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Results for “Mendelian Randomization Analysis”

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PubMed2026

Mapping the immune-genetic architecture of Epstein-Barr virus-related phenotypes and multiple sclerosis through a single-cell genetic framework for target prioritization and pharmacologic hypothesis generation.

BACKGROUND: Multiple sclerosis (MS) is a severe neuroinflammatory disease causing substantial long-term disability. Strong epidemiologic evidence links Epstein-Barr virus (EBV) exposure with MS risk, but genetic evidence for immune target prioritization in EBV-related phenotypes remains limited. METHODS: We integrated single-cell cis-eQTL data from 14 immune cell types with GWASs of an EBV-related clinical phenotype and MS using a single-cell Mendelian randomization framework with colocalization analyses. Candidate eGenes were evaluated in independent cohorts. For multi-SNP instruments, we performed heterogeneity, pleiotropy, MR-Egger, weighted median, mode-based, and MR-PRESSO sensitivity analyses. We also conducted phenome-wide association analyses and queried DrugBank to annotate candidate compounds targeting prioritized genes. RESULTS: We prioritized 43 immune-cell-specific candidate eGenes with convergent genetic support, including 6 for the EBV-related phenotype and 37 for MS. SERPINB1 in NK cells was associated with increased risk of the EBV-related phenotype, whereas HLA-G was associated with decreased risk. For MS, APOM and MSH5 showed protective associations, while AHI1 showed cell-type-dependent, bidirectional associations across immune lineages. Colocalization and independent cohort evaluation supported these findings. Among FDR-significant multi-SNP associations, MR-Egger intercept tests did not indicate directional pleiotropy, although a small subset showed heterogeneity or MR-PRESSO signals. Phenome-wide analyses identified no significant adverse phenotypic associations among evaluable genes at the prespecified threshold. DrugBank annotation nominated sodium nitroprusside, fasudil, artenimol, and choline as hypothesis-generating compounds for experimental follow-up. CONCLUSIONS: This study provides a single-cell genetic framework for prioritizing immune-cell-specific candidate targets for EBV-related phenotypes and MS, and nominates genetically supported targets and pharmacologic hypotheses for experimental investigation.

Humans↗

PubMed2026

Mitochondrial Function-Related Genes in Sleep Disorders: A Multi-Omics Mendelian Randomization Study.

Mitochondrial dysfunction is linked to sleep disorders in previous report, but the potential roles of specific genes remain unclear. This study aimed to dissect different subtype-specific genetic associations and their underlying mechanisms. A multi-omics Summary-data-based Mendelian Randomization (SMR) approach was performed to identify potential causal links between mitochondrial function-related genes and sleep disorders. We integrated GWAS data from FinnGen database (the discovery set), independent GWAS datasets (covering different sleep-disorder subtypes and used for validation), and cis-QTLs (including mQTLs, eQTLs, and pQTLs) to perform systematic exploration. Specially, we performed targeted validation of tissue-specific effects, leveraging gene expression data from disease-relevant brain regions within the GTEx database. Our SMR analysis identified mitochondrial function-related genes potentially modulating sleep disorders across biological layers, initially identifying 102 genes at the methylation level, 48 at the gene expression level, and 6 at the protein abundance level. Integrative analysis subsequently prioritized DCXR and ACADVL and revealed their distinct, subtype-specific associations. DCXR exhibited a protective role in sleep apnea while ACADVL showed a paradoxical risk conferring role in daytime sleepiness. In addition, the analysis identified an epigenetic regulatory mechanism for DCXR in which its expression and protein levels are modulated by DNA methylation. Finally, validation in brain-hypothalamus tissue confirmed DCXR as a significant potential protective factor (OR = 0.929, 95% CI: 0.887-0.973, P_HEIDI = 0.999, FDR = 0.2449). Our findings implicate key mitochondrial genes, particularly DCXR and ACADVL, in the pathophysiology of specific sleep disorder subtypes, highlighting potential avenues for precision medicine. Clinical trial number: Not applicable.

