Mendelian randomization: genetic anchors for causal inference in epidemiological studies

Mendelian randomisation studies for causal inference in chronic obstructive pulmonary disease: A narrative review

BACKGROUND AND OBJECTIVE

Most non-randomised controlled trials are unable to establish clear causal relationships in chronic obstructive pulmonary disease (COPD) due to the presence of confounding factors. This review summarises the evidence that the Mendelian randomisation method can be a powerful tool for performing causal inferences in COPD.

METHODS

A non-systematic search of English-language scientific literature was performed on PubMed using the following keywords: 'Mendelian randomisation', 'COPD', 'lung function', and 'GWAS'. No date restrictions were applied. The types of articles selected included randomised controlled trials, cohort studies, observational studies, and reviews.

RESULTS

Mendelian randomisation is becoming an increasingly popular method for identifying the risk factors of COPD. Recent Mendelian randomisation studies have revealed some risk factors for COPD, such as club cell secretory protein-16, impaired kidney function, air pollutants, asthma, and depression. In addition, Mendelian randomisation results suggest that genetically predicted factors such as PM2.5, inflammatory cytokines, growth differentiation factor 15, docosahexaenoic acid, and testosterone may have causal relationships with lung function.

CONCLUSION

Mendelian randomisation is a robust method for performing causal inferences in COPD research as it reduces the impact of confounding factors.

The causal relationship between gut microbiota and preterm birth: a two-sample Mendelian randomization study

BACKGROUND

Preterm birth, a significant global health concern, has been associated with alterations in the gut microbiota. However, the causal nature of this relationship remains uncertain due to the limitations inherent in observational studies.

PURPOSE

To investigate the potential causal relationship between gut microbiota imbalances and preterm birth.

METHODS

We conducted a two-sample Mendelian randomization (MR) study using genome-wide association study (GWAS) data from the MiBioGen consortium focusing on microbiota and preterm birth. Single nucleotide polymorphisms (SNPs) associated with the microbiota were selected as instrumental variables. The inverse variance weighting (IVW) method was used to estimate causality. We confirmed pleiotropy and identified and excluded outlier SNPs using MR-PRESSO and MR-Egger regression. Cochran's Q test was applied to assess heterogeneity among SNPs, and a leave-one-out analysis was performed to evaluate the influence of individual SNPs on overall estimates.

RESULTS

Our findings provide evidence for a causal link between specific components of the gut microbiota and preterm birth, with the identification of relevant metabolites.

CONCLUSION

This study highlights the causal role of gut microbiota imbalances in preterm birth, offering novel insights into the development of preterm birth and potential targets for prevention strategies.

Evaluation of causal relationships between genetic liability to inflammatory bowel disease and autism spectrum disorder by Mendelian randomization analysis

BACKGROUND

Emerging observational studies have indicated the association between autism spectrum disorder (ASD) and IBD, including Crohn's disease (CD) and ulcerative colitis (UC), whereas the causality remains unknown.

METHODS

Summary-level data from large-scale genome-wide association (GWAS) studies of IBD and ASD were retrieved. Mendelian randomisation analyses were performed with a series of sensitivity tests.

RESULTS

Genetic predisposition to ASD was not associated with the risk of IBD (odds ratio [OR] = 0.99, 95% confidence interval [CI = 0.91-1.06, p = 0.70; OR [95% CI]: 1.03 [0.93-1.13], p = 0.58 for CD; OR [95% CI]: 0.96 [0.87-1.05], p = 0.37 for UC) in the IIBDGC dataset. In the FinnGen dataset, their causal effects were unfounded (OR [95% CI]: 1.04 [0.94-1.15], p = 0.49 for IBD; OR [95% CI]: 1.08 [0.89-1.31], p = 0.42 for CD; OR [95% CI]: 1.00 [0.88-1.13], p = 0.95 for UC). In the meta-analysis of two datasets, the OR was 1.01 (95% CI 0.96-1.07, p = 0.45). For the risk of ASD under genetic liability to IBD, the OR from meta-analysis was 1.03 (95% CI 1.01-1.05, p = 0.01).

CONCLUSION

Our findings indicate genetic predisposition to ASD might not increase the risk of IBD, whereas genetic liability to IBD is associated with an increased risk of ASD. Further investigations using more powerful datasets are warranted.

Gene prediction of the relationship between iron deficiency anemia and immune cells

BACKGROUND

Observational studies have shown a potential link between immune factors and the risk of iron deficiency anemia (IDA), yet the causal relationship between immune cells and IDA remains enigmatic. Herein, we used Mendelian randomization (MR) to assess whether this association is causal.

METHODS

We selected IDA genetic variants, including 8376 samples and 9810691 single nucleotide polymorphisms, and immune cells from a large open genome-wide association study (GWAS) for a bidirectional MR study. The primary method was inverse variance weighting (IVW), and auxiliary analyses were MR-Egger, weighted median, simple mode and weighted mode. The reliability of the results was subsequently verified by heterogeneity and sensitivity analysis.

RESULTS

IVW method showed that 19 types of immune cells may be the risk factors of IDA, whereas 15 types of immune cells are the protective factors of IDA. Reverse MR analysis suggested that immune cells from upstream etiology of IDA are not involved in follow-up immune activities. Next, we selected 731 immune cell types as the results. The research revealed that IDA may result in a rise in 23 kinds of immune cells and a reduction in 12 kinds of immune cells. In addition, sensitivity analysis demonstrated no evidence of heterogeneity or horizontal pleiotropy.

CONCLUSIONS

From a genetic standpoint, our study suggests that specific immune cells may be involved in the occurrence of IDA. Inversely, IDA may also contribute to immune dysfunction, thus guiding future clinical investigations.

Causal associations of metabolic dysfunction-associated steatotic liver disease with gestational hypertension and preeclampsia: a two-sample Mendelian randomization study

BACKGROUND

Hypertensive disorders of pregnancy (HDPs), which include gestational hypertension (GH) and preeclampsia (PE), are the primary causes of maternal morbidity and mortality worldwide. Recent studies have found a correlation between metabolic dysfunction-associated steatotic liver disease (MASLD) and HDPs, but the causality of this association remains to be identified. Therefore, this study aims to evaluate the causal relationship between MASLD and HDPs through Mendelian randomization (MR) analysis.

METHODS

The summary statistics from genome-wide association studies were employed to conduct a two-sample MR analysis. Five complementary MR methods, including inverse variance weighting (IVW), MR-Egger, weighted median, simple mode and weighted mode were performed to assess the causality of MASLD on GH and PE. Furthermore, we conducted various sensitivity analyses to ensure the stability and reliability of the results.

RESULTS

Genetically predicted MASLD significantly increased the risk of GH (IVW: OR = 1.138, 95% CI: 1.062-1.220, p < 0.001), while there was little evidence of a causal relationship between MASLD and PE (IVW: OR = 0.980, 95% CI: 0.910-1.056, p = 0.594). The sensitivity analyses indicated no presence of heterogeneity and horizontal pleiotropy.

CONCLUSION

This MR study provided evidence supporting the causal effect of MASLD on GH. Our findings underscore the significance of providing more intensive prenatal care and early intervention for pregnant women with MASLD to prevent potential adverse obstetric outcomes.

Dietary habits and risk of diabetic kidney disease: a two-sample and multivariate Mendelian randomization study

OBJECTIVE

We explored the causal relationship between certain dietary habits and the risk of developing diabetic kidney disease (DKD) using two-sample Mendelian randomization and multivariate Mendelian randomization.

RESEARCH DESIGN AND METHODS

This study is based on pooled data from a genome-wide association study (GWAS) of 83 dietary habits in a European population. We performed a two-sample Mendelian randomization analysis using GAWS data on diabetic nephropathy in a European population. Validation was then performed against positive results (p < 0.05) in different GAWS data on diabetic nephropathy of European origin. Finally, multivariate Mendelian randomization analyses were performed on dietary habits with positive results (p < 0.05) in both datasets and GWAS data on postprandial glucose in the European population.

RESULTS

This study showed causal relationships between 18 dietary habits and the risk of developing DKD. After validation, causal relationships were found between the risk of DKD and two dietary habits: abstaining from sugar consumption (OR 2.86; 95%CI 1.35, 6.08; p = 0.006) and consuming whole grain/multigrain bread (OR 0.53; 95%CI 0.32, 0.89; p = 0.016). Correcting for the effect of postprandial glucose, the multivariate MR results showed that never eating sugar increased the risk of developing DKD (OR 0.08; 95%CI 0.018, 0.36; p = 0.001), whereas eating whole grain/multigrain bread did not reduce the risk of developing DKD (OR 1.37; 95%CI 0.55, 3.41; p = 0.50).

CONCLUSIONS

Our MR results suggest a causal relationship between never eating sugar and an increased risk of developing DKD. Therefore, people with diabetes need a reasonable range of sugar intake.

A practical guide for nephrologist peer reviewers: understanding and appraising Mendelian randomization studies

Identifying risk factors for disease onset and progression has been a core focus in nephrology research. Mendelian Randomization (MR) has emerged as a powerful genetic epidemiological approach, utilizing genome-wide association studies (GWAS) to establish causal relationships between modifiable risk factors and kidney disease outcomes. MR uses genetic variants as instrumental variables to infer causal relationships between exposures and disease outcomes. This method leverages the natural randomization of genetic variants to balance confounders, akin to matched cohorts in observational research. The rapid increase in MR studies on kidney disease poses challenges for journals and peer reviewers, especially clinicians unfamiliar with the methodology. High-quality MR studies use strong, well-validated genetic instruments with clear biological relevance, thoroughly testing for pleiotropy and confounding factors using methods like MR-Egger. Sensitivity analyses, such as MR-PRESSO, should ensure findings remain consistent across various assumptions. Effect sizes with confidence intervals should be reported and discussed within established biological mechanisms. Additionally, limitations must be transparently addressed, with recommendations for replication in future studies, to strengthen findings. This article guides readers in understanding MR application in nephrology and identifying high-quality MR studies, helping peers avoid pitfalls while seizing new opportunities in advancing kidney disease research.

