Interpreting findings from Mendelian randomization using the MR-Egger method

The causal relationship between bacterial pneumonia and diabetes: a two-sample mendelian randomization study

BACKGROUND

Previous observational studies have established the high prevalence of bacterial pneumonia in diabetic patients, which in turn leads to increased mortality. However, the presence of a causal connection between bacterial pneumonia and diabetes remains unobserved.

METHODS

We chose genome-wide significant (Ρ < 1 × 10-5 and Ρ < 1 × 10-6) and independent (r2 < 0.001) single-nucleotide polymorphisms (SNPs) as instrumental variables (IVs) to proceed a bidirectional two-sample MR study. The extracted SNPs explored the relationship between bacterial pneumonia and diabetes by Inverse variance weighted (IVW), MR-Egger, and weighted median methods. In addition, we conducted the Heterogeneity test, the Pleiotropy test, MR-presso and the Leave-one-out (LOO) sensitivity test to validate the reliability of results.

RESULTS

In an MR study with bacterial pneumonia as an exposure factor, four different types of diabetes as outcome. It was observed that bacterial pneumonia increases the incidence of GDM (OR = 1.150 (1.027-1.274, P = 0.011) and T1DM (OR = 1.277 (1.024-1.531), P = 0.016). In the reverse MR analysis, it was observed that GDM (OR = 1.112 (1.023-1.201, P = 0.009) is associated with an elevated risk of bacterial pneumonia. However, no significant association was observed bacterial pneumonia with T1DM and other types of diabetes (P > 0.05).

CONCLUSION

This study utilizing MR methodology yields robust evidence supporting a bidirectional causal association between bacterial pneumonia and GDM. Furthermore, our findings suggest a plausible causal link between bacterial pneumonia and T1DM.

Exploring the relationship between creatine supplementation and renal function: insights from Mendelian randomization analysis

BACKGROUND

Creatine supplementation is ubiquitously consumed by fitness enthusiasts due to its perceived advantages in enhancing athletic performance. Although there is an increasing concern within this demographic regarding its possible impact on renal function, there is still a lack of rigorous scientific investigations into this alleged association.

METHODS

Data were collected through an online survey on the participants' demographics, creatine usage and concerns related to renal function. The reliability and validity of the survey were assessed using SPSS software. A total of 1129 participants responded to the survey, and chi-square tests were utilized for data analysis. To explore the potential association between creatine levels (as the exposure) and renal function (as the outcome), we utilized open-access genetic databases, and Mendelian randomization (MR) techniques were used to confirm this correlation.

RESULTS

Chi-square analysis revealed no significant association between creatine usage and renal function among the participants. Our MR analysis further supported this finding, demonstrating no significant association between creatine levels and six indicators assessing renal function (IVW, all with p values exceeding 0.05). Similar p values were consistently observed across other MR methods, confirming the absence of a statistical correlation.

CONCLUSIONS

This MR study offers compelling evidence indicating that creatine levels are not statistically associated with renal function, suggesting the potential to alleviate concerns within the fitness community and emphasizing the significance of evidence-based decision-making when considering nutritional supplementation.

Causal association and shared genetics between telomere length and COVID-19 outcomes: New evidence from the latest large-scale summary statistics

Background

Observational studies suggested that leukocyte telomere length (LTL) is shortened in COVID-19 patients. However, the genetic association and causality remained unknown.

Methods

Based on the genome-wide association of LTL (N = 472,174) and COVID-19 phenotypes (N = 1086,211-2597,856), LDSC and SUPERGNOVA were used to estimate the genetic correlation. Cross-trait GWAS meta-analysis, colocalization, fine-mapping analysis, and transcriptome-wide association study were conducted to explore the shared genetic etiology. Mendelian randomization (MR) was utilized to infer the causality. Upstream and downstream two-step MR was performed to investigate the potential mediating effects.

Results

LDSC identified a significant genetic association between LTL and all COVID-19 phenotypes (rG < 0, p < 0.05). Six significant regions were observed for LTL and COVID-19 susceptibility and hospitalization, respectively. Colocalization analysis found rs144204502, rs34517439, and rs56255908 were shared causal variants between LTL and COVID-19 phenotypes. Numerous biological pathways associated with LTL and COVID-19 outcomes were identified, mainly involved in -immune-related pathways. MR showed that longer LTL was significantly associated with a lower risk of COVID-19 severity (OR [95% CI] = 0.81 [0.71-0.92], p = 1.24 ×10-3) and suggestively associated with lower risks of COVID-19 susceptibility (OR [95% CI] = 0.96 [0.92-1.00], p = 3.44 ×10-2) and COVID-19 hospitalization (OR [95% CI] = 0.89 [0.80-0.98], p = 1.89 ×10-2). LTL partially mediated the effects of BMI, smoking, and education on COVID-19 outcomes. Furthermore, six proteins partially mediated the causality of LTL on COVID-19 outcomes, including BNDF, QPCT, FAS, MPO, SFTPB, and APOF.

Conclusions

Our findings suggested that shorter LTL was genetically associated with a higher risk of COVID-19 phenotypes, with shared genetic etiology and potential causality.

Genetic association between celiac disease and chronic kidney disease: a two-sample Mendelian randomization study

OBJECTIVE

A two-sample Mendelian randomization (MR) analysis was performed to elucidate the causal impact of celiac disease on the risk of chronic kidney disease (CKD).

METHODS

The study comprised data from three genome-wide association studies involving individuals of European ancestry. The study groups included participants with celiac disease (n = 24,269), CKD (n = 117,165), and estimated glomerular filtration rate levels based on serum creatinine (eGFRcrea, n = 133,413). We employed four widely recognized causal inference algorithms: MR-Egger, inverse variance weighted (IVW), weighted median, and weighted mode. To address potential issues related to pleiotropy and overall effects, MR-Egger regression and the MR-PRESSO global test were performed. Heterogeneity was assessed using Cochran's Q test.

RESULTS

We identified 14 genetic variants with genome-wide significance. The MR analysis provided consistent evidence across the various methodologies, supporting a causal relationship between celiac disease and an elevated risk of CKD (odds ratio (OR)IVW = 1.027, p = 0.025; ORweighted median = 1.028, P = 0.049; ORweighted mode = 1.030, p = 0.044). Furthermore, we observed a causal link between celiac disease and a decreased eGFRcrea (ORIVW = 0.997, P = 2.94E-06; ORweighted median = 0.996, P = 1.68E-05; ORweighted mode = 0.996, P = 3.11E-04; ORMR Egger = 0.996, P = 5.00E-03). We found no significant evidence of horizontal pleiotropy, heterogeneity, or bias based on MR-Egger regression, MR-PRESSO, and Cochran's Q test.

CONCLUSION

The results of this study indicate a causal relationship between celiac disease and an increased risk of CKD.

Recent advances in the application of Mendelian randomization to chronic kidney disease

OBJECTIVE

Chronic kidney disease (CKD) is a condition influenced by both genetic and environmental factors and has been a focus of extensive research. Utilizing Mendelian randomization, researchers have begun to untangle the complex causal relationships underlying CKD. This review delves into the advances and challenges in the application of MR in the field of nephrology, shifting from a mere summary of its principles and limitations to a more nuanced exploration of its contributions to our understanding of CKD.

METHODS

Key findings from recent studies have been pivotal in reshaping our comprehension of CKD. Notably, evidence indicates that elevated testosterone levels may impair renal function, while higher sex hormone-binding globulin (SHBG) levels appear to be protective, predominantly in men. Surprisingly, variations in plasma glucose and glycated hemoglobin levels seem unaffected by genetically induced changes in the estimated glomerular filtration rate (eGFR), suggesting an independent pathway for renal function impairment.

RESULTS

Furthermore, lifestyle factors such as physical activity and socioeconomic status emerge as significant influencers of CKD risk and kidney health. The relationship between sleep duration and CKD is nuanced; short sleep duration is linked to increased risk, while long sleep duration does not exhibit a clear causal effect. Additionally, lifestyle factors, including diet, exercise, and mental wellness activities, play a crucial role in kidney health. New insights also reveal a substantial causal connection between both central and general obesity and CKD onset, while no significant links were found between genetically modified LDL cholesterol or triglyceride levels and kidney function.

CONCLUSION

This review not only presents the recent achievements of MR in CKD research but also illuminates the path forwards, underscoring critical unanswered questions and proposing future research directions in this dynamic field.

Mendelian randomization analysis revealed that albuminuria is the key factor affecting socioeconomic status in CKD patients

Previous studies indicate a strong correlation between the incidence of chronic kidney disease (CKD) and lower economic status. However, these studies often struggle to delineate a clear cause-effect relationship, leaving healthcare providers uncertain about how to manage kidney disease in a way that improves patients' financial outcomes. Our study aimed to explore and establish a causal relationship between CKD and socioeconomic status, identifying critical influencing factors. We utilized summary meta-analysis data from the CKDGen Consortium and UK Biobank. Genetic variants identified from these sources served as instrumental variables (IVs) to estimate the association between CKD and socioeconomic status. The presence or absence of CKD, estimated glomerular filtration rate (eGFR), and albuminuria were used as exposures, while income and regional deprivation were analyzed as outcomes. We employed the R packages 'TwoSampleMR' and 'Mendelianrandomization' to conduct both univariable and multivariable Mendelian randomization (MR) analyses, assessing for potential pleiotropy and heterogeneity. Our univariable MR analysis revealed a significant causal relationship between high levels of albuminuria and lower income (OR = 0.84, 95% CI: 0.73-0.96, p = 0.013), with no significant pleiotropy detected. In the multivariable MR analysis, both CKD (OR = 0.867, 95% CI: 0.786-0.957, p = 0.0045) and eGFR (OR = 0.065, 95% CI: 0.010-0.437, p = 0.0049) exhibited significant effects on income. This study underscores that higher albuminuria levels in CKD patients are associated with decreased income and emphasizes the importance of effective management and treatment of albuminuria in CKD patients to mitigate both social and personal economic burdens.

Molecular mechanisms underlying Tao-Hong-Si-Wu decoction treating hyperpigmentation based on network pharmacology, Mendelian randomization analysis, and experimental verification

CONTEXT

Hyperpigmentation, a common skin condition marked by excessive melanin production, currently has limited effective treatment options.

OBJECTIVE

This study explores the effects of Tao-Hong-Si-Wu decoction (THSWD) on hyperpigmentation and to elucidate the underlying mechanisms.

MATERIALS AND METHODS

We employed network pharmacology, Mendelian randomization, and molecular docking to identify THSWD's hub targets and mechanisms against hyperpigmentation. The Cell Counting Kit-8 (CCK-8) assay determined suitable THSWD treatment concentrations for PIG1 cells. These cells were exposed to graded concentrations of THSWD-containing serum (2.5%, 5%, 10%, 15%, 20%, 30%, 40%, and 50%) and treated with α-MSH (100 nM) to induce an in vitro hyperpigmentation model. Assessments included melanin content, tyrosinase activity, and Western blotting.

RESULTS

ALB, IL6, and MAPK3 emerged as primary targets, while quercetin, apigenin, and luteolin were the core active ingredients. The CCK-8 assay indicated that concentrations between 2.5% and 20% were suitable for PIG1 cells, with a 50% cytotoxicity concentration (CC50) of 32.14%. THSWD treatment significantly reduced melanin content and tyrosinase activity in α-MSH-induced PIG1 cells, along with downregulating MC1R and MITF expression. THSWD increased ALB and p-MAPK3/MAPK3 levels and decreased IL6 expression in the model cells.