Humans↗

PubMed2025

Causal relationship between frailty and diabetes subtypes: A bidirectional Mendelian randomization study.

Frailty and diabetes mellitus (DM) are closely linked, but their causal relationship remains unclear. This study aims to determine the bidirectional causal relationship between frailty and different DM subtypes using Mendelian randomization (MR). We performed a 2-sample MR analysis using summary statistics from large-scale genome-wide association studies. The inverse-variance weighting method was the primary analytical approach, with MR-Egger regression and weighted median methods for sensitivity analysis. Horizontal pleiotropy and heterogeneity were assessed using MR-PRESSO and Cochran Q test. Genetically predicted frailty was significantly associated with an increased risk of type 2 diabetes (T2DM) and gestational diabetes (GDM) (odds ratio [OR] = 2.142, 95% confidence interval [CI]: 1.751-2.621, P < .001; OR = 2.280, 95% CI: 1.368-3.800, P = .002), but no causal relationship was observed for type 1 diabetes or glycemic traits (P > .05). Conversely, genetically predicted type 1 diabetes, T2DM, GDM, and postprandial glucose levels (2-hour post-load glucose) increased the risk of frailty (OR = 1.026, 95% CI: 1.014-1.038, P < .001; OR = 1.046, 95% CI: 1.033-1.058, P < .001; OR = 1.068, 95% CI: 1.040-1.096, P < .001; OR = 1.095, 95% CI: 1.049-1.144, P < .001). Sensitivity analyses confirmed the robustness of these findings. This study provides genetic evidence supporting a bidirectional causal relationship between frailty and diabetes, particularly T2DM and GDM. These findings highlight the need for early frailty screening in diabetic patients and better metabolic management in frail populations.

Humans↗

PubMed2026

Causal Relationships Between Oral Microbiota and Inflammatory Skin Diseases.

INTRODUCTION AND AIMS: The oral microbiome has been increasingly linked to systemic inflammation and immune dysregulation, but whether specific oral bacteria causally contribute to inflammatory skin diseases remains unclear due to confounding and reverse causation. This study aimed to assess the causal effects of 43 oral microbiota taxa on the risk of five inflammatory skin diseases using a Mendelian randomization (MR) approach. METHODS: We performed a two-sample MR analysis using genetic instruments for oral microbiota derived from publicly available genome-wide association studies and outcome data from the FinnGen consortium. Causal effects of oral taxa on systemic lupus erythematosus, vitiligo, pemphigus, localized scleroderma, and dermatitis herpetiformis were estimated. The inverse-variance weighted method served as the primary analysis, complemented by sensitivity analyses to evaluate horizontal pleiotropy, heterogeneity, and reverse causality. RESULTS: MR analyses identified several putative causal associations between oral microbiota and inflammatory skin diseases. Genus Granulicatella and an unknown Streptococcus species (ASV0009) showed causal effects on systemic lupus erythematosus. Family Lachnospiraceae_[XIV] and an unknown Rothia species (ASV0016) were associated with vitiligo. Five oral microbiota taxa demonstrated causal associations with pemphigus. Actinomyces species micronuciformis was linked to localized scleroderma. Order Fusobacteriales and an unknown Neisseria species (ASV0004) were associated with dermatitis herpetiformis. No significant heterogeneity or horizontal pleiotropy was detected in sensitivity analyses. CONCLUSION: This MR study provides genetic evidence supporting a causal role of specific oral bacteria in the development of several inflammatory skin diseases, highlighting the oral microbiome as a potential contributor to cutaneous autoimmunity and inflammation. CLINICAL RELEVANCE: Our findings highlight the putative role of the oral microbiome as a plausible candidate for mechanistic and clinical investigations into the prevention or adjunctive management of selected inflammatory skin diseases. However, oral hygiene improvement, targeted antimicrobials, and other microbiota-directed interventions were not directly tested in this MR study and remain hypothetical strategies requiring validation in experimental and clinical studies.

