 cases of unruptured IAs, 5 140 cases of aSAH, and 71,934 controls. MR analyses were conducted using inverse variance-weighted as the primary method, with weighted median, weighted mode, and MR-Egger as additional methods. To prioritize lipid risk factors, we applied multivariable Mendelian randomization-Bayesian model averaging.

RESULTS

We identified 5 plasma lipids associated with IAs and 4 with aSAH. Phosphatidylcholine (14:0_18:2) was significantly associated with both IAs and aSAH, with odds ratios of 1.44 (95 % confidence interval [CI] 1.17-1.77, Padjusted = 0.036) for IAs and 1.53 (95 % CI 1.20-1.94, Padjusted = 0.036) for aSAH. In multivariable MR, phosphatidylcholine (14:0_18:2) and phosphatidylcholine (18:0_20:3) emerged as the strongest risk factors for IAs and aSAH, respectively.

CONCLUSION

Our study identifies specific plasma lipids, particularly phosphatidylcholine (14:0_18:2) and phosphatidylcholine (18:0_20:3), as significant risk factors for IAs and aSAH. These findings suggest that phosphatidylcholines could serve as predictive biomarkers for aneurysm risk. Further research is needed to validate these associations and clarify the underlying mechanisms.

Identification of Alzheimer's disease susceptibility genes by the integration of genomics and transcriptomics

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disease. With the deepening of clinical and genomic research, a series of biomarkers and risk factors related to AD have been identified. However, the exact molecular mechanism of AD is not completely understood.

METHODS

By combining expression quantitative trait loci (eQTLs) analysis with the results of genome-wide association studies (GWAS), the candidate genes (CG) related to AD were screened out accurately. We identified that intersection genes of differentially expressed genes (DEGs) and CG are the key genes. Then, GO, KEGG, and GSEA were utilized for functional enrichment analysis. Finally, we predicted AD responses to immunotherapy by the single sample gene set enrichment analysis (ssGSEA).

RESULTS

A total of 253 DEGs were identified. The three key genes (VASP, SURF2, and TARBP1) were identified by taking the intersection of DEGs and CG. Through Mendelian randomization (MR) analysis, it was found that the risk of AD was significantly increased when VASP expression increased (OR = 0.1.046), while the risk of AD was significantly decreased when SURF2 (OR = 0.897) and TARBP1(OR = 0.920) expression increased. Subsequently, the functional analysis indicated that the core genes were mainly enriched in Leukocyte Transendothelial Migration, cGMP-PKG signaling pathway, and Rap1 signaling pathway. Through ssGSEA analysis showed that all three core genes were significantly related to M2 macrophages.

CONCLUSIONS

Three core genes were screened by integrating eQTLs data, GWAS data and transfer group data, and the potential mechanism of diagnosis and treatment of AD was revealed.

The Relationship Between Serum Uric Acid and Gynecologic Cancer Risk: A Mendelian Randomization Study

Aim

High serum uric acid (UA) levels have been linked to cancer development through chronic inflammation and oxidative damage. Traditional epidemiological studies have shown inconsistent results regarding the relationship between uric acid and gynecological cancers. This study uses Mendelian randomization (MR) to explore the potential association between serum UA levels and various gynecological cancers.

Methods

In this two-sample MR study, summary statistical data of the genome-wide association studies (GWASs) on serum UA levels were extracted from the UK Biobank (UKB), and those on gynecological cancers were obtained from the FinnGen consortium, the Epidemiology of Endometrial Cancer Consortium (E2C2), and the Ovarian Cancer Association Consortium (OCAC). Inverse variance weighted (IVW), weighted median, MR-Egger, weighted mode, MR-Pleiotropy RESidual Sum and Outlier (MR-PRESSO), and MR-Radial methods were utilized to investigate the bidirectional causal associations of serum UA levels with gynecological cancers. The evaluation indexes were odds ratios (ORs) and confidence intervals (CIs). Tests for horizontal pleiotropism and heterogeneity of instrumental variables (IVs) were performed, respectively using MR-Egger test and Cochran's Q statistics. In addition, leave-one-out and MR scatter plots were employed for sensitivity analyses.

Results

IVW estimates suggested that serum UA levels elevated 1 unit had a potential causal association with higher odds of both cervical cancer (CC) (OR=1.147, 95% CI: 1.020-1.290) and invasive mucinous ovarian cancer (IMOC) (OR=1.199, 95% CI: 1.033-1.393). Also, endometrial carcinoma (EC) had a potential causal association with it (OR=1.012, 95% CI: 1.000-1.024). Additionally, sensitivity analyses showed the potential causal associations between UA and CC/IMOC were relatively robust.

Conclusion

An elevated serum UA level had potential associations with CC and IMOC, whereas patients with EC should pay attention to it in clinical practice, which may reduce the potential risk of gynecological cancers. However, further evidence is needed to clarify the true relationships between UA and gynecological cancers.

Insomnia Associated With Increased Risk of Atopic Dermatitis: A Two-Sample Mendelian Randomization Study

BACKGROUND

The causal relationships between sleep traits and allergic diseases remain unclear. This study sought to explore their causal associations using Mendelian randomization (MR) analysis.

METHODS

This study utilized summary-level data from genome-wide association studies (GWAS) and selected genetic variants associated with sleep traits as instrumental variables (IVs). For the primary analysis, the inverse-variance weighted (IVW) method was utilized. To further evaluate causal effects, we applied weighted median, weighted mode, and MR-Egger regression. Sensitivity analyses, such as linkage disequilibrium score (LDSC) regression, MR-Egger regression, Cochran's Q test, leave-one-out analysis, and MR-PRESSO, were carried out to confirm result robustness.

RESULTS

IVW analysis revealed that genetically predicted insomnia was causally associated with a higher risk of atopic dermatitis (OR = 1.79, 95% CI: 1.17-2.74, P = 0.01), and preferring an evening chronotype was causally associated with a lower risk of allergic rhinitis (IVW: OR = 0.99, 95% CI: 0.99-1.00, P = 0.02). The LDSC analysis further identified a significant genetic correlation between insomnia and atopic dermatitis (rg = 0.107, P = 0.039), but not between chronotype and allergic rhinitis (rg = -0.036, P = 0.339). No significant connections were identified between other sleep traits and allergic diseases. The MR-Egger intercept test did not indicate pleiotropy, except for the association with allergic asthma.

CONCLUSION

Chronotype and insomnia were causally associated with the efficacy of sleep-based interventions in allergic disease management.

Evaluating the Causal Relationship Between Human Blood Metabolites and the Susceptibility to Alopecia Areata

BACKGROUND

Alopecia areata, a common autoimmune disease, is not fully understood in terms of its cause. However, research suggests that an imbalance in specific blood metabolites may trigger immune system dysfunction, leading to an attack on hair follicles and ultimately resulting in alopecia areata.

METHODS

Two-sample MR analysis was conducted to investigate the causal relationship between plasma metabolites and alopecia areata using various methods. Heterogeneity and pleiotropy were assessed, robustness of findings evaluated, and reverse MR performed for effect analysis.

