Consistent Estimation in Mendelian Randomization with Some Invalid Instruments Using a Weighted Median Estimator

Personal history of irradiation and risk of breast cancer: A Mendelian randomisation study

Background

Studies on the relationship between personal history of irradiation and breast cancer have been reported for a long time. Still, epidemiological studies have not been conclusive, and the causal relationship is unclear. To address this issue, we employed Mendelian randomisation (MR) analysis to examine the association between individual radiation exposure history and breast cancer.

Methods

We used a series of quality control methods to select single nucleotide polymorphism (SNP) closely related to exposure. Meanwhile, several analysis methods were used to analyse the sample data to make the conclusion more reliable. To evaluate the horizontal pleiotropy, heterogeneity and stability of SNPs for breast cancer, the MR-Egger intercept test, Cochran's Q test and 'leave one' sensitivity analysis were used. Finally, the outlier variation determined by the Mendelian Randomisation Pleiotropy RESidual Sum and Outlier test is gradually eliminated to reduce the influence of heterogeneity and horizontal pleiotropy.

Results

After implementing rigorous quality control procedures, we carefully chose 102 qualified instrumental variables closely associated with the selected exposure for sensitivity analysis. This was conducted to evaluate the heterogeneity, level multiplicity, and stability of SNPs in the context of personal radiation history and its correlation with breast cancer. The results of the inverse variance weighted method analysis revealed a positive correlation between personal radiation and a heightened risk of breast cancer (odds ratio (OR) = 1.52; 95% confidence interval (CI) = 1.30-1.77). We also validated on another data set; the results were similar (OR = 1.51; 95% CI = 1.27-1.81). Furthermore, the findings from the sensitivity analysis were consistent. At the genetic level, our research demonstrated that personal radiation exposure is associated with an elevated risk of breast cancer.

Conclusions

Using genetic data provides evidence and strengthens the causal link that personal radiation causes breast cancer.

Novel Insights into Causal Effects of Serum Lipids and Apolipoproteins on Cardiovascular Morpho-Functional Phenotypes

Previous observational studies have explored the association between serum lipids, apolipoproteins, and adverse ventricular/aortic structure and function. However, whether a causal link exists is uncertain. This study employed a two-sample Mendelian randomization (MR), colocalization, reverse, and multivariable MR (MVMR) approach to examine the causal associations among five serum lipids, two apolipoproteins, and 32 cardiac magnetic resonance (CMR) traits. Utilizing single-nucleotide polymorphisms (SNPs) linked to serum lipids and apolipoproteins as instrumental variables. CMR traits from seven independent genome-wide association studies served as preclinical endophenotypes, offering insights into aortic and cardiac structure/function. The primary analysis utilized a random-effects inverse variance method (IVW), followed by sensitivity and validation analyses. In the primary IVW MR analyses, genetically predicted low-density lipoprotein cholesterol (LDL-C) levels were positively correlated with increased descending aorta strain (DAo strain) (β = 0.098; P = 2.69E-07) and ascending aorta strain (AAo strain) (β = 0.079; P = 5.19E-05). Genetically predicted high-density lipoprotein cholesterol (HDL-C) levels were positively correlated with left ventricular radial peak diastolic strain rate (LV-PDSRll) (β = 0.176; P = 2.89E-05) and the left ventricular longitudinal peak diastolic strain rate (LV-PDSRrr) (β = 0.059; P = 2.44E-06), and negatively correlated with left ventricular regional wall thickness (LVRWT). While apolipoprotein B (ApoB) levels were positively correlated with AAo strain (β = 0.076; P = 1.16E-05), DAo strain (β = 0.065; P = 2.77E-05). A shared causal variant was identified to demonstrate the associations of ApoB with AAo strain and DAo strain using colocalization analysis. Sensitivity analyses confirmed the robustness of these associations. Targeting lipid and apolipoprotein levels through interventions may provide novel strategies for the primary prevention of CVDs.

Systematic evaluation of multifactorial causal associations for Alzheimer's disease and an interactive platform MRAD developed based on Mendelian randomization analysis

Alzheimer's disease (AD) is a complex degenerative disease of the central nervous system, and elucidating its pathogenesis remains challenging. In this study, we used the inverse-variance weighted (IVW) model as the major analysis method to perform hypothesis-free Mendelian randomization (MR) analysis on the data from MRC IEU OpenGWAS (18,097 exposure traits and 16 AD outcome traits), and conducted sensitivity analysis with six models, to assess the robustness of the IVW results, to identify various classes of risk or protective factors for AD, early-onset AD, and late-onset AD. We generated 400,274 data entries in total, among which the major analysis method of the IVW model consists of 73,129 records with 4840 exposure traits, which fall into 10 categories: Disease, Medical laboratory science, Imaging, Anthropometric, Treatment, Molecular trait, Gut microbiota, Past history, Family history, and Lifestyle trait. More importantly, a freely accessed online platform called MRAD (https://gwasmrad.com/mrad/) has been developed using the Shiny package with MR analysis results. Additionally, novel potential AD therapeutic targets (CD33, TBCA, VPS29, GNAI3, PSME1) are identified, among which CD33 was positively associated with the main outcome traits of AD, as well as with both EOAD and LOAD. TBCA and VPS29 were negatively associated with the main outcome traits of AD, as well as with both EOAD and LOAD. GNAI3 and PSME1 were negatively associated with the main outcome traits of AD, as well as with LOAD, but had no significant causal association with EOAD. The findings of our research advance our understanding of the etiology of AD.

Mendelian randomization study reveals a causal relationship between body mass index in children and risk of autoimmune diseases

Newly emerging evidence indicates that body mass index (BMI) is a potential risk factor for autoimmune diseases (ADs). Nevertheless, the exact causal connection between ADs and BMI in children remains uncertain. To investigate the relationship between BMI in children and ADs, a 2-sample Mendelian randomization (MR) analysis was conducted. In this analysis, several regression methods were utilized, including the inverse-variance weighted (IVW), weighted mode, weighted median, and MR-Egger regression. Publicly available summary statistics datasets from meta-analyses of genome-wide association studies (GWAS) were employed, specifically focusing on BMI in children of European descent (n = 39,620) from the UK Biobank (ebi-a-GCST90002409) as the exposure group. The outcomes were derived from individuals included in the Finnish biobank study FinnGen, with 42,202 cases and 176,590 controls representing the ADs group (finngen_R5_AUTOIMMUNE). For instrumental variables, we carefully selected 16 single nucleotide polymorphisms (SNPs) from GWAS on BMI in children. Our analysis implemented the IVW method, which demonstrated supporting evidence for a causal association between BMI in children and ADs. The results indicated a significant effect with a beta coefficient of 0.22, standard error (SE) of 0.05, odds ratio (OR) of 1.25, and a 95% confidence interval (CI) ranging from 1.13 to 1.38, with a P-value of <.05. We also utilized the weighted median method, which yielded similar findings to the IVW method. The OR estimates from the weighted median analysis showed a beta coefficient of 0.20, SE of 0.06, OR of 1.22, and a 95% CI ranging from 1.08 to 1.36, with a P-value of <.05. No significant association was observed in the MR-Egger and Weighted mode analyses. The findings from the MR analysis suggest that there is evidence supporting a potential causal link between BMI in children and an increased susceptibility to ADs.

A Mendelian randomization study of the association between serum uric acid and osteoporosis risk

Background

The relationship between serum uric acid (SUA) and osteoporosis (OP) has yielded conflicting results in observational studies. This Mendelian randomization (MR) study aims to elucidate the causal association between SUA and OP.

Methods

A two-sample MR analysis was conducted using summary-level data from genome-wide association studies (GWAS). Two sets of polygenic instruments strongly associated (p < 5 × 10-8) with SUA were extracted from the CKDGen consortium and UK biobank. Polygenic instruments associated with OP (p < 5 × 10-8) were derived from FinnGen biobank and UK biobank. Inverse variance weighting (IVW) was employed as the primary analysis method. Additionally, we utilized MR-Egger, weighted median, the simple mode method, and the weighted mode as complementary analyses. Cochran's Q statistics were used to assess heterogeneity, with MR-Egger intercept testing and MR pleiotropy residual sum and outlier (MR-PRESSO) to examine horizontal pleiotropy. Sensitivity analysis was performed using the leave-one-out method.