Humans↗

PubMed2026

Deciphering miRNA-mediated genetic architecture of immune cell subsets in hypertrophic scars and keloids: A 2-step Mendelian randomization study unveiling causal associations.

This study aimed to investigate the potential causal roles of specific circulating microRNAs (miRNAs) and immune cell subsets in the pathogenesis of hypertrophic scars and keloids using a 2-step Mendelian randomization framework. We employed a 2-sample Mendelian randomization approach to evaluate the causal relationships between miRNAs, immune cell genotypes, and scar phenotypes. The analysis integrated miRNA expression quantitative trait loci, immune cell genome-wide association studies, and scar datasets. A 2-step mediation analysis was conducted to assess the indirect effects of miRNAs on scars through immune cell genotypes, using inverse variance weighted methods and complementary sensitivity analyses to ensure robustness. Our analysis identified significant associations between specific miRNAs and scar phenotypes. Notably, miR-6887-5p exhibited a total effect on keloid formation risk (β = 0.324, 95% confidence interval [CI]: 0.073-0.576) and a direct effect (β = 0.283, 95% CI: 0.027, 0.538), with a marginally significant mediation effect through B-cell activating factor receptor on CD20- CD38- B cells (β = 0.042, 95% CI: -0.001, 0.084, P = .047). For hypertrophic scars, miR-345-5p demonstrated a significant total effect (β = -0.501, 95% CI: -0.903, -0.099) and direct effect (β = -0.469, 95% CI: -0.872, -0.066), with a significant mediation effect through CD28+ CD45RA- CD8dim T cell percentage (β = -0.032, 95% CI: -0.062, -0.002, P = .034). miR-4801 showed a significant total effect (β = -0.246, 95% CI: -0.429, -0.064) and direct effect (β = -0.218, 95% CI: -0.402, -0.033), with a marginally significant mediation effect through T cell absolute count (β = -0.028, 95% CI: -0.057, -0.000, P = .043). These findings highlight the interplay between miRNAs and immune cell subsets in scar pathogenesis. This study provides preliminary evidence for the causal roles of specific miRNAs and immune cell subsets in scar formation, emphasizing the potential of miRNA-immune cell axes as therapeutic targets. While the identified associations offer important insights into the molecular mechanisms of scar heterogeneity, further validation through mechanistic studies and clinical trials is necessary to translate these genetic insights into clinical interventions.

Humans↗

PubMed2026

Identification and genetic validation of potential therapeutic targets for pulmonary hypertension through multi-omics causal inference.

Pulmonary hypertension (PH) underscores the urgent need for novel therapeutic targets. This study aimed to employ a proteome-wide Mendelian randomization (MR) approach to systematically identify circulating proteins causally associated with PH, thereby providing genetically validated candidate targets for drug development. We adopted a 2-sample MR design, integrating large-scale plasma proteomic quantitative trait loci (pQTL) data (encompassing 4148 proteins) and summary statistics from a large-scale PH genome-wide association study (2047 cases, 8301 controls). Candidate targets were screened through a multilayered analytical pipeline comprising proteomic MR, transcriptomic MR, and summary-data-based Mendelian randomization. The ultimately identified MR-Identified Causal Candidate Targets (MR-ICTs) underwent rigorous Bayesian colocalization analysis, followed by biological characterization through functional enrichment analysis, single-cell transcriptomics, and phenome-wide association studies. Through robust genetic causal inference, this study provides that circulating proteins such as LYZ, GREM2, NID1, and PF4V1 play causal roles in PH pathogenesis. These findings offer a set of rigorously genetically validated, high-priority therapeutic targets for developing novel PH treatments, specifically addressing key pathological mechanisms such as innate immunity, BMP signaling pathway dysregulation, and platelet activation. Our multi-dimensional analysis ultimately identified 6 MR-ICTs causally associated with PH. Notably, the causal associations for lysozyme C (LYZ), gremlin-2 (GREM2), nidogen-1 (NID1), and platelet factor 4 variant 1 (PF4V1) were stringently validated by Bayesian colocalization analysis (posterior probability for hypothesis 4 [PPH4], indicating a shared causal variant, > 0.99). Functional enrichment analysis revealed significant involvement of these targets in immune response and TGF-β signaling pathways. Single-cell analysis further elucidated their cell-type-specific expression, with LYZ predominantly expressed in monocytes and PF4V1 almost exclusively in platelets.