RESULTS

The MR analysis found a positive causal relationship between alpha-ketoglutarate, propionylcarnitine (c3) and other metabolites with alopecia areata risk. Conversely, xylose 3-(3-hydroxyphenyl)propionate, glycochenodeoxycholate glucuronide (1) along with other metabolites, showed a protective effect against alopecia areata development. Both BWMR and MR-PRESSO confirmed the accuracy of the above results. Reverse MR revealed no reverse causality between plasma metabolites and AA. The robustness of the results was confirmed using the leave-one-out method, which demonstrated no influential instrumental variables affecting the outcomes while accounting for heterogeneity and eliminating horizontal gene pleiotropy effects on estimating causal effects.

CONCLUSION

This study establishes a causal relationship between plasma metabolism and alopecia areata, enhancing our understanding of its underlying mechanisms. These findings also provide valuable references for future screening and prevention strategies.

The Causality between Gut Microbiota and Hypertension and Hypertension-related Complications: A Bidirectional Two-Sample Mendelian Randomization Analysis

BACKGROUND

Recent studies have highlighted a connection between gut microbiota and hypertension, yet the precise nature of this relationship remains unclear.

OBJECTIVE

This research aims to analyze the causal link between gut microbiota and hypertension, along with associated complications, utilizing two-sample bidirectional Mendelian randomization (MR).

MATERIALS AND METHODS

Summary data from genome-wide association studies (GWAS) meta-analyses, including gut microbiota GWAS data from 24 cohorts, and the latest GWAS data for hypertension-related conditions were acquired. Employing various MR methods, including Inverse-variance weighted (IVW), MR-Egger, Weighted Median, Simple Mode, and Weighted Mode, we investigated the association between gut microbiota and hypertension-related conditions. Sensitivity analyses were conducted for result stability, and reverse MR analysis assessed the potential for reverse causality.

RESULTS

The Mendelian randomization analysis involving 199 microbial taxa and four phenotypes identified 46 microbial taxa with potential causal links to hypertension and its complications. Following Bonferroni correction, genus.Victivallis showed a robust causal relationship with hypertension (OR = 1.08, 95% CI = 1.04-1.12, P = 9.82e-5). This suggests an 8% increased risk of hypertension with each unit rise in genus.Victivallis abundance.

CONCLUSION

In conclusion, this study establishes a causal connection between gut microbiota and hypertension, along with common associated complications. The findings unveil potential targets and evidence for future hypertension and complication treatment through gut microbiota interventions, offering a novel avenue for therapeutic exploration.

Biological pathways underlying the relationship between childhood maltreatment and Multimorbidity: A two-step, multivariable Mendelian randomisation study

Childhood maltreatment has been associated with multimorbidity of depression, coronary artery disease and type 2 diabetes. However, the biological mechanisms underlying this association remain unclear. We employed two-step and multivariable Mendelian randomisation (MR) to understand the role of three potential biological mediating mechanisms - inflammation (92 proteins), metabolic processes (54 markers), and cortisol - in the link between childhood maltreatment liability and multimorbidity. Using summary statistics from large-scale genome-wide association studies of European ancestry for childhood maltreatment (N = 185,414) and multimorbidity (Neffective = 156,717), we tested for the presence of an indirect effect via each mediator individually. We found a potential role of metabolic pathways. Up to 11% of the effect of childhood maltreatment on multimorbidity was mediated by triglycerides (indirect effect [95% CI]: 0.018 [0.009-0.027]), 8% by glycated haemoglobin (indirect effect: 0.013 [0.003-0.023]), and up to 7% by high-density lipoprotein cholesterol (indirect effect: 0.011 [0.005-0.017]). We did not find evidence for mediation via any inflammatory protein or cortisol. Our findings shed light on the biological mechanisms linking childhood maltreatment liability to multimorbidity, highlighting the role of metabolic pathways. Future studies may explore underlying pathways via non-biological mediators (e.g., lifestyle factors) or via multiple mediators simultaneously.

Investigating the causal and genetic relationship between migraine and Parkinson's disease

OBJECTIVE

The relationship between migraine and Parkinson's disease (PD) remains controversial. We aimed to investigate the causal and genetic associations between migraine and PD.

METHODS

Genetic data for migraine [any migraine (AM), migraine without aura (MO), and migraine with aura (MA)] and PD were sourced from the latest genome-wide meta-analyses conducted by the International Headache Genetics Consortium and the International Parkinson's Disease Genomics Consortium, respectively. Various analyses were performed to evaluate the potential causal associations and explore genetic correlations between these conditions.

RESULTS

The analyses indicated that AM (odds ratio [OR] 1.02, 95% confidence interval [CI] 0.91-1.14; p = 0.785), MO (OR 0.94, 95% CI 0.84-1.07; p = 0.358), and MA (OR 1.01, 95% CI 0.95-1.06; p = 0.846) were not significantly associated with the risk of PD. Similarly, reverse analyses also demonstrated no significant causality between PD and the risks of migraine or its subtypes. After adjusting for coronary heart disease, AM (OR 0.99, 95% CI 0.90-1.10; p = 0.897), MO (OR 0.94, 95% CI 0.86-1.03; p = 0.207), and MA (OR 1.00, 95% CI 0.93-1.07; p = 0.902) remained unrelated to PD risk. Likewise, PD was found to be unassociated with AM (OR 0.96, 95% CI 0.92-1.02; p = 0.168), MO (OR 0.95, 95% CI 0.86-1.05; p = 0.287), and MA (OR 1.02, 95% CI 0.93-1.13; p = 0.669). These null findings persisted even when adjusting for hypertension. Apart from above causal inference results, no significant genetic correlation was found between AM (rg = -0.06, p = 0.127), MA (rg = -0.05, p = 0.516), or MO (rg = -0.06, p = 0.492) and PD, and no correlations were observed across specific genomic regions. Additionally, no shared heritability was observed between PD and migraine, or its subtypes, in tissue expression.

CONCLUSION

Our study suggests that there is no significant causal association or genetic correlation between migraine and PD from a genetic perspective.

The Causal Relationship Between Neurotrophic Factors and Delirium: A Mendelian Randomization Study

BACKGROUND

Several observational studies have revealed that different neurotrophic factors (NTFs) are associated with delirium, yet the direction and magnitude of the causal association remain poorly understood. Herein, we performed a two-sample Mendelian randomization (MR) analysis to investigate the causal relationship between these factors and delirium.

METHODS

GWAS data for delirium were sourced from the FINN10 database; GWAS data for risk factors (protein kinase C-binding protein NELL1, neurotrophin-3, neurotrophin-4, brain-derived neurotrophic factor levels, nerve growth factor, ciliary neurotrophic factor, and glial cell-derived neurotrophic factor levels) were from the IEU Open GWAS. Inverse-variance weighted (IVW) was used as a primary analysis. MR-Egger, weighted median (WM), and weighted model were applied to validate the robustness of the results. The MR-Egger regression method was used to explore the presence of horizontal pleiotropy, and the MR pleiotropy residual sum, and outlier (MR-PRESSO) method was applied to detect potential outliers. Cochran's Q test assessed heterogeneity among instrumental variables (IVs). The leave-one-out (LOO) method was used to enhance the precision and veracity of our findings.

RESULTS

IVW analyses revealed no association between risk factors and delirium. MR Egger, WM, and the weighted mode approach further confirmed these data. MR-Egger regression analysis confirmed the absence of directional pleiotropy in our analysis. Heterogeneity and sensitivity analyses showed reliable results.