DISCUSSION AND CONCLUSION

THSWD mitigates hyperpigmentation by targeting ALB, IL6, and MAPK3. This study paves the way for clinical applications of THSWD as a novel treatment for hyperpigmentation and offers new targeted therapeutic strategies.

Causal effect of lipoprotein(a) level on chronic kidney disease of European ancestry: a two-sample Mendelian randomization study

INTRODUCTION

Chronic kidney disease is a growing health issue, and the options of prevention and therapy remain limited. Although a number of observational studies have linked higher Lp(a) [lipoprotein(a)] levels to the kidney impairment, the causal relationship remains to be determined. The purpose of this study was to assess the causal association between Lp(a) levels and CKD.

METHODS

We selected eight single-nucleotide polymorphisms (SNPs) significantly associated with Lp(a) levels as instrumental variables. Genome-wide association study (GWAS) from CKDGen consortium yielded the summary data information for CKD. We designed the bidirectional two-sample Mendelian randomization (MR) analyses. The estimates were computed using inverse-variance weighted (IVW), simple median, weighted median, and maximum likelihood. MR-Egger regression was used to detect pleiotropy.

RESULTS

Fixed-effect IVW analysis indicated that genetically predicted Lp(a) levels were associated with CKD significantly (odds ratio, 1.039; 95% CI, 1.009-1.069; p = 0.010). The SNPs showed no pleiotropy according to result of MR-Egger test. Results from sensitivity analyses were consistent. In the inverse MR analysis, random-effect IVW method showed CKD had no causal effect on the elevated Lp(a) (odds ratio, 1.154; 95% CI, 0.845-1.576; p = 0.367).

CONCLUSION

In this bidirectional two-sample MR analysis, the causal deteriorating effects of genetically predicted plasma Lp(a) levels on the risk of CKD were identified. On the contrary, there is no evidence to support a causal effect of CKD on Lp(a) levels.

Causal relationship between 731 immune cells and the risk of diabetic nephropathy: a two‑sample bidirectional Mendelian randomization study

OBJECTIVE

Previous observational studies have indicated associations between various immune cells and diabetic nephropathy (DN). However, the causality remains unclear. We aimed to further evaluate the causal association between immune cells and DN using bidirectional two-sample Mendelian randomization (MR) analysis.

METHOD

The DN data were retrieved from the IEU OpenGWAS Project database, while the data for 731 immune cells were sourced from GWAS summary statistics by Orru ̀ et al. The investigation into the causal relationship between immune cells and DN employed the inverse variance weighted (IVW), weighted median (WME), and MR-Egger methods. The stability and reliability of the findings underwent evaluation through Cochran's Q test, MR-Egger intercept's P-value, MR-PRESSO, and Leave-One-Out (LOO) method.

RESULT

The IVW estimates suggested a positive causal effect of CD25 on IgD-CD38dim B cell, CD25 on naive-mature B cell, CD127 on granulocyte, SSC-A on HLA DR + Natural Killer, HLA DR on plasmacytoid Dendritic Cell, and HLA DR on Dendritic Cell on DN. Conversely, the abundance of Myeloid Dendritic Cell, CD62L- Dendritic Cell %Dendritic Cell, CD86+ myeloid Dendritic Cell %Dendritic Cell, CD14- CD16-, CX3CR1 on CD14- CD16-, and SSC-A on CD4+ T cell had negative causal effects on DN. However, after correcting the P value for significant causality results using the FDR method, it was concluded that only Myeloid Dendritic Cells had a causal relationship with DN (FDR-p = 0.041), while the other immune cells showed no significant association with DN, so their relationship was suggestive. The results were stable with no observed horizontal pleiotropy and heterogeneity. Reverse MR analysis indicated no causal relationship between DN and the increased risk of positively identified immune cells.

CONCLUSION

This study provides an initial insight into the genetic perspective of the causal relationship between immune cells and DN. It establishes a crucial theoretical foundation for future endeavors in precision medicine and individualized treatment.

Association between hypothyroidism and nephrotic syndrome: a bidirectional two-sample Mendelian randomization analysis

BACKGROUND

There is a close clinical association between hypothyroidism and nephrotic syndrome (NS) was close, but whether there is genetic causality between the two is not known.

OBJECTIVE

Using pooled data from a genome-wide association study (GWAS), the association between hypothyroidism and NS was explored via Mendelian randomization (MR) analysis.

METHODS

Single-nucleotide polymorphisms (SNPs) associated with hypothyroidism (or NS) were screened as genetic instrumental variables (IVs) from pooled GWAS data, and inverse-variance weighting (IVW) was used for the main analysis to estimate causal effects, with MR-Egger, weighted median, and weighted mode used as complementary methods. Sensitivity analyses, including Cochran's Q test, MR-Egger intercept, MR-PRESSO and leave-one-out, were also conducted to assess the robustness of the results.

RESULTS

Genetically predicted hypothyroidism was positively associated with the risk of developing NS (IVW: OR = 1.18, 95% CI: 1.07-1.30, p = 0.00; MR-Egger: OR = 1.36, 95% CI: 1.10-1.68, p = 0.01), and the MR-Egger intercept (intercept = -0.02, p = 0.14), MR-PRESSO test (p = 0.14), Cochran's Q test (p = 0.15) and leave-one-out test results supported the robustness of the results. Genetically predicted NS status might not be associated with an increased risk of developing hypothyroidism (IVW: OR = 1.01, 95% CI: 1.00-1.03, p = 0.08; MR-Egger: OR = 1.01, 95% CI: 0.98-1.04, p = 0.43), and the MR-Egger intercept (intercept < 0.01, p = 0.69), MR-PRESSO test (p = 0.64), Cochran's Q test (p = 0.61) and leave-one-out test results supported the robustness of the results.

CONCLUSION

Hypothyroidism status could increase the risk of developing NS.

The shared genetic etiology of antisocial behavior and psychiatric disorders: Insights from pleiotropy and causality analysis

BACKGROUND

Antisocial behavior (ASB) infringes on the rights of others and significantly disrupts social order. Studies have shown that ASB is phenotypically associated with various psychiatric disorders. However, these studies often neglected the importance of genetic foundations.

METHODS

This study utilized genome-wide association studies and pleiotropy analysis to explore the genetic correlation between ASB and psychiatric disorders. Linkage disequilibrium score regression (LDSC) and high-definition likelihood (HDL) methods were employed to assess genetic correlations, and the PLACO method was used for pleiotropy analysis. Functional annotation and biological pathway analysis of identified pleiotropic genes were performed using enrichment analysis. Furthermore, Mendelian randomization (MR) analysis was conducted to validate these causal relationships.

RESULTS

LDSC and HDL analysis showed that significant positive genetic correlations were between ASB and attention deficit hyperactivity disorder (ADHD), schizophrenia (SCZ), major depressive disorder (MDD), and post-traumatic stress disorder (PTSD). Multiple potential pleiotropic genetic loci were identified, particularly the FOXP2 and MDFIC genes located at the 7q31.1 locus. Enrichment analysis showed that these pleiotropic genes are highly expressed in several brain regions (such as the hypothalamus, cerebellar hemisphere, cortex, and amygdala) and immune-related cells. MR analysis further confirmed the causal effects ADHD, SCZ, and MDD on ASB risk.

CONCLUSION

This study reveals significant genetic correlations and potential causal mechanisms between ASB and various psychiatric disorders. The MR analysis confirmed the causal effects of psychiatric disorders on ASB. These findings deepen our understanding of the genetic architecture of psychiatric disorders and ASB.

Identifying genetic determinants of sarcopenia-related traits: a Mendelian randomization study of druggable genes

BACKGROUND

Sarcopenia, characterized by progressive muscle mass and function loss, particularly affects the elderly, and leads to severe consequences such as falls and mortality. Despite its prevalence, targeted pharmacotherapies for sarcopenia are lacking. Utilizing large-sample genome-wide association studies (GWAS) data is crucial for cost-effective drug discovery.

METHODS

Herein, we conducted four studies to understand the putative causal effects of genetic components on muscle mass and function. Study 1 employed a two-sample Mendelian randomization (MR) on 15,944 potential druggable genes, investigating their potential causality with muscle quantity and quality in a European population (N up to 461,089). Study 2 validated MR results through sensitivity analyses and colocalization analyses. Study 3 extended validation across other European cohorts, and study 4 conducted quantitative in vivo verification.

RESULTS

MR analysis revealed significant causality between four genes (BLOC-1 related complex subunit 7, BORCS7; peptidase m20 domain containing 1, PM20D1; nuclear casein kinase and cyclin dependent kinase substrate 1, NUCKS1 and ubiquinol-cytochrome c reductase complex assembly factor 1, UQCC1) and muscle mass and function (p-values range 5.98 × 10-6 to 9.26 × 10-55). To be specific, BORCS7 and UQCC1 negatively regulated muscle quantity and quality, whereas enhancing PM20D1 and NUCKS1 expression showed promise in promoting muscle mass and function. Causal relationships remained robust across sensitivity analyses, with UQCC1 exhibiting notable colocalization effects (PP·H4 93.4 % to 95.8 %). Further validation and in vivo replication verified the potential causality between these genes and muscle mass as well as function.

CONCLUSIONS

Our druggable genome-wide MR analysis identifies BORCS7, PM20D1, NUCKS1, and UQCC1 as causally associated with muscle mass and function. These findings offer insights into the genetic basis of sarcopenia, paving the way for these genes to become promising drug targets in mitigating this debilitating condition.

Enhancing insight into ferroptosis mechanisms in sepsis: A genomic and pharmacological approach integrating single-cell sequencing and Mendelian randomization

This research investigated the intricate relationship between ferroptosis and sepsis by utilizing advanced genomic and pharmacological methodologies. Specifically, we obtained expression quantitative trait loci (eQTLs) for 435 genes associated with ferroptosis from the eQTLGen Consortium and detected notable cis-eQTLs for 281 of these genes. Next, we conducted a detailed analysis to assess the impact of these eQTLs on susceptibility to sepsis using Mendelian randomization (MR) with data from a cohort of 10,154 sepsis patients and 452,764 controls sourced from the UK Biobank. MR analysis revealed 16 ferroptosis-related genes that exhibited significant associations with sepsis outcomes. To bolster the robustness of these findings, sensitivity analyses were performed to assess pleiotropy and heterogeneity, thus confirming the reliability of the causal inferences. Furthermore, single-cell RNA sequencing data from sepsis patients offered a detailed examination of gene expression profiles, demonstrating varying levels of ferroptosis marker expression across different cell types. Pathway enrichment analysis utilizing gene set enrichment analysis (GSEA) further revealed the key biological pathways involved in the progression of sepsis. Additionally, the use of computational molecular docking facilitated the prediction of interactions between identified genes and potential therapeutic compounds, highlighting novel drug targets. In conclusion, our integrated approach combining genomics and pharmacology offers valuable insights into the involvement of ferroptosis in sepsis, laying the groundwork for potential therapeutic strategies targeting this cell death pathway to enhance sepsis management.