Results

The IVW analysis conducted across four groups confirms no significant causal relationship between SUA concentration and OP: UKB-UKB (OR: 1.001, 95% CI: 0.999-1.003, p=0.464), CKD-UKB (OR: 1.001, 95% CI: 0.999-1.003, p=0.349), UKB-Fin (OR: 0.934, 95% CI: 0.747-1.168, p=0.549), CKD-Fin (OR: 1.041, 95%CI: 0.934-1.161, p=0.470). Furthermore, additional four MR analyses corroborated these findings. Upon excluding all outliers identified by the MR-PRESSO test, no significant directional pleiotropy was observed, except for some data heterogeneity noted in the UKB-UKB group (Q=50.65, P=0.002). Additionally, a leave-one-out analysis indicated that no single SNP exerted undue influence on the results.

Conclusion

This MR analysis provides convincing genetic evidence that there is no causal association between SUA and OP, SUA is unlikely to increase or reduce the risk of OP.

Decoding skin mysteries: Unveiling the link between microbiota and keloid scars through a Mendelian randomization study

The cause of keloids remains unclear, but studies suggest a link between skin microbiota and keloid formation. However, the causal relationship has not been confirmed. This study utilized Genome-Wide Association Studies (GWAS) data from 2 population-based German cohorts, comprising a total of 1656 skin samples. To bolster the reliability of our results, we incorporated GWAS data from 3 keloid cohorts, encompassing 2555 patients and 870,556 controls (GWAS ID: keloid1, ebi-a-GCST90018874; keloid2, bbj-a-131; keloid3, ebi-a-GCST90018654). Subsequently, we employed bidirectional 2-sample Mendelian randomization (MR) analysis to probe the causal relationship between the variables. The primary method employed was the inverse-variance weighted (IVW) method, supported by heterogeneity analysis, horizontal pleiotropy testing, outlier detection, and "leave-one-out" sensitivity analysis. By synthesizing the results from 3 groups of MR analyses, we discovered a negative causal association between a.ASV063 [Finegoldia (unc.)] located on the volar forearm and keloid disease (IVW (keloid1) odds ratio (OR): 0.939, 95% confidence interval (CI): 0.886-0.994, P = .032; IVW (keloid2) OR: 0.897, 95% CI: 0.813-0.990, P = .031; IVW (keloid3) OR: 0.900, 95% CI: 0.825-0.981, P = .017). Similarly, a negative causal relationship may also exist between the genus: Bacteroides from the antecubital fossa and keloid disease (IVW (keloid1) OR: 0.928, 95% CI: 0.884-0.973, P = .002; IVW (keloid2) OR: 0.891, 95% CI: 0.820-0.968, P = .007; IVW (keloid3) OR: 0.918, 95% CI: 0.849-0.992, P = .030). Additionally, no reverse causation was found, with all analyses showing no signs of horizontal pleiotropy or heterogeneity. This study offers new insights for the prevention and treatment of keloids.

Mediation effect of plasma metabolites on the relationship between immune cells and the risk of prostatitis: A study by bidirectional 2-sample and Bayesian-weighted Mendelian randomization

According to the findings of multiple observational studies, immune disorder was a risk factor for prostatitis. However, it remained unknown whether there was a direct causal relationship between immune cells and prostatitis or whether this relationship was mediated by plasma metabolites. Based on the pooled data of a genome-wide association study (GWAS), a genetic variant was used to predict the effects of 731 immunophenotypes on the risk of prostatitis and determine whether the effects were mediated by 1400 metabolites. The bidirectional 2-sample Mendelian randomization (MR) method was adopted to uncover the causal relationship between immunophenotypes and prostatitis. Subsequently, a 2-step MR method was employed to evaluate whether the metabolites mediated this causal relationship and quantify the mediating effects and the corresponding ratios. In addition, the Bayesian-weighted Mendelian randomization (BWMR) method was employed to verify the results. Among the 731 immunophenotypes analyzed, 16 had causal relationships with the risk of prostatitis, including 11 with positive correlations (P < .05, beta > 0) and 5 with negative correlations (P < .05, beta < 0). The MR analysis screened out 9 metabolites related to the risk of prostatitis. The X - 24344 levels mediated the causal relationship between CD3 on CD39+ activated Treg and prostatitis (mediation effect: 0.01; ratio: 9.82%). Both histidine betaine (hercynine) levels and the proline-to-glutamate ratio mediated the causal relationship between CD14-CD16+ monocyte absolute count and prostatitis, with the mediation effects of -0.016 (14.20%) and -0.008 (7.24%), respectively. The glutamine degradant levels mediated the causal relationship between HLA DR+ CD4+ %T cells and prostatitis, with a mediation effect of -0.012, accounting for 8.07% of the total. The present study indicated that the immune cell subsets predicted based on gene expression profiles were potentially beneficial or harmful risk factors of prostatitis, and plasma metabolites may serve as the mediating factors of the relationship. The study thus shed light on deciphering the immunologic mechanism of prostatitis.

Association between dietary fat intake and the risk of Alzheimer's disease: Mendelian randomisation study

BACKGROUND

Observational studies have shown a controversial relationship between dietary fat intake and Alzheimer's disease, and the causal effects are unclear.

AIMS

To assess the causal effects of total fat, saturated fat and polyunsaturated fat (PUF) intakes on the risk of Alzheimer's disease.

METHOD

A two-sample Mendelian randomisation analysis was performed using genome-wide association study summary statistics on different types of fat intake from UK Biobank (n = 51 413) and on late-onset Alzheimer's disease (LOAD; 4282 cases, n = 307 112) and all forms of Alzheimer's disease (6281 cases, n = 309 154) from the FinnGen consortium. In addition, a multivariable Mendelian randomisation (MVMR) analysis was conducted to estimate the effects independent of carbohydrate and protein intakes.

RESULTS

Genetically predicted per standard deviation increase in the total fat and saturated fat intakes were associated with 44 and 38% higher risks of LOAD (total fat: odds ratio = 1.44, 95% CI 1.03-2.02; saturated fat: odds ratio = 1.38, 95% CI 1.002-1.90; P = 0.049). The associations remained significant in the MVMR analysis (total fat: odds ratio = 3.31, 95% CI 1.74-6.29; saturated fat: odds ratio = 2.04, 95% CI 1.16-3.59). Total fat and saturated fat intakes were associated with a higher risk of all forms of Alzheimer's disease in the MVMR analysis (total fat: odds ratio = 2.09, 95% CI 1.22-3.57; saturated fat: odds ratio = 1.60, 95% CI 1.01-2.52). The PUF intake was not associated with LOAD or all forms of Alzheimer's disease.

CONCLUSIONS

This study indicated that total dietary fat intake, especially saturated fat, contributed to the risk of Alzheimer's disease, and the effects were independent of other nutrients. These findings informed prevention strategies and management for Alzheimer's disease directly towards reducing dietary saturated fat intake.

Genetic architectures of the human hippocampus and those involved in neuropsychiatric traits

BACKGROUND

The hippocampus, with its complex subfields, is linked to numerous neuropsychiatric traits. While most research has focused on its global structure or a few specific subfields, a comprehensive analysis of hippocampal substructures and their genetic correlations across a wide range of neuropsychiatric traits remains underexplored. Given the hippocampus's high heritability, considering hippocampal and subfield volumes (HASV) as endophenotypes for neuropsychiatric conditions is essential.

METHODS

We analyzed MRI-derived volumetric data of hippocampal and subfield structures from 41,525 UK Biobank participants. Genome-wide association studies (GWAS) on 24 HASV traits were conducted, followed by genetic correlation, overlap, and Mendelian randomization (MR) analyses with 10 common neuropsychiatric traits. Polygenic risk scores (PRS) based on HASV traits were also evaluated for predicting these traits.