Investigating causal relationships between gene expression and major depressive disorder via brain bulk-tissue and cell type-specific eQTL: A Mendelian randomization and Bayesian colocalization study

BACKGROUND

Major depressive disorder (MDD) is a highly prevalent psychiatric disorder with complex genetic underpinnings. While genome-wide association studies (GWAS) have identified multiple risk loci, pinpointing causal genes within the human brain remains challenging, particularly given the regulatory complexity across different cell types.

METHODS

We performed summary data-based MR (SMR) and Bayesian colocalization analyses by integrating bulk-tissue eQTL data from 888 individuals with single-cell eQTL datasets from 192 donors representing major brain cell types (excitatory and inhibitory neurons, astrocytes, microglia, oligodendrocytes, OPCs/COPs, endothelial cells, and pericytes). GWAS summary statistics for MDD (170,756 cases and 329,443 controls) were used to assess the causal impact of gene expression. Sensitivity analyses, including the heterogeneity in dependent instruments (HEIDI) test and Steiger filtering, ensured robust inference.

RESULTS

In bulk tissue analyses, five genes (BTN3A2, SLC12A5, AREL1, GMPPB, and ZNF660) emerged as having robust causal evidence for MDD, displaying consistent MR signals and strong colocalization. Cell type-specific analyses revealed additional candidate genes in excitatory neurons (FLOT1, AL450423.1), astrocytes (AL121821.1), and oligodendrocytes (YLPM1, COP1).

CONCLUSION

Our integrative approach reveals that causal gene expression profiles differ markedly between bulk-tissue and specific brain cell types, emphasizing cellular heterogeneity in MDD pathogenesis and informing precision therapeutic strategies. These findings underscore the necessity of considering cell type-specific gene regulation when developing therapeutic interventions for MDD.

Comprehensive genetic analysis based on multi - omics reveals novel therapeutic targets for mitral valve prolapse and drug molecular dynamics simulation

OBJECTIVE

Mitral valve prolapse (MVP), the most prevalent primary valvular disease, serves as a direct risk factor for multiple cardiovascular disorders and exhibits a high prevalence in the general population. As no specific pharmacological therapies currently exist for MVP, the identification of precise therapeutic targets is imperative.

METHOD

We conducted comprehensive causal genetic inference by integrating genetic data from expression quantitative trait loci (eQTL) and genome-wide association studies (GWAS). Analytical approaches included Mendelian Randomization (MR), colocalization analysis, Summary-data-based Mendelian Randomization (SMR), Linkage Disequilibrium Score Regression (LDSC), and High-Definition Likelihood (HDL) analysis. Protein quantitative trait loci (pQTL) were utilized to validate gene expression. Replication analyses were performed using additional exposure datasets. Methylation quantitative trait loci (mQTL) were employed to elucidate regulatory roles of methylation sites on genes and disease pathogenesis. Phenome-Wide Association Study (PheWAS) was conducted to predict potential adverse effects of gene-targeted therapies. Drug candidates targeting identified genes were predicted via the Drug Signature Database (DSigDB) and validated through molecular docking. Core targets were identified using the STRING database, followed by molecular dynamics simulations.

RESULT

Two-sample MR analysis showed that genetically predicted 266 genes had positive or negative causal relationships with MVP. Colocalization analysis indicated that 9 genes had a posterior probability greater than 0.75. Subsequent SMR analysis excluded the gene GAPVD1. HDL analysis showed that except for the gene PTPN1, the remaining 7 genes were all significantly genetically associated with MVP, and LDSC analysis further showed that only NMB was associated with MVP. Validation using pQTL data confirmed that increased NMB protein expression reduced the risk of MVP. Replication analysis further verified this conclusion. In addition, SMR analysis of methylation sites for 8 genes indicated that multiple methylation sites played a key role in gene regulation of mitral valve prolapse. PheWAS results showed that targeted therapy for 8 genes did not detect other causal associations at the genome-wide significance level. Molecular docking showed that quercetin had good binding ability with 8 target genes. The STRING database identified 3 core target proteins, and molecular dynamics simulations further verified the binding ability of quercetin with core target proteins.

CONCLUSION

This study successfully predicted the potential of multiple druggable genes as effective therapeutic targets for MVP through genetic methods, validated the potential of quercetin as a drug, and provided new ideas for drug treatment strategies for MVP.

Phosphatidylcholine and frailty: a Mendelian randomization study and immune mediation

OBJECTIVE

Lipid metabolism plays a significant role in the aging process, and the prevalence of frailty increases with advancing age. However, few studies have employed Mendelian randomization (MR) to investigate the associations between lipids and frailty.

METHODS

This study utilized large-scale genome-wide association study (GWAS) and a bidirectional two-sample, two-step MR approach to explore the causal associations of 179 lipid species with the frailty index (FI) and the mediating effects of immune cells. The inverse variance weighted (IVW) method was used primarily to evaluate the MR results. Heterogeneity and horizontal pleiotropy were assessed via Cochran's Q, the MR-Egger intercept, MR-PRESSO and leave-one-out analysis. Phenome-wide MR (Phe-MR) was used to analyse the potential roles of frailty-related phosphatidylcholine species in diseases.

RESULTS

MR analysis revealed a causal relationship between PC species and FI. Specifically, PC (18:0_20:5), LPC (18:0_0:0), LPC (16:0_0:0), and ether-PC (O-16:0_22:5) are positively correlated with the FI, whereas PC(18:1_20:2), PC(16:0_18:3), PC(16:0_20:1), ether-PC (O-18:0_16:1), and ether-PC (O-16:1_16:0) are negatively correlated with the FI. Reverse MR analysis indicated no strong association between the FI and the nine PCs. Mediation analysis revealed that Sw mem %lymphocyte partially mediated the effect of LPC (18:0_0:0) on FI. Phe-MR analysis revealed that nine frailty-related PCs were broadly associated with various diseases.

CONCLUSION

This study provides novel evidence that supports the causal association between PC species and frailty, with the immune system playing a crucial role in this pathway. These findings offer new insights into potential targets for the intervention of frailty in the elderly population.

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.

Bidirectional Mendelian randomization analysis of plasma lipidome and psychiatric disorders

BACKGROUND

Evidence from observational studies and clinical experiments suggests a close association between plasma lipidome and psychiatric disorders. However, the causal relationship between plasma lipidome and psychiatric disorders remains insufficiently determined. Plasma lipidome are relatively easy to measure and regulate clinically, and they play a crucial role in neuronal signal transduction, making them a focus of interest as potential therapeutic targets for psychiatric disorders.

METHODS

In this study, we utilized the latest Finnish population-based genome-wide association study (GWAS) data on 179 lipid species. We downloaded data on five psychiatric disorders from the IEU database, including schizophrenia, bipolar disorder, depression, autism from the PGC consortium, and anxiety disorder from the Neale lab. Using two-sample bidirectional Mendelian randomization (MR) analysis, we assessed the relationship between these 179 lipid species and the risk of the five psychiatric disorders. To validate the assumptions of Mendelian randomization, we conducted tests for horizontal pleiotropy and heterogeneity.

RESULTS

After applying FDR correction to assess the relationship between 179 lipid species traits and the risk of five psychiatric disorders, our analysis provided evidence of a causal relationship specifically between genetic susceptibility in the plasma lipidome and bipolar disorder. This relationship notably involves eight phosphatidylcholines (PCs) and two sterols, with PCs displaying a dual and complex role in the disorder. Reverse Mendelian randomization (MR) analysis did not reveal a significant causal impact of psychiatric disorders on the plasma lipidome.

LIMITATIONS

Despite using two-sample bidirectional Mendelian randomization analysis, the complex biological pathways and potential confounding factors may still affect the accuracy of the causal relationships. The impact of genetic variations on the lipidome and psychiatric disorders may involve multiple mechanisms, which cannot be fully elucidated in this study.

CONCLUSION

This study identified a causal relationship between genetic susceptibility in plasma lipidome and bipolar disorder, indicating that plasma lipidome may influence the risk of psychiatric disorders and providing direction for exploring them as potential intervention targets. The findings not only deepen our understanding of the etiology of psychiatric disorders but also provide a critical theoretical foundation for future clinical interventions and prevention strategies, potentially contributing to the development of novel therapeutic approaches.

Potential of CETP inhibition in treating dyslipidemia in systemic lupus erythematosus: Novel and comprehensive evidence from clinical studies and Mendelian randomization

OBJECTIVE

Cardiovascular diseases from abnormal lipid metabolism significantly increase mortality in systemic lupus erythematosus (SLE). The causal link between dyslipidemia and SLE is unclear.

METHODS

Lipid metabolism in patients with SLE was evaluated based on clinical data from 511 patients with SLE and 706 healthy individuals. Bidirectional Mendelian randomization (MR) was employed to assess causal links between 179 plasma lipid metabolites, lipid-lowering drug targets, and SLE risk. Genetic instruments from GWAS and eQTL data were used to evaluate CETP and APOA4 effects. Peripheral blood CETP and apolipoprotein levels in SLE patients were validated via ELISA.

RESULTS

SLE patients exhibited reduced HDL-C (P < 0.0001), APOA1 (P < 0.0001), and APOA4 (P < 0.0001), alongside elevated triglycerides (TG, P < 0.0001), APOC3, APOD, and APOF. MR identified three lipid metabolites-PC(18:2_20:4), TG(56:6), and TG(58:7)-as causal factors for SLE (P < 2.79E-5). CETP inhibition significantly reduced SLE risk via HDL-C modulation (OR = 0.72, P = 3.38E-08) and influenced LDL-C, TG, and apolipoproteins. Clinical validation confirmed elevated CETP and reduced APOA4 in SLE, correlating with disease activity. APOA4 activation showed protective effects, while PCSK9 inhibition lacked relevance.