The effects of immunomodulatory drugs on cerebral small vessel disease: A mediation Mendelian randomization analysis

BACKGROUND

There are only a few recognized drug targets for cerebral small vessel disease (CSVD). Though inflammation is increasingly implicated in the development of CSVD, it remains unclear whether immunomodulation could become a therapeutic target. Accordingly, the Mendelian randomization (MR) method was used to assess the genetically proxied impacts of IL6 receptor (IL6R) inhibitor, IL1β inhibitor, Tumor necrosis factor (TNF) inhibitor and β-tubulin inhibitor on CSVD through.

METHODS

Single nucleotide polymorphisms (SNPs) near the IL6R, IL1β, TNFRSF1A and β-tubulin genes were identified as genetic proxies for immunomodulatory drugs. These SNPs exhibited significant associations with serum C-reactive protein (CRP) levels in a large European genome-wide association study. The causal effects of immunomodulatory drugs on CSVD manifestations and the mediation influence of 731 peripheral blood immune phenotypes linking these drugs to CSVD manifestations were examined using a two-sample two-step MR approach.

RESULTS

A total of 9, 18, 4 and 1 SNP were identified to proxy the effects of IL1β inhibitor, IL6R inhibitor, TNF inhibitor and β-tubulin inhibitor, respectively. MR analysis showed a significant causal relationship between IL1β inhibition and reduced volume of periventricular white matter hyperintensity (PWMH). IL6R inhibition was associated with a reduced risk of small vessel stroke, decreased axial diffusivity and mean diffusivity. Genetically proxied TNF inhibition may decrease the occurrence of cerebral microbleeds (CMBs) and severe enlarged perivascular spaces located at white matter (WM-EPVS). It could also protect WM integrity, as evidenced by the reduced volumes of PWMH and deep white matter hyperintensity (DWMH). Various peripheral blood immune phenotypes exhibited significant associations with immunomodulatory drugs. Notably, the median fluorescence intensity (MFI) of CD45 on CD8br cells partially mediated the effects of IL1β inhibitor on PWMH volume. Indirect effects of TNF inhibition on PWMH and DWMH volume through the MFI of CD127 on CD28- CD8br cells were observed. The effects of TNF inhibition on the occurrence of any CMBs were partially mediated by the MFI of CD45 on natural killer T cells, and the effects of TNF inhibition on the occurrence of lobar CMBs were partially mediated by the MFI of HLA DR on CD33- HLA DR+ cells. Furthermore, the MFI of HLA DR on CD33- HLA DR+ cells partially mediated the effects of TNF inhibition on WM-EPVS.

CONCLUSIONS

IL1β inhibitor, IL6R inhibitor and TNF inhibitor were associated with lower burden of CSVD while the activation of certain immune cells such as Tregs and myeloid cells partially mediated their protective effects.

Causal association between Neuroticism and risk of aortic aneurysm: A bidirectional two-sample Mendelian randomization study

BACKGROUND

The objective of this study was to analyze the causal relationship between Neuroticism and aortic aneurysm using Mendelian randomization (MR). The study aimed to establish a foundation for the development of effective prevention and treatment strategies.

METHODS

Genetic association data for Neuroticism were obtained from the UK Biobank, which included 393,411 individuals and 11,968,760 single nucleotide polymorphisms (SNPs). Genetic association data for aortic aneurysm were obtained from a genome-wide association study (GWAS), which included 479,194 individuals and 24,191,825 SNPs. Heterogeneity was assessed using the Cochran's Q statistic test. The study also utilized the MR Pleiotropy RESidual Sum and Outlier (Mr-PRESSO) test, as well as the MR-Egger regression method, to examine horizontal pleiotropy and determine the reliability of the findings through the leave-one-out method.

RESULTS

Forward MR analysis showed that the risk of aortic aneurysm was elevated in individuals with genetically predicted Neuroticism compared to those without Neuroticism (OR = 1.1315, 95 % CI: 1.0269-1.2468; P = 0.0126). The Cochran's Q test showed no heterogeneity (P > 0.05), and the MR-PRESSO test did not identify instrumental variables of horizontal pleiotropy (P > 0.05). The MR analysis remained robust after removing SNPs one by one. Inverse MR analysis did not observe an association between aortic aneurysm and having Neuroticism OR = 1.030, 95 % CI: 0.9459-1.118, P = 0.488).

CONCLUSION

Our study has established a clear causal relationship between genetically determined Neuroticism and the development of aortic aneurysms. It is therefore important to intensify screening and prevention efforts for aortic aneurysms in neurotic patients. It also opens new avenues for exploring the disease's pathogenesis.

Druggable genome-wide Mendelian randomization for identifying the role of integrated stress response in therapeutic targets of bipolar disorder

For bipolar disorder (BD), the inconsistency of treatment guidelines and the long phases of pharmacological adjustment remain major challenges. BD is known to be comorbid with many medical and psychiatric conditions and they may share inflammatory and stress-related aetiologies, which could give rise to this association. The integrated stress response (ISR) responds to various stress conditions that lead to alterations in cellular homeostasis. However, as a causative mechanism underlying cognitive deficits and neurodegeneration in a broad range of brain disorders, the impact of ISR on BD is understudied. Mendelian randomization has been widely used to repurpose licensed drugs and discover novel therapeutic targets. Thus, we aimed to identify novel therapeutic targets for BD and analyze their pathophysiological mechanisms, using the summary data-based Mendelian Randomization (SMR) and Bayesian colocalization (COLOC) methods to integrate the summary-level data of the GWAS on BD and the expression quantitative trait locus (eQTL) study in blood. We utilized the GWAS data including 41,917 BD cases and 371,549 controls from the Psychiatric Genomics Consortium and the eQTL data from 31,684 participants of predominantly European ancestry from the eQTLGen consortium. The SMR analysis identified the EIF2B5 gene that was associated with BD due to no linkage but pleiotropy or causality. The COLOC analysis strongly suggested that EIF2B5 and the trait of BD were affected by shared causal variants, and thus were colocalized. Utilizing data in EpiGraphDB we find other putative causal BD genes (EIF2AK4 and GSK3B) to prioritize potential alternative drug targets.

Causal relationship between sex hormones and cutaneous melanoma: a two-sample Mendelian randomized study

This study aimed to elucidate the genetic aspects of the relationship between sex hormones and cutaneous melanoma risk, providing valuable insights into this complex association. In this study, we used estradiol, bioavailable testosterone, sex hormone-binding globulin, and total testosterone as the exposure and melanoma as the outcome for two-sample Mendelian randomization analysis. In this study, a random-effects inverse-variance weighting (IVW) model was used as the main analysis model, and the corresponding weighted median, simple mode, weighted mode, and Mendelian randomization‒Egger methods were used as supplementary methods. We assessed both heterogeneity and horizontal pleiotropy in our study, scrutinizing whether the analysis results were affected by any individual single nucleotide polymorphism. The random-effects IVW method indicated that estradiol [odds ratio (OR), 1.000; 95% confidence interval (CI), 0.998-1.003; P  = 0.658], bioavailable testosterone (OR = 1.001, 95% CI, 0.999-1.003; P  = 0.294), sex hormone-binding globulin (IVW: OR, 1.000; 95% CI, 0.998-1.003; P  = 0.658), and total testosterone (IVW: OR, 1.002; 95% CI, 0.999-1.005; P  = 0.135) were not genetically linked to cutaneous melanoma. No analyses exhibited heterogeneity, horizontal pleiotropy, or deviations. We were unable to find genetic evidence for a causal relationship between sex hormones and the occurrence of cutaneous melanoma in this study. These results are limited by sample size and population, so the causal relationship between sex hormones and cutaneous melanoma needs to be further studied.

Serum uric acid, body mass index, and cardiovascular diseases: A multiple two-step Mendelian randomization study

BACKGROUND AND AIMS

A number of health issues, including high serum uric acid (SUA) and cardiovascular disease (CVD), have been linked to obesity based on observational evidence, though it's currently unclear how these issues are causally related. In order to determine whether obesity mediates this association, we set out to investigate the causal relationship between SUA, obesity, and CVD.

METHODS AND RESULTS

From publicly available genome-wide association studies, we acquired instrumental variables that had a strong correlation to SUA and body mass index (BMI). We employed multiple two-step Mendelian randomization (MR) analyses, using genetic and clinical data from various publicly available biological databases. The mediating role of BMI was examined through mediation analysis. SUA was genetically correlated with BMI [OR = 1.080, 95% CI: 1.024-1.139, P = 0.005]. There was a positive causal effect of SUA on AF [OR = 0.892, 95% CI: 0.804-0.990, P = 0.032], CAD [OR = 0.942, 95% CI: 0.890-0.997, P = 0.037], and EHT [OR = 1.080, 95% CI: 1.024-1.139, P = 0.005]. Among them, BMI mediated the effects of SUA on AF (42.2%; 95% CI, 35.3%-51.9%), CAD (76.3%; 95% CI, 63.4%-92.0%), and EHT (10.0%; 95% CI, 0%-20.0%).

CONCLUSION

Our research revealed a causal relationship between high SUA exposure and an increased risk of obesity. Additionally, a high SUA level was linked to an increased risk of various CVDs. Given that individuals with high SUA are more likely to be susceptible to AF, CAD, and EHT, attention must be given to their weight status.

Exploring the heart-brain and brain-heart axes: Insights from a bidirectional Mendelian randomization study on brain cortical structure and cardiovascular disease

INTRODUCTION

The bidirectional relationship between the brain cortex and cardiovascular diseases (CVDs) remains inadequately explored.

METHODS

This study used bidirectional Mendelian randomization (MR) analysis to explore the interactions between nine phenotypes associated with hypertension, heart failure, atrial fibrillation (AF), and coronary heart disease (CHD), and brain cortex measurements. These measurements included total surface area (SA), average thickness (TH), and the SA and TH of 34 regions defined by the Desikan-Killiany atlas. The nine traits were obtained from sources such as the UK Biobank and FinnGen, etc., while MRI-derived traits of cortical structure were sourced from the ENIGMA Consortium. The primary estimate was obtained using the inverse-variance weighted approach. A false discovery rate adjustment was applied to the p-values (resulting in q-values) in the analyses of regional cortical structures.

RESULTS

A total of 1,260 two-sample MR analyses were conducted. Existing CHD demonstrated an influence on the SA of the banks of the superior temporal sulcus (bankssts) (q=0.018) and the superior frontal lobe (q=0.018), while hypertension was associated with changes in the TH of the lateral occipital region (q=0.02). Regarding the effects of the brain cortex on CVD incidence, total SA was significantly associated with the risk of CHD. Additionally, 16 and 3 regions exhibited significant effects on blood pressure and AF risk, respectively (q<0.05). These regions were primarily located in the frontal, temporal, and cingulate areas, which are associated with cognitive function and mood regulation.

CONCLUSION

The detection of cortical changes through MRI could aid in screening for potential neuropsychiatric disorders in individuals with established CVD. Moreover, abnormalities in cortical structure may predict future CVD risk, offering new insights for prevention and treatment strategies.

Estimated bone mineral density and white matter hyperintensities: A bidirectional Mendelian randomization study

PURPOSE

Greater white matter hyperintensities (WMH) in older adults have been associated with reduced bone mineral density (BMD) and increased fractures and falls. However, it is unclear whether there is a causal relationship between BMD reduction and WMH. In this study, Mendelian randomization (MR) was used to find the causality between WMH and estimated BMD (eBMD).