Hypertension, Pulmonary↗

PubMed2025

Gut fungi are associated with human genetic variation and disease risk.

Human genetic determinants of the gut mycobiome remain uninvestigated despite decades of research highlighting tripartite relationships between gut bacteria, genetic background, and disease. Here, we present the first genome-wide association study on the number and types of human genetic loci influencing gut fungi relative abundance. We detect 148 fungi-associated variants (FAVs) across 7 chromosomes that statistically associate with 9 fungal taxa. Of these FAVs, several occur in the protein-coding genes PTPRC, ANAPC10, NAV2, and CDH13. Additional FAVs link to tissue-specific gene expression as fungi-associated expression quantitative trait loci. Notably, the relative abundance of gut yeast Kazachstania associates with genetic variation in CDH13 encoding T-cadherin, a protein linked to cardiovascular disease. Kazachstania forms a causal relationship with cardiovascular disease risk in a mendelian two-sample randomization analysis. These findings establish previously unrecognized connections between human genetics, gut fungi, and chronic disease, broadening the paradigm of human-microbe interactions in the gut to the mycobiome.

Humans↗

PubMed2026

Novel Insights into Immune Cell Function in Type 2 Diabetes Mediated by Gut Microbiota: A Two-Sample Mendelian Randomization Study.

INTRODUCTION: The role of immune cells in type 2 diabetes mellitus (T2DM) development is well-studied, but their interactions with the gut microbiota and the mediating role in this process remain unclear. METHODS: We analyzed 731 immune cell phenotypes (3,757 Europeans), 473 gut microbiota traits (5,959 Finns), and T2DM data (over 400,000 Finns). Mendelian randomization (MR) was based on three assumptions: the instrumental variable (IV) is associated with exposure, IV is not influenced by confounding, and IV affects the outcome only through exposure. We selected single-nucleotide polymorphisms (SNPs) from genome-wide association studies as instrumental variables (IVs) to infer causal effects in two-sample MR analysis. RESULTS: We identified 36 immune cell phenotypes associated with T2DM, including 29 protective factors and seven risk factors, as well as 10 gut microbiota significantly linked to T2DM, with eight protective factors and two risk factors. MR revealed that five gut microbiota mediated the relationship between immune cells and T2DM. For example, the effects of CD3 on resting Treg (OR: 1.0136), CD3 on CM CD4+ (OR: 1.0180), and CD3 on naive CD4+ cells (OR: 1.0150) in T2DM were found to be partially mediated by the species Bacillus. AYThe corresponding mediation effect proportions were 8.99%, 11.8%, and 11.4%. DISCUSSION: MR analysis identified multiple gut microbiota mediators in the relationship between immune cells and T2DM, addressing previous observational evidence. Limitations included the European ancestry bias, among others. CONCLUSION: This study has highlighted the gut microbiota as a mediator between immune cells and T2DM, offering new insights for its early prevention and intervention.

Diabetes Mellitus, Type 2↗

PubMed2026

Genetic evidence that advanced COVID-19 accelerates longitudinal brain atrophy: A Mendelian randomization study.