RESULTS

Our analysis identified 352 independent genetic variants surpassing a significance threshold of 2.1 × 10-9 within the 24 HASV traits, located across 93 chromosomal regions. Notably, the regions 12q14.3, 17q21.31, 12q24.22, 6q21, 9q33.1, 6q25.1, and 2q24.2 were found to influence multiple HASVs. Gene set analysis revealed enrichment of neural differentiation and signaling pathways, as well as protein binding and degradation. Of 240 HASV-neuropsychiatric trait pairs, 75 demonstrated significant genetic correlations (P < 0.05/240), revealing 433 pleiotropic loci. Particularly, genes like ACBD4, ARHGAP27, KANSL1, MAPT, ARL17A, and ARL17B were involved in over 50 HASV-neuropsychiatric pairs. Leveraging Mendelian randomization analysis, we further confirmed that atrophy in the left hippocampus, right hippocampus, right hippocampal body, and right CA1-3 region were associated with an increased risk of developing Parkinson's disease (PD). Furthermore, PRS for all four HASVs were significantly linked to a higher risk of Parkinson's disease (PD), with the highest hazard ratio (HR) of 1.30 (95% CI 1.18-1.43, P = 6.15 × 10⁻⁸) for right hippocampal volume.

CONCLUSIONS

These findings highlight the extensive distribution of pleiotropic genetic determinants between HASVs and neuropsychiatric traits. Moreover, they suggest a significant potential for effectively managing and intervening in these diseases during their early stages.

The impact of sleep problems on cerebral aneurysm risk is mediated by hypertension: a mediated Mendelian randomization study

Introduction

Cerebral aneurysm (CA) is a common vascular disease. The risk factors of CA include hypertension, smoking, and a family history of genetic predisposition. Although sleep-related problems have been found to have a strong association with cardiovascular disease, there is a lack of research regarding the causal relationship with cerebral aneurysms.

Methods

In this study, we investigated the causal relationship between four sleep-related problems, including snoring, insomnia, narcolepsy, and napping during the day, and CA using a two-sample Mendelian randomization (MR) analysis. Moreover, the potential confounders before sleep problems and CA were further analyzed by multivariate MR (MVMR).

Results

The causal relationship between insomnia and CA was obtained analytically by means of six MR analyses. There was a strong causal effect relationship between insomnia and CA, which suggests this as a potential risk factor [odds ratio (OR) = 8.35, 95% confidence interval (CI) = 2.422-28.791, p = 7.772e-04]. On this basis, hypertension was identified as a mediator between insomnia and CA by MVMR, with a mediating effect of 52.538% (OR = 3.05, 95% CI = 1.549-4.55, p = 0.015).

Conclusion

The causal relationship between insomnia and CA was predicted using genetic variance data, and insomnia was found to be a potential risk factor. Furthermore, hypertension is a mediator between insomnia and CA. Therefore, focusing on sleep problems and improving sleep quality may be an active and effective strategy to prevent CA.

Effects of multiple fluid intake on Urolithiasis by mendelian randomization study

Urolithiasis, a common and recurrent condition, imposes a significant global health burden. This study investigates the causal relationship between various types of fluid intake and urolithiasis using univariable and multivariable Mendelian randomization (MR) approaches. Genetic data for urolithiasis were obtained from the FinnGen Consortium (n = 400,681), while genetic measures for nine fluid types were sourced from meta-analyses of genome-wide association studies (GWAS). The analysis revealed that genetically predicted coffee intake (OR: 0.571, 95% confidence interval (CI): 0.341-0.958, p = 0.034) and ground coffee intake (OR: 0.219, 95% CI: 0.005-0.923, p = 0.038) were protective factors for upper urinary calculi. Additionally, a standard deviation (SD) increase in tea intake was associated with a 53% reduction in risk (OR: 0.473, 95% CI: 0.320-0.700, p < 0.001). Conversely, milk intake (OR: 1.072, 95% CI: 1.018-1.130) and alcohol intakefrequency (OR: 1.304, 95% CI: 1.083-1.570, p = 0.005) increased the risk of upper urinary calculi. These findings highlight the association of tea with reduced risk of urolithiasis, instead for milk and alcohol intake, in formulating prevention strategies for urolithiasis.

Assessing the causal relationship between CRP, IL-1α, IL-1β, and IL-6 levels and intervertebral disc degeneration: a two-sample Mendelian randomization study

Growing research has suggested an association between chronic inflammation and Intervertebral disc degeneration (IVDD), but whether there is a causal effect remains unknown. This study adopted two-sample Mendelian randomization (MR) approach to explore the etiological role of chronic inflammation in IVDD risk. Here, summary statistics for C-reactive protein (CRP), interleukin (IL)-1 α , IL-1 β , IL-6 expression and IVDD were obtained from genome-wide association studies (GWAS) of European ancestry. MR analyses were conducted by using inverse variance weighted (IVW), Wald Ratio, weighted median, and MR-Egger method. Sensitivity analyses were conducted to assess the robustness of the results. The MR analyses suggested a lack of causal association of CRP, IL-6 , and IL-1 α levels on IVDD (CRP-IVDD: odds ratio [OR] = 0.97, 95% confidence interval [CI] 0.86-1.09, P = 0.583; IL-6-IVDD: OR = 1.04, 95% CI 0.86-1.27, P = 0.679; IL-1 α -IVDD: OR = 1.09, 95%CI 1.00-1.18, P = 0.058). However, there was a sign of a connection between genetically elevated IL-1 β levels and a decreased IVDD incidence (OR = 0.87, 95%CI 0.77-0.99, P = 0.03). Our findings suggest a connection between IL-1 β levels and the risk of IVDD. However, due to the support of only one SNP, heterogeneity and pleiotropy tests cannot be performed, the specific underlying mechanisms warrant further investigation.

Relationships between emotional states, bipolar disorder, and gastrointestinal disorders: A two-sample Mendelian randomization study

BACKGROUND

Functional gastrointestinal symptoms are frequently observed in patients with bipolar affective disorder, but the causal relationship between these conditions remains unclear. To establish causality, this study utilized Mendelian randomization (MR) with data from large-scale genomic research. The investigation aimed to elucidate the relationship between emotional states, bipolar disorder, and functional gastrointestinal disorders (FGIDs).

METHODS

Summary statistics from GWAS were utilized for mood swings (UK biobank, N = 451,619), irritable mood (UK biobank, N = 373,733), bipolar disorder (UK biobank, N = 352,006),functional dyspepsia (FinnGen biobank, N = 194,071), and irritable bowel syndrome (UK biobank, N = 486,601). All GWAS summary statistics were derived from individuals of European ancestry. The primary analysis employed the inverse variance-weighted method for Mendelian randomization (MR). Additionally, we conducted tests for heterogeneity and pleiotropy to ensure the robustness of our results.

RESULTS

A suggestive positive causal relationship was identified between mood swings-related conditions and IBS using the inverse variance-weighted (IVW) method [mood swings-IBS: OR/95%CI: 3.221(2.417,4.294), P(1.42E-15); irritable mood-IBS: OR/95%CI: 1.881(1.615,2.191), P(4.56E-16); bipolar disorder-IBS: OR/95%CI: 1.003(1.001,1.006), P(0.009)]. For functional dyspepsia, a suggestive positive causal relationship was observed with mood swings [mood swings-FD: OR/95%CI: 2.827(1.124,7.109), P(0.027)]. In the reverse analysis, causal relationship was observed between IBS and emotional states [IBS and mood swings: OR/95%CI: 1.030(1.021,1.040), P(1.10E-10); IBS and irritable mood: OR/95%CI: 1.064(1.041,1.087), P(2.58E-08)].

CONCLUSIONS

Mood swings, irritable mood, and bipolar disorder were associated with an increased risk of functional gastrointestinal disorders (FGIDs). Additionally, reverse analysis revealed a causal relationship between irritable bowel syndrome (IBS) and both mood swings and irritable mood. These findings suggest that targeted emotional interventions may be beneficial for patients with FGIDs. Further research is warranted to explore the relationship between mood instability-related disorders and FGIDs, particularly IBS.

A novel framework with automated horizontal pleiotropy adjustment in mendelian randomization

The presence of horizontal pleiotropy in Mendelian randomization (MR) analysis has long been a concern due to its potential to induce substantial bias. In recent years, many robust MR methods have been proposed to address this by relaxing the "no horizontal pleiotropy" assumption. Here, we propose a novel two-stage framework called CMR, which integrates a conditional analysis of multiple genetic variants to remove pleiotropy induced by linkage disequilibrium, followed by the application of robust MR methods to model the conditional genetic effect estimates. We demonstrate how the conditional analysis can reduce horizontal pleiotropy and improve the performance of existing MR methods. Extensive simulation studies covering a wide range of scenarios of horizontal pleiotropy showcased the superior performance of the proposed CMR framework over the standard MR framework in which marginal genetic effects are modeled. Moreover, the application of CMR in a negative control outcome analysis and investigation into the causal role of body mass index across various diseases highlighted its potential to deliver more reliable results in real-world applications.