CONCLUSION

Bidirectional Mendelian randomization analyses confirmed dyslipidemia as a causal antecedent to SLE, with no evidence of reverse causation. A variety of MR analyses and clinical validation indicated that targeting HDL-C regulation offers significant advantages for managing dyslipidemia in patients with SLE, with CETP identified as the optimal pharmacological target.

Disentangling the effects of nicotine versus non-nicotine constituents of tobacco smoke on major depressive disorder: A multivariable Mendelian randomisation study

BACKGROUND AND AIMS

There is growing evidence that tobacco smoking causes depression, but it is unclear which constituents of tobacco smoke (e.g. nicotine, carbon monoxide) may be responsible. We used Mendelian randomisation (MR) to measure the independent effect of nicotine on depression, by adjusting the effect of circulating nicotine exposure [via nicotine metabolite ratio (NMR)] for the overall effect of smoking heaviness [via cigarettes per day (CPD)] to account for the non-nicotine constituents of tobacco smoke.

DESIGN

Univariable MR and multivariable MR (MVMR) were used to measure the total and independent effects of genetic liability to NMR and CPD on major depressive disorder (MDD). Our primary method was inverse variance weighted (IVW) regression, with other methods as sensitivity analyses.

SETTING AND PARTICIPANTS

For the exposures, we used genome-wide association study (GWAS) summary statistics among European ancestry individuals for CPD (n = 143 210) and NMR (n = 5185). For the outcome, a GWAS of MDD stratified by smoking status was conducted using individual-level data from UK Biobank (n = 35 871-194 881).

MEASUREMENTS

Genetic variants associated with NMR (n = 6) and CPD (n = 53).

FINDINGS

Univariable MR-IVW indicated a causal effect of CPD on MDD [odds ratio (OR) = 1.13, 95% confidence interval (CI) = 1.04-1.23, P = 0.003] but no clear evidence for an effect of NMR on MDD (OR = 0.98, 95% CI = 0.97-1.00, P = 0.134). MVMR indicated a causal effect of CPD on MDD when accounting for NMR (IVW: OR = 1.19, 95% CI = 1.03-1.37, P = 0.017; Egger: OR = 1.13, 95% CI = 0.89-1.43, P = 0.300) and weak evidence of a small effect of NMR on MDD when accounting for CPD (IVW: OR = 0.98, 95% CI = 0.96-1.00, P = 0.057; Egger: OR = 0.98, 95% CI = 0.96-1.00, P = 0.038).

CONCLUSIONS

The role of nicotine exposure in risk of depression cannot be entirely dismissed. However, the causal effect of tobacco smoking increasing depression risk appears to be largely independent of circulating nicotine exposure, which implies the role of alternative causal pathways.

The Plasma Proteome and Risk of Future Venous Thromboembolism-Results from the HUNT Study

This study aimed to identify novel plasma proteins associated with first-lifetime venous thromboembolism (VTE) and molecular pathways involved in VTE pathogenesis.A case-cohort comprising incident VTE cases (n = 294) and a randomly sampled age- and sex-weighted subcohort (n = 1,066) was derived from the Trøndelag Health Study (HUNT3, n = 50,800). Blood samples were collected and stored at cohort inclusion (2006-2008), and participants were followed up to 5 years. Proteome-wide analyses was performed using the 7k SomaScan® proteomics platform, and weighted Cox-regression models adjusted for age, sex, and sample batch were conducted, with the Bonferroni method applied to account for multiple testing. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were applied on the top-ranked 200 proteins associated with VTE.Out of 7,288 human proteins, 7 proteins were significantly associated with higher VTE risk with p-value <6.9 × 10-6 (hazard ratios per 1 standard deviation increase in protein levels ranging from 1.39 to 1.86). Except for coagulation factor VIII and tumor necrosis factor soluble receptor II, these proteins were novel associations and included collagen alpha-3(VI):BPTI/Kunitz inhibitor, histo-blood group ABO system transferase, peroxidasin, human epididymis protein 4, and regulator of G protein signaling 3. KEGG analyses of the top-ranked 200 proteins revealed significant pathway enrichment of nine proteins in the complement (mainly lectin pathway) and coagulation (mainly intrinsic pathway) cascades.Our proteome-wide analysis led to discovery of five novel protein candidates associated with 5-year risk of future VTE. KEGG analyses supported an interplay between the complement and coagulation pathways in the pathogenesis of VTE.

Association of Immune Cell Phenotypes With Oral Cancer: A Two-Sample Mendelian Randomisation Study

OBJECTIVES

The purpose of this study is to assess the potential causal relationship between immune cell phenotype and oral cancer using Mendelian randomisation analysis.

METHODS

A two-sample Mendelian randomisation (MR) analysis using summary statistics from genome-wide association studies in European populations was conducted to explore causal relationships between immune cell phenotypes and the risk of oral cancer. Inverse-variance weighting, MR-EGGER, simple mode, weighted median, and weighted mode were applied for MR analysis. Sensitivity analyses, including the Steiger test, Cochran's Q test, Egger intercept, and leave-one-out analysis, were performed to assess the robustness of the results. Additionally, colocalisation analysis was carried out to further validate causal associations.

RESULTS

A total of 21 immune cell phenotypes were identified as risk factors for oral cancer, while 6 immune cell phenotypes demonstrated protective effects. Sensitivity analyses indicated a lack of robustness in four causal relationships. Genetic variants at rs9469077 on chr6 might be shared between CD28-CD127-CD25++CD8br AC of regulatory T cells and oral cancer.

CONCLUSION

This MR study provides evidence for a strong association between immune cells and oral cancer, highlighting specific immune cell phenotypes as significant risk factors for the development of oral cancer. These findings offer a foundation for future precision immunotherapy strategies for oral cancer. Further studies are required to confirm the relationship between immune cells and oral cancer risk and to elucidate the underlying mechanisms.

CLINICAL RELEVANCE

This study confirms the potential relationship between specific immune cell phenotypes and oral cancer, providing theoretical support for future immunotherapy against oral cancer.

Comprehensive immunogenomic landscape analysis unveils CD33 + myeloid cell-driven immunomodulatory signatures in melanoma development

BACKGROUND

Understanding the causal relationships between immune cell populations and cancer development remains a critical challenge in tumor immunology.

METHODS

We employed Mendelian Randomization analysis leveraging genome-wide association studies of 612 immune cell traits and 91 cancer types to systematically evaluate causal associations. Single-cell RNA sequencing and computational deconvolution analyses were performed to characterize myeloid cell subpopulations in melanoma samples.

FINDINGS

Our analysis revealed significant relationships between specific immune cell subsets and cancer risk, particularly highlighting the role of CD33 + myeloid cells in melanoma pathogenesis. Single-cell RNA sequencing identified distinct CD33high myeloid subpopulations characterized by elevated expression of complement cascade components and chemokine signaling pathways. Through computational deconvolution of The Cancer Genome Atlas melanoma cohort, we demonstrated that elevated CD33high monocyte abundance correlates with increased immune dysfunction scores, reduced CD8 + T cell infiltration, and poor survival outcomes.

INTERPRETATION

Here we delineate the multifaceted mechanisms through which CD33 + myeloid cell populations orchestrate perturbations in the tumor-immune microenvironmental landscape, manifesting in compromised immunosurveillance and enhanced tumor progression. Our findings illuminate novel therapeutic opportunities through targeted modulation of myeloid cell function, while providing a systematic framework for understanding the complex interplay between immune cell populations and oncogenic processes.

COVID-19 Predisposition Inherently Increases Cardiovascular Risk Before SARS-CoV-2 Infection

As COVID-19 transitions to an endemic stage, its long-term impacts on health, particularly cardiovascular disease (CVD), remain significant. While prior studies have focused on cardiovascular complications following SARS-CoV-2 infection, the question of inherent cardiovascular risk associated with genetic predisposition to COVID-19 has been less explored. This study investigates whether individuals genetically predisposed to COVID-19 may also be at higher risk for CVD, independent of actual infection. Using Mendelian randomization (MR) analysis with data from pre-pandemic, SARS-CoV-2-naive populations, this study assessed the impact of genetic susceptibility to COVID-19 on various CVD outcomes across 18 distinct cohorts. This approach allowed us to simulate COVID-19 predisposition without infection, providing insights into cardiovascular risks associated solely with genetic susceptibility. These findings reveal a significant association between genetic predisposition to COVID-19 and elevated risks for several CVD outcomes, particularly hypertensive heart disease. Notably, individuals with a genetic profile linked to severe COVID-19 (hospitalization-prone) showed a marked increase in risk for hypertensive heart disease. These findings suggest a shared genetic architecture that predisposes individuals to both COVID-19 and cardiovascular risks, irrespective of viral exposure. COVID-19 susceptibility, thus, may act as a "natural stress test," revealing latent cardiovascular vulnerabilities. This connection implies that individuals predisposed to severe COVID-19 may have inherently higher cardiovascular risks, even without SARS-CoV-2 infection. This study highlights the value of COVID-19 susceptibility as a novel marker for assessing CVD risk, enabling timely preventive strategies and mitigating future CVD burden in the post-COVID-19 era. Moreover, this study highlights disease predisposition as a "black box" until clinical onset. While COVID-19 demands an external viral trigger for acute onset, cardiovascular disease unfolds much more slowly, requiring prolonged exposure to detrimental lifestyle and genetic factors. Together, their intersection illustrates how acute environmental triggers and chronic disease processes can converge to influence overall health outcomes.