Coronavirus disease 2019 (COVID-19) was reported to persist long-term in the brain and leave several long-term neurologic sequelae. However, the causal relationship between COVID-19 and brain aging is still unknown. The genome-wide association study (GWAS) data on COVID-19 phenotypes (susceptibility, hospitalization, and severity), involving a total of 5,779,391 participants, were collected from the COVID-19 Host Genetics Initiative. In addition, GWAS data on longitudinal changes in 15 brain structures, assessed via magnetic resonance imaging across the lifespan, were sourced from the ENIGMA Consortium and involved 15,640 participants. Two-sample Mendelian randomization was conducted to infer the causal relationship between COVID-19 and longitudinal brain changes. Multi-trait GWAS meta-analysis, colocalization, and fine-mapping analyses were performed to identify shared genetic etiologies. H3K27me3 ChIP-seq was used to evaluate the regulatory effect of colocalized loci. Two-step Mendelian randomization was applied to explore potential mediating mechanisms across multi-omics layers, including proteomics, metabolomics, and immunomics. Our results showed that COVID-19 hospitalization (β = -262.405, P = .041) and severity (β = -177.676, P = .049) were genetically associated with atrophied volume of total brain during longitudinal change. This suggests that individuals with advanced COVID-19 may be more susceptible to accelerated global brain aging. Caudate was genetically affected by all COVID-19 phenotypes. Seven variants were shared between advanced COVID-19 and global brain aging. rs117169628 was colocalized between advanced COVID-19 and global brain aging, and exerted an inhibitory effect on CDH15 expression, further strengthening the causality. Six metabolites, 1 protein, and 1 immune trait were identified as potential mediators. Our study indicates that advanced COVID-19 might be genetically associated with accelerated brain aging. Brain health should be paid more attention in long COVID-19.

Humans↗

PubMed2025

Assessing the causal association between celiac disease and Alzheimer disease and frontotemporal dementia: A bidirectional Mendelian randomization approach.

This study aimed to investigate the bidirectional causal relationship between celiac disease (CD) and the risk of Alzheimer disease (AD) or frontotemporal dementia (FTD) using Mendelian randomization (MR), in order to clarify prior inconsistent findings. We analyzed summary-level genome-wide association study (GWAS) data for CD, AD, and FTD. Single-nucleotide polymorphisms (SNPs) strongly associated with each condition were selected as genetic instruments. MR analysis was conducted in 2 directions: from CD to AD/FTD and from AD/FTD to CD. Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) was used to detect and correct for pleiotropy, and Cochran Q assessed heterogeneity. Leave-one-out and Mendelian Randomization-Egger (MR-Egger) regression sensitivity analyses were performed to evaluate robustness. No evidence of a causal effect was found between CD and either AD or FTD in either direction (P > .05). Similarly, genetic liability to AD or FTD did not increase the risk of CD. Sensitivity analyses supported the robustness of the results, showing no pleiotropy or heterogeneity. Our findings suggest that CD is not causally linked to the development of AD or FTD. While shared genetic factors or comorbidities may exist, the association is likely noncausal, and other mechanisms of cognitive decline in CD patients warrant further study.

Humans↗

PubMed2025

Genetic pleiotropy underlying obesity and autoimmune disorders: a large-scale cross-trait gwas analysis in European ancestry populations.