METHODS

We performed a two-sample bidirectional MR analysis using statistical data obtained from publicly available genome-wide association studies (GWAS). The main method of MR analysis is the inverse-variance weighted (IVW) method. To identify and account for the impact of horizontal pleiotropy, we also employed MR-Egger regression, MR pleiotropy residual sum, and outlier (MR-PRESSO).

RESULTS

MR analysis found a causal relationship between eBMD and WMH (IVW OR = 0.938, 95 % CI: 0.889-0.990, p = 0.020). Our causal estimates are unlikely to be distorted by horizontal pleiotropy according to heterogeneity test (both p > 0.05) and MR-Egger regression (p > 0.05). However, in the reverse MR analysis, there was no evidence that WMH was causally correlated with eBMD (IVW OR = 0.979, 95 % CI: 0.954-1.005, p = 0.109).

CONCLUSION

Our results suggest that low eBMD increased the risk of WMH; conversely, no evidence that WMH causally affects eBMD was found.

Body shape from birth to adulthood is associated with skeletal development: A Mendelian randomization study

BACKGROUND

Observational studies have shown that childhood obesity is associated with adult bone health but yield inconsistent results. We aimed to explore the potential causal association between body shape and skeletal development.

METHODS

We used two-sample Mendelian randomization (MR) to estimate causal relationships between body shape from birth to adulthood and skeletal phenotypes, with exposures including placental weight, birth weight, childhood obesity, BMI, lean mass, fat mass, waist circumference, and hip circumference. Independent genetic instruments associated with the exposures at the genome-wide significance level (P < 5 × 10-8) were selected from corresponding large-scale genome-wide association studies. The inverse-variance weighted analysis was chosen as the primary method, and complementary MR analyses included the weighted median, MR-Egger, weighted mode, and simple mode.

RESULTS

The MR analysis shows strong evidence that childhood (β = -1.29 × 10-3, P = 8.61 × 10-5) and adulthood BMI (β = -1.28 × 10-3, P = 1.45 × 10-10) were associated with humerus length. Tibiofemoral angle was negatively associated with childhood BMI (β = -3.60 × 10-1, P = 3.00 × 10-5) and adolescent BMI (β = -3.62 × 10-1, P = 2.68 × 10-3). In addition, genetically predicted levels of appendicular lean mass (β = 1.16 × 10-3, P = 1.49 × 10-13), whole body fat mass (β = 1.66 × 10-3, P = 1.35 × 10-9), waist circumference (β = 1.72 × 10-3, P = 6.93 × 10-8) and hip circumference (β =1.28 × 10-3, P = 4.34 × 10-6) were all associated with tibia length. However, we found no causal association between placental weight, birth weight and bone length/width.

CONCLUSIONS

This large-scale MR analysis explores changes in growth patterns in the length/width of major bone sites, highlighting the important role of childhood body shape in bone development and providing insights into factors that may drive bone maturation.

Causal impact of statins on susceptibility to osteoarthritis: insights from a two-sample Mendelian randomization analysis

BACKGROUND

Osteoarthritis is a widely prevalent cause of pain and disability among older adults. It is an incurable condition, and most treatments are aimed at alleviating symptoms.

AIM

This study aimed to investigate the impact of statins on osteoarthritis by using a two-sample Mendelian randomization approach, using genetic variants associated with statin use as instrumental variables.

METHOD

Information on single nucleotide polymorphisms associated with statin medication was obtained from the FinnGen study, and data on osteoarthritis were sourced from the UK Biobank. The inverse variance weighted method was used as the primary analytical approach for the Mendelian randomization analysis. Sensitivity analyses were conducted to evaluate horizontal pleiotropy and heterogeneity. To examine the genetic relationship between statins and osteoarthritis, linkage disequilibrium score regression-based estimates were used.

RESULTS

Mendelian randomization analysis indicated a positive effect of statin use on the treatment of osteoarthritis (odds ratio 0.951, 95% confidence interval 0.914-0.99, p < 0.05). This conclusion was supported by various Mendelian randomization methods. Sensitivity analyses revealed no significant directional pleiotropy or influential single nucleotide polymorphisms that could compromise the overall causal inference. Linkage disequilibrium score regression-based estimates suggested a modest genetic correlation between statin use and osteoarthritis (Rg = 0.098, Se = 0.034, p < 0.05), thus reinforcing the robustness of the Mendelian randomization analysis.

CONCLUSION

Statins reduce the risk of osteoarthritis, aligning with the results of observational studies. Further research is essential to validate these results and explore the underlying mechanisms in detail.

Blood cell traits and venous thromboembolism in East Asians: Observational and genetic evidence

Previous studies have indicated that various blood cell traits are associated with a higher risk of venous thromboembolism (VTE). However, the causal relationship remains uncertain. We collected data from the China pulmonary thromboembolism registry study and the China pulmonary health study, using propensity score matching and two-sample Mendelian randomization analyses with summary statistics from genome-wide association studies of blood cell traits and VTE in the East Asian population. Our findings revealed that platelet (PLT) count and hemoglobin (Hb) levels were significantly higher in VTE patients compared to the general population (p value <0.01). Genetically predicted Hb levels were positively associated with VTE, with an odds ratio (OR) of 2.38 (1.13-5.01), p value = 0.022. Similarly, genetically predicted PLT count was positively correlated with VTE, with an OR of 1.33 (1.02-1.74), p value = 0.038. These results suggest a causal relationship and potential targets for prevention.

Modifiable factors mediating the effects of educational attainment on gestational diabetes mellitus: A two-step Mendelian randomization study

BACKGROUND

Although there is currently a wealth of evidence to indicate that maternal educational attainment is associated with gestational diabetes mellitus (GDM), the specific modifiable risk factors that mediate the causal relationship between these two variables have yet to be identified.

AIM

To identify the specific modifiable risk factors that mediate the causal relationship between the level of maternal education and GDM.

METHODS

Mendelian randomization (MR) was conducted using data from genome-wide association studies of European populations. We initially performed a two-sample MR analysis using data on genetic variants associated with the duration of education as instruments, and subsequently adopted a two-step MR approach using metabolic and lifestyle factors as mediators to examine the mechanisms underlying the relationship between the level of maternal education and risk of developing GDM. In addition, we calculated the proportions of total causal effects mediated by identified metabolic and lifestyle factors.

RESULTS

A genetically predicted higher educational attainment was found to be associated with a lower risk of developing GDM (OR: 0.71, 95%CI: 0.60-0.84). Among the metabolic factors assessed, four emerged as potential mediators of the education-GDM association, which, ranked by mediated proportions, were as follows: Waist-to-hip-ratio (31.56%, 95%CI: 12.38%-50.70%), body mass index (19.20%, 95%CI: 12.03%-26.42%), high-density lipoprotein cholesterol (12.81%, 95%CI: 8.65%-17.05%), and apolipoprotein A-1 (7.70%, 95%CI: 4.32%-11.05%). These findings proved to be robust to sensitivity analyses.

CONCLUSION

Our findings indicate a causal relationship between lower levels of maternal education and the risk of developing GDM can be partly explained by adverse metabolic profiles.

Mendelian randomization analysis separated the independent impact of childhood obesity and adult obesity on socioeconomic status, psychological status, and substance use

Background

Obesity is linked to a variety of psychosocial and behavioral outcomes but the causalities remain unclear yet. Determining the causalities and distinguishing between the separate effects of childhood and adult obesity is critical to develop more targeted strategies to prevent adverse outcomes.

Methods

With single nucleotide polymorphisms (SNPs) used as genetic variables, we employed univariable Mendelian randomization (UVMR) to explore the causalities between childhood and adult body mass index (BMI) and socioeconomic status, psychological status, and substance use. Genetic data for childhood and adult BMI came respectively from 47,541 children aged 10 years and 339,224 adult participants. The outcome data were obtained from corresponding consortia. The direct impact of childhood BMI and adult BMI was then examined using a multivariable MR (MVMR).

Results

UVMR found that higher childhood BMI was linked causally to lower household income (β = -0.06, 95 % CI = -0.08 ∼ -0.03, P = 4.86 × 10-5), decreased subjective well-being (β = -0.07, 95 % CI = -0.12 ∼ -0.03, P = 1.74 × 10-3), and an increased tendency of smoking regularly (OR = 1.12, 95 % CI = 1.04-1.20, P = 1.52 × 10-3). Similar results were observed in adult BMI. MVMR further revealed that after adjusting with adult BMI, childhood BMI remained an isolated impact on household income. The impacts of adult BMI on the outcomes were diminished when adjusting with childhood BMI.

Conclusion

The findings indicate the impacts of childhood obesity on subjective well-being and smoking initiation are a result of higher BMI sustaining into adulthood, whereas the effect on household income is attributed to a lasting impact of obesity in early life. The results would help facilitate more targeted strategies for obesity management to prevent adverse outcomes.

Association between various cathepsins and uterine leiomyoma: A Mendelian randomization analysis

Emerging evidence suggests a tentative association between cathepsins and uterine leiomyoma (UL). Previous investigations have predominantly focused on the role of cathepsins in the metastasis and colonization of gynecological malignancies. Still, observational studies may lead to confounding and biases. We employed a bidirectional Mendelian randomization (MR) analysis to elucidate the causative links between various cathepsins and UL. Instrumental variables (IVs) of cathepsins and UL within the European cohort were from extant genome-wide association study datasets. Sensitivity assessments was executed, and the heterogeneity of the findings was meticulously dissected to affirm the solidity of the outcomes. Our findings reveal the association between cathepsin B (CTSB) and an elevated risk of developing UL (all cancers excluded) [Inverse Variance Weighted (IVW) method]: OR = 1.06, 95%CI [1.02, 1.11], P = 0.008895711. Although the association does not persist after multiple testing or Steiger filtering, this finding adds to our understanding of the causal relationship between CTSB of various cathepsins and UL (all cancers excluded) and may herald new therapeutic avenues for individuals affected by this condition.

Role of CD86 on granulocyte in mediating the effect of Genus Roseburia on periodontitis

OBJECTIVES

This study aimed to explore the causal link between the gut microbiota and periodontitis, and to delineate and quantify the intermediary role of immune cells, so as to provide new insights into the pathogenesis, prevention and treatment of periodontitis.

MATERIALS AND METHODS

We employed a two-sample Mendelian randomization (MR) approach to analyze the genetic predictors of gut microbiota composition (covering 412 gut microbiota taxa and functions) and periodontitis (involving 4,784 cases and 272,252 controls) derived from genome-wide association study (GWAS) datasets. A subsequent two-step MR analysis was conducted to evaluate the extent to which immune cell traits (encompassing 731 immune cell characteristics) mediate the influence of gut microbiota on periodontitis risk.

RESULTS

Our analysis implicated nine gut microbiota taxa as causal factors in periodontitis susceptibility (p < 0.05). Notably, the Genus Roseburia was identified as exerting a protective effect against periodontitis, partially mediated through the upregulation of CD86 expression on granulocytes, with an 8.15% mediation effect observed.

CONCLUSIONS

Our findings establish a causal relationship between the gut microbiota and periodontitis, highlighting the protective role of Roseburia against this condition. A notable proportion of this protective effect is mediated via the upregulation of CD86 on granulocytes.

CLINICAL RELEVANCE

It can provide new ideas for the pathogenesis, prevention and treatment for periodontitis through exploring the causal link between the gut microbiota and periodontitis, and describing and quantifying the intermediary role of immune cells.