Integrating genome-wide information and wearable device data to explore the link of anxiety and antidepressants with pulse rate variability

This study explores the genetic and epidemiologic correlates of long-term photoplethysmography-derived pulse rate variability (PRV) measurements with anxiety disorders. Individuals with whole-genome sequencing, Fitbit, and electronic health record data (N = 920; 61,333 data points) were selected from the All of Us Research Program. Anxiety polygenic risk scores (PRS) were derived with PRS-CS after meta-analyzing anxiety genome-wide association studies from three major cohorts- UK Biobank, FinnGen, and the Million Veterans Program (NTotal =364,550). PRV was estimated as the standard deviation of average five-minute pulse wave intervals over full 24-hour pulse rate measurements (SDANN). Antidepressant exposure was defined as an active antidepressant prescription at the time of the PRV measurement in the EHR. Anxiety PRS and antidepressant use were tested for association with daily SDANN. The potential causal effect of anxiety on PRV was assessed with one-sample Mendelian randomization (MR). Anxiety PRS was independently associated with reduced SDANN (beta = -0.08; p = 0.003). Of the eight antidepressant medications and four classes tested, venlafaxine (beta = -0.12, p = 0.002) and bupropion (beta = -0.071, p = 0.01), tricyclic antidepressants (beta = -0.177, p = 0.0008), selective serotonin reuptake inhibitors (beta = -0.069; p = 0.0008) and serotonin and norepinephrine reuptake inhibitors (beta = -0.16; p = 2×10-6) were associated with decreased SDANN. One-sample MR indicated an inverse effect of anxiety on SDANN (beta = -2.22, p = 0.03). Anxiety and antidepressants are independently associated with decreased PRV, and anxiety appears to exert a causal effect on reduced PRV. Those observational findings provide insights into the impact of anxiety on PRV.

Diabetes affects AD through plasma Aβ40: A Mendelian randomization study

Amyloid and tau proteins are important proteins in the pathological changes of Alzheimer's disease (AD), while Aβ pathology and tau pathology are the most critical factors contributing to the development of AD. Some studies have shown that there is a causal relationship between AD and diabetes mellitus, but there are no studies showing a causal relationship between diabetic traits and AD biomarkers, so further exploration is needed. We first summarized and analyzed the currently published literature on the link between diabetes and AD through a systematic review. Forest plots were used to observe whether there is an association between diabetes and AD. Then a two-sample Mendelian randomization (MR) analysis based on GWAS summary statistics was performed to verify the causal relationship between diabetic traits and AD biomarkers. Based on summary statistics from the GWAS, potential causal relationships between diabetic traits and AD biomarkers were explored separately. The results of the meta-analysis part showed that diabetes can increase the risk of AD. Meanwhile, our two-sample MR results showed a significant causal relationship between diabetes and plasma Aβ40. In addition, our two-sample MR results also showed a causal relationship between increased HbA1c and plasma APLP2. Other diabetic traits may have potential effects on different AD plasma markers.

Causal association of cathepsins and endometriosis: A Mendelian randomization study

Endometriosis is a prevalent reproductive disorder that affects a significant number of women globally. Cathepsins, which are lysosomal cysteine proteases, contribute to several physiological and pathological processes, including the attachment and invasion of endometrial tissue. Nevertheless, the causal relationship between cathepsins and endometriosis remains undetermined. The aim of this study was to explore the potential relationship between cathepsins and endometriosis using genetic polymorphisms. We employed a 2-sample Mendelian randomization (MR) analysis (including inverse-variance weighted [IVW] method and reverse MR analysis) to investigate the causal association between 9 cathepsins and endometriosis. The IVW method provides efficient and robust causal estimates when genetic instruments are valid, making it the standard approach in MR analysis. And the reverse MR analysis ensures the robustness and directionality of causal inference. The univariable MR analysis results indicate that Cathepsin H increases the risk of overall endometriosis (IVW: OR [95%] = 1.037 [1.007 to 1.067], P = .013), endometriosis of ovary (IVW: OR [95%] = 1.022 [1.001 to 1.042], P = .046), endometriosis of pelvic peritoneum OR [95%] = 1.046 [1.002 to 1.089], P = .047), and deep endometriosis (IVW: OR [95%] = 1.050 [1.002 to 1.099], P = .048). The multivariable MR analysis retained stable after adjusting for other types of cathepsins. And reverse MR analyses suggest that overall endometriosis may lead to increased Cathepsin H levels (IVW: OR [95%] = 1.017 [1.003, 1.073], P = .041). The results of the sensitivity analyses were consistent with the main findings. Our MR analysis yields robust evidence supporting a causal relationship between Cathepsin H and the susceptibility to endometriosis, potentially inspiring directions in endometriosis diagnosis and treatment.

Endothelial selective adhesion molecule and interleukin-16 play an intermediary role in psoriasis complicated with acute myocardial infarction: A Mendelian randomization study

Psoriasis is a prevalent inflammatory skin disorder, often associated with an increased risk of atherosclerosis. Despite growing evidence suggesting a potential link between psoriasis and acute myocardial infarction (AMI), the causal relationship remains uncertain and is still a subject of debate. This study aims to fill this knowledge gap by utilizing Mendelian randomization (MR) and mediation analysis to systematically evaluate the causal association between psoriasis and AMI. Additionally, we seek to identify potential mediators that may influence this relationship, thereby providing new insights into the underlying mechanisms that could explain the observed association. The psoriasis GWAS dataset (2802 cases, 212,242 controls) was obtained from the FinnGen study, while genetic associations with endothelial selective adhesion molecule (ESAM) and interleukin (IL)-16 levels were derived from meta-analyses by Sun et al (3301 individuals) and Ahola-Olli et al (3483 individuals), respectively. AMI outcome data (3927 cases, 333,272 controls) were extracted from the UK Biobank. Two-sample MR analyses were conducted to assess the causal effects of psoriasis, ESAM, and IL-16 on AMI risk. MR mediation analysis was used to determine whether ESAM and IL-16 mediate the effect of psoriasis on AMI. To minimize the impact of population differences, we employed robust genetic instruments (F > 10) for each exposure, conducted sensitivity analyses (MR-Egger and weighted median) to check for pleiotropy, and ensured the validity of our results across different populations. The genetic liability to psoriasis (odds ratio [OR]: 1.00078; 95% confidence interval [CI]: 1.00008-1.00148; P = .028479), ESAM (OR: 1.00208; 95% CI: 1.00019-1.00397; P = .031089), and IL-16 (OR: 1.00118; 95% CI: 1.00009-1.00227; P = .033826) were associated with higher AMI risks. The proportion of the effects of genetically-predicted psoriasis mediated through genetically-predicted ESMA and IL-16 was 24.8% (95% CI 8.3%-41.2%) and 16.1% (95% CI 5.3%-26.8%), respectively. Genetic liability to psoriasis is correlated with a higher risk of AMI, which is partially mediated by ESAM and IL-16. The targeted intervention of ESAM and IL-16 might help decrease the risk of AMI in psoriasis patients.

Causal relationships between plasma proteins and Alzheimer's disease using bidirectional Mendelian randomization

BackgroundAlzheimer's disease (AD) is influenced by a complex interplay of genetic, immune, and metabolic factors. Identifying plasma proteins causally linked to AD could help clarify these pathways and uncover potential therapeutic targets.ObjectiveThis study aims to investigate the causal relationships between AD and plasma proteins.MethodsWe conducted a two-stage, two-sample Mendelian randomization (MR) analysis to explore the causal relationships between plasma protein levels and AD risk. In both stages, we used non-overlapping genome-wide association study datasets for exposures (plasma protein levels) and outcome (AD) to ensure robust and independent analyses. We examined both forward (from plasma proteins to AD risk) and reverse (from AD to plasma protein expression) causal effects to elucidate potential bidirectional relationships.ResultsOur MR analysis identified 25 plasma proteins with causal associations to AD, with many implicated in immune and lipid metabolic pathways. These findings reinforce the roles of inflammation and lipid metabolism in AD pathogenesis and offer novel insights into specific proteins that may serve as biomarkers or therapeutic targets.ConclusionsThis study provides further support for the relationship between immune and lipid metabolic dysregulation and AD, advancing our understanding of the molecular mechanisms underlying disease progression and highlighting key proteins for future research and therapeutic development.

Association of modifiable risk factors and telomere length with five neuroendocrine neoplasms: a bidirectional Mendelian randomization study

BACKGROUND

 The timely recognition of modifiable risk factors holds paramount importance in tumor prevention. We aimed to scrutinize the causal relationships between a spectrum of genetically modifiable risk factors and five distinct neuroendocrine neoplasms.

METHODS

A bidirectional two-sample Mendelian randomization (MR) analysis was employed to elucidate the causal relationships between 41 potential risk factors and five neuroendocrine neoplasms.

RESULTS

Height, obesity class 1, 2, and 3, overweight, waist-to-hip ratio, waist circumference, and serum uric acid were identified as factors associated with an augmented risk of colorectal neuroendocrine neoplasms (all p < 0.05). Conversely, a negative correlation was observed between fasting glucose and the risk of colorectal neuroendocrine neoplasms (p = 0.031). Platelet count exhibited a negative correlation with lung neuroendocrine neoplasms (p = 0.02). Moreover, the waist-to-hip ratio demonstrated a negative association with the risk of pancreatic neuroendocrine neoplasms. Atrial fibrillation, mean cell heamoglobin, and mean cell volume were positively associated with the risk of small intestine neuroendocrine neoplasms. In gastric neuroendocrine neoplasms, obesity class 1 and 2, overweight, and telomere length were implicated in their heightened risk. Following adjustment for multiple tests, obesity class 1 remained statistically significant to colorectal neuroendocrine neoplasms, and telomere length maintained significance in association with gastric neuroendocrine neoplasms. The outcomes of reverse MR suggested a bidirectional causal relationship between telomere length and gastric neuroendocrine neoplasms.