BACKGROUND: Obesity and autoimmune disorders represent a significant comorbidity burden, yet their shared genetic architecture is not fully understood. Elucidating the pleiotropic genetic basis underlying both conditions is crucial for unraveling the mechanisms driving their co-occurrence and advancing therapeutic strategies. METHODS: We conducted a large-scale cross-trait analysis integrating genome-wide association study (GWAS) summary data for obesity and 17 autoimmune diseases. Genetic correlations were assessed using LD score regression and high-definition likelihood. Cross-trait pleiotropic analysis was performed using Stratified Pleiotropic Locus Mapping (PLACO) to identify shared loci, followed by Bayesian colocalization to confirm shared causal variants. Gene-level and tissue-specific heritability analyses were conducted, and drug targets were prioritized via summary-based Mendelian randomization (SMR). Finally, immune co-localization and bidirectional Mendelian randomization were employed to elucidate immunological mechanisms and causal relationships. RESULTS: Our analysis identified eight autoimmune diseases with significant genetic correlations to obesity. We discovered 10,324 pleiotropic SNPs, which mapped to 52 independent risk loci, with nine loci confirmed as shared causal variants by colocalization. Gene-level analysis revealed 133 unique pleiotropic genes, including CLN3, SH2B1, and MMEL1, enriched in pathways of hematopoietic cell differentiation and immune homeostasis. Tissue-specific heritability was most prominent in the spleen, whole blood, and EBV-transformed lymphocytes. Immuno-co-localization implicated six IgD+ CD38- %B cell-related traits as key pathological conduits. Bidirectional Mendelian randomization established a causal role of obesity in hypothyroidism, psoriasis, and multiple sclerosis, while revealing an inverse causal association of type 1 diabetes with obesity risk. CONCLUSIONS: This study demonstrates a robust shared genetic foundation between obesity and multiple autoimmune diseases, pinpointing specific pleiotropic loci, genes, and immune cell subsets. Our findings provide a mechanistic framework for their comorbidity and highlight potential targets for therapeutic intervention.

Humans↗

PubMed2025

Causal association between 91 circulating inflammatory proteins and primary open-angle glaucoma: a bidirectional Mendelian randomization study.

BACKGROUND: Glaucoma, especially primary open-angle glaucoma (POAG), is a leading cause of irreversible vision loss. While elevated intraocular pressure is a major risk factor, the pathogenesis of POAG also involves genetics, oxidative stress, abnormal hemodynamics, and inflammatory factors. The role of systemic inflammation in POAG remains a subject of debate. This study aimed to investigate the causal relationships between circulating inflammatory proteins and POAG using a bidirectional Mendelian randomization (MR) approach. METHODS: A bidirectional two-sample MR analysis was conducted using genome-wide association study summary statistics. The primary stage involved 91 circulating inflammatory proteins and POAG, followed by a replication stage to verify significant findings using independent data and meta-analysis. The random-effects inverse-variance weighted model was employed as the primary method, complemented by multiple sensitivity analyses employed to ensure robustness, including multivariable MR to adjust for potential confounders. RESULTS: In the primary stage, 9 circulating inflammatory proteins were found to have significant causal effects on POAG. Specifically, the higher levels of Delta and Notch-like epidermal growth factor-related receptor (DNER) (OR: 1.12, 95 % CI: 1.04-1.21, P = 0.004), leukemia inhibitory factor (LIF) (OR: 1.20, 95 % CI: 1.06-1.36, P = 0.003), matrix metalloproteinase-10 (MMP-10) (OR: 1.08, 95 % CI: 1.02-1.16, P = 0.013), and stem cell factor (SCF) (OR: 1.09, 95 % CI: 1.03-1.15, P = 0.005) were positively associated with the risk of POAG. Conversely, the levels of fibroblast growth factor 19 (FGF-19) (OR: 0.88, 95 % CI: 0.82-0.95, P = 0.002), interleukin-18 (IL-18) (OR: 0.92, 95 % CI: 0.86-0.99, P = 0.019), IL-18 receptor 1 (IL-18R1) (OR: 0.96, 95 % CI: 0.92-1.00, P = 0.037), tumor necrosis factor ligand superfamily member 14 (TNFSF14) (OR: 0.91, 95 % CI: 0.86-0.97, P = 0.004), and tumor necrosis factor-related activation-induced cytokine (TRANCE) (OR: 0.94, 95 % CI: 0.88-1.00, P = 0.041) exhibited inverse associations with the risk of POAG. Multivariable MR analysis adjusting for confounders supported the roles of DNER, FGF-19, IL-18, IL18R1, LIF, and SCF. The replication stage confirmed the significant associations for FGF-19 (OR: 0.89, 95 % CI: 0.84-0.95, P = 4.63 × 10-4), IL-18 (OR: 0.93, 95 % CI: 0.89-0.97, P = 0.002), IL-18R1 (OR: 0.96, 95 % CI: 0.93-0.99, P = 0.023), and LIF (OR: 1.18, 95 % CI: 1.04-1.34, P = 0.013). Sensitivity analyses further supported the robustness of these findings. CONCLUSION: This study elucidated the causal relationships between circulating inflammatory proteins and POAG, highlighting FGF-19, IL-18, IL-18R1, and LIF as potential therapeutic targets. These findings provide new insights for the prevention and management of POAG, although further studies are needed to understand the precise biological mechanisms.