Causal relationships between dyslexia and the risk of eight dementias

Observational and genetic studies have reported the relationship between dyslexia and Alzheimer's disease (AD). Until now, the causal effect of dyslexia on AD risk has remained unclear. We conducted a two-sample univariable Mendelian randomization (MR) analysis to determine the causal association between dyslexia and the risk of AD, vascular dementia (VD), Lewy body dementia (LBD), and frontotemporal dementia (FTD) and its four subtypes. First, we selected 42 dyslexia genetic variants from a large-scale genome-wide association studies (GWAS) dataset and extracted their corresponding GWAS summary statistics from AD, VD, LBD, and FTD. Second, we selected four MR methods, including inverse-variance weighted (IVW), weighted median, MR-Egger, and MR-PRESSO. Heterogeneity, horizontal pleiotropy, and leave-one-out sensitivity analysis were then used to evaluate the reliability of all causal estimates. We also conducted multivariable MR (MVMR) and mediation analysis to assess the potential mediating role of cognitive performance (CP) or educational achievement (EA) on the causal association between dyslexia and AD. Two MVMR methods, including MV IVW and MV-Egger, and two-step MR were used to perform the analysis. Using IVW, we found a significant causal association between increased dyslexia and increased risk of AD (OR = 1.15, 95% CI: 1.04-1.28, P = 0.006), but not VD, LBD, FTD, or its four subtypes. MR-PRESSO further supported the statistically significant association between dyslexia and AD (OR = 1.15, 95% CI: 1.05-1.27, P = 0.006). All sensitivity analyses confirmed the reliability of causal estimates. Using MV IVW and mediation analysis, we found no causal relationship between dyslexia and AD after adjusting for CP but not EA, CP mediated the total effect of dyslexia on AD with a proportion of 46.32%. We provide genetic evidence to support a causal effect of increased dyslexia on increased risk of AD, which was largely mediated by CP. Reading activity may be a potential intervention strategy for AD by improving cognitive function.

Causality between neuroticism personality clusters and female reproductive diseases in European population: a two-sample bidirectional mendelian randomization study

BACKGROUND

The causality between neuroticism, a personality trait characterized by the tendency to experience negative emotions, and female reproductive diseases remains unclear. To provide evidence for the development of effective screening and prevention strategies, this study employed Mendelian randomization (MR) to investigate the causality between neuroticism clusters and female reproductive diseases.

METHODS

Instrumental variables were obtained from large-scale genome-wide association studies of populations of European descent involving three neuroticism clusters (depressed affect, worry, sensitivity to environmental stress, and adversity [SESA]) in the Complex Trait Genetics database and six female reproductive diseases (infertility, polycystic ovary syndrome [PCOS], spontaneous abortion, recurrent spontaneous abortion, endometriosis, and uterine fibroids) in the FinnGen database. The bidirectional two-sample MR analysis was conducted using the inverse variance-weighted, weighted median, and MR-Egger methods, whereas the sensitivity analysis was conducted using the Cochran's Q-test, MR-Egger intercept, and leave-one-out analysis.

RESULTS

In the forward analysis, genetically predicted depressed affect and worry components of neuroticism significantly increased the risk of infertility (depressed affect: odds ratio [OR] = 1.399, 95% confidence interval [CI]: 1.054-1.856, p = 0.020; worry: OR = 1.587, 95% CI: 1.229-2.049, p = 0.000) and endometriosis (depressed affect: OR = 1.611, 95% CI: 1.234-2.102, p = 0.000; worry: OR = 1.812, 95% CI: 1.405-2.338, p = 0.000). Genetically predicted SESA component of neuroticism increased only the risk of endometriosis (OR = 1.524, 95% CI: 1.104-2.103, p = 0.010). In the reverse analysis, genetically predicted PCOS was causally associated with an increased risk of the worry component of neuroticism (Beta = 0.009, 95% CI: 0.003-0.016, p = 0.003).

CONCLUSIONS

The MR study showed that the three neuroticism personality clusters had definite causal effects on at least one specific female reproductive disease. Moreover, PCOS may increase the risk of the worry component of neuroticism. This finding suggests the need to screen for specific female reproductive diseases in populations with high neuroticism and assess the psychological status of patients with PCOS.

Identification of novel drug targets for osteoarthritis by integrating genetics and proteomes from blood

BACKGROUND

Osteoarthritis (OA) is a degenerative osteoarticular disease, involving genetic predisposition. How the risk variants confer the risk of OA through their effects on proteins remains largely unknown. Therefore, we aimed to discover new and effective drug targets for OA and its subtypes.

METHODS

A proteome-wide association study (PWAS) was performed based on OA and its subtypes genome-wide association studies (GWAS) summary datasets and the protein quantitative trait loci (pQTL) data. Subsequently, Mendelian randomization (MR) and colocalization analysis was conducted to estimate the associations between protein and OA risk. The replication analysis was performed in an independent dataset of human plasma pQTL data.

RESULTS

The abundance of seven proteins was causally related to OA, two proteins to knee OA and six proteins to hip OA, respectively. We replicated 2 of these proteins using an independent pQTL dataset. With the further support of colocalization, and higher ECM1 level was causally associated with a higher risk of OA and hip OA. Higher PCSK1 level was causally associated with a lower risk of OA. And higher levels of ITIH1, EFEMP1, and ERLEC1 were associated with decreased risk of hip OA.

CONCLUSION

Our study provides new insights into the genetic component of protein abundance in OA and a promising therapeutic target for future drug development.

Mendelian randomization analysis reveals causal effects of blood lipidome on gestational diabetes mellitus

BACKGROUND

Observational studies have revealed associations between maternal lipid metabolites and gestational diabetes mellitus (GDM). However, whether these associations are causal remain uncertain.

OBJECTIVE

To evaluate the causal relationship between lipid metabolites and GDM.

METHODS

A two-sample Mendelian randomization (MR) analysis was performed based on summary statistics. Sensitivity analyses, validation analyses and reverse MR analyses were conducted to assess the robustness of the MR results. Additionally, a phenome-wide MR (Phe-MR) analysis was performed to evaluate potential side effects of the targeted lipid metabolites.

RESULTS

A total of 295 lipid metabolites were included in this study, 29 of them had three or more instrumental variables (IVs) suitable for sensitivity analyses. The ratio of triglycerides to phosphoglycerides (TG_by_PG) was identified as a potential causal biomarker for GDM (inverse variance weighted (IVW) estimate: odds ratio (OR) = 2.147, 95% confidential interval (95% CI) 1.415-3.257, P = 3.26e-4), which was confirmed by validation and reverse MR results. Two other lipid metabolites, palmitoyl sphingomyelin (d18:1/16:0) (PSM(d18:1/16:0)) (IVW estimate: OR = 0.747, 95% CI 0.583-0.956, P = 0.021) and triglycerides in very small very low-density lipoprotein (XS_VLDL_TG) (IVW estimate: OR = 2.948, 95% CI 1.197-5.215, P = 0.015), were identified as suggestive potential biomarkers for GDM using a conventional cut-off P-value of 0.05. Phe-MR results indicated that lowering TG_by_PG had detrimental effects on two diseases but advantageous effects on the other 13 diseases.

CONCLUSION

Genetically predicted elevated TG_by_PG are causally associated with an increased risk of GDM. Side-effect profiles indicate that TG_by_PG might be a target for GDM prevention, though caution is advised due to potential adverse effects on other conditions.

Socioeconomic status, individual behaviors and risk of anxiety disorders: A Mendelian randomization study

BACKGROUND

The association between socioeconomic status and individual behaviors (SES/IB) and anxiety disorders has garnered increasing attention, yet the impact of SES/IB on anxiety disorders remains unclear. Therefore, we employed a Mendelian randomization (MR) design to evaluate the causal relationship between SES/IB and anxiety disorders.

METHODS

We conducted a two-sample MR study to assess the causal effects of SES and IB (smoking behaviors, drinking behaviors, sleeping behaviors, habitual physical activity, leisure sedentary behaviors, and reproductive behaviors) on anxiety disorders. A series of filtering steps were taken to select eligible genetic instruments robustly associated with each of the traits. The inverse variance weighted was used for preliminary analysis, and multiple methods were used for sensitivity testing.

RESULTS

After Bonferroni correction and rigorous quality control, we found that educational attainment (odds ratio [OR]:0.75; 95 % confidence interval [CI]:0.69-0.81; P = 9.21E-12), alcohol consumption per week (OR: 1.62; 95 % CI: 1.33-1.97; P = 1.80E-06), insomnia (OR: 1.68; 95 % CI: 1.43-1.97; P = 1.45E-10),age at first birth (OR: 0.59; 95 % CI: 0.50-0.68; P = 1.31E-11),and number of sexual partners (OR: 2.19; 95 % CI: 1.71-2.80; P = 6.64E-10) were causally associated with anxiety disorders.

LIMITATIONS

The subjects included in this study were all of European descent, and whether this finding can be generalized to other populations needs to be further demonstrated.

CONCLUSIONS

The MR Study provides strong evidence that some factors influence anxiety disorders.

Causal relationships between gut microbiota and polycystic ovarian syndrome: A bidirectional Mendelian randomization study

INTRODUCTION

Previous studies have established a link between gut microbiota and polycystic ovary syndrome (PCOS), but little is known about their precise causal relationship. Therefore, this study aims to explore whether there are precise causal relationships between gut microbiota and PCOS.

MATERIAL AND METHODS

We performed a bidirectional two-sample Mendelian randomization (MR) analysis. Datasets were from the largest published meta-analysis on gut microbiota composition and the FinnGen cohort of the IEU Open Genome-Wide Association Study Project database. Inverse variance weighted (IVW), MR-Egger, constrained maximum likelihood-based Mendelian randomization, weighted median, weighted mode, and simple mode were used. Cochran's Q and MR-Egger intercept tests were employed to measure the heterogeneity.

RESULTS

A total of 211 gut microbiota taxa were identified in MR analysis. Nine taxa of bacteria, including Alphaproteobacteria (0.55, 0.30-0.99, p = 0.04), Bacilli (1.76, 1.07-2.91, p = 0.03), Bilophila (0.42, 0.23-0.77, p < 0.01), Blautia (0.16, 0.03-0.79, p = 0.02), Burkholderiales (2.37, 1.22-4.62, p = 0.01), Candidatus Soleaferrea (0.65, 0.43-0.98, p = 0.04), Cyanobacteria (0.51, 0.31-0.83, p = 0.01), Holdemania (0.53, 0.35-0.81, p < 0.01), and Lachnospiraceae (1.86, 1.04-3.35, p = 0.03), were found to be associated with PCOS in the above MR methods included at least IVW method. Cochran's Q statistics and MR-Egger intercept test suggested no significant heterogeneity. In addition, 69 taxa were shown significant for at least the IVW method in reverse MR analysis, of these, 25 had a positive correlation, and 37 had a negative correlation. Additionally, Alphaproteobacteria and Lachnospiraceae (0.95, 0.91-0.98, p < 0.01; 0.97, 0.94-0.99, p = 0.02, respectively) were shown a bidirected causally association with PCOS.

CONCLUSIONS

Our study provides evidence of the bidirectional causal association between gut microbiota and PCOS from a genetic perspective.

Association between psychiatric disorders and irritable bowel syndrome: A bidirectional Mendelian randomization study

OBJECTIVE

Previous studies have suggested that irritable bowel syndrome (IBS) is strongly associated with psychiatric disorders. However, it is unclear whether this association is causal, concomitant, or accidental. Thus, we performed Mendelian randomization (MR) analysis to evaluate the causal effects of several psychiatric disorders on IBS.