CONCLUSION

No association between other factors and delirium was identified; however, further research is needed to determine if these results apply to other races. Also, advances in molecular biology and epigenetics may shed light on this topic.

Assessment of causality association between serum adiponectin levels and the risk of Alzheimer's disease and Parkinson's disease: a Mendelian randomization study

Background

Until recently, the association between circulating adiponectin (ADPN) levels and the risk of Alzheimer's disease (AD) and Parkinson's disease (PD) remained unclear.

Methods

We utilized public data from the IEU GWAS database to conduct a two-sample bidirectional Mendelian randomization (MR) analysis and multiple sensitivity analyses. The MR analysis was performed using the aggregated data, with the genetic risk score (GRS) serving as an instrumental variable.

Results

The MR analyses revealed no significant causal association between genetically determined ADPN levels and the risk of AD (ORIVW = 0.852, 95% confidence interval [CI]: 0.586-1.117, p = 0.235) or PD (ORIVW = 0.830, 95% CI: 0.780-1.156, p = 0.606). Conversely, neither AD nor PD demonstrated any causal association with ADPN levels. The GRS approach yielded similar results (p > 0.05). However, it exhibited a negative correlation with interleukin 1β (IL1β, βIVW = -0.31; 95% CI: -0.55 to -0.07, p = 0.011). The Cochrane's Q test and MR-PRESSO analysis revealed no evidence of pleiotropy.

Conclusion

Our findings provide no evidence to substantiate a causal relationship between ADPN levels and the risk of AD and PD or vice versa. However, elevated levels of ADPN may correlate with lower levels of IL1β.

Celiac Disease Increases the Risk of Multiple Sclerosis: Evidence from Mendelian Randomization and the Role of CCL19

Celiac disease (CeD) is an autoimmune disorder triggered by gluten, primarily affecting the small intestine but potentially impacting other systems, including the nervous system through the gut-brain axis. This study employed Mendelian randomization (MR) to explore the causal relationships between CeD and several neurological disorders, with a particular focus on multiple sclerosis (MS). Utilizing genetic data from the OpenGWAS and Finngen databases, we applied various MR methods, including Inverse Variance Weighted (IVW), IVW-multiplicative random effects (MRE), weighted median (WM), MR-Egger, and robust adjusted profile score (RAPS), to investigate these associations. The analysis revealed no significant causal relationship between CeD and several other neurological disorders, but a significant positive association with MS was found (IVW OR=1.1919, 95% CI: 1.0851~1.3092, p=0.0002). Further analysis indicated that the mediator CCL19 plays a significant role in the pathway from CeD to MS, suggesting that CCL19 may be a key factor in the immune response linking these conditions. This mediation effect highlights the potential mechanism through which CeD increases the risk of developing MS. These findings emphasize the complexity of the relationship between CeD and MS, indicating the need for further research to understand these connections better and their clinical implications.

A Mendelian randomization study on the causal association of circulating cytokines with diabetic nephropathy

BACKGROUND

Circulating cytokines were reported to be related to diabetic nephropathy (DN) in observational studies. However, the causal relationship between them remains unknown. This study aimed to investigate the causal relationship between DN and circulating cytokines with genetic data in the frame of Mendelian Randomization (MR).

METHODS

We performed a two-sample MR analysis to investigate the causal relationship in individuals of European ancestry, utilizing publicly available genome-wide association study (GWAS) statistics. We selected eligible instrumental SNPs that were significantly related to the circulating cytokines. Multiple MR analysis approaches were employed, including inverse variance weighted (IVW), Weighted Median, MR-Egger, Weighted Mode, Simple Mode, and MR pleiotropy residual sum and outlier (MR-PRESSO) methods.

RESULTS

We found evidence supporting the causal role of genetically predicted circulating levels in the increased risk of DN. Specifically, we observed associations for interferon-gamma [OR = 1.352, 95% CI: 1.089-1.678, P = 0.006], stem cell factor [OR = 1.252, 95% CI: 1.028-1.525, P = 0.025], and stromal-cell-derived factor 1 alpha [OR = 1.326, 95% CI: 1.017-1.727, P = 0.037]. Additionally, MR analysis revealed a negative causal association between macrophage inflammatory protein 1b and DN [OR = 0.921, 95% CI: 0.858-0.988, P = 0.022]. The results obtained from MR-Egger, Weighted Median, Weighted Mode, and Simple Mode methods were consistent with the Inverse Variance Weighted (IVW) estimates. Sensitivity analyses showed no evidence of horizontal pleiotropy, suggesting that the causal estimates were not biased.

CONCLUSIONS

Our findings offer promising leads for developing novel therapeutic targets for DN. By identifying the role of inflammatory cytokines in this debilitating condition through a genetic epidemiological approach, our study made contributions to a better understanding of the underlying disease mechanisms.

The relationship between infectious pathogen antibodies, plasma metabolites, and breast cancer: A Mendelian randomization study with mediation analysis

Breast cancer (BC) has the second highest incidence rate among women worldwide. Although there are various treatment methods, the prognosis is poor once metastasis occurs. However, the extent to which pathogens of infectious diseases influence the risk of BC remains unclear. The goal of this study is to determine if these pathogens are causally related to BC development. A Mendelian randomization (MR) analysis is used to assess the causal relationship between infectious pathogen antibodies and the risk of BC, as well as their potential intermediary factors. Two-sample MR analysis using inverse variance weighting (IVW) is conducted to determine the causal relationship between infectious pathogen antibodies and the risk of BC. Additionally, the mediating role of 1400 metabolites between infectious pathogen antibodies and the risk of BC is analyzed. There were 5 infectious pathogen antibodies and 86 metabolites associated with BC (P < .05). There were 14 metabolites that mediated the pathway between infectious pathogen antibodies and BC. X-07765 levels showed a significant negative mediating effect on the relationship between Anti-human herpes virus 6 IgG seropositivity and BC (beta = -0.0025, 95% CI [-0.0046, -0.0003], P = .0236), accounting for 14.8% of the effect (95% CI: 27.7-1.99). This study provides a thorough evaluation of the causal relationships among infectious pathogen antibodies, plasma metabolites, and BC. Our research has identified 5 infectious pathogen antibodies that exhibit a causal relationship with BC, mediated through 86 distinct metabolites.

Plasma protein levels and hepatocellular carcinoma: a Mendelian randomization study with drug screening implications

BACKGROUND

Hepatocellular carcinoma (HCC) remains a significant cause of cancer-related mortality, highlighting the need for novel therapeutic strategies. Identifying key proteins and potential therapeutic agents is critical for improving treatment outcomes.

METHODS

We employed Mendelian randomization to identify proteins associated with HCC risk and utilized drug enrichment and molecular docking analyses to discover potential therapeutic agents. The efficacy of identified drugs was evaluated in vitro using immune-tumor co-culture systems and in vivo in a murine HCC model. Single-cell expression profiling and clinical sample analyses were conducted to explore expression patterns.

RESULTS

Our analyses identified 16 proteins linked to HCC pathogenesis. Among the therapeutic agents tested, Belinostat significantly enhanced T cell-mediated cytotoxicity against HCC cells and effectively reduced tumor growth in vivo. Single-cell analysis revealed significant modulation of immune cells within the tumor microenvironment, suggesting potential mechanisms for the observed therapeutic effects.