Humans↗

PubMed2026

Genetic insights into the relationship between age at menarche and mental health-related phenotypes.

BACKGROUND: Multiple observational studies have reported associations between age at menarche (AAM) and mental health problems, yet their shared genetic architecture remains poorly characterized. METHODS: We leveraged genome-wide association study summary statistics for AAM and 15 mental health-related phenotypes. We conducted a multi-method integrative analysis encompassing linkage disequilibrium score regression, pleiotropic analysis under the composite null hypothesis, functional mapping and annotation, multi-marker analysis of genomic annotation, pathway enrichment, and bidirectional two-sample Mendelian randomization (MR) to explore shared genetic architecture and potential causal relationships. RESULTS: Our study identified significant genetic correlations between AAM and eight mental health-related phenotypes (miserableness, fed-up feelings, nervous feelings, ever thought that life is not worth living, ever self-harmed, depression, ever smoker, and age started smoking in former smokers). A total of 155 pleiotropic loci, 18 colocalized loci (e.g., 6q16.3), and 203 pleiotropic genes (e.g., LIN28B) were identified. These genes are expressed in multiple regions, including the cerebral cortex and hypothalamus, and are involved in various biological processes and signaling pathways. Additionally, MR analysis revealed causal associations between AAM and 5 mental health-related phenotypes (mood swings, miserableness, fed-up feelings, and age at which smokers started smoking in former/current smokers). CONCLUSIONS: Our study revealed extensive genetic associations between AAM and mental health-related phenotypes, and further explored the potential causal relationships between them. These findings enhance our understanding of the relationship from a genetic perspective and establish a foundation for future research to explore the biological pathways and environmental interactions contributing to these associations.

Genome-Wide Association Study↗

PubMed2026

A bi-directional Mendelian randomization study of sarcopenia-related traits and renal function.

The association between sarcopenia and renal function has been reported in observational studies; however, the directionality and potential causal nature of these associations remain uncertain. We assessed whether genetically predicted sarcopenia-related traits are associated with renal function and vice versa using bidirectional Mendelian randomization (MR). We conducted a bidirectional two-sample MR analysis using publicly available European-ancestry GWAS summary statistics for appendicular lean mass (ALM), hand-grip strength (left and right), and walking pace, and for renal function (cystatin C-based estimated glomerular filtration rate [eGFRcystatin C] and urinary albumin excretion [UAE]). Causal estimates were primarily obtained using inverse-variance weighted (IVW) models, complemented by sensitivity analyses (MR-Egger intercept, weighted median/mode, MR-PRESSO, Radial MR, and leave-one-out). In forward MR, genetically predicted walking pace was positively associated with eGFRcystatin C. Genetically predicted ALM and grip strength (right and left) were inversely associated with UAE. In reverse MR, genetically predicted UAE was inversely associated with ALM and right-hand grip strength. Estimates were broadly consistent across sensitivity analyses, and outlier-robust analyses (MR-PRESSO/Radial MR) yielded similar results. These findings provide genetic evidence consistent with bidirectional relationships between sarcopenia-related traits and renal function (particularly UAE), under standard MR assumptions. Given potential limitations (e.g., heterogeneity, pleiotropy, and possible sample overlap), the results should be interpreted cautiously and complemented by other lines of evidence.

Humans↗

PubMed2026

Biological Mechanisms Underlying the Cardiovascular Effects of Branched-Chain Amino Acids: A Proteome-Wide Mendelian Randomization Study.