CONCLUSION

This study provided genetic evidence for the causal relationships between potentially modifiable risk factors and the risk of five neuroendocrine neoplasms. Therapeutic approaches to these factors may provide a basis for preventing neuroendocrine neoplasms.

Bidirectional mendelian randomization assessment of causality between lactate levels and multiple autoimmune diseases

Bidirectional two-sample Mendelian randomization (MR) was performed to provide genetic evidence for the causal association between multiple sclerosis (MS), type 1 diabetes(T1D), rheumatoid arthritis (RA) and inflammatory bowel disease (IBD), Crohn's disease (CD), systemic lupus erythematosus (SLE), ulcerative colitis (UC) and lactate levels. Inverse variance weighted (IVW), weighted median estimator (WME), weighted mode, and MR-Egger regression were used to assess the potential causal links. Sensitivity analysis included Cochran's Q test for heterogeneity, Steiger test of directionality for directionality, MR-Egger regression, MR pleiotropy residual sum and outlier (MR-PRESSO), and leave-one-out method. MR analysis utilized 510 SNPs associated with seven different kinds of autoimmune diseases and 11 SNPs associated with lactate levels as IVs. No significant genetic association between any autoimmune diseases and lactate levels was discovered by IVW. While IVW revealed no significant associations, exploratory analyses using WME and weighted mode methods identified nominal links between RA/IBD and lactate levels (RA: WME OR = 1.01, P = 0.010; weighted mode OR = 1.01, P = 0.008; IBD: weighted mode OR = 1.01, P = 0.042). These findings, though not surviving FDR correction, warrant further investigation. In reverse MR analysis, there was no significant association between lactate level exposure and any autoimmune disease outcomes. MR-Egger regression indicated potential horizontal pleiotropy in the RA-lactate analysis and Cochran's Q test suggest no absence of heterogeneity. Potential reverse causality in the analysis of SLE as outcomes and lactate levels as exposures was discovered by MR Steiger. Based on limited evidence, Our MR Analysis found a possible genetic causal association between RA and lactate level difference.

The causal role of homocysteine in multiple diseases: a systematic review of Mendelian randomization studies

BACKGROUND

Homocysteine (Hcy) has been implicated in the development of multiple diseases; however, its causal role remains unclear. Mendelian randomization (MR) studies provide a robust approach to assessing causality by minimizing confounding and reverse causation.

OBJECTIVE

This study aimed to evaluate the causal role of Hcy in various diseases by synthesizing evidence from MR studies.

METHODS

We performed a comprehensive literature search in PubMed, the Cochrane Library, Embase, and Web of Science for MR studies published up to May 30, 2024. Studies investigating the association between genetic predisposition to Hcy levels and specific diseases were included.

RESULTS

Findings from 33 MR studies (covering 31 distinct primary outcomes) suggest that genetically elevated Hcy levels are associated with an increased risk of several health conditions, including: Five cardiovascular diseases: small vessel stroke, small artery occlusion stroke, stroke, subarachnoid hemorrhage, and ischemic stroke. Six musculoskeletal diseases: soft tissue disorders, osteoporosis with pathological fractures, hospital-diagnosed osteoarthritis (OA), overall OA, knee OA, and hip OA. One musculoskeletal biomarker: waist-to-hip ratio (WHR) adjusted for BMI. Two digestive system diseases: gastric cancer and non-alcoholic fatty liver disease. Three digestive biomarkers: alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). One urogenital system disease: chronic kidney disease. Two mental disorders: schizophrenia and bipolar disorder type I. One metabolic disorder: metabolic syndrome. Conversely, elevated Hcy levels are associated with a reduced risk of: One neurological disorder: multiple sclerosis. Two neurological biomarkers: gray matter volume and total brain volume. Five musculoskeletal biomarkers: heel bone mineral density (BMD), right/left grip strength, walking pace, and appendicular lean mass. One urogenital system biomarker: estimated glomerular filtration rate. Additionally, genetically reduced plasma Hcy levels correlated with higher forearm BMD.

CONCLUSION

These findings provide significant evidence for the role of Hcy in disease causation and may contribute to the development of future preventive measures or therapeutic strategies.

Causal association between polyunsaturated fatty acids and acne: a two-sample Mendelian randomization study

BACKGROUND

Observational studies have demonstrated a close association between polyunsaturated fatty acids (PUFAs) and acne. However, the findings of clinical trials have been inconsistent, leaving the causal relationship between PUFAs and acne unclear.

OBJECTIVES

To investigate the causal association between genetically proxied PUFAs and acne risk.

METHODS

Mendelian randomization (MR) was performed using single nucleotide polymorphisms associated with PUFAs as instrumental variables. The causal associations between PUFAs and acne were estimated among 115 006 UK Biobank participants and 363 927 participants of Finnish descent.

RESULTS

Genetically predicted docosahexaenoic acid (DHA) levels [β = -0.303, 95% confidence interval (CI) -0.480 to -0.126; P = 7.74 × 10-4] and its percentage to total fatty acids (β = -0.402, 95% CI -0.651 to -0.258; P = 5.91 × 10-6) showed a significant causal association with a decreased risk of acne. Conversely, genetically predicted percentages of linoleic acid (LA) in total fatty acids (β = 0.768, 95% CI 0.411-0.126; P = 2.87 × 10-4) and omega-6 : omega-3 ratio (β = 0.373, 95% CI 0.142-0.604; P = 4.48 × 10-3) were robustly associated with an increased risk of acne. These effects were attenuated after excluding a genetic variant of rs174528 located upstream of FADS1, highlighting the biologic link between FADS1 and delta-5 desaturase activity. Multivariable MR analysis indicated that PUFAs were causally associated with acne, independent of body mass index.

CONCLUSIONS

Our study indicates that high DHA levels and their ratios to total fatty acids have causal protective effects against acne, while high LA levels and omega-6 : omega-3 ratio are associated with increased acne risk. This association was largely attributable to the influence of genetic variants related to FADS1.

Causal Relationship Between Blood Metabolites and Prostate Cancer Risk: A Two-Sample Mendelian Randomization Study

Recent research has increasingly suggested an association between changes in specific blood metabolites and prostate cancer (PCa) development. However, it remains unclear whether these observed associations represent a causal relationship. To reveal the potential causal associations between blood metabolites and PCa risk, we conducted a comprehensive two-sample Mendelian randomization (MR) analysis. We used genetic instruments for 514 and 490 metabolites from two independent comprehensive genome-wide association studies. These studies included 14,295 individuals of European ancestry from the INTERVAL/EPIC-Norfolk cohorts and 8299 individuals of European ancestry from the Canadian Longitudinal Study on Aging cohort. Summary statistics of PCa risk involving 122,188 cases and 604,640 controls of European ancestry individuals were analyzed. The associations between metabolites and PCa risk were evaluated using the inverse-variance weighted method, supplemented by sensitivity analyses including MR-Egger and MR-PRESSO tests. Additionally, we conducted a phenome-wide MR analysis to assess the potential side effects of targeting the identified metabolites for PCa intervention. Our analysis revealed 107 unique blood metabolites significantly associated with PCa risk, with 43 of these associations consistently replicated using instruments from two independent data sets. This study provides novel insights into the potential role of specific metabolites in the etiology of PCa, which warrants further investigations.

Causal relationship between metabolic dysfunction-associated fatty liver disease and endotoxin biomarkers: A Mendelian randomization study

Although the relationship among lipopolysaccharides (LPS), LPS-binding proteins, and metabolic dysfunction-associated fatty liver disease (MAFLD) is widely studied, no conclusive evidence is available. In this study, we used mendelian randomization (MR) to study the causal relationship of LPS, LPS-binding proteins, and MAFLD. Using bidirectional two-sample MR method, we evaluated data from the genome wide association study; for this analysis, nonalcoholic fatty liver disease (NAFLD), liver fat percentage, and other metabolic syndromes were employed as outcomes. Furthermore, MR analysis mainly involved the inverse variance weighted method. Heterogeneity and pleiotropy tests were also conducted. LPS was found to have a causal relationship with NAFLD, obesity, high density lipoprotein cholesterol, and TG levels. Furthermore, TG levels and LBP had significant causal relationships. This study mainly concluded that LPS is a risk factor for NAFLD, obesity, high density lipoprotein cholesterol, and TG, corroborating it's the LPS role in MAFLD pathogenesis. Hence, optimizing the gut microbiota using proper diet, probiotics, or fecal microbiota transplantation may help to reduce inflammation and (IR), thereby improving lipid and glucose metabolism disorders. Although a causal relationship between TG and LBP was observed, further studies are required to determine a specific mechanism.

The mediating role of key amino acid and vitamin metabolite ratios in the effects of 5 dietary habits on psoriatic arthritis: A Mendelian randomization study

The causal relationship between dietary habits and psoriatic arthritis (PsA) remains unclear, and the mediating role of human plasma metabolites in this relationship is unexamined. This study aims to elucidate the causal relationship between 80 dietary patterns and PsA using a 2-sample Mendelian randomization (MR) analysis. A 2-step MR approach was employed to investigate whether 1400 human plasma metabolites could serve as potential mediators between dietary habits and PsA. To ensure the reliability of the results, heterogeneity and pleiotropy tests were conducted. Our MR analysis identified 5 dietary factors exhibiting significant inverse causal associations with PsA risk (P < .05): red wine intake (odds ratio (OR) = 0.62), total alcohol intake (OR = 0.59), cheese intake (OR = 0.56), monthly alcohol drinks (OR = 0.66), and decaffeinated coffee preference (OR = 0.62). Mediation analysis revealed distinct metabolite pathways underlying these associations. Red wine intake-PsA relationship: Gamma/beta-tocopherol levels mediated 17.8% of the protective effect, followed by citrate (7.2% mediation). Cheese intake-PsA association: Arginine levels accounted for 7.4% of the effect, with phosphate-to-threonine ratio mediating an additional 7.2%. Decaffeinated coffee preference-PsA link: Three amino acid ratios demonstrated significant mediation-glutamate/alanine (12.2%), ornithine/glutamate (10.9%), and arginine/glutamate (8.9%). These results underscore the potential role of plasma metabolites as mediators in the causal relationship between these 5 dietary habits and PsA.