CONCLUSION

This study highlights the potential of Belinostat as a promising therapeutic agent for HCC. By modulating immune responses and tumor growth, Belinostat offers a novel approach to HCC treatment, warranting further clinical investigation to validate its efficacy and therapeutic potential.

Prolonged leisure time television watching as a risk factor for chronic obstructive pulmonary disease: Insights from Mendelian randomization

Leisure sedentary behaviors are associated with an increased risk of chronic obstructive pulmonary disease (COPD), but whether this relationship is causal remains unknown. This study aimed to identify genetic determinants associated with leisure sedentary behaviors and estimate their potential causal effect on COPD risk. COPD case-control data were obtained from the Finnish biobank. Genome wide association analyses of leisure television watching, leisure computer use, and driving behavior in the UK Biobank identify 110, 82 and 6 genetic loci (P ＜ 5 × 10-8), respectively. A 2-sample Mendelian randomization (MR) analysis estimated a causal relationship between a 1.5-hour increase in television watching and a rise in COPD risk (OR = 2.725, 95% CI = 1.989-3.777, P = 7.113 × 10-10). This relationship persisted independently of age at smoking initiation, daily cigarette consumption, educational years, and body mass index in comprehensive MR analyses. However, multivariate MR analyses showed that genetically predicted leisure time spent on computers and driving did not robustly influence COPD risk. In conclusion, this MR study suggests that a genetic predisposition for prolonged time spent watching television significantly increases the risk of COPD, corroborating findings from observational studies.

Causal role of MiRNAs in chronic rhinosinusitis: mendelian randomization and validation study

BACKGROUND

Despite significant advances in understanding the epigenetic landscape of chronic rhinosinusitis (CRS), the specific microRNAs (miRNAs) with a causal role in CRS pathogenesis remain unclear.

OBJECTIVE

This study aims to identify miRNAs that causally contribute to CRS and to elucidate their clinical relevance and underlying molecular mechanisms.

METHODS

We employed Mendelian randomization (MR) analysis, leveraging mirQTLs as exposure variables and two independent CRS datasets as outcomes, to identify miRNAs causally linked to CRS. Robustness of the findings was ensured through multiple sensitivity analyses. The expression levels of identified CRS-associated miRNAs were validated using qRT-PCR, and their diagnostic potential was assessed through ROC curve analysis. Target genes and potential pathways regulated by the causal miRNAs were predicted via MiRNet and enrichment analyses, followed by experimental validation using western blotting and immunohistochemistry.

RESULTS

MiR-130a-3p and miR-196b-5p were significantly associated with an increased risk of CRS, while miR-339-3p was associated with a decreased risk. These associations were confirmed by qRT-PCR, and no evidence of pleiotropy or heterogeneity was observed. ROC analysis revealed diagnostic potential for these miRNAs in CRS. Enrichment and experimental analyses suggested that the MAPK and PI3K-AKT pathways are predominantly activated by the target genes of the positively and negatively associated miRNAs, respectively.

CONCLUSIONS

MiR-130a-3p and miR-196b-5p are positively associated with CRS risk, whereas miR-339-3p is protective. These miRNAs represent promising diagnostic biomarkers and therapeutic targets for CRS. The MAPK and PI3K-AKT pathways likely mediate the effects of these causal miRNAs, offering further insight into the molecular mechanisms underlying CRS.

Depression reduces cognitive function partly through effects on BMI and hypertension: a large observational study and Mendelian randomization analysis

BACKGROUND

While abundant evidence suggests a correlation between depression and the risk of cognitive impairments, the causal relationship, as well as the mechanisms mediating this association, remain uncertain.

METHODS

We conducted an observational study within the National Health and Nutrition Examination Survey (NHANES), simultaneously employing weighted multivariable-adjusted linear regression to explore the association between them. Subsequently, Mendelian randomization analysis was employed to investigate the causal relationship between them as well as the mediating effects.

RESULTS

The observational analysis of NHANES data indicates that depression is independently associated with cognitive function. Regarding MR, genetically predicted depression is causally related to cognitive function in the IVW method (OR 0.33, 95% CI 0.14-0.78, P = 0.012). Furthermore, depression leads to obesity (OR = 1.91, P = 2.53 × 10 - 3) and elevated blood pressure (OR 2.34, P = 3.62 × 10 - 3). Waist circumference (OR = 0.85, P = 3.00 × 10 - 4), BMI (OR = 0.84, P = 1.06 × 10 - 6), and hypertension (OR = 0.95, P = 4.00 × 10 - 3) all contribute to cognitive function. Additionally, there is no causal association between cognitive function and depression (OR 1.00, 95% CI 0.99-1.01, P = 0.559) in reverse Mendelian randomization. Mediation analysis indicates that BMI and hypertension mediate 9.9% and 3.6% of the cognitive function under depression conditions, respectively.

CONCLUSIONS

Our study indicates that depression can lead to obesity and hypertension, which can reduce cognitive function. These findings underscore the importance of timely identification and management of depression in patients with cognitive impairments and suggest that treatments aimed at reducing weight and lowering blood pressure may help prevent cognitive impairment.

Exploring causal relationship between 41 inflammatory cytokines and marginal zone lymphoma: A bidirectional Mendelian randomization study

Purpose

Marginal zone lymphoma (MZL) is a rare subtype of non-Hodgkin lymphoma, and its diagnosis primarily relies on pathological biopsy. The study aims to investigate the causal relationships between 41 inflammatory cytokines and MZL using a two-sample bidirectional Mendelian randomization (MR) approach, providing new insights and methodologies for rapid differential diagnosis and treatment strategies.

Methods

Causal associations between 41 inflammatory cytokines and MZL were examined using genetic variant data from two large-scale genome-wide association studies. The inverse variance weighting method was employed, and multiple sensitivity analyses, including MR-Egger, weighted median, simple model, and weighted model methods, were conducted to strengthen the robustness of the findings.

Results

Elevated levels of MIG and IL-10 were associated with an increased risk of MZL (MIG: OR = 1.57, p = 0.035; IL-10: OR = 1.69, p = 0.021), while higher B-NGF levels exhibited a protective effect (OR = 0.46, p = 0.027). Reverse MR analysis revealed a negative correlation between MZL and IFN-γ levels (OR = 0.97, p = 0.015).

Conclusions

MIG, IL-10, B-NGF, and IFN-γ are potential biomarkers and therapeutic targets for MZL. IFN-γ likely acts as a downstream molecule in MZL pathogenesis, offering novel insights into MZL-related research, clinical diagnosis, and treatment strategies.