Association between circulating inflammatory proteins and benign prostatic disease: a Mendelian randomization study

Previous research has suggested that circulating inflammatory proteins are associated with benign prostatic disease (BPD). This Mendelian randomization (MR) study was conducted to further investigate the causal relationship between 91 inflammatory proteins and BPD. Genome-wide association study (GWAS) summarized data of benign prostatic hyperplasia (BPH) and prostatitis were obtained from the FinnGen Biobank. The latest study offered the GWAS data on 91 proteins related to inflammation. We performed a bidirectional MR to investigate the causal association between inflammatory proteins and BPD. The outcomes of the IVW method indicated that decreased levels of circulating interleukin-17 C (IL-17 C) (OR = 0.92, 95%CI = 0.85-0.99, p-value = 0.0344) were suggestively associated with a higher risk of BPH and elevated levels of interleukin-10 receptor subunit alpha (IL-10RA) (OR = 1.24, 95%CI = 1.05-1.47, p-value = 0.0132) and urokinase-type plasminogen activator (uPA) (OR = 1.13, 95%CI = 1.00-1.28, p-value = 0.0421) were suggestively related to a higher risk of prostatitis. Furthermore, reverse MR revealed that BPH may promote the expression of circulating factors, including natural killer cell receptor 2B4 (CD244) (OR = 1.07, 95%CI = 1.01-1.13, p-value = 0.0192), T-cell surface glycoprotein CD6 isoform (CD6) (OR = 1.07, 95%CI = 1.01-1.13, p-value = 0.0192), and leukemia inhibitory factor receptor (LIF-R) (OR = 1.07, 95%CI = 1.01-1.15, p-value = 0.0163). Moreover, the results of sensitivity analyses indicate that heterogeneity and horizontal pleiotropy are unlikely to distort the findings. The results of this study indicate a potential association between circulating inflammatory proteins and BPD, which may become new diagnostic indicators or drug targets for clinical application in the prevention and treatment of BPD. However, further investigation is required.

The role of mitochondrial DNA copy number in autoimmune disease: a bidirectional two sample mendelian randomization study

Background

Mitochondrial DNA (mtDNA) plays an important role in autoimmune diseases (AD), yet the relationship between mitochondria and autoimmune disease is controversial. This study employed bidirectional Mendelian randomization (MR) to explore the causal relationship between mtDNA copy number and 13 ADs (including ankylosing spondylitis [AS], Crohn's disease [CD], juvenile rheumatoid arthritis [JRA], polymyalgia rheumatica [PMR], psoriasis [PSO], rheumatoid arthritis [RA], Sjogren's syndrome [SS], systemic lupus erythematosus [SLE], thyrotoxicosis, type 1 diabetes mellitus [T1DM], ulcerative colitis [UC], and vitiligo).

Methods

A two-sample MR analysis was performed to assess the causal relationship between mtDNA copy number and AD. Genome-wide association study (GWAS) for mtDNA copy number were obtained from the UK Biobank (UKBB), while those associated with AD were sourced from the FinnGen Biobank. Inverse variance weighting (IVW) was the primary analysis method, complemented by three sensitivity analyses (MR-Egger, weighted median, weighted mode) to validate the results.

Results

IVW MR analysis identified significant associations between mtDNA copy number and CD (OR=2.51, 95% CI 1.56-4.22, P<0.001), JRA (OR=1.87, 95% CI 1.17-7.65, P=0.022), RA (OR=1.71, 95%CI 1.18-2.47, P=0.004), thyrotoxicosis (OR=0.51, 95% CI0.27-0.96, P=0.038), and T1DM (OR=0.51, 95% CI 0.27-0.96, P=0.038). Sensitivity analyses indicated no horizontal pleiotropy.

Conclusions

Our study revealed a potential causal relationship between mtDNA copy number and ADs, indicating that these markers may be relevant in exploring new therapeutic approaches.

Causal relationship between oral microbiota and epilepsy risk: Evidence from Mendelian randomization analysis in East Asians

OBJECTIVE

Gut microbiota can traverse into the brain, activate the vagus nerve, and modulate immune responses and inflammatory processes, thereby influencing the onset of epileptic seizures. However, research on oral microbiota and epilepsy remains limited, and observational studies have been inconsistent. We aim to estimate the potential links between oral microbiota and epilepsy and elucidate which specific oral microbes may directly influence the pathogenesis of epilepsy.

METHODS

A two-sample MR analysis was conducted using genome-wide association study (GWAS) data specific to OM and epilepsy in East Asian individuals. Single nucleotide polymorphisms (SNPs) independent of confounders served as instrumental variables (IVs) to deduce causality. MR methodologies, including inverse variance weighted (IVW), MR-Egger, weighted median, and weighed mode methods, were utilized. Sensitivity analysis, including Cochrane's Q test, MR-Egger intercept test, and leave-one-out analysis, was applied to confirm the robustness of results.

RESULTS

Among the 3117 bacterial taxa examined, we observed that 14 OM, like s_Streptococcus_mitis, s_Streptococcus_pneumoniae, and s_Haemophilus, were positively associated with epilepsy, while 7 OM, like g_Fusobacterium and g_Aggregatibacter, were negatively related to epilepsy. The MR-Egger intercept suggested that no evidence of horizontal pleiotropy was observed (p > 0.05). The leave-one-out analysis validated the robustness of the results.

SIGNIFICANCE

This study underscores the effect of OM on epilepsy, suggesting potential mechanisms between the OM and epilepsy. Further investigation into the potential role of the OM is needed to enhance our in-depth understanding of the pathogenesis of epilepsy.

PLAIN LANGUAGE SUMMARY

Previous research has demonstrated that the microbiota may influence the onset of epileptic seizures. We applied 3117 oral microbiota from the newest publicly available database of East Asian populations. Mendelian randomization analysis was utilized to estimate the causal relationship between oral microbiota and epilepsy. Our results showed that a causal effect exists between 21 oral microbiota and epilepsy. We provided genetic evidence for risk assessment and early intervention in epilepsy.

Vitamin D levels and risk of ocular disorders: insights from bidirectional and multivariable Mendelian randomization analysis

Purpose

This study aimed to assess the causal relationships between vitamin D levels and ocular disorders.

Methods

Independent genetic variables were obtained from genome-wide association studies (GWAS) and publicly available databases. The summary statistics for 25-hydroxyvitamin D (25(OH)D) were obtained from two large-scale GWAS studies, with sample sizes of 324,105 and 417,580 European individuals. The genetic variants of myopia, primary open angle glaucoma (POAG), anterior iridocyclitis, senile cataract, diabetic retinopathy (DR), retinal vein occlusion (RVO), wet age-related macular degeneration (WAMD) and optic neuritis were extracted from the latest release of FinnGen consortium, which contains genome data from Finnish participants. Subsequently, Mendelian randomization (MR) analyses were conducted to obtain effect estimates. Additionally, we performed multivariable MR analysis and mediation analysis to validate the results.

Results

In the discovery dataset, genetically predicted vitamin D concentration was found to be causally associated with an increased risk of WAMD, (odd ratio (OR) = 1.35, 95% confidence interval (CI) = 1.09-1.67, P IVW = 0.005). However, no causal effects of genetically predisposed vitamin D levels on the risk of most types of ocular disorders were observed. Reverse MR revealed no causal relationships between the ocular diseases and vitamin D concentrations. The MR analyses of the validation dataset yielded consistent results. Additionally, the causal effect of vitamin D levels on the risk of WAMD remained significant after adjusting for potential confounders in the multivariable MR analysis (OR = 1.86, 95% CI = 1.26-2.73, P IVW = 0.002).

Conclusion

Our MR analysis results provide robust evidence of a causal relationship between genetically predicted 25(OH)D levels and an increased risk of WAMD in European population. These findings offer important insights into the management and control of ocular disorders.