METHODS

Summary data of genome-wide association studies (GWASs) were obtained mainly from the Psychiatric Genomics Consortium (PGC) on individuals of European ancestry and from a recent GWAS on IBS. We used three MR methods, the inverse-variance weighting (IVW), weighted median (WM), and MR-Egger regression (MR-Egger). In addition, two other indicators, namely, the MR-IVW Cochran's Q statistic and MR-Egger intercept, were used to assess heterogeneity and detect directional horizontal pleiotropy, respectively.

RESULTS

Heritability was high for bipolar disorder (81.18 %, 95 % CI = 73.18-148.18 %), schizophrenia (33.88 %, 95 % CI = 33.57-38.19 %), and panic disorder (30.66 %, 95 % CI = 20.74-40.58 %). For other disorders, there was a low liability-scale SNP heritability for major depressive disorder (MDD) (0.67 %, 95 % CI = 0.61-0.73 %), anxiety disorder (7.63 %, 95 % CI = 1.67-13.59 %), PTSD (0.96 %, 95 % CI = 0.12-1.8 %), and IBS (2.44 %, 95 % CI = 2.13-2.75 %). We also observed that schizophrenia had a significant causal effect on IBS according to MR-IVW. Notably, the individual causal estimates of genetic instruments for MDD and schizophrenia were heterogeneous, but no pleiotropic effects were observed.

CONCLUSIONS

Our analyses revealed the causal effects of MDD and schizophrenia on IBS, a matter that has been subject to debate for decades, and also showed that IBS had causal effects on MDD.

Genetic estimation of causalities between educational attainment with common digestive tract diseases and the mediating pathways

BACKGROUND

The association between education, intelligence, and cognition with digestive tract diseases has been established. However, the specific contribution of each factor in the pathogenesis of these diseases are still uncertain.

METHOD

This study employed multivariable Mendelian randomization (MR) to assess the independent effects of education, intelligence, and cognition on gastrointestinal conditions in the FinnGen and UK Biobank European-ancestry populations. A two-step MR approach was employed to assess the mediating effects of the association.

RESULTS

Meta-analysis of MR estimates from FinnGen and UK Biobank showed that 1- SD (4.2 years) higher education was causally associated with lower risks of gastroesophageal reflux (OR: 0.58; 95% CI: 0.50, 0.66), peptic ulcer (OR: 0.57; 95% CI: 0.47, 0.69), irritable bowel syndrome (OR: 0.70; 95% CI: 0.56, 0.87), diverticular disease (OR: 0.69; 95% CI: 0.61, 0.78), cholelithiasis (OR: 0.68; 95% CI: 0.59, 0.79) and acute pancreatitis (OR: 0.54; 95% CI: 0.41, 0.72), independently of intelligence and cognition. These causal associations were mediating by body mass index (3.7-22.3%), waist-to-hip ratio (8.3-11.9%), body fat percentage (4.1-39.8%), fasting insulin (1.4-5.5%) and major depression (6.0-12.4%).

CONCLUSION

Our findings demonstrate a causal and independent association between education and six common digestive tract diseases. Additionally, our study highlights five mediators as crucial targets for preventing digestive tract diseases associated with lower education levels.

Serum trace elements and osteoarthritis: A meta-analysis and Mendelian randomization study

OBJECTIVE

This study aims to establish the correlation between shifts in serum trace element (TE) levels and the progression of osteoarthritis (OA), while also exploring the underlying causal relationship between these variables.

METHODS

An investigation was conducted, which included a systematic review, a meta-analysis of observational studies, and a two-sample Mendelian randomization (MR) study.

RESULTS

This meta-analysis revealed significant differences in serum levels of copper, manganese, cadmium, and selenium between OA patients and healthy controls, after adjusting for heterogeneity. Specifically, significant disparities were observed for copper (SMD 0.118 [95 % CI: 0.061 ∼ 0.175], P < 0.001), manganese (SMD -0.180 [95 % CI: -0.326 ∼ -0.034], P = 0.016), cadmium (SMD 0.227 [95 % CI: 0.131 ∼ 0.322], P < 0.001), and selenium (SMD -0.138 [95 % CI: -0.209 ∼ -0.068], P < 0.001), while zinc levels did not show a significant difference (SMD -0.02 [95 % CI: -0.077 ∼ 0.038], P = 0.503). Further, MR analysis suggested a causal link between genetically predicted serum copper level changes and OA development, but not for other TEs.

CONCLUSION

The study suggests that there is an association between the occurrence of OA and variations in serum levels of copper, manganese, cadmium, and selenium. Elevated serum copper may play a pivotal role. Further research is needed to explore the therapeutic potential of TE level modulation in OA management.

Role of blood lipids in mediating the effect of dietary factors on gastroesophageal reflux disease: a two-step mendelian randomization study

BACKGROUND

Growing studies have indicated an association between dietary factors and gastroesophageal reflux disease (GERD). However, whether these associations refer to a causal relationship and the potential mechanism by which dietary factors affect GERD is still unclear.

METHODS

A two-step mendelian randomization analysis was performed to obtain causal estimates of dietary factors, blood lipids on GERD. Independent genetic variants associated with 13 kinds of dietary factors and 5 kinds of blood lipids at the genome-wide significance level were selected as instrumental variables. The summary statistics for GERD were obtained from European Bioinformatics Institute, including 129,080 cases and 473,524 controls. Inverse variance weighted was utilized as the main statistical method. MR-Egger intercept test, Cochran's Q test, and leave-one-out analysis were performed to evaluate possible heterogeneity and pleiotropy. And the potential reverse causality was assessed using Steiger filtering.

RESULTS

The results of the inverse variance weighted method indicated that genetically predicted total pork intake (OR = 2.60, 95% CI: 1.21-5.58, p = 0.0143), total bread intake (OR = 0.68, 95% CI: 0.46-0.99, p = 0.0497), total cereal intake (OR = 0.42, 95% CI: 0.31-0.56, p = 2.98E-06), and total cheese intake (OR = 0.41, 95% CI: 0.27-0.61, p = 1.06E-05) were associated with the risk of GERD. Multivariable Mendelian randomization analysis also revealed a negative association between total cereal intake, total cheese intake and the risk of GERD, but the effect of total pork intake and total bread intake on GERD disappeared after adjustment of smoking, alcohol consumption, use of calcium channel blockers, BMI, physical activity levels, and biological sex (age adjusted). Furthermore, the concentration of low-density lipoprotein cholesterol (LDL-C) is negatively correlated with total cheese intake, which mediates the impact of total cheese intake on GERD. The proportion mediated by LDL-C is 2.27% (95%CI: 1.57%, 4.09%).

CONCLUSIONS

This study provides evidence that an increase in total cereal intake and total cheese intake will decrease the risk of GERD. Additionally, LDL-C mediates the causal effect of total cheese intake on GERD. These results provide new insights into the role of dietary factors and blood lipids in GERD, which is beneficial for disease prevention.

Causal association between blood metabolites and abdominal aortic calcification: A bidirectional Mendelian randomization study

Previous studies have reported correlations between metabolic factors and abdominal aortic calcification (AAC). However, the causal relationship between blood metabolites and AAC remains to be fully explored. We employed bidirectional two-sample Mendelian randomization (MR) to investigate the potential causal relationships between 486 blood metabolites and AAC. The inverse variance weighted method was primarily utilized for MR analysis, and the MR-Egger, weighted median, and Robust Adjusted Profile Score methods were used for supplementary analysis. Sensitivity analyses were conducted using Radial MR, MR-PRESSO, Cochran Q test, MR-Egger intercept, and leave-one-out analysis to evaluate the heterogeneity and pleiotropy. Furthermore, the Steiger test and linkage disequilibrium score regression were used to assess genetic correlation and directionality. Multivariable MR analysis was performed to evaluate the direct effect of metabolites on AAC. Through rigorous screening, we identified 6 metabolites with presumed causal effects on AAC: 4-methyl-2-oxopentanoate (effect size [ES] 0.46, 95% confidence interval [CI]: 0.10-0.82), erythrose (ES -0.35, 95% CI: -0.59 to -0.11), 10-undecenoate (11:1n1) (ES 0.14, 95% CI: 0.03-0.25), 1-myristoylglycerophosphocholine (ES 0.31, 95% CI: 0.11-0.50), glycerol 2-phosphate (ES 0.20, 95% CI: 0.04-0.37), and the unidentified metabolite X-11469 (ES 0.19, 95% CI: 0.08-0.30). Multivariable MR analysis revealed that genetically predicted erythrose, 10-undecenoate, 1-myristoylglycerophosphocholine, and X-11469 could directly affect AAC independent of other metabolites. Reverse MR analysis revealed an alteration in 12 blood metabolites due to AAC, including caffeine, 1,7-dimethylurate, arachidonic acid, and 1-arachidonoylglycerophosphocholine. This study provides evidence supporting a causal relationship between metabolites and AAC. These findings help elucidate the underlying biological mechanisms of AAC and may offer insights into screening, prevention, and treatment approaches.

Causal relationship between multiple sclerosis and spinal stenosis: Two-sample Mendelian randomization

To investigate the causal relationship between multiple sclerosis and spinal stenosis using Mendelian randomization (MR). Genetic loci independently associated with multiple sclerosis and spinal stenosis in people of European origin were selected as instrumental variables using pooled data from genome wide association studies (GWAS). Three MR analyses, MR-Egger, Weighted median and inverse variance weighting (IVW), were used to investigate the causal relationship between multiple sclerosis and spinal stenosis. Heterogeneity and multiplicity tests were performed, and sensitivity analyses were performed using the "leave-one-out" method to explore the robustness of the results. The IVW results showed an OR (95% CI) of 1.05 (1.01-1.08), P = .016, indicating a causal relationship between MS and spinal stenosis. And no heterogeneity and multiplicity were found by the test, and sensitivity analysis also showed robust results. In this study, genetic data were analyzed and explored using 2-sample MR analysis, and the results showed a causal relationship between multiple sclerosis and the occurrence of spinal stenosis.

Causal linkage of psoriasis with ageing: Mendelian randomization and enrichment analysis towards telomere length and psoriasis

OBJECTIVE

Several studies demonstrated potential associations between the telomere length (TL) in leukocytes and psoriasis or psoriatic arthritis (PsA). This study aimed to investigate whether there was the causal genetic relationship between TL and psoriatic diseases bidirectionally.

METHODS

Two-sample univariable MR (UVMR) analysis was applied to explore the bidirectional causal association of TL with overall psoriasis, psoriasis vulgaris (PV) and PsA. Multivariable MR (MVMR) and the mediation effects analysis were applied to test whether the bidirectional associations between TLs and psoriasis were mediated by body mass index (BMI), alcohol, and smoking status.

RESULTS

According to the UVMR results, a negative causal impact of TL on the risk of overall psoriasis was found (OR = 0.775; 95% CI: 0.646-0.931; P = 6.36 × 10-3), and a similar trend was observed in the reversed direction for psoriasis-TL (IVW-β = -0.0097; 95% CI: -0.0170 to -0.0024; P = 9.12 × 10-3). There were also negative genetic associations between TL and PV bidirectionally. The independent association of genetically predicted TL and overall psoriasis persisted in the MVMR results controlled for BMI, smoking, and alcohol consumption (ORMVMR = 0.736; 95% CI: 0.597 to 0.907; P = 0.004). An independent significant association of genetic predisposition to PsA with TL was also found (βMVMR = 0.006; 95% CI: 0.001 to 0.012; P = 0.033). The mediation analysis showed that BMI partially mediated the reverse association between PSO and TL.