A causal effects of neutrophil extracellular traps and its biomarkers on acute respiratory distress syndrome: a two-sample Mendelian randomization study

Previous studies have indicated an association between neutrophil extracellular traps (NETs) and acute respiratory distress syndrome (ARDS). This study aimed to investigate the potential causal effects of NETs and NETs-related biomarkers on ARDS or vice-versa. A two-sample Mendelian randomization (MR) utilizing genome-wide association studies (GWAS) data was employed to analyze the causality. The primary analysis was conducted using inverse-variance weighted (IVW) methods; weighted median, MR-Egger, and weighted model methods were used to validate the results. Horizontal pleiotropy and outlier detection were assessed via MR-Egger and MR pleiotropy residual sum and outlier (MR-PRESSO), respectively; Cochran's Q test evaluated heterogeneity, while Leave-one-out analyses were used to evaluate the presence of predominant instrumental variables (IVs). IVW method suggested causal associations between genetically predicted IL-13 and a higher risk of ARDS [OR (95%CI) = 1.52 (1.03-2.23), P = 0.047], while there was no causal effect of other factors on ARDS (all P > 0.05). Also, ARDS had no effect on NETs and NETs-related biomarkers (all P > 0.05). Cochran's Q confirmed no significant heterogeneity. MR-Egger regression ruled out horizontal pleiotropy's influence, and MR-PRESSO analysis identified no outliers, reinforcing the study's findings. This MR study established a causal relationship between IL-13 and ARDS, suggesting its potential role as a therapeutic target and biomarker of ARDS. Future work should delve into the underlying mechanisms and clinical applications.

Exploring the Causal Role of miR-941 in Chronic Rhinosinusitis: Insights from Transcriptomics and Genomics

Purpose

Despite significant advancements in the epigenetics of chronic rhinosinusitis (CRS), particularly in the domain of microRNA (miRNA), little is known about miRNAs that play a causal role in CRS. This study aims to identify miRNAs with a causal relationship to CRS and explore their potential clinical value and mechanisms in CRS.

Methods

We conducted small RNA sequencing on blood and nasal samples to find miRNAs with consistent expression differences in CRS. These miRNAs were confirmed via qRT-PCR and assessed for clinical relevance through Spearman correlation and statistical analysis used to evaluate diagnostic accuracy. Bidirectional Mendelian randomization (MR, a genetic causal inference method) analyzed their causal links to CRS. Target genes of causally significant miRNAs were identified using miRWalk, and their mechanisms were explored through pathway enrichment and validation studies.

Results

We identified differentially expressed miRNAs in blood and nasal tissues using a |log2(Fold Change)| > 0.58 and P-value < 0.05 threshold. Following False Discovery Rate correction, hsa-miR-941 was identified as an upregulated miRNA in both CRS patient samples. The experimental validation of miR-941 expression closely matched sequencing results. Spearman and statistical analysis associated miR-941 expression changes with CRS severity and diagnostic accuracy. Bidirectional MR demonstrated a significant association of miR-941 with CRS risk, without evidence of reverse causality. Target gene and Western blot assays suggested miR-941's potential influence on CRS through the PI3K/AKT pathway.

Conclusion

There is a positive causal relationship between hsa-miR-941 and CRS, making hsa-miR-941 a valuable target for the diagnosis and treatment of CRS. These findings position miR-941 as a valuable biomarker and therapeutic target, providing new opportunities for precision medicine in CRS treatment. miR-941 may exert its effects by modulating the PI3K/AKT signaling pathway.

Ulcerative colitis increases the risk of atrioventricular block: evidence from a Mendelian randomized analysis

Although inflammatory bowel disease (IBD) has been linked to cardiovascular disease in a growing body of literature, the relationship between IBD and arrhythmia remains unclear. To investigate the causal relationship between inflammatory bowel disease and arrhythmia, we conducted this Mendelian randomization (MR) analysis. We identified single nucleotide polymorphisms (SNP) associated with IBD as instruments, including IBD, ulcerative colitis (UC), and Crohn's disease (CD). SNPs of two arrhythmia phenotypes as outcome data, namely atrioventricular block (AVB), and paroxysmal tachycardia (PTA). The inverse variance weighting method was used to analyze the two-sample Mendelian randomization with four other methods, including MR Egger, Weighted median, Simple mode, and Weighted mode. Sensitivity analysis involves different methods to detect and adjust for bias in results, including heterogeneity analysis, pleiotropy analysis, and leave-one-out sensitivity analysis. To ensure the rigor of the analysis results, we selected another set of exposure data sets and conducted the MR verification analysis using the same method. Results suggested UC is significantly associated with an increased risk of AVB (odds ratio, OR 1.178, 95% CI 1.070-1.297, P = 0.000828), the verification analysis results are consistent with this (OR 1.048, 95% CI 1.007-1.091, P = 0.022947). Our study suggests a potential risk increase of atrioventricular block in patients with UC. These results also provide further evidence that inflammatory bowel disease may increase the risk of developing arrhythmia.

Causal Associations of Inflammatory Cytokines With Osteosarcopenia: Insights From Mendelian Randomization and Single Cell Analysis

Background: Osteosarcopenia, the coexistence of osteoporosis and sarcopenia, poses significant challenges in aging populations due to its dual impact on bone and muscle health. Inflammation, mediated by specific cytokines, is thought to play a crucial role in the development of osteosarcopenia, though the underlying mechanisms are not fully understood. Objective: This study aimed to clarify the causal role of circulating cytokines in the pathogenesis of osteosarcopenia by employing mendelian randomization (MR) and single-cell RNA sequencing (scRNA-seq) to identify cell-specific cytokine expression patterns. The ultimate objective was to uncover potential pathological mechanisms and therapeutic targets for treating osteosarcopenia. Methods: A two-sample MR approach was employed, leveraging publicly available genome-wide association study (GWAS) data from multiple cohorts. A total of 91 circulating cytokines were examined using genetic instruments, and their causal effects on traits related to osteoporosis and sarcopenia were evaluated. Various complementary and sensitivity analyses were performed to ensure robust findings. Additionally, scRNA-seq datasets from human muscle and bone marrow were analyzed to validate the single-cell expression profiles of candidate cytokines. Results: MR analysis identified several cytokines with causal effects on osteosarcopenia traits, including LTA, CD40, CXCL6, CXCL10, DNER (delta and notch-like epidermal growth factor-related receptor), and VEGFA (vascular endothelial growth factor A). LTA and CD40 were protective for both bone and muscle, while VEGFA posed a risk. Other cytokines demonstrated opposite effects on bone and muscle. Single cell analysis revealed distinct expression patterns, with LTA highly expressed in lymphocytes, CD40 in immune cells, and VEGFA in various musculoskeletal cell types. Age-related differences in cytokine expression were also noted, with LTA more highly expressed in younger individuals, and VEGFA in older individuals. Conclusion: This study offers preliminary insights into the inflammatory mechanisms potentially driving osteosarcopenia, identifying key cytokines that may be involved in its pathogenesis. By integrating MR and scRNA-seq data, we highlight potential therapeutic targets, though further research is needed to confirm these findings and their implications for musculoskeletal health.

Plasma cytokine levels and PCOS risk: Mendelian randomization analysis reveals IL6R as a preventive factor

BACKGROUND

Polycystic ovary syndrome is a prevalent gynecological condition affecting primarily women of childbearing age. It is characterized by elevated androgen levels, ovulatory dysfunction, and morphological abnormalities. Despite extensive research from various perspectives, the etiology and pathogenesis of PCOS remain unclear. While controversial, many believe that individuals with PCOS exhibit a chronic low-grade inflammatory state. Cytokines play diverse roles in the initiation and progression of inflammation, contributing to this inflammatory milieu. Therefore, the aim of this study was to utilize publicly available genome-wide association study data to explore the potential causal relationship between cytokines and PCOS.