The Causal Relationship between Immune-Mediated Inflammatory Diseases and Aortic Aneurysm: A Bidirectional Two-Sample Mendelian Randomization Study

Methods

We sourced genetic association data from public genome-wide association study databases for populations of European ancestry. Adhering to MR principles, we identified valid instrumental variables from genetic variants. A range of statistical methods were applied for MR analysis, with the inverse variance weighted (IVW) method emerging as the most reliable estimator of causality in this context.

Results

The causal estimates obtained using the IVW method revealed a significant association between genetically predicted AA and rheumatoid arthritis (RA; OR = 1.06, 95% CI = 1.01-1.12, P=0.029). Conversely, genetically predicted RA showed nonsignificant causal estimates of AA (OR = 0.97, 95% CI = 0.92-1.02, P=0.204). Additionally, there was no evidence to suggest that AA may increase the risk of inflammatory bowel disease (IBD), Crohn's disease (CD), ulcerative colitis (UC), systemic lupus erythematosus (SLE), and psoriasis (PSO). The sensitivity analysis confirmed the absence of heterogeneity or horizontal pleiotropy effects.

Conclusion

Our findings shed light on the causal effects between genetically predisposed AA and RA. They also suggest the potential clinical utility of human leukocyte antigen (HLA) risk genetic markers for developing personalized treatment and prevention strategies.

Mendelian randomization analysis of maternal coffee consumption during pregnancy on offspring neurodevelopmental difficulties in the Norwegian Mother, Father and Child Cohort Study (MoBa)

BACKGROUND

Previous observational epidemiological studies have suggested that coffee consumption during pregnancy may affect fetal neurodevelopment. However, results are inconsistent and may represent correlational rather than causal relationships. The present study investigated whether maternal coffee consumption was observationally associated and causally related to offspring childhood neurodevelopmental difficulties (NDs) in the Norwegian Mother, Father and Child Cohort Study.

METHODS

The observational relationships between maternal/paternal coffee consumption (before and during pregnancy) and offspring NDs were assessed using linear regression analyses (N = 58694 mother-child duos; N = 22 576 father-child duos). To investigate potential causal relationships, individual-level (N = 46 245 mother-child duos) and two-sample Mendelian randomization (MR) analyses were conducted using genetic variants previously associated with coffee consumption as instrumental variables.

RESULTS

We observed positive associations between maternal coffee consumption and offspring difficulties with social-communication/behavioral flexibility, and inattention/hyperactive-impulsive behavior (multiple testing corrected p < 0.005). Paternal coffee consumption (negative control) was not observationally associated with the outcomes. After adjusting for potential confounders (smoking, alcohol, education and income), the maternal associations attenuated to the null. MR analyses suggested that increased maternal coffee consumption was causally associated with social-communication difficulties (individual-level: beta = 0.128, se = 0.043, p = 0.003; two-sample: beta = 0.348, se = 0.141, p = 0.010). However, individual-level MR analyses that modelled potential pleiotropic pathways found the effect diminished (beta = 0.088, se = 0.049, p = 0.071). Individual-level MR analyses yielded similar estimates (heterogeneity p = 0.619) for the causal effect of coffee consumption on social communication difficulties in maternal coffee consumers (beta = 0.153, se = 0.071, p = 0.032) and non-consumers (beta = 0.107, se = 0.134, p = 0.424).

CONCLUSIONS

Together, our results provide little evidence for a causal effect of maternal coffee consumption on offspring NDs.

Relationship between hearing impairment and dementia and cognitive function: a Mendelian randomization study

BACKGROUND

There is a substantial body of observational research indicating an association between hearing impairment and dementia, yet the causal relationship and underlying mechanisms remain uncertain. This study aims to investigate the causal relationship between hearing impairment and its subtypes with dementia and cognitive function using two-sample Mendelian randomization (MR) analysis.

METHODS

We performed two-sample MR analysis to examine the causal effects of hearing impairment and its subtypes, including conductive and sensorineural hearing loss (CSHL), conductive hearing loss (CHL), sensorineural hearing loss (SHL), and sudden sensorineural hearing loss (SIHL), on six dementia phenotypes (overall dementia, Alzheimer's disease [AD], Lewy body dementia [DLB], frontotemporal dementia [FTD], Parkinson's disease dementia, and vascular dementia) and four cognitive functions. Additionally, multivariable MR (MVMR) analysis was employed to investigate potential mediating mechanisms.

RESULTS

Genetically determined CSHL was associated with an elevated risk of DLB (odds ratio [OR] 1.69; 95% CI 1.08 to 2.63; P = 0.021) and FTD (OR 1.66; 1.04 to 2.67; P = 0.035), but not AD (P = 0.958). Genetic predisposition to CHL was found to link with increased risks of AD (OR 1.07; 1.01 to 1.14; P = 0.031). Genetically determined SHL was causally associated with an elevated risk of semantic dementia (OR 3.81; 1.09 to 13.37; P = 0.037). Genetically predicted CHL and SIHL were both causally associated with lower general cognitive performance (β -0.015 and - 0.043; P = 0.007 and 0.013) and fluid intelligence score (β -0.045 and - 0.095; P = 0.037 and 0.040). In MVMR analysis, the causal relationship between hearing impairment and dementia was mediated by loneliness, depressed mood, and brain cortical volume, particularly the medial temporal lobe, but not by aging or ischemic stroke.

CONCLUSION

Overall, the study provides evidence supporting a causal relationship between hearing impairment and increased risks of different types of dementia (including AD, FTD, and DLB), as well as poorer general cognitive function. These findings underscore the importance of addressing hearing impairment as a modifiable risk factor for dementia.

Bidirectional Two-Sample Mendelian Randomization Analysis Reveals Causal Associations Between Modifiable Risk Factors and Fibromyalgia

Introduction

This study aims to investigate the potential causal effects of modifiable risk factors on Fibromyalgia (FM).

Methods

Genetic variants associated with 34 exposure factors were obtained from Genome-wide association studies (GWAS). Summary statistics for FM were acquired from the FinnGen consortium. Bidirectional Mendelian randomization (MR) analysis was conducted between all exposures and outcomes. The inverse-variance weighted (IVW) method was employed as the primary estimation technique. Heterogeneity and pleiotropy were assessed using MR-PRESSO global test, the weighted median, Cochran's Q statistic and MR-Egger.

Results

Depression (OR=2.087, 95% CI: 1.466-2.971), alcohol consumption (OR=1.489, 95% CI: 1.094-2.028), body fat percentage (OR=1.524, 95% CI: 1.153-2.013) and body mass index (BMI) (OR=1.542, 95% CI: 1.271-1.872) were associated with an increased risk of FM among genetically susceptible individuals. Conversely, higher education level (OR=0.404, 95% CI: 0.297-0.549), longer years of education (OR=0.489, 95% CI: 0.290-0.825) and higher household income (OR=0.328, 95% CI: 0.215-0.502) were protective against FM. Additionally, rheumatoid arthritis (OR=1.138, 95% CI: 1.061-1.221) and ankylosing spondylitis (OR=1.079, 95% CI: 1.021-1.140) were identified as important risk factors for FM.

Conclusion

This MR study unveiled a complex causal relationship between modifiable risk factors and FM. Psychosocial factors significantly increase the odds of FM, while obesity and some autoimmune diseases that frequently coexist with FM demonstrate causal associations. Additionally, lifestyle habits such as alcohol consumption are causally related to FM. Further investigation is needed to determine whether risk factors contribute to the pathogenesis of FM through mechanisms involving central sensitization, inflammatory, and hyperalgesia. This study enhances our understanding of the factors that drive FM onset and progression, offering valuable insights for future targeted prevention and treatment strategies.

Ischemic stroke and sarcopenia have an asymmetric bidirectional relationship based on a two-sample Mendelian randomization study

Background

We investigated the potential relationship between age-related conditions, particularly sarcopenia and ischemic stroke (IS), through a two-sample Mendelian randomization (MR) study.

Methods

We conducted a two-sample bidirectional MR study to investigate the relationship between sarcopenia and stroke. Genetic instruments for sarcopenia were derived from the UK Biobank, while data on IS and its subtypes were obtained from the MEGASTROKE consortium. Inverse variance weighting (IVW) served as the primary analytical method. Additionally, heterogeneity and pleiotropy were assessed to ensure the robustness of the findings.