Using eQTL Mendelian randomization and transcriptomic analysis to identify the relationship between ion channel genes and intracranial aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a complex condition associated with high disability and mortality rates, leading to poor clinical outcomes. Previous observational studies have suggested a link between ion channel genes and aSAH, but the causal relationship remains uncertain. This study utilized Mendelian randomization (MR) to explore the causal association between ion channel genes and aSAH, employing 5 MR methods: inverse variance weighted (IVW), MR-Egger, maximum likelihood, weighted median, and weighted mode. If results from these methods are inconclusive, IVW will be prioritized as the primary outcome. Additionally, MR-Egger, MR-PRESSO, and Cochrane Q tests were conducted to assess heterogeneity and pleiotropy. The stability of MR findings was evaluated using the leave-one-out approach; Bonferroni correction tested the strength of the causal relationship between exposure and outcome. The MR analysis revealed that CACNA2D3 was positively correlated with aSAH (OR 1.245; 95% confidence intervals [CI] 1.008-1.537; P = .042), while ANO6 showed a negative correlation (OR 0.728; 95% CI 0.533-0.993; P = .045). Our findings indicate that increased expression of CACNA2D3 promotes aSAH whereas elevated levels of ANO6 inhibit it. Transcriptome data from intracranial aneurysm samples confirmed significant differential expression of CACNA2D3 and ANO6 between ruptured and unruptured groups. CACNA2D3 being higher in ruptured cases while ANO6 was more expressed in unruptured ones. Furthermore, GeneMANIA analysis along with functional enrichment provided insights into risk factors for aSAH. Through MR analysis, we established a causal link between ion channel genes and aSAH, which helps to better understand the pathogenesis of aSAH and provide new therapeutic targets.

Post-traumatic stress disorder, attention deficit and hyperactivity disorder, and 24 gastrointestinal diseases: Evidence from Mendelian randomization analysis

Post-traumatic stress disorder (PTSD) and Attention deficit and hyperactivity disorder (ADHD) are common mental illnesses. Observational studies have indicated that these conditions often co-occur with gastrointestinal diseases. However, the causal relationship between PTSD and ADHD with gastrointestinal diseases remain unclear. We conducted Mendelian randomization (MR) analysis to investigate these associations. We selected genetic instrument data with genome-wide significance levels for PTSD and ADHD from the psychiatric genomics consortium open genome-wide association study platform. Summary statistics for the 24 gastrointestinal diseases were obtained from the FinnGen study. We used the "TwoSampleMR" package in R to perform a 2-sample MR analysis and conducted sensitivity analysis of the results. We found that genetic susceptibility to PTSD was associated with 1 gastrointestinal disease, specifically pancreatic cancer (P = .003; odds ratios [OR] = 1.295; 95% CI, 1.094-1.531). Genetic susceptibility to ADHD was associated with 4 gastrointestinal diseases: gastroesophageal reflux (P = .014; OR = 1.100; 95% CI, 1.020-1.186), gastric ulcer (P = .004; OR = 1.208; 95% CI, 1.061-1.376), duodenal ulcer (P = .020; OR = 1.206; 95% CI, 1.029-1.413), and chronic gastritis (P = .021; OR = 1.122; 95% CI, 1.018-1.237). This study provides MR evidence supporting causal relationship between PTSD and ADHD with specific gastrointestinal diseases.

Genetic association between coffee consumption and multiple myeloma mediated by plasma metabolites: a Mendelian randomization study

Background: Multiple myeloma (MM) is a hematologic malignancy closely associated with diets and metabolic disorders, showing an increasing incidence trend. Genome-wide association studies (GWAS) contribute to exploring the causal relationships between diets, metabolites, and MM, thereby revealing biological mechanisms underlying cancer progression. Methods: This study included large-scale GWAS data for two diets, four metabolomics, and MM. The two-sample Mendelian randomization (MR) analysis was conducted to assess causalities between these dietary patterns, metabolites, and MM. The MR analysis primarily employed the inverse variance weighted (IVW) method, supported by multiple sensitivity analysis and reverse MR analysis to validate significant associations. Mediation analysis identified specific metabolites mediating the causal relationships between diets and MM. Results: Univariate MR analysis suggested that coffee consumption (ORIVW = 2.72; 95% CI: 1.21-6.10; PIVW = 0.015, P_fdr = 0.022), decaffeinated coffee consumption (ORIVW = 7.10; 95% CI: 1.33-37.87; PIVW = 0.022, P_fdr = 0.022), ground coffee consumption (ORIVW = 4.04; 95% CI: 1.25-13.02; PIVW = 0.019, P_fdr = 0.022), instant coffee consumption (ORIVW = 6.13; 95% CI: 1.95-19.34; PIVW = 0.002, P_fdr = 0.008), and coffee max liking (ORIVW = 2.94; 95% CI: 1.23-7.03; PIVW = 0.015, P_fdr = 0.035) were associated with increased MM risk. Metabolomic MR analysis identified 19 plasma metabolites, 1 blood and urine biomarker, and 4 plasma lipids with significant association with MM. Mediation analysis indicated that hippurate and cinnamoylglycine mediated 35.55% (P < 0.001) and 21.85% (P = 0.002) of the genetically predicted effect of coffee consumption on MM risk, respectively. Cinnamoylglycine contributed 12.63% (P = 0.042) to the total causal effect of ground coffee consumption on MM. Hippurate (21.43%, P < 0.001), 3-hydroxyhippurate (4.39%, P = 0.031), and cinnamoylglycine (8.79%, P = 0.010) mediated the genetically predicted impact of instant coffee consumption on MM risk. Metabolic pathway analysis suggested that glutathione metabolism significantly contributes to MM pathogenesis (P = 0.002, FDR < 0.05). Conclusions: Our findings support the adverse causal effects of various coffee consumption on MM risk, identifying hippurate, 3-hydroxyhippurate, and cinnamoylglycine as key mediators, driving the relationship potentially through the glutathione metabolism pathway.

An investigation of causality between obstructive sleep apnea and interstitial lung disease: Insights from two-sample mendelian randomization

BACKGROUND

Previous observational studies have suggested a potential link between obstructive sleep apnea (OSA) and interstitial lung disease (ILD), however, the casual relationship between OSA and ILD remains uncertain.

OBJECTIVE

This study aims to rigorously assess the potential causal relationship between OSA and ILD.

METHODS

The study utilized genome-wide association studies (GWAS) data on OSA and ILD. Univariable and multivariable Mendelian randomization (MR) were employed to explore the causal relationship. Multiple MR methods such as MR Egger, weighted median, inverse variance weighting (IVW), and weighted mode were used.

RESULTS

Univariate MR analyses using IVW analysis indicates a potential association between ILD and an increased risk of OSA (Odds ratio (OR) = 1.071, 95 % CI: 1.018 to 1.126, P = 0.007). However, no compelling evidence supports a reverse causal relationship in the findings above. A thorough analysis further validates the reliability of the present study. Following adjustment for the effects of smoking and BMI in multivariate MR analyses, ILD still has a positive independently association with OSA risk (OR = 1.117, 95 % CI: 1.018 to 1.225, P = 0.020).

CONCLUSIONS

Our study identifies ILD as a causal risk factor for OSA, providing the evidence for the prevention and treatment of the disease.

No association between anti-cytomegalovirus seropositivity and arthritis: evidence from the cross-sectional epidemiology and genetic association analyses

Human cytomegalovirus (CMV), a β-herpesvirus associated with chronic inflammation and lifelong latency, has been implicated in the pathogenesis of arthritis. However, the nature of this relationship remains controversial. In this study, we integrate cross-sectional epidemiology analyses, genetic correlation assessments, and Mendelian randomization (MR) approaches to elucidate the potential association between CMV infection and arthritis-related conditions. Observational analysis of 5133 participants from the NHANES database revealed a positive association between CMV IgG seropositivity and arthritis (OR: 1.24; 95 % CI: 1.03-1.48; P = 0.02), particularly with the rheumatoid arthritis (RA) subtype (OR: 1.94; 95 % CI: 1.21-3.12; P < 0.01). However, these associations lost statistical significance after adjustment for multiple covariates (all P > 0.05). Subgroup and interaction analyses across different demographic and clinical subpopulations further confirmed the absence of these associations. Similarly, subtype analyses indicated no significant association between CMV IgG seropositivity and osteoarthritis (OA), other-arthritis, or unknown-arthritis, even before covariate adjustment. Linkage disequilibrium score regression (LDSC) analysis did not reveal a significant genetic correlation between anti-CMV IgG levels and arthritis, including RA and OA (all P > 0.05), suggesting no shared genetic basis. Furthermore, bidirectional MR analyses found no evidence of a causal relationship between CMV antibody responses-including IgG and three CMV-related peptide antigens (pp28, pp52, and pp150)-and arthritis, RA, or OA (all P > 0.05). Collectively, these findings suggest that previously reported positive associations between CMV seropositivity and arthritis may have been confounded by other covariates rather than reflecting a true causal relationship.

Association between circulating inflammatory proteins and gout: A Mendelian randomization study

Clinical studies have consistently demonstrated that inflammation is a critical factor in the pathophysiology and progression of gout. This study aims to explore the causal relationship between CIPs and gout, utilizing MR in conjunction with meta-analyses. We utilized genetic data pertaining to gout from the GWAS which involved 3576 cases and 147,221 control participants. A total of 132 CIPs were extracted from the GWAS data to identify SNPs associated with gout. The primary analytical approach was the IVW method. Sensitivity analyses indicated no pleiotropy or heterogeneity. The IVW results revealed that several CIPs were associated with gout in European populations. The analysis results indicate that FGF-21, MMP-1, G-CSF, and IFN-γ are involved in the pathogenesis of gout, and gout may influence the expression of CXCL1, IL-1Ra, and TNF-α. Consequently, targeted research focusing on specific CIPs could provide a promising strategy for the treatment and prevention of gout, offering potential therapeutic targets for the underlying inflammatory mechanisms of the disease.