METHODS

To accurately investigate the causal relationship between cytokines and PCOS, we initially defined cytokines using the GeneCrad and then identified cytokines in two independent large-scale plasma proteins. Subsequently, we employed a two-sample Mendelian randomization analysis framework. A series of quality control procedures were implemented to select eligible instrumental variables closely associated with the exposure. MR analysis was conducted using genome-wide association studies of PCOS in two independent European ancestry groups. Cochran, s Q test, MR-Egger and intercept test were employed to assess heterogeneity and pleiotropy in PCOS. Co-localization analysis, summary-data-based Mendelian randomization analysis, and HEIDI testing were utilized to further corroborate the relationship between positive findings and PCOS. Finally, systematical Mendelian randomization analysis between healthy lifestyle factors and PCOS-related proteins was conducted to identify which proteins could act as interventional targets by lifestyle changes.

RESULTS

In our investigation, we performed Mendelian randomization analysis on 33 cytokines in relation to PCOS using data from the deCODE and the Fenland. Our findings revealed that the plasma level of IL6R emerges as a notable protective factor against PCOS, exhibiting a substantial effect size. Moreover, we identified CCL22 as a significant risk factor for PCOS, a finding that was similarly validated and supported by independent cohorts.

CONCLUSION

Our Mendelian randomization analysis, leveraging genome-wide association study data from a sizable population cohort, unequivocally delineated a causal relationship between IL6R and PCOS. These results underscore the involvement of cytokines in the pathogenesis of PCOS and highlight their potential as promising therapeutic targets for addressing this intricate disease.

Association between allopurinol and hepatocellular carcinoma: analysis of genetic risk and patient survival

BACKGROUND

Despite the widespread clinical use of allopurinol for managing hepatocellular carcinoma (HCC) and gout, its potential hepatotoxicity and its effect on the risk of HCC remain unclear. This study aimed to comprehensively assess the potential correlations between allopurinol exposure and HCC risk.

METHODS

We utilized genome-wide association study data from the IEU OpenGWAS project as instrumental variables (IVs) for Mendelian randomization (MR) analysis to investigate the causal relationship between allopurinol and HCC. Subsequently, we investigated the potential mediating factors (gout, liver fat, and percentage of liver fat, etc.) between allopurinol use and HCC. Furthermore, we analyzed assessed survival outcomes using the Kaplan-Meier method to compare patient subgroups by differential Xanthine dehydrogenase (XDH) expression.

RESULTS

MR analysis established a causal link between allopurinol use and increased HCC risk (OR: 1.013, 95% CI 1.004-1.023, p = 0.006). Causal relationships were also observed between gout (OR: 1.011, p = 0.008) and HCC. Mediation analysis indicated that gout mediated 61.6% of the effect of allopurinol on HCC. Survival analysis showed that higher expression of XDH was associated with improved survival of HCC patients (HR = 0.62, 95% CI 0.441-0.884, p = 0.008), indicating a 38% decrease in mortality risk compared to the lower expression group.

CONCLUSIONS

This study demonstrated a causal relationship between allopurinol use and an increased risk of HCC based on genetic evidence. Allopurinol should be used with caution in patients with or at risk for HCC.

The role of preeclampsia in breast cancer risk: insights from Mendelian randomization study

BACKGROUND

The relationship between preeclampsia and breast cancer risk is still debated, with observational studies yielding inconsistent results. This research aims to clarify the causal link between preeclampsia and breast cancer using Mendelian randomization (MR) methods.

METHODS

We utilized genome-wide association study (GWAS) data to identify single nucleotide polymorphisms (SNPs) that are significantly associated with preeclampsia, which served as genetic instruments. A two-sample Mendelian randomization (TSMR) approach was applied, primarily using inverse variance weighting (IVW) to assess the causal impact of preeclampsia on breast cancer risk. To strengthen our findings, a meta-analysis of IVW estimates from both discovery and validation cohorts was performed, complemented by sensitivity analyses to investigate heterogeneity and potential horizontal pleiotropy.

RESULTS

In the discovery cohort, IVW analysis revealed a potential inverse relationship between preeclampsia and breast cancer risk (OR, 0.971; 95% CI, 0.947-0.996; P = 0.022). However, the validation cohort did not demonstrate a significant causal association (OR, 0.992; 95% CI, 0.975-1.008; P = 0.327). The combined meta-analysis indicated that preeclampsia might be linked to a lower risk of breast cancer (OR, 0.986; 95% CI, 0.972-0.999; P = 0.041). In subgroup analysis, preeclampsia was found to have a potential association only with estrogen receptor (ER)-negative breast cancer (OR, 0.956; 95% CI, 0.916-0.999; P = 0.043), while no significant link was observed with estrogen receptor (ER)-positive breast cancer (OR, 0.972; 95% CI, 0.945-1.000; P = 0.051). Sensitivity analyses indicated no significant heterogeneity or evidence of horizontal pleiotropy (P > 0.05).

CONCLUSION

This MR study, supported by a robust meta-analysis, suggests that preeclampsia may have a protective effect against breast cancer, especially ER-negative breast cancer. However, to firmly establish this relationship, additional prospective studies with larger populations are warranted. Moreover, further exploration of the biological mechanisms underlying this potential association is needed through both in vitro and in vivo research.

Genetic Association Between High-Risk HPV (HPV16 and HPV18) Infection and Tumor Development: A Mendelian Randomization Analysis

Background and Aims

Observational and experimental studies have provided substantial evidence supporting a link between cervical cancer and human papillomavirus (HPV) infection. Nevertheless, there is uncertainty regarding the association of benign and malignant cancers with HPV infection.

Methods

The study was divided into two approaches, Mendelian randomization (MR) and multivariate Mendelian randomization (MVMR), to investigate the link between HPV and both benign and malignant cancers. This study employed genetic variants as instrumental variables to mitigate potential biases arising from confounding factors and reverse causality. In 338 cases and 1000 controls in the European ancestry of Germany, independent genetic variations were identified as having a substantial correlation (p < 5 × 10-5) with exposure and HPV infection. The outcome variables data of various carcinomas were acquired from the Genome-wide association summary data. Meanwhile, benign tumors from the FinnGen and UK Biobank (UKB) consortium were acquired as well.

Results

Following correction for multiple testing, the MVMR method was employed and the causal association was investigated between genetic liability to HPV infection and various malignancies, including bone and articular cartilage, bladder cancer, secondary malignant neoplasm of the liver, prostate cancer, as well as benign tumors including melanocytic naevi of the lip, brain, bronchus and lung, lip, mouth and pharynx, pancreas, and haemangioma and lymphangioma, and female genitalia.

Conclusions

From a genetic standpoint, HPV may contributes to the formation of benign and malignant tumors in female genital cancer as well as malignancies in other regions of the body, which should inform public health policy.

Identification of novel biomarkers for gastric adenocarcinoma through two-sample Mendelian randomization analysis of the human plasma proteome

BACKGROUND

Papillary gastric adenocarcinoma (PGC), a histological subtype of gastric cancer (GC), is characterized by malignant potential and poor prognosis. Therefore, identifying novel biomarkers is urgently needed to enhance PGC diagnosis and treatment outcomes.