Results

The analysis indicates a negative correlation between appendicular lean mass (ALM) and small vessel stroke (SVS; OR = 0.790, 95% CI: 0.703-0.888, p < 0.001), a positive correlation with cardioembolic stroke (CES; OR = 1.165, 95% CI: 1.058-1.284, p = 0.002), and no causal relationship with any ischemic stroke (AIS) or large artery stroke (LAS). Additionally, SVS is negatively associated with right-hand grip strength (OR = 0.639, 95% CI: 0.437-0.934, p = 0.021), while AIS, LAS, and CES do not exhibit a causal relationship with grip strength. Furthermore, no causal relationship was identified between left-hand grip strength, usual walking pace, and IS or its subtypes. MR analysis reveals only a negative association between CES and usual walking pace (OR = 0.989, 95% CI: 0.980-0.998, p = 0.013), with no associations found between other IS subtypes and sarcopenia-related traits.

Conclusion

This study demonstrates that a reduction in ALM and right-hand grip strength is associated with SVS, whereas decreased ALM may serve as a protective factor against CES. Conversely, our analysis suggests that CES can impact walking speed. Overall, these findings provide valuable insights into the prevention and treatment of these conditions.

Potential genetic association between coffee/caffeine consumption and erectile dysfunction: a Mendelian randomization study and meta-analysis

Background

Coffee is a widely consumed beverage with potential benefits for various chronic diseases. Its effect on reducing erectile dysfunction (ED) risk is unclear. This Mendelian randomization (MR) study investigates the impact of coffee/caffeine consumption on ED.

Methods

Two sets of coffee consumption-associated genetic variants at the genome-wide significance level were obtained from recent studies of coffee consumption. Taking into account other sources of caffeine, genetic variants associated with caffeine consumption from tea were also obtained. The inverse variance weighted (IVW) method was utilized as the primary analysis. Sensitivity analysis methods and meta-analysis methods were performed to confirm the robustness of the results, while the genetic variants associated with confounders, e.g., diabetes and hypertension, were excluded.

Results

Genetically predicted coffee/caffeine consumption was unlikely to be associated with the risk of ED in the Bovijn datasets, with similar directional associations observed in the FinnGen datasets. The combined odds ratio for ED was 1.011 (95% CI 0.841-1.216, p=0.906) for coffee consumption from the genome-wide meta-analysis, 1.049 (95% CI 0.487-2.260, p=0.903) for coffee consumption from the genome-wide association study, and 1.061 (95% CI 0.682-1.651, p=0.793) for caffeine from tea.

Conclusion

Using genetic data, this study found no association between coffee/caffeine consumption and the risk of ED.

Causal impacts of smoking on pain conditions and the mediating pathways: a mendelian randomization study

Smoking is a risk factor for multiple diseases. We performed mendelian randomization (MR) analyses to investigate the causal association of smoking initiation on pain conditions and the potential mediating pathways. Genetic associated with smoking initiation at the genome-wide significance level were selected as instrumental variables. Genetic associations with 10 pain conditions were derived from the FinnGen and UK Biobank study. Multivariable MR analysis was conducted to explore the mediation effects of depression, insomnia and sedentary behavior. A series of sensitivity analyses were conducted to assess the stability of our research findings. Genetic liability to smoking initiation was associated with an increased risk of angina pectoris, dorsalgia, low back pain, pain in limb, pain in joint, pain in thoracic spine and sciatica in both FinnGen and UK Biobank study. These causal associations were largely mediated by major depression (2.9- 39.5%), sedentary behavior (13.0- 31.2%), insomnia (10.3- 33.1%) and combination of all three mediators (30.2- 65.3%). The effects of smoking on outcomes were partly attenuated after adjusting for depression, sedentary behavior and insomnia respectively, and the direct effect of smoking initiation on pain was diminished toward null after adjusting for combined three mediators. These results were robust to sensitivity analyses. Our findings illustrated the causal effect of smoking and a broad range of pain conditions, and major depression, sedentary behavior and insomnia mediate many of these associations.

Causal role of 731 immune cells in diabetic nephropathy: a bi-directional two-sample Mendelian randomization study

BACKGROUND

The primary cause of end-stage renal disease (ESRD) is diabetic nephropathy (DN), and a growing body of research indicates that immunology plays a part in how DN develops into ESRD. Our objective is to identify causal relationships between various immune invading cells and DN to identify possible targets for immunotherapy.

METHODS

This study used a complete Mendelian randomization (MR) analysis with two samples to identify the underlying mechanism linking immune cell characteristics with DN. Using publicly available genetic data, we investigated the causal link between 731 immune cell profiles and DN risk. Included were four different types of immune systems: morphological parameters (MP), absolute cell (AC), relative cell (RC), and median fluorescence intensities (MFI). The results' robustness, heterogeneity, and horizontal pleiotropy were confirmed through extensive sensitivity analysis.

RESULTS

Following FDR (False Discovery Rate correction method) correction, no statistically significant differences were observed; however, six immunophenotypes were shown to be significantly associated with DN risk at the 0.25 level. Only CD28+ CD4- CD8- T cells were identified as the protective immunophenotype (OR = 0.588, 95% CI 0.437-0.792, P = 4.71 × 10-4). Moreover, DN had no discernible impact on immunophenotyping after FDR correction. Surprisingly, three unadjusted phenotypes with low P values were discovered to be positively correlated with the risk of DN: CD20 on IgD- CD27- B cells (OR = 1.263, 95% CI 1.076-1.482, P = 4.22 × 10-3), CD8 on naive CD8 + T cells with Effector Memory (OR = 1.107, 95% CI 1.013-1.209, P = 2.40 × 10-2), and CD8 on Effector Memory CD8 + T cells (OR = 1.126, 95% CI 1.024-1.239, P = 1.46 × 10-2).

CONCLUSIONS

Our findings provide a genetic basis for the association between immune cells and DN and should inform future clinical research.

Causal links between circulatory inflammatory cytokines and risk of digestive polyps: a Mendelian randomization analysis

Background

There is a high morbidity of polyps in the digestive tract, and certain subtypes of polyps are thought to induce cancer progression and often recur, which may be associated with chronic inflammation. Mendelian randomization (MR) can help identify potential causative relationships and inform early treatment action.

Methods

We performed a bidirectional two-sample MR analysis implementing the results from genome-wide association studies for 41 serum cytokines from 8,293 Finnish individuals, and three types of polyps from European ancestry, respectively, including gastric polyp (6,155 cases vs. 341,871 controls), colonic polyp (22,049 cases vs. 332,368 controls) and gallbladder polyp (458 cases vs. 340,083 controls). Inverse-variance weighted (IVW), weight median (WM), and MR-Egger methods were used for calculating causal estimates. Furthermore, Bayesian model averaging MR (MR-BMA) method was employed to detect the dominant causal circulatory cytokines with adjustment for pleiotropy effects.

Results

Our univariable MR using inverse-variance weight method identified causal associations of IL-2ra (OR: 0.892, 95%CI: 0.828-0.961, p = 0.003), MIG (OR: 1.124, 95%CI: 1.046-1.207, p = 0.001) and IL-18 (OR: 0.912, 95%CI: 0.852-0.977, p = 0.008) with gastric polyp, MIP1b (OR: 0.956, 95%CI: 0.927-0.987, p = 0.005) and IL-6 (OR: 0.931, 95%CI: 0.870-0.995, p = 0.035) with colonic polyp and IL-9 (OR: 0.523, 95%CI: 0.345-0.794, p = 0.0007) with gallbladder polyp. Finally, our MR-BMA analysis prioritized MIG (MIP = 0.332, MACE = 0.022; PP: 0.264, MSCE = 0.059), IL-18 (MIP = 0.302, MACE = -0.020; PP: 0.243, MSCE = -0.059) and IL-2ra (MIP: 0.129; MACE: -0.005; PP: 0.112, MSCE: -0.031) for gastric polyp, and MIP1b (MIP = 0.752, MACE = -0.033; PP: 0.665, MSCE = -0.044) and IL-6 (MIP: 0.196; MACE: -0.012; PP: 0.140, MSCE: -0.064) for colonic polyp, and IL-9 (MIP = 0.936, MACE = -0.446; PP: 0.781, MSCE = -0.478) for gallbladder polyp as the top-ranked protective factors.