BACKGROUND: Ischemic heart disease (IHD) is the leading cause of morbidity and mortality. Branched-chain amino acids (BCAAs) are associated with higher IHD risk, but the underlying biological pathways remain unclear. OBJECTIVES: This study aims to explore these pathways using 2-step proteome-wide Mendelian randomization. METHODS: We examined the associations between genetic proxies for BCAAs and 2922 proteins in the United Kingdom Biobank Pharma Proteomics Project, supplemented by a meta-analysis with data from deCODE to identify proteins associated with BCAAs. Next, we tested their effects on IHD risk using Coronary Artery Disease Genome-wide Replication and Meta-analysis plus Coronary Artery Disease Genetics Consortium (122,733 cases and 424,528 controls) and replicated in FinnGen (31,640 cases and 187,152 controls). We conducted sensitivity analyses using genetic instruments from deCODE. Proteins associated with IHD risk and, in a consistent direction, with genetically predicted BCAAs were considered potential mediators. RESULTS: Genetic proxies for BCAAs were associated with 40 proteins. Among these, 6 proteins showed consistent evidence of mediation, including complement C1s subcomponent, coagulation factor II, granulin, proprotein convertase subtilisin/kexin type 9, sex hormone-binding globulin, and V-set and transmembrane domain-containing protein 2-like. These proteins are involved in inflammation, coagulation, lipid metabolism, and cellular stress response. All associations were robust across different analytical methods and replicated in independent datasets. Mediation analysis showed that these proteins accounted for 6.5% to 32.1% of the association between BCAAs and IHD risk. CONCLUSIONS: This study identified 6 proteins that potentially link BCAAs to IHD, implicating pathways related to inflammation, coagulation, lipid metabolism, and cellular stress responses. To our knowledge, these findings provide novel mechanistic insights into the BCAA-IHD relationship and highlight potential protein targets for future prevention and intervention strategies.

Amino Acids, Branched-Chain↗

PubMed2026

Shared Genetic Basis, Biological Function and Causal Relationship Between Sleep Traits and Hypothyroidism: Evidence from a Comprehensive Genetic Analysis.

BACKGROUND: This research attempts to clarify whether there are any genetic similarities between sleep traits and hypothyroidism based on publicly accessible large-scale genomewide association studies. METHODS: The methodology included colocalization analysis, cross-phenotype association analysis, and linkage disequilibrium score regression analysis to find common genetic overlap. Through tissue function specificity and functional mapping, we were able to identify the shared genetic level. Genetic instrumental factors were used for causal inference in two-sample univariate and multivariable Mendelian randomization analyses. RESULTS: A hereditary correlation between hypothyroidism and napping during the day and getting up in the morning (rg= -0.0982, P= 0.0007; rg= -0.101, P= 0.0001). MAGI3, and HLA-DRB1 BX296568.1 may be potential targets for shared treatments. Colocalization and tissue-specific analysis demonstrated that the common genes and SNPs were identified in the thyroid, lung, brain, and lymphatic tissues. Functional analysis emphasized the importance of these common genes in processes like as protein transport, inflammatory response, and MHC class II protein synthesis. Furthermore, an association has been established between hypothyroidism and sleep duration (IVW, OR 1.5208; 95% CI 1.1142-2.0758, P=0.0082) and getting up in the morning (IVW, OR 1.8375; 95%CI: 1.4502-2.3284, P=4.73E-07). Furthermore, the reverse MR analysis revealed no causal connection between aberrant sleep traits and hypothyroidism. The enduring impact of insomnia on hypothyroidism persists despite controlling for alcohol consumption and smoking habits. CONCLUSION: Certain genetic correlations between sleep traits and hypothyroidism have been emphasized. These findings may elucidate the origin of comorbidity and have implications for future clinical trials.

Humans↗

PubMed2025

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

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

Humans↗

PubMed2024

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

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

Humans↗