METHODS

This study utilized two-sample Mendelian randomization (MR) to explore potential causal relationships between human blood plasma proteins and GC. Heterogeneity testing, pleiotropy assessment, and directionality analyses were performed to evaluate identified plasma proteins. Additionally, pathway enrichment analysis was conducted to elucidate the molecular mechanisms underlying the causal associations between plasma proteins and GC development.

RESULTS

MR analysis of 4,907 plasma proteins related to GC risk identified 90 proteins with potential causal relationships. The findings revealed that DNAJB9, CHCHD10, and suppressor of cytokine signaling 3 exhibited protective effects against GC, while Syntaxin-8, alcohol dehydrogenase 7, and UDP-glucose 4-epimerase were associated with increased GC risk at the genetic level.

CONCLUSION

In the present study, the six plasma proteins identified through comprehensive MR analysis may serve as potential biomarkers for GC, offering new insights for future molecular diagnosis and therapeutic strategies.

Genetic Evidence for Causal Effects of Immune Cell Subtypes on Postherpetic Neuralgia

Background

Recent evidence indicates that immune cells are crucial in modulating the pathogenesis of postherpetic neuralgia (PHN), with significant associations identified between immune responses and the development of PHN. However, the specific dynamic immune profile, the underlying molecular mechanisms, and especially the causal relationship between immune cells and PHN have yet to be comprehensively elucidated.

Methods

We implemented a comprehensive analytical framework incorporating two-sample Mendelian randomization (MR), multivariable Mendelian randomization(MVMR), and colocalization analyses to elucidate the causal relationships between immune cell phenotypes and PHN. Utilizing publicly available genetic datasets, we explored potential causal associations between 731 immune cell phenotypes and susceptibility to PHN. Comprehensive sensitivity analyses were performed to assess the robustness of the findings, evaluate heterogeneity, and investigate horizontal pleiotropy.The Steiger directionality test was utilized to address and reduce the likelihood of reverse causation.

Results

After applying the Bonferroni-adjusted, eight immune cell phenotypes exhibited significant causal associations with PHN. Further MVMR analysis revealed a significant positive causal relationship between CD27 on IgD- CD38dim B cell and the risk of PHN, with an odds ratio (OR) of 1.228 (95% confidence interval [CI]: 1.059-1.566, P = 0.011). Colocalization analysis offered limited evidence supporting a shared genetic architecture.

Conclusion

Our findings present compelling genetic evidence that identifies CD27 on IgD- CD38dim B cell as a potential therapeutic target for the prevention and treatment of PHN. This study reinforces the mechanistic connection between immune cell function and the pathogenesis of PHN, highlighting the necessity for further exploration in this area. These insights provide significant guidance for future clinical research and the development of therapeutic strategies.

Mendelian randomization study highlights the role of hematological traits on Type-2 diabetes mellitus in African ancestry individuals

Introduction

Observational studies have identified associations between hematological traits and type-2 diabetes mellitus (T2D). However, it is difficult to infer causal effects due to the potential of confounding. Our study utilizes the Mendelian randomization (MR) approach to address the above limitation and investigate the causal effect of hematological traits such as white blood cell (WBC), platelets (PLT), and red blood cell (RBC) on T2D in individuals of African ancestry.

Methods

The participating cohorts included participants of African ancestry in the Blood Cell consortium and the Million Veteran Program dataset. Using GWAS summary statistics, we applied a univariable and multivariable Two-sample MR to estimate the causal relationship between hematological traits and T2D.

Results

In the main IVW MR estimates, genetically predicted levels of mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and mean corpuscular volume (MCV) were associated with decreased risk of T2D. We also observed a decreased risk of T2D with genetically predicted total WBC count and neutrophil count (NEU), for the WBC traits. The multivariable analysis further supported the direct associations of genetically predicted MCH, MCHC, and MCV levels with a decreased risk of T2D. For the European ancestry, a similar pattern of association was observed for MCH and MCV.

Discussion

These findings indicate that hematological traits may differentially play a role in the development of T2D and be affected by T2D. However, further research is needed to validate and explore the biological pathways and mechanisms involved in these associations.

Causal associations between atrial fibrillation and esophageal cancer: a two-sample Mendelian randomization study

Background

Previous studies indicated that atrial fibrillation (AF) patients had a significantly higher esophageal cancer (EC) risk. However, influencing by confounding factors, the causal effect is uncertain. In this study, we aimed to validate the causal relationship between AF and EC by Mendelian randomization (MR) analysis.

Methods

An observational analysis was conducted using the data from the National Health and Nutrition Examination Survey (NHANES) and UK Biobank. Then a two-sample MR method was employed to assess the causal effect of AF on EC. The exposure of AF was collected from publicly available genome-wide association studies (GWASs). Meanwhile, the EC outcome data were derived from the UK Biobank and the FinnGen consortium. A set of 108 single-nucleotide polymorphisms (SNPs) served as instrumental variables (IVs). The effect estimates were calculated using the inverse variance weighted (IVW) method.

Results

Genetically predicted AF was associated with an increased risk of EC [odds ratio (OR), 1.73; 95% confidence interval (CI): 1.01-1.73; P=0.04]. The similar results could be found by sensitivity analyses and no any evidence of horizontal pleiotropy was observed.

Conclusions

This two-sample MR analysis suggested that AF was causally associated with an increased risk of EC.

Lipid metabolism-associated metabolites on cardiovascular diseases: a two-sample Mendelian randomized study

Background

There is a growing body of evidence indicating that metabolites are associated with an increased risk of cardiovascular diseases (CVDs), the underlying causality of these associations remains largely unchallenged. Given the inherent difficulty in establishing causality using epidemiological data, we employed the technique of Mendelian randomization to investigate the potential role of plasma metabolite factors in influencing the risk of CVDs.

Methods

The exposure was based on 1,400 plasma metabolites, and outcomes involved four CVD datasets from public databases. Initial causality was assessed by inverse variance weighting (IVW), followed by sensitivity analyses using MR-Egger regression, weighted median, and Multiple Effectiveness Residual Sums and Outliers (MR-PRESSO) method. Potential heterogeneity and multivalence were assessed using the MR-Egger intercept and Cochran's Q statistic. After Bonferroni correction, causal associations were found to be significant with p-values less than 0.05. All statistical analyses were rigorously executed in R software.

Results

Our findings identified causal relationships between 15 metabolites and cardiovascular disease. Of these, 4 were associated with AA (aortic aneurysm), 7 with atrial fibrillation and flutter, 2 with HF (heart failure), and 3 with stroke.

Conclusion

This is the first systematic mendelian randomization analysis using genome-wide data to assess the causal relationship between serum metabolites and different cardiovascular diseases, providing preliminary evidence for the impact of lipid metabolism disorders on cardiovascular disease risk.

Assessing the potential causal effects of 1099 plasma metabolites on 2099 binary disease endpoints

Metabolites are small molecules that are useful for estimating disease risk and elucidating disease biology. Here, we perform two-sample Mendelian randomization to systematically infer the potential causal effects of 1099 plasma metabolites measured in 6136 Finnish men from the METSIM study on risk of 2099 binary disease endpoints measured in 309,154 Finnish individuals from FinnGen. We find evidence for 282 putative causal effects of 70 metabolites on 183 disease endpoints. We also identify 25 metabolites with potential causal effects across multiple disease domains, including ascorbic acid 2-sulfate affecting 26 disease endpoints in 12 disease domains. Our study suggests that N-acetyl-2-aminooctanoate and glycocholenate sulfate affect risk of atrial fibrillation through two distinct metabolic pathways and that N-methylpipecolate may mediate the putative causal effect of N6,N6-dimethyllysine on anxious personality disorder.