Conclusion

Our research advances the current understanding of the function of certain inflammatory biomarker pathways in the genesis and malignant mutation of polyps in the digestive tract. Deeper substantiation is necessary to assess the potential of these cytokines as pharmacological or lifestyle targets for digestive polyps prevention.

A genetically informed study reveals modifiable pathways in skin cancer

BACKGROUND

Identifying modifiable risk factors is essential for the prevention of skin cancer; however, establishing causality can be challenging in conventional epidemiological studies. This study aimed to determine the causal associations of potentially modifiable risk factors with skin cancer using Mendelian randomization (MR).

METHODS

Genetic instruments for 53 risk factors, including socioeconomic status, dietary and lifestyle factors, anthropometric measures, medication use, and comorbidities, were identified from previous genome-wide association studies. Two-sample MR analyses were performed using summary statistics for three major types of skin cancer: melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). Findings were verified using multiple MR methods under different assumptions and replication datasets.

RESULTS

Genetic liability to sunburn occasions, actinic keratosis, and prior skin cancers was associated with a higher risk of all three types of skin cancer, whereas genetic liability to vitiligo was associated with a lower risk. For specific skin cancer types, genetically predicted higher nevus counts and occupational class were associated with an increased risk of melanoma. Genetic liability to rheumatoid arthritis, type 2 diabetes, and increased physical activity were associated with a lower risk of BCC. Genetically predicated body mass index showed a negative association with BCC, and a positive association with SCC.

CONCLUSIONS

Our study reaffirmed several previously established risk factors and identified novel potential risk factors for skin cancer. Further work is needed to unravel the biological pathways in different skin cancer types and translate our findings to inform public health policies.

Gut microbiota causally impacts adrenal function: a two-sample mendelian randomization study

Some studies have reported that the gut microbiota can influence adrenal-related hormone levels. However, the causal effects of the gut microbiota on adrenal function remain unknown. Therefore, we employed a two-sample Mendelian randomization (MR) study to systematically investigate the impact of gut microbiota on the function of different regions of the adrenal gland. The summary statistics for gut microbiota and adrenal-related hormones used in the two-sample MR analysis were derived from publicly available genome-wide association studies (GWAS). In the MR analysis, inverse variance weighting (IVW) was used as the primary method, with MR-Egger, weighted median, and cML-MA serving as supplementary methods for causal inference. Sensitivity analyses such as the MR-Egger intercept test, Cochran's Q test, and leave-one-out analysis were used to assess pleiotropy and heterogeneity. We identified 27 causal relationships between 23 gut microbiota and adrenal function using the IVW method. Among these, Sellimonas enhanced the function of the adrenal cortex reticularis zone (beta = 0.008, 95% CI: 0.002-0.013, P = 0.0057). The cML-MA method supported our estimate (beta = 0.009, 95% CI: 0.004-0.013, P = 2 × 10- 4). Parasutterella, Sutterella, and Anaerofilum affect the functioning of different regions of the adrenal gland. Notably, pleiotropy was not observed. Our findings revealed that the gut microbiota is causally associated with adrenal function. This enhances our understanding of the gut-microbiota-brain axis and provides assistance in the early diagnosis and treatment of adrenal-related diseases in clinical practice.

Causal relationship between beta-2 microglobulin and B-cell malignancies: genome-wide meta-analysis and a bidirectional two-sample Mendelian randomization study

Background

Beta-2 microglobulin (β2M) is acknowledged as a prognostic biomarker for B-cell malignancies. However, insights into the impact of β2M on B-cell malignancy risk, and vice versa, are limited.

Methods

We conducted a genome-wide meta-analysis (GWMA), bidirectional two-sample Mendelian randomization (TSMR) analysis, and pathway enrichment analysis to explore the causal relationship between β2M and B-cell malignancies and the underlying biological processes.

Results

The GWMA identified 55 lead SNPs across five genomic regions (three novel: WDR72, UMOD, and NLRC5) associated with β2M. In the UKB, genetically predicted β2M showed a positive association with diffuse large B-cell lymphoma (DLBCL; odds ratio [OR]: 1.742 per standard deviation increase in β2M; 95% confidence interval [CI]: 1.215-2.498; P = 3.00 × 10-3; FDR = 7.50× 10-3) and Hodgkin lymphoma (HL; OR: 2.270; 95% CI: 1.525-3.380; P = 5.15 × 10-5; FDR =2.58 × 10-4). However, no associations were found with follicular lymphoma (FL), chronic lymphoid leukemia (CLL), or multiple myeloma (MM). Reverse TSMR analysis revealed no association between genetically predicted B-cell malignancies and β2M. In FinnGen, β2M was found to be associated with an increased risk of DLBCL (OR: 2.098; 95% CI: 1.358-3.242; P = 8.28 × 10-4; FDR = 4.14 × 10-3), HL (OR: 1.581; 95% CI: 1.167-2.142; P = 3.13 × 10-3; FDR = 5.22 × 10-3), and FL (OR: 2.113; 95% CI: 1.292-3.455; P = 2.90 × 10-3; FDR = 5.22 × 10-3). However, no association was found with CLL or MM. Reverse TSMR analysis indicated that genetically predicted DLBCL, FL, and MM may perturb β2M levels. Pathway enrichment analysis suggested that the innate immune system represents a convergent biological process underlying β2M, DLBCL, and HL.

Conclusions

Our findings suggested that elevated levels of β2M were associated with an increased risk of DLBCL and HL, which is potentially linked to dysfunction of the innate immune system.

Causality between diabetes and membranous nephropathy: Mendelian randomization

BACKGROUND

Membranous nephropathy (MN) has not yet been fully elucidated regarding its relationship with Type I and II Diabetes. This study aims to evaluate the causal effect of multiple types of diabetes and MN by summarizing the evidence from the Mendelian randomization (MR) study.

METHODS

The statistical data for MN was obtained from a GWAS study encompassing 7979 individuals. Regarding diabetes, fasting glucose, fasting insulin, and HbA1C data, we accessed the UK-Biobank, within family GWAS consortium, MAGIC, FinnGen database, MRC-IEU, and Neale Lab, which provided sample sizes ranging from 17,724 to 298,957. As a primary method in this MR analysis, we employed the Inverse Variance Weighted (IVW), Weighted Median, Weighted mode, MR-Egger, Mendelian randomization pleiotropy residual sum, and outlier (MR-PRESSO) and Leave-one-out sensitivity test. Reverse MR analysis was utilized to investigate whether MN affects Diabetes. Meta-analysis was applied to combine study-specific estimates.

RESULTS

It has been determined that type 2 diabetes, gestational diabetes, type 1 diabetes with or without complications, maternal diabetes, and insulin use pose a risk to MN. Based on the genetic prediction, fasting insulin, fasting blood glucose, and HbA1c levels were not associated with the risk of MN. No heterogeneity, horizontal pleiotropy, or reverse causal relationships were found. The meta-analysis results further validated the accuracy.

CONCLUSIONS

The MR analysis revealed the association between MN and various subtypes of diabetes. This study has provided a deeper understanding of the pathogenic mechanisms connecting MN and diabetes.

Primary Aldosteronism Influences Cardiac Structure, Function, and Disease Risk: Evidence From Mendelian Randomization Analysis

Although observational studies have linked primary aldosteronism (PA) with cardiovascular diseases (CVDs), the causality remains uncertain. In this study, we aimed to investigate whether PA is causally associated with CVD risk and cardiac magnetic resonance (CMR) parameters using the Mendelian randomization (MR) method. Independent and genome-wide significant single nucleotide polymorphisms for PA were extracted from genome-wide association study (GWAS) summary statistics. Genetic associations with the CVDs and CMR parameters were obtained from recent large-scale GWASs or genetic consortia. Inverse-variance weighted (IVW) method was utilized for the preliminary estimates, and multiple sensitivity analyses (including weighted median, Cochran's Q test, MR-Egger, MR-PRESSO, and leave-one-out analysis) were conducted to verify the robustness of the results. The MR analyses using the IVW method showed that genetically predicated PA was significantly associated with atrial fibrillation (OR = 1.046, 95% CI: 1.029-1.062, padj < 0.001), myocardial infarction (OR = 1.029, 95% CI: 1.005-1.053, padj = 0.027), heart failure (OR = 1.023, 95% CI: 1.004-1.042, padj = 0.027), any stroke (OR = 1.062, 95% CI: 1.031-1.095, padj < 0.001), any ischemic stroke (OR = 1.058, 95% CI: 1.022-1.095, padj = 0.004), and small vessel stroke (OR = 1.116, 95% CI: 1.041-1.196, padj = 0.004). Notably, PA also had a causal effect on adverse cardiac remodeling, including larger ventricular and atrial volumes, higher ventricular stroke volume, and reduced left atrial emptying fraction. Our findings support a causal role of PA in higher cardiovascular disease risk and adverse cardiac remodeling. Given the diagnostic delay and disease burden in PA, more attention should be paid to the screening and treatment of PA to reduce the incidence of cardiovascular outcomes.