Involvement of disulfidptosis in the pathophysiology of autism spectrum disorder

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder, with oxidative stress recognized as a key pathogenic mechanisms. Oxidative stress disrupts intracellular dynamic- thiol/disulfide homeostasis (DTDH), potentially leading to disulfidptosis, a newly identified cell death mechanism. While studies suggest a link between DTDH and ASD, direct evidence implicating disulfidptosis in ASD pathogenesis remains limited. In this study, Mendelian randomization analysis revealed a significant causal association between disulfidptosis-related sulfhydryl oxidase 1 and 2 and ASD (OR1 = 0.883, OR2 = 0.924, p < 0.05). A positive correlation between protein disulfide-isomerase and cognitive performance (OR = 1.021, p < 0.01) further supported the role of disulfidptosis in ASD. Seven disulfidptosis-related genes (TIMP1, STAT3, VWA1, ADA, IL5, PF4, and TXNDC12) were identified and linked to immune cell alterations. A TF-miRNA-mRNA regulatory network and a predictive model (AUC = 0.759) were constructed and external validation datasets (AUC = 0.811). Immune infiltration analysis demonstrated altered expression of naive B cells and three other types of immune cells in ASD children. Animal experiments further validated the differential expression of key genes, highlighting their relevance to ASD pathogenesis. Animal experiments found that BTBR mice exhibit glucose starvation and NADPH depletion, with the specific indicator Slc7a11 being highly expressed. Silencing Slc7a11 can improve core ASD impairments in BTBR mice. CONCLUSION: This study establishes the first mechanistic link between disulfidptosis and ASD, identifies seven key genes and their regulatory network, and develops a predictive model with clinical utility. Animal experiments further confirmed the strong association between disulfidpotosis and ASD phenotypes. These findings offer novel therapeutic targets for modulating oxidative stress in ASD.

Magnesium is a key trace element in obstructive sleep apnea: evidence from Mendelian randomization analysis and NHANES database

BACKGROUND

Obstructive sleep apnea (OSA) is a prevalent disorder posing significant health hazards. Studies have suggested an association between trace elements and OSA; however, the causal relationship of this association remains unclear.

METHODS

This study investigated the potential causal relationship between magnesium and OSA, with magnesium status evaluated through magnesium-related single nucleotide polymorphisms (SNPs) and magnesium depletion score (MDS). Mendelian Randomization (MR) and the National Health and Nutrition Examination Survey (NHANES) were used to mitigate confounders and ensure a more robust assessment.

RESULTS

MR analysis indicated a significant protective effect of magnesium against OSA (odds ratio [OR]<1, P < 0.05). A reverse MR analysis of OSA on magnesium did not show significant causal effects (P > 0.05). NHANES analysis further demonstrated a strong positive correlation between MDS and OSA, with participants scoring above 1 exhibiting a 64 % increased likelihood of developing OSA (OR = 1.64, 95 % confidence interval [CI]: 1.32-2.05, P < 0.001). Adjusted multivariable logistic regression models confirmed the robustness of this association (Model II: OR = 1.36, 95 % CI: 1.08-1.72, P = 0.018; Model III: OR = 1.30, 95 % CI: 1.03-1.63, P = 0.045). Subgroup and interaction analysis revealed no statistically significant interactions (P > 0.05).

CONCLUSION

We confirmed the causal relationship between magnesium and OSA, underscoring magnesium's role in OSA pathogenesis and suggesting that MDS may serve as a promising biomarker for identifying high-risk populations. Further studies on the biological mechanisms linking magnesium deficiency to OSA may contribute to its treatment.

Evaluating the Causal Role of Genetically Inferred Immune Cells and Inflammatory Cytokines on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Background/Objectives: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a multifaceted and diverse disorder with an ambiguous etiology. Recent evidence indicates that immune system impairment and inflammatory mechanisms are pivotal to the initiation and advancement of ME/CFS. Nonetheless, the causal relationships among these factors remain inadequately comprehended. Methods: This study investigated the causative contributions of immunological dysfunction and inflammatory variables in ME/CFS utilizing genome-wide association study (GWAS) data. We employed Mendelian randomization (MR) to investigate associations between 91 inflammatory cytokines, 731 immune cell characteristics, and the risk of ME/CFS. Summary statistics for immune cell traits and inflammatory cytokines were sourced from European GWAS cohorts (n = 3757 and n = 14,824, respectively), while ME/CFS data were obtained from the UK Biobank (n = 462,933, including 2076 cases). We predominantly employed the inverse variance weighted (IVW) approach, complemented by MR-Egger, weighted median, BWMR, and MR-RAPS tests to guarantee robust and precise outcomes. Results: The study revealed significant causal links between various inflammatory factors, immune cell characteristics, and the risk of ME/CFS. Increased CXCL5 and CCL20 levels were significantly linked to a higher risk of ME/CFS, while elevated TNF levels were inversely related to ME/CFS risk. Furthermore, 13 immune cell characteristics were identified as having substantial causal associations with the likelihood of ME/CFS. These data are supportive of the causality that immune system dysfunction and inflammatory variables play a pivotal role in the development of ME/CFS. Conclusions: This study provides new insights into the causal role of immune system dysfunction in the development of ME/CFS, contributing to a deeper understanding of its underlying mechanisms. These results offer a foundation for identifying diagnostic biomarkers and developing targeted therapeutic strategies. Future research should validate these findings using multi-center cohort studies and further investigate the mechanisms behind key factors to enable the development of personalized treatment approaches.

Causal relationship between circulating inflammatory proteins and atherosclerosis: a bidirectional Mendelian randomization study and meta-analysis

BACKGROUND

Atherosclerosis (AS) is a chronic inflammatory disease that significantly contributes to cardiovascular morbidity and mortality. Despite extensive research efforts, the connections between circulating inflammatory proteins (CIPs) and different subtypes of AS remain poorly understood. This study aims to clarify these relationships through Mendelian randomization (MR) analysis.

METHODS

We utilized summary statistics from genome-wide association studies (GWAS) that included 14,824 European participants to analyze inflammatory protein levels, alongside data from the IEU GWAS database for AS phenotypes. Our primary approach for MR analysis was the inverse variance weighted method. To ensure the validity and robustness of the causal relationships, we conducted tests for pleiotropy and heterogeneity, as well as reverse MR analysis to assess the possibility of reverse causality. Finally, we performed a meta-analysis to consolidate and interpret our findings comprehensively.

RESULTS

Our MR analysis identified several significant associations: elevated artemin [odds ratio (OR) = 1.195], glial cell line-derived neurotrophic factor (hGDNF) (OR = 1.173), and tumor necrosis factor (TNF) (OR = 1.179) levels increased peripheral atherosclerosis (PA) risk; higher CUB domain-containing protein 1 (OR = 0.534), interleukin (IL)-8 (OR = 0.274), monocyte chemoattractant protein-3 (OR = 0.373), transforming growth factor-alpha (OR = 0.306), and tumor necrosis factor receptor superfamily member 9 (OR = 0.423) levels decreased cerebral artery atherosclerosis risk; fibroblast growth factor 21 (FGF-21) (OR = 1.122), hGDNF (OR = 1.108), and IL-22 receptor subunit alpha-1 (IL-22RA1) (OR = 1.235) levels were positively associated with coronary artery atherosclerosis (COA) risk; while IL-13 (OR = 0.909) and TNF-beta levels (OR = 0.954) were negatively associated with COA risk. C-X-C motif chemokine 6 levels (CXCL6) (OR = 1.353) and hGDNF (OR = 1.161) were identified as risk factors for atherosclerosis, excluding cerebral, coronary, and peripheral arterial disease (AECCP). In contrast, IL-2 receptor subunit beta levels (OR = 0.801) and IL-6 levels (OR = 0.788) were found to be protective factors for AECCP. Additionally, CXCL6 (OR = 1.261), FGF-21 (OR = 1.090), IL-22RA1 (OR = 1.127), and hGDNF (OR = 1.134) exhibited a risk effect against overall AS risk, while IL-6 (OR = 0.834) exhibited a protective effect against overall AS risk.

CONCLUSIONS

This study identifies specific CIPs that have significant causal effects on various forms of AS through MR analysis. The findings suggest potential biomarkers and treatment targets for preventing and managing different manifestations of AS in clinical practice.

Dissecting immune-mediated pathways in rheumatoid arthritis: A multivariate mediation analysis of antibodies and circulating proteins

Rheumatoid arthritis (RA) is a chronic inflammatory disorder with complex etiologies involving immune responses and circulating proteins. This study investigates the causal relationships between antibody immune responses, plasma circulating proteins, and the development of RA using Mendelian Randomization (MR) analysis; A two-sample and multivariate MR analysis was conducted to explore the mediating causal relationship between 46 antibody immune responses and RA through 4,907 plasma circulating proteins. Genetic variations were utilized as instrumental variables (IVs) to infer causality, ensuring that they met the assumptions of relevance, independence, and exclusion restriction. Data were sourced from the FinnGen R10 dataset, UK Biobank, and the SomaScan platform, providing a robust foundation for the analysis. Statistical methods including IVW, weighted median, and mode-based approaches were employed, complemented by sensitivity analyses to ensure the robustness of the findings; The study identified significant causal relationships between six antibody immune responses and RA, with three specific responses-Epstein-Barr virus EBNA-1, Epstein-Barr virus ZEBRA, and Anti-polyomavirus 2 IgG seropositivity-showing strong associations. However, reverse causality was detected for EBNA-1 and ZEBRA, leading to their exclusion from further analysis. Additionally, 12 plasma circulating proteins were found to have significant causal relationships with RA, with KCNIP3 emerging as a key protective factor. Multivariate MR analysis revealed that KCNIP3 mediates the relationship between Anti-polyomavirus 2 IgG seropositivity and RA, suggesting a potential protective mechanism. This study highlights the intricate relationships between specific antibody responses, circulating proteins, and RA risk. The findings suggest that certain proteins, particularly KCNIP3, may mediate the effects of immune responses on RA development, offering potential targets for therapeutic intervention.