CONCLUSION

This MR study revealed an association between genetic indicators of shortened TL and risk of overall psoriasis and PV, and genetic predisposition to PsA was associated with longer TL. Key message What is already known on this topic?  Telomere length (TL) is acknowledged to reflect an individual's biological age but is also associated with dysregulated immune function and immunosenescence. The impact of aging on psoriasis is controversial. Existing evidence suggests that aging may influence pathological changes and clinical course but whether aging is an independent risk factor remains unclear. What this study adds?  The current study found an association between genetic indicators of shortened TL and the risk of overall psoriasis and psoriasis vulgaris (PV). There was a bidirectional link between genetically indicated overall psoriasis and shortened TL. A possible positive genetic association between PsA and TL was also found. How this study might affect research, practice, or policy?  Our study may provide evidence for TL as new diagnostic and therapeutic strategies in clinical practices for psoriasis. Greater efforts to psoriasis management may substantially reduce the aging attributable to TL shortening. Future large-scale GWAS and experimental studies are warranted to examine the mechanistic basis for links between TL and psoriasis to improve understanding and illuminate possible therapeutic targets for psoriatic disease.

Causal link between childhood obesity and adult osteoporosis: An investigation through Mendelian randomization

The intricate link between childhood obesity and adult osteoporosis has been a subject of numerous clinical inquiries, yet the genetic underpinnings of this association remain enigmatic. Our research aims to unravel the association between adult osteoporosis and childhood obesity using genome-wide association study data for Mendelian randomization (MR) analysis. Utilizing a pool of single-nucleotide polymorphism data associated with childhood obesity obtained from a previous genome-wide association study report involving a study population of 13,848 people in Europe, alongside data of adult osteoporosis sourced from Neale Lab (5266 cases and 331,893 controls). Various methods for MR were used in our research, including weighted mode, simple mode, weighted median, MR-Egger, and the inverse-variance weighted (IVW). We also used Cochran Q test of IVW to assess for heterogeneity, MR-Egger intercept and MR-Pleiotropy RESidual Sum and Outlier (MR-PRESSO) analysis for pleiotropy, and leave-one-out analysis for the result stability. The instrumental variables associated with 11 single-nucleotide polymorphisms were selected. MR analyses unveiled a noteworthy link between genetically forecasted childhood obesity and the onset of adult osteoporosis based on the odds ratio, 95% confidence interval, and P-value from the results of IVW, MR-Egger, weighted median: simple mode, and weighted mode analyses. No significant heterogeneity was found by the assessment using MR-Egger and IVW. Similarly, there was no indication of pleiotropy based on the MR-PRESSO and MR-Egger analyses. Leave-one-out analysis confirmed the stability of the results. Our research suggests that childhood obesity, as predicted by genetic factors, may pose a significant risk for the development of osteoporosis in adulthood.

Causal relationship between systemic circulatory inflammatory regulators and intervertebral disc degeneration: A bidirectional 2-sample Mendelian randomization study

In the context of the development of intervertebral disc degeneration (IDD), inflammatory mediators play a pivotal role. Nevertheless, due to the influence of the inflammatory microenvironment, the causal relationship between specific inflammatory mediators and the development of IDD remains uncertain. The understanding of the causal relationship between inflammatory mediators and IDD is of great importance in preventing and delaying disc degeneration in the future. We utilized genetic data concerning systemic circulating inflammatory regulators obtained from a Genome-Wide Association Study (GWAS) analyzing 41 serum cytokines in a cohort of 8293 individuals from Finland. The genetic data for IDD were derived from the most recent GWAS summary statistics conducted within the FinnGen consortium, encompassing 37,636 IDD cases and 270,964 controls. Our analysis employed bidirectional 2-sample Mendelian randomization (MR) techniques, which included several MR methods such as MR Egger, weighted median, inverse variance weighted, weighted mode, and simple mode. Additionally, the MR-PRESSO method was employed to identify horizontal pleiotropy, heterogeneity was quantified using the Cochran Q statistic, and MR-Egger intercept analysis was performed to assess pleiotropy. We established causal relationships between 3 specific inflammatory factors and IDD. Elevated levels of MIP-1β (OR = 0.956, 95% CI: -0.08 to -0.006; P = .02) and IFN-G (OR = 0.915, 95% CI: -0.16 to -0.02; P = .01) expression were associated with a reduced risk of IDD. Conversely, genetic susceptibility to IDD was linked to a decrease in IL-13 levels (OR = 0.967, 95% CI: -0.063 to -0.004; P = .03). In this study, we have identified inflammatory factors that exhibit a causal relationship with the onset and progression of IDD, as supported by genetic predictions.

Association of MCP-4, NRTN, and PD-L1 with the risk of hepatic fibrosis: A Mendelian randomization study

Previous studies have confirmed the affiliation between specific inflammatory cytokines and Hepatic fibrosis (HF); however, contradictions remain in the causality. The study implemented a bidirectional two-sample Mendelian randomization (MR) analysis with published statistics derived from Genome-wide Association Studies (GWAS) to investigate casualties between inflammatory cytokines and HF. Additionally, MR analysis was also introduced to consider if 1400 blood metabolites act as the key mediators in this process. Single nucleotide polymorphisms (SNPs) with strong correlations to inflammatory factors were selected for multiple MR analyses in this study. The inverse variance weighted method (IVW) was chosen as the principal analysis, and the others as the supportive. Besides, sensitivity tests were involved to identify potential heterogeneity and pleiotropic level. IVW methods revealed that a relatively high level of prediction-based monocyte chemoattractant protein-4 (MCP-4) (95% CI: 1.014-3.336, P = .045), along with neurturin (NRTN) (95% CI: 1.204-4.004, P = .010), may increase the risk of HF; while programmed cell death 1 ligand 1 (PD-L1) (95% CI: 0.223-0.928, P = .030), showed a protective effect on HF. No significant statistical differences were detected on any other inflammatory cytokines, nor did the impact of HF genetic predisposition on the 91 circulating inflammatory cytokines-related characteristics.

Can Omega-3 prevent the accidence of stroke: a mendelian randomization study

BACKGROUND

The lipid-lowering effects of Omega-3 fatty acids have been widely reported, yet their impact on ischemic stroke remains controversial. Reports on the protective effects of unsaturated fatty acids, such as Omega-6 and Omega-7, as well as saturated fatty acids in cardiovascular diseases, including hypertension and ischemic stroke, are less frequent.

OBJECTIVES

This study aims to identify fatty acids associated with blood pressure and ischemic stroke through Mendelian randomization. Besides, it seeks to determine whether specific fatty acids can prevent ischemic stroke by managing blood pressure and revealing the specific mechanisms of this action.

METHODS

This research involved downloading relevant data from websites and extracting SNPs that met the standard criteria as instrumental variables. Simultaneously, the 'MR-PRESSO' package and 'Mendelian Randomization' package were used to eliminate confounding SNPs that could bias the study results. Then, inverse variance weighting and the weighted median were employed as primary analysis methods, accompanied by sensitivity analysis to assess the validity of the causal relationships. Initially, multivariable Mendelian randomization was used to identify fatty acids linked to blood pressure and the incidence of ischemic stroke. The causal link between certain fatty acids and the initiation of ischemic stroke was then investigated using bidirectional and mediator Mendelian randomization techniques. Stepwise Regression and the Product of Coefficients Method in mediator Mendelian randomization were utilized to ascertain whether specific fatty acids reduce ischemic stroke risk by lowering blood pressure.

RESULTS

Multivariable Mendelian randomization analysis indicated a potential inverse correlation between Omega-3 intake and both blood pressure and ischemic stroke. Consequently, Omega-3 was selected as the exposure, with blood pressure and ischemic stroke-related data as outcomes, for further bidirectional and mediation Mendelian Randomization analyses. Bidirectional Mendelian Randomization revealed that Omega-3 significantly influences DBP (P = 1.01e-04) and IS (P = 0.016). It also showed that DBP and SBP significantly affect LAS, SVS, CES, IS, and LS. Mediator Mendelian Randomization identified five established mediating pathways: Omega-3-Diastolic blood pressure-Small vessel stroke, Omega-3-Diastolic blood pressure-Cardioembolic stroke, Omega-3-Diastolic blood pressure-Lacunar stroke, Omega-3-Diastolic blood pressure-Large artery atherosclerosis stroke, and Omega-3-Diastolic blood pressure-Ischemic stroke. Of these, four pathways are complete mediation, and one pathway is partial mediation.

CONCLUSIONS

The findings suggest that Omega-3 may indirectly reduce the incidence of ischemic stroke by lowering blood pressure. Thus, blood pressure modulation might be one of the mechanisms through which Omega-3 prevents ischemic stroke. In summary, incorporating an increased intake of Omega-3 in the diet can serve as one of the dietary intervention strategies for patients with hypertension. Additionally, it can act as an adjunctive therapy for the prevention of ischemic strokes and their complications.

Does Gastroesophageal Reflux Disease Increase the Risk of Sepsis and Its 28-day Mortality? A Causal Study Using a Mendelian Randomization Approach

BACKGROUND

Gastroesophageal reflux disease (GERD) is a prevalent gastrointestinal disorder. Recent studies indicate that GERD may exert systemic effects, potentially elevating the risk of severe infections, including sepsis. Nevertheless, the causal relationship between GERD and sepsis, as well as sepsis-related 28-day mortality, remains uncertain.

AIM

The aim of this study is to investigate the causal relationship between GERD and the risk of sepsis, including 28-day mortality of sepsis.

METHODS

This study utilized a two-sample Mendelian Randomization (MR) approach to analyze data from publicly available genome-wide association studies (GWAS) databases ( https://gwas.mrcieu.ac.uk/ ). The analysis comprised 129,080 cases and 473,524 controls for GERD; 11,643 patients and 474,841 controls for sepsis; and 1,896 patients and 484,588 controls for 28-day mortality from sepsis. The objective was to evaluate the causal impact of GERD on the risk of sepsis and 28-day sepsis mortality. Genetic variation data pertinent to GERD were obtained from the most recent genome-wide association studies (GWAS). The primary analysis employed the Inverse Variance Weighted (IVW) method. Sensitivity and pleiotropy analyses were performed to validate the robustness of the findings.

RESULTS

MR analysis revealed a notable link between genetically predicted GERD and increased sepsis risk (odds ratio [OR] 1.37, 95% confidence interval [CI] 1.24-1.52; p = 2.79 × 10-9). Moreover, GERD correlated with elevated 28-day mortality of sepsis (OR 1.44, 95% CI 1.11-1.85; p = 5.34 × 10-3). These results remained consistent throughout various sensitivity analyses, indicating their resilience against potential pleiotropy and other biases.

CONCLUSION

This study indicates that genetic predisposition to GERD may be linked to an elevated risk of sepsis and its associated 28-day mortality. However, the study does not establish a direct causal relationship for GERD itself, nor does it assess the impact of GERD treatment. Further research is needed to explore the underlying mechanisms and potential therapeutic interventions involved.