Causal relationship between serum 25-hydroxyvitamin D and coronary heart disease: A bi-directional two-sample Mendelian randomization study

BACKGROUND AND AIM

Coronary heart disease (CHD) is the leading cause of severe cardiovascular events, such as acute myocardial infarction. This study investigates the interaction between serum 25-hydroxyvitamin D (25(OH)D) levels and CHD. However, most current studies are observational, which may introduce bias into the results.

METHODS AND RESULTS

We conducted a two-way, two-sample Mendelian randomization study. The CHD sample was drawn from the 2021 population in the FinnGen database (cases: 21,012; controls: 197,780), while the serum 25(OH)D sample was obtained from the 2020 European population in the GWAS Catalog database (417,580 cases). Based on the inverse variance weighted (IVW) results, we found that the risk of CHD decreased with increasing serum 25(OH)D concentrations (P < 0.05), and that higher CHD risk was associated with lower serum 25(OH)D concentrations (P = 0.04).

CONCLUSIONS

Our study found that increased serum 25(OH)D concentration may serve as a protective factor against CHD. Additionally, we found that CHD can be a risk factor that affects serum 25(OH)D concentrations in humans.

Association between gestational diabetes mellitus and offspring health: a two-sample mendelian randomization study

BACKGROUND

Gestational diabetes mellitus (GDM) constitutes a significant contributor to maternal and fetal morbidity, which is observed to be associated with future risks of offspring health. Nevertheless, it is essential to acknowledge that observational findings may be susceptible to residual confounding and bias.

METHODS

To investigate the association of GDM with offspring health, a genome-wide genetic association study employing Mendelian Randomization (MR) is conducted between May 31 and November 30, 2023. The inverse-variance-weighted (IVW) is utilized in the primary analysis stage. The study data of the majority patients are European ancestry, which are sourced from the IEU open genome-wide association study project.

RESULTS

Genetically predicted GDM is associated with an increased risk of various short- and long-term health problem in offspring. For fetal and neonatal conditions, GDM is linked to an elevated risk of preterm delivery [ odd ratio (OR) = 1.150, false discovery rate (FDR)-adjusted PIVW = 0.009] and placental disorders (OR = 2.143, FDR-adjusted PIVW = 0.028). In respiratory diseases, it is associated with a higher likelihood of influenza (OR = 1.175, FDR-adjusted PIVW = 0.008), bacterial pneumonia (OR = 1.141, FDR-adjusted PIVW = 0.008), congenital malformations of the respiratory system (OR = 1.673, FDR-adjusted PIVW = 0.033), influenza with pneumonia (OR = 1.078, FDR-adjusted PIVW = 0.008), and need for non-invasive ventilation (OR = 1.265, FDR-adjusted PIVW = 0.028). In terms of neurodevelopmental and psychiatric outcomes, GDM is linked to a higher risk of cerebral palsy (OR = 1.721, FDR-adjusted PIVW = 0.008). For urinary conditions, GDM increases the risk of acute tubulo-interstitial nephritis (OR = 1.098, FDR-adjusted PIVW = 0.008). No association is identified between genetically predicted GDM and major digestive diseases, such as gastroesophageal reflux, or cardiovascular conditions in offspring.

CONCLUSIONS

The findings of this study provide genetic evidence supporting an association between GDM and higher risk of offspring diseases. This supports classification of GDM as risk factors for short- and long-term offspring health.

Bidirectional relationship between platelet count and skin cancer: tumor drug resistance mechanisms

BACKGROUND

Platelets (PLT) play a crucial role in tumor progression, including tumor growth, metastasis, and immune evasion. However, the relationship between PLT count and specific skin cancer subtypes, particularly melanoma skin cancer (MSC) and non-melanoma skin cancer (NMSC), remains poorly understood. Clarifying this association could identify potential biomarkers and therapeutic targets for personalized treatments.

METHODS

We applied bidirectional Mendelian randomization (MR) to investigate the causal relationship between PLT count and skin cancer risk, focusing on MSC and NMSC. Genetic variants associated with PLT and skin cancer served as instrumental variables for causal inference. Nine MR analysis methods, with inverse-variance weighted (IVW) as the primary method, were used to assess robustness, heterogeneity, and pleiotropy.

RESULTS

Forward MR analysis showed no significant relationship between PLT count and overall skin cancer or NMSC. However, elevated PLT was linked to an 18.6% increased risk of MSC. Reverse MR analysis revealed that skin cancer, particularly NMSC, negatively affected PLT count, while MSC was associated with a positive influence on PLT levels. No significant heterogeneity or pleiotropy was detected.

CONCLUSIONS

Our findings reveal a bidirectional, subtype-specific relationship between PLT and skin cancer. Elevated PLT levels specifically increase the risk of MSC, while MSC influences PLT count positively. In contrast, NMSC is associated with lower PLT levels. These results suggest that PLT could serve as both a prognostic marker and a potential therapeutic target, particularly for MSC. Further research is needed to explore the molecular mechanisms underlying these associations and to investigate the role of PLT in overcoming tumor resistance to therapies.

Causal association between metabolic syndrome and ovarian dysfunction: a bidirectional two-sample mendelian randomization

BACKGROUND

The relationship between Metabolic Syndrome (MetS) and ovarian dysfunction has been widely reported in observational studies, yet it remains not fully understood. This study employs genetic prediction methods and utilizes summary data from genome-wide association studies (GWAS) to investigate this causal link.

METHODS

We employed a bidirectional two-sample Mendelian Randomization (MR) analysis utilizing MetS and ovarian dysfunction summary data from GWAS. Inverse variance weighted (IVW) was employed as the primary MR method, supplemented by Weighted Median, Weighted Mode, and MR-Egger methods. The robustness of the results was further assessed through sensitivity analyses including MR-Egger regression, MR-PRESSO, Cochran's Q, and leave-one-out test.

RESULTS

Our MR analysis identified a causal relationship between genetically determined insulin resistance (OR = 0.26, 95% CI: 0.08-0.89, P = 0.03), waist circumference (OR = 2.14, 95% CI: 1.45-3.15, P < 0.001), BMI (OR = 2.1, 95% CI: 1.56-2.83, P < 0.001) and ovarian dysfunction. Conversely, reverse MR analysis confirmed causal effects of ovarian dysfunction on metabolic syndrome (OR = 0.98, 95% CI: 0.97-0.99, P < 0.001) and waist circumference (OR = 0.99, 95% CI: 0.98-0.99, P = 0.02). The results of MR-Egger regression test indicated that the whole analysis was not affected by horizontal pleiotropy. Additionally, the MR-PRESSO test identified outliers in SNPs, but after removal of outliers, results remained unchanged.

CONCLUSION

This study reveals a bidirectional causal connection between metabolic syndrome and ovarian dysfunction via genetic prediction methods. These findings are crucial for advancing our understanding of the interactions between these conditions and developing strategies for prevention and treatment.