Causal relationship between immunophenotypes and rheumatoid arthritis: A 2-sample Mendelian randomization study

As previous studies have demonstrated an association between immune inflammation and rheumatoid arthritis (RA), our study aimed to lend novel insight by exploring the potential causal association between RA and different immunophenotypes. Data were obtained from the genome-wide association study (GWAS) from Finn Gen. The dataset of GWAS contains a cohort of 6236 RA cases and 147,221 controls in European population. Data on immune cell traits are publicly available from the GWAS catalog. A total of 731 immunophenotypes were included in this study including absolute cell counts (ACs), median fluorescence intensity, morphological parameters, and relative cell counts. Mendelian randomization analysis was performed by several methods, and sensitivity analysis and visualization of the results were also carried out. After being adjusted by false discovery rate (FDR), 6 immune phenotypes were significantly and causally associated with the development of RA: CD16 on CD14+ CD16+ monocytes (adjusted odds ratio [OR]: 0.950, 95% confidence interval [CI]: 0.924-0.977, P = 4.04 × 10-4), CD62L-CD86+ myeloid DC %DC (adjusted OR: 1.048, 95% CI: 1.021-1.076, P = 4.29 × 10-4), CD62L-CD86+ myeloid DC AC (adjusted OR: 1.050, 95% CI: 1.024-1.076, P = 1.11 × 10-4), CD62L- myeloid DC AC (adjusted OR: 1.067, 95% CI: 1.033-1.101, P = 8.35 × 10-5), DC AC (adjusted OR: 1.105, 95% CI: 1.062-1.149, P = 7.73 × 10-7), myeloid DC AC (adjusted OR: 1.060, 95% CI: 1.029-1.091, P = 9.96 × 10-5). In addition, we found that CD62L- Dendritic cell % increases with the onset of RA (OR: 1.136, 95% CI: 1.064-1.213, P = 1.36 × 10-4, PFDR = 0.099). This study explored the association between different immunophenotypes and RA, which may lend some novel insights into RA pathogenesis and facilitate the development of new treatments.

Insights from bidirectional Mendelian randomization: Evaluating the influence of circulating inflammatory cytokines on prostatitis

Research on prostatitis has primarily focused on inflammatory cytokines in semen or prostatic secretions, with relatively few studies investigating circulating inflammatory cytokines. To explore the relationship between prostatitis and circulating inflammatory cytokines, this study employed bidirectional two-sample Mendelian randomization (MR) to assess the potential associations between prostatitis and 91 circulating inflammatory cytokines. We performed bidirectional MR to explore causal links between 91 circulating inflammatory cytokines and prostatitis. Data were sourced from 14,824 individuals of European ancestry and the Finngen database for prostatitis. The inverse variance-weighted (IVW) method was the primary tool, complemented by MR-Egger, weighted median, weighted mode, and MR-PRESSO to enhance result robustness. Heterogeneity and pleiotropy evaluations were conducted, and GO/KEGG enrichment analyses were used to explore the biological pathways linked to these inflammatory factors and prostatitis. The MR results revealed that Interleukin-10 receptor A (IL-10RA), Natural Killer Cell Receptor 2B4 (CD244), and urokinase-type plasminogen activator (uPA) were identified as risk factors for prostatitis (IVWIL-10RA: OR = 1.242, 95% CI: 1.043-1.478, P = .015; IVWCD244: OR = 1.143, 95% CI: 1.002-1.305, P = .047; IVWuPA: OR = 1.141, 95% CI: 1.009-1.290, P = .035). Conversely, Interleukin-12B (IL-12B) exhibited a protective effect against prostatitis (IVWIL-12B: OR = 0.909, 95% CI: 0.842-0.981, P = .014). Moreover, reverse MR analysis results indicate that prostatitis decreases plasma levels of chemokine (C-C motif) ligand 23 (CCL23), IL-5, and TNF-related activation-induced cytokine (TRANCE) (IVWCCL23: OR = 0.949, 95% CI: 0.906-0.993, P = .025; IVWIL-5: OR = 0.938, 95% CI: 0.890-0.988, P = .016; IVWTRANCE: OR = 0.947, 95% CI: 0.905-0.992, P = .021). This bidirectional MR study identified potential causal links between 7 circulating inflammatory cytokines and prostatitis, offering insights into its pathogenesis and potential targets for future therapies.

The relationship between cathepsins and nasopharyngeal carcinoma: a Mendelian randomization analysis

BACKGROUND

Observational studies have shown the potential for cathepsins (CTS) to have an effect on nasopharyngeal carcinoma (NPC), but their conclusions are susceptible to confounding factors.

METHODS

To investigate the causal relationship between CTS and NPC, Mendelian randomization (MR) was conducted. Genetic data for nine CTS (CTS B, E, F, G, H, L2, O, S and Z) was obtained from a genome-wide association study. As the data on outcome, genetic data of NPC was utilized from a FinnGen study. MR was performed using five analytical methods including Inverse Variance-Weighted (IVW) method, MR-Egger test, Weighted Median test, Simple Mode test and Weighted Mode test, with the IVW as the main analysis method. Cochran's Q test, MR-PRESSO global test and "leave-one-out" sensitivity test were used in sensitivity analysis. Reverse MR was performed to investigate whether there is reverse causality between NPC and CTS. MR Steiger test was used to determine the direction of the interaction between CTS and NPC.

RESULTS

Overall, the authors found favorable evidence to support the association between Cathepsin F (CTSF) and NPC. CTSF was associated to increase the risk of NPC (odds ratio [OR] = 1.845, 95% confidence intervals [CI] = 1.086 ~ 3.136, P = 0.024) according to IVW. The results proved to be stable and robust in the sensitivity analysis. In the Steiger test, the causal effect of CTS on NPC was shown to be unidirectional.

CONCLUSIONS

These findings suggest that CTSF may plays an important role in NPC thus providing new research ideas for future basic research endeavors and clinical applications.

Identifying blood mitochondrial DNA copy number as a biomarker for development of neurodegenerative diseases: Evidence from Mendelian randomization analysis

Mitochondrial dysfunction has been associated with neurodegenerative diseases (NDDs). This study aimed to explore the association between blood mitochondrial DNA copy number (mtDNA-CN) and development of NDDs. This study was based on two-sample Mendelian randomization (MR) analysis. The genome wide association study (GWAS) data of NDDs including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), age-related macular degeneration (AMD), multiple sclerosis (MS), Parkinson's disease (PD), primary open-angle glaucoma (POAG), and vascular dementia (VD) was obtained from FinnGen consortium. Inverse-variance weighted (IVW) was applied as the primary approach for MR estimation. MR results revealed that blood mtDNA-CN exhibited a significant relationship with the incidence of AD (IVW-P = 0.011, odds ratio [OR] = 0.65) and AMD (IVW-P = 0.038, OR = 0.64). However, there was no significant association observed between blood mtDNA-CN and other NDDs (IVW-P > 0.05). Our findings supported the relationship between mitochondrial dysfunction and development of AD and AMD, and that blood mtDNA-CN may serve as a potential biomarker for the incidence of these two NDDs.

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.

Unveiling new insights into migraine risk stratification using machine learning models of adjustable risk factors

BACKGROUND

Migraine ranks as the second-leading cause of global neurological disability, affecting approximately 1.1 billion individuals worldwide with severe quality-of-life impairments. Although adjustable risk factors-including environmental exposures, sleep disturbances, and dietary patterns-are increasingly implicated in pathogenesis of migraine, their causal roles remain insufficiently characterized, and the integration of multimodal evidence lags behind epidemiological needs.

METHODS

We developed a three-step analytical framework combining causal inference, predictive modeling, and burden projection to systematically evaluate modifiable factors associated with migraine. First, two-sample mendelian randomization (MR) assessed causality between five domains (metabolic profiles, body composition, cardiovascular markers, behavioral traits, and psychological states) and the risk of migraine. Second, we trained ensemble machine learning (ML) algorithms that incorporated these factors, with Shapley Additive exPlanations (SHAP) value analysis quantifying predictor importance. Finally, spatiotemporal burden mapping synthesized global incidence, prevalence, and disability-adjusted life years (DALYs) data to project region-specific risk and burden trajectories through 2050.

RESULTS

MR analyses identified significant causal associations between multiple adjustable factors (including overweight, obesity class 2, type 2 diabetes [T2DM], hip circumference [HC], body mass index [BMI], myocardial infarction, and feeling miserable) and the risk of migraine (P < 0.05, FDR-q < 0.05). The Random Forest (RF)-based model achieved excellent discrimination (Area under receiver operating characteristic curve [AUROC] = 0.927), identifying gender, age, HC, waist circumference [WC], BMI, and systolic blood pressure [SBP] as the predictors. Burden mapping projected a global decline in migraine incidence by 2050, yet persistently high prevalence and DALYs burdens underscored the urgency of timely interventions to maximize health gains.

CONCLUSIONS

Integrating causal inference, predictive modeling, and burden projection, this study establishes hierarchical evidence for adjustable migraine determinants and translates findings into scalable prevention frameworks. These findings bridge the gap between biological mechanisms, clinical practice, and public health policy, providing a tripartite framework that harmonizes causal inference, individualized risk prediction, and global burden mapping for migraine prevention.