The impact of sex hormones on metabolic syndrome: univariable and multivariable Mendelian randomization studies

BACKGROUND

Observational studies have found associations between sex hormones and metabolic syndrome(Mets), but the causal relationships remains unclear. This study utilizes univariable and multivariable Mendelian randomization (MR) to elucidate the associations between sex hormones (including sex hormone-binding globulin(SHBG), estradiol(E2), testosterone(T)) and Mets and its subtypes (including waist circumference(WC), fasting blood glucose(FBG), high blood pressure(HBP), high-density lipoprotein(HDL-C), triglycerides(TG)).

METHODS

We utilized summary data from large-scale genome-wide association studies. Univariable Mendelian randomization (UMVMR) analysis was primarily conducted using the inverse variance weighted method (IVW), with secondary analyses employing the weighted median, MR-Egger regression, simple mode method, and weighted mode method. Subsequently, multivariable Mendelian randomization (MVMR) was employed to assess the causal relationships between SHBG, T, E2, and MetS and its components: WC, FPG, HBP, HDL-C, and TG. Sensitivity analyses were conducted to assess result reliability.

RESULTS

Genetically predicted SHBG was significantly negatively associated with MetS (UMVMR: β=-0.72; 95% CI = 0.41 to 0.57; P = 1.28e-17; MVMR: β=-0.60; 95% CI=-0.83 to -0.38; P < 0.001). Positive causal relationships were observed between SHBG and WC(MVMR: β = 0.10; 95% CI = 0.03 to 0.17; P = 0.01) and HDL-C (MVMR: β = 0.41; 95% CI = 0.21 to 0.60; P < 0.001), while negative causal relationships were found between SHBG and HBP (MVMR: β=-0.02; 95% CI=-0.04 to -0.00; P = 0.02), TG (MVMR: β=-0.48; 95% CI=-0.70 to -0.26; P < 0.001). Genetically predicted E2 exhibited a negative association with TG (MVMR: β=-1.49; 95% CI=-2.48 to -0.50; P = 0.003). Genetically predicted T was negatively associated with TG (MVMR: β=-0.36; 95% CI=-0.71 to -0.00; P = 0.049) and WC (MVMR: β=-0.13; 95% CI=-0.24 to -0.02; P = 0.02), with inconsistent sensitivity analyses. Additionally, No other causal associations were found.

CONCLUSION

Our study indicates that SHBG is a protective factor for MetS, potentially delaying its onset and progression through improvements in HBP and TG. Furthermore, T and E2 may improve TG levels, with T also reducing WC levels. Importantly, our study provides new insights for the prevention and treatment of MetS.

No genetic causal association between human papillomavirus and lung cancer risk: a bidirectional two-sample Mendelian randomization analysis

INTRODUCTION

Several observational or retrospective studies have previously been conducted to explore the possible association between lung cancer and human papillomavirus (HPV) infection. However, there may be inconsistencies in the data and conclusions due to differences in study design and HPV testing methods. There are currently no studies that provide conclusive evidence to support the involvement of HPV in the occurrence and development of lung cancer. Therefore, the relationship between HPV and lung cancer remains controversial and uncertain. This study aimed to explore whether HPV infection is causally related to lung cancer risk by systematically performing a two-way Two-Sample Mendelian Randomization (TSMR) analysis.

METHODS

In the International Lung Cancer Consortium (ILCCO) genome-wide association study dataset, we included 11,348 lung cancer (LUCA) cases, including 3275 squamous cell carcinoma (LUSC) cases, 3442 adenocarcinoma (LUAD) cases, and 15,861 cases of control. Using genetic variants associated with the HPV E7 protein as instrumental variables, we summarized statistics associated with HPV infection in the MRC IEU OpenGWAS database, which included the HPV-16 E7 protein and the HPV-18 E7 protein. Two-sample Mendelian randomization (MR) results are expressed as odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Based on a comprehensive analysis of genome-wide association study (GWAS) data from public databases, we mainly used inverse-variance weighted (IVW) to estimate causal relationships, while using MR-Egger, weighted median, simple mode, and weighted mode, and other four methods as supplements. Two-sample MR Analysis revealed no causal relationship between exposure factors (HPV-16 E7 protein and HPV-18 E7 protein) and outcome factors (lung cancer (LUCA) and its subtypes squamous cell carcinoma (LUSC) and adenocarcinoma (LUAD)) in forward MR Analysis using the IVW approach.HPV-16 E7 protein and LUCA and its subtypes LUSC and LUAD by IVW method results: [OR] = 1.002; 95% [CI]: 0.961 - 1.045; p = 0.920; [OR] = 1.023; 95% [CI]: 0.966 - 1.084; p = 0.438; [OR] = 0.994; 95% [CI]: 0.927 - 1.066; p = 0.872); HPV-18 E7 protein and LUCA and its subtypes LUSC and LUAD by IVW method results: [OR] = 0.965; 95% [CI]: 0.914 - 1.019; p = 0.197; [OR] = 0.933; 95% [CI]: 0.834 - 1.043; p = 0.222; [OR] = 1.028; 95% [CI]: 0.945 - 1.118; p = 0.524. It was observed through reverse MR that LUCA and its subtypes LUSC and LUAD were used as exposure factors, and HPV infection (HPV-16 E7 protein and HPV-18 E7 protein) was used as the outcome factors, the results of the IVW method are also invalid.LUCA and HPV-16 E7 protein and HPV-18 E7 protein by IVW method results: [OR] = 1.036; 95% [CI]: 0.761 - 1.411; p = 0.82; [OR] = 1.318; 95% [CI]: 0.949 - 1.830; p = 0.099; LUSC and HPV-16 E7 protein and HPV-18 E7 protein by IVW method results: [OR] = 1.123; 95% [CI]0.847 - 1.489; p = 0.421; [OR] = 0.931; 95% [CI]: 0.660 - 1.313; p = 0.682; LUAD and HPV-16 E7 protein and HPV-18 E7 protein by IVW method results: [OR] = 1.182; 95% [CI] 0.983 - 1.421; p = 0.075; [OR] = 1.017; 95% [CI]: 0.817 - 1.267; p = 0.877.Our results indicate that there is no causal relationship between genetically predicted HPV infection and LUCA and its subtypes LUSC and LUAD. In addition, in the reverse MR analysis, we did not observe a significant causal relationship between LUCA and its subtypes LUSC and LUAD on HPV infection.

CONCLUSIONS

Our findings do not support a genetic association between HPV infection and lung cancer.

Analysis of the Relationship Between Parkinson's Disease and Diabetic Retinopathy Based on Bioinformatics Methods

The objective of the study was to explore the relationship and potential mechanism between Parkinson's disease (PD) and diabetic retinopathy (DR) using bioinformatics methods. We first examined the causal relationship between PD and DR by Mendelian randomization (MR) analysis. The datasets of PD and DR patients from the Gene Expression Omnibus database were used to identify differentially expressed genes (DEGs). Then, we performed the Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and immune infiltration analysis. We also constructed a protein-protein interaction network and receiver operating characteristic (ROC) curve. Finally, an online website was used for drug prediction. The MR analysis demonstrated a causal relationship between DR and PD (odds ratio [OR] = 0.86; 95% confidence interval [CI] 0.79-0.93; p = 3.24E - 04), in which DR acted as a protective factor against PD. There were 81 DEGs identified from the PD and DR datasets, of which 29 genes had protein interaction relationships, and enrichment analysis showed that these genes were mainly related to immune pathways. As indicated by immune cell infiltration analysis, the expression of immune cells between PD and the control group was significantly different. ROC curve results showed five genes had diagnostic value, and several potential chemical compounds were predicted to target the genes. Our findings demonstrate a reduced risk of PD in patients with DR. We also found that PD and DR are closely related in terms of inflammation, which provides clues for further exploring the common mechanisms and interaction of these two diseases.

Causal relationship between OHSS and immune cells: A Mendelian randomization study

OBJECTIVE

To confirm the causal relationship between immune cells and Ovarian Hyperstimulation Syndrome.

DESIGN

Obtaining data, collecting single nucleotide polymorphisms, detecting instrumental variables heterogeneity, assessing causality, and assessing bidirectional causality.

SUBJECTS

A two sample Mendelian study to confirm the causal relationship between immune cells and Ovarian Hyperstimulation Syndrome.

EXPOSURE

Immune cell phenotype (including 22 million SNPs from GWAS on 3757 European individuals).

MAIN OUTCOME MEASURES

Inverse variance weighting, one-sample analysis, MR-Egger, weighted median and weighted mode are used to assess the causal relationship between 731 immunophenotypes and Ovarian Hyperstimulation Syndrome. The weighted median and Mendelian Randomization multi-effect residuals and Mendelian Randomization multi-effect residuals and outlier tests are used to assess bidirectional causality between this two.

RESULTS

After False Discovery Rate correction, 9 immunophenotypes were found to be significantly associated with the risk of Ovarian Hyperstimulation Syndrome. B cell panel: IgD+ AC (OR, 0.90) 、CD19 on CD24+ CD27+ (OR, 0.86) 、BAFF-R on CD20- CD38 (OR, -1.22); Mature T cell group panel: EM DN (CD4 -CD8-) AC (OR, 1.46); Myeloid cell panel: Mo MDSC AC (OR, 1.13) 、CD45 on CD33br HLA-DR+ (OR, 0.87); Monocyte panel: HLA-DR on monocyte (OR, 0.86) 、CCR2 on CD14+ CD16+ monocyte (OR, 1.15) 、cDC panel: HLA-DR on myeloid DC (OR, 0.89).

CONCLUSION

This study shows the potential link between OHSS and immune cells by genetic means, providing new ideas for future clinical and basic research.

The impact of depression-mediated gut microbiota composition on Irritable Bowel Syndrome: A Mendelian study

OBJECTIVE

This study uses a two-sample Mendelian randomization (MR) analysis to delineate the causal influence of gut microbiota on the occurrence of irritable bowel syndrome (IBS), concurrently assessing the potential mediating function of depression within this framework.

METHODS

Several two-sample MR methods were used to assess the causal repercussions of gut microbiota on the onset of both IBS and depression. Following this, gut microbiota and depression, which demonstrated notable causal associations, were integrated as exposure variables in a multivariable Mendelian randomization (MVMR) framework to construct a model encompassing gut microbiota, depression, and IBS. Mediation effects were assessed by examining the indirect pathway of gut microbiota → depression → IBS.

RESULTS

Two-sample MR analysis unveiled a statistically significant causal association (P < 0.05) between specific bacterial group within the gut microbiota, notably p_Actinobacteria(OR = 0.829225), c_Clostridia(OR = 0.798897), s_Desulfovibrio_piger(OR = 1.163912), g_Streptococcus(OR = 1.132735), c_Actinobacteria(OR = 0.829224), and the onset of IBS. In the MVMR analysis, the relationship between depression and IBS was significant across Model 3, Model 7, Model 8, and Model 13 (P < 0.05). Assessment of mediation effects revealed that c_Clostridia and o_Clostridiales indirectly impacted IBS through depression, with masking effect ratios of 168.46 % and 168.44 %, respectively.

CONCLUSION

These findings underscore a resilient causal association between the composition of gut microbiota and the initiation of IBS. Furthermore, depression serves as a mediator for particular groups of gut bacteria, thereby contributing to the development of IBS. These observations imply that interventions targeting mental health may potentially alleviate the risk of IBS onset attributable to adverse configurations of gut microbiota.