Association of the gut microbiome and different phenotypes of COPD and asthma: a bidirectional Mendelian randomization study

Mounting evidence has revealed the association between gut microbiota and both chronic obstructive pulmonary disease (COPD) and asthma; however, the causal association between gut microbiota and specific disease phenotypes remains to be determined. This study employed bidirectional two-sample Mendelian randomization (MR) analyses to investigate the potential causal relationship between gut microbiota and these conditions. The research utilized genome-wide association study (GWAS) data from the MiBioGen consortium for gut microbiota and the integrative epidemiology unit (IEU) Open GWAS for these conditions. Four MR analysis methods were employed: the inverse variance weighted (IVW) test, MR-Egger, weighted median, and weighted mode methods. The IVW method results are considered the primary findings. Sensitivity analyses, including heterogeneity tests, horizontal pleiotropy analysis, and leave-one-out analysis, were used to enhance robustness. Our MR study identified eight gut microbiota taxa potentially associated with the risk of different types of COPD and asthma. These include two taxa for early-onset COPD: Streptococcaceae [odds ratio (OR) = 1.315, 95% confidence interval (CI) = 1.071-1.616, P = 0.009] and Holdemanella (OR = 1.199, 95% CI = 1.063-1.352, P = 0.003); three for later-onset COPD: Acidaminococcaceae (OR = 1.312, 95% CI = 1.098-1.567, P = 0.003), Holdemania (OR = 1.165, 95% CI = 1.039-1.305, P = 0.009), and Marvinbryantia (OR = 0.814, 95% CI = 0.697-0.951, P = 0.009); one for allergic asthma: Butyricimonas (OR = 0.794, 95% CI = 0.693-0.908, P = 0.001); and two for non-allergic asthma: Clostridia (OR = 1.255, 95% CI = 1.043-1.511, P = 0.016) and Clostridiales (OR = 1.256, 95% CI = 1.048-1.506, P = 0.014).IMPORTANCEIndividuals with diverse phenotypes of chronic obstructive pulmonary disease (COPD) and asthma exhibit different responses to the conventional "one treatment fits all" approach. Recent research has revealed the significant role of the gut-lung axis in both COPD and asthma. However, the specific impact of gut microbiota on different subtypes of these conditions remains poorly understood. Our study has identified eight gut microbiota that may be associated with the risk of different types of COPD and asthma. These findings provide evidence suggesting a potential causal relationship between gut microbiota and various phenotypes of COPD and asthma. This offers a new perspective on the origins of different disease phenotypes and points toward future exploration of phenotype-specific and personalized therapies.

Exploring the hub Genes and Potential Mechanisms of Complement system-related Genes in Parkinson Disease: Based on Transcriptome Sequencing and Mendelian Randomization

An accurate diagnosis of Parkinson's disease (PD) remains challenging and the exact cause of the disease is unclean. The aims are to identify hub genes associated with the complement system in PD and to explore their underlying molecular mechanisms. Initially, differentially expressed genes (DEGs) and key module genes related to PD were mined through differential expression analysis and WGCNA. Then, differentially expressed CSRGs (DE-CSRGs) were obtained by intersecting the DEGs, key module genes and CSRGs. Subsequently, MR analysis was executed to identify genes causally associated with PD. Based on genes with significant MR results, the expression level and diagnostic performance verification were achieved to yield hub genes. Functional enrichment and immune infiltration analyses were accomplished to insight into the pathogenesis of PD. qRT-PCR was employed to evaluate the expression levels of hub genes. After MR analysis and related verification, CD93, CTSS, PRKCD and TLR2 were finally identified as hub genes. Enrichment analysis indicated that the main enriched pathways for hub genes. Immune infiltration analysis found that the hub genes showed significant correlation with a variety of immune cells (such as myeloid-derived suppressor cell and macrophage). In the qRT-PCR results, the expression levels of CTSS, PRKCD and TLR2 were consistent with those we obtained from public databases. Hence, we mined four hub genes associated with complement system in PD which provided novel perspectives for the diagnosis and treatment of PD.

Potential causal and temporal relationship between plasma triglyceride levels and circulating leukocyte

Circulating triglyceride (TG) and leukocytes, the main components of the vascular system, may impact each other and co-fuel atherosclerosis. While the causal relationship between plasma TG levels and leukocyte counts remains unclear. Bidirectional Mendelian randomization (MR) analysis was conducted to investigate the potential causal relationship between TG levels and the counts of leukocytes and their subtypes. A cross-lagged panel model (CLPM) using longitudinal healthy screening data (13,389 adults with a follow-up of 4 years) was fitted to examine the temporal relationship between them. Genetically predicted plasma TG levels were positively associated with total leukocyte counts (TLC) [β(se) = 0.195(0.01)], lymphocyte counts (LC) [β(se) = 0.196(0.019)], and neutrophil counts (NC) [β(se) = 0.086(0.01)], which remained significant after adjusting for several confounders. Inversely, the genetically predicted TLC [β(se) = 0.033(0.008)], LC [β(se) = 0.053(0.008)], and NC [β(se) = 0.034(0.008)] were positively associated with plasma TG levels. However, when all three of them were put into the MR model adjusted for each other, only LC was significantly associated with TG levels. There was no association between genetically predicted TG levels and monocyte counts (MC), basophil counts, and eosinophil counts. The results of CLPM showed that the temporal effect of elevated TLC, MC, LC, and NC on plasma TG levels was stronger than the inverse effect. Our findings suggest causal associations of plasma TG levels with TLC, LC, and NC. In turn, LC was positively associated with plasma TG levels. Additionally, elevated circulating LC may precede high plasma TG levels.

Causal association between thyroid function and the risk of infertility: a Mendelian randomization study

Objectives

Thyroid dysfunction is commonly associated with the risk of infertility in both females and males. However, recent randomized controlled trials have demonstrated that thyroid function levels in females are not significantly related to infertility, and evidence on the association between male thyroid function and infertility is limited. We aim to investigate the association between thyroid function levels and infertility in both females and males.

Method

A two-sample Mendelian randomization study was conducted using four methods, with the inverse variance weighted method (IVW) as the primary approach. Data on thyroid function as the exposure were obtained from the ThyroidOmics Consortium and UK Biobank, including over 700,000 individuals from a large meta-analysis of genome-wide association studies for thyroid function and dysfunction. The outcome data for infertility in both sex encompassed more than 70,000 individuals from the FinnGen Consortium. All participants were adults of European ancestry. The MR Egger regression intercept and Cochran's Q test were employed to evaluate directional pleiotropy and heterogeneity.

Results

The results indicated no causal effect of thyroid-stimulating hormone (TSH) and free tetraiodothyronine (fT4) on female and male infertility. Furthermore, no causal association between hypo- and hyperthyroidism and infertility were identified. Notably, we observed a causal relationship between high TSH and endometriosis-related infertility (OR=0.82, 95% CI: 0.74-0.91, P = 1.49E-04).

Conclusions

This study did not find evidence for casual relationship between thyroid function levels and risk of infertility. The findings suggest that overall thyroid function levels may not be a significant predictor of infertility risk.

The Causal Relationship between Inflammatory Cytokines and Liver Cirrhosis in European Descent: A Bidirectional Two-Sample Mendelian Randomization Study and the First Conclusions

BACKGROUND

Observational studies have highlighted the pivotal role of inflammatory cytokines in cirrhosis progression. However, the existence of a causal link between inflammatory cytokines and cirrhosis remains uncertain. In this study, we conducted a bidirectional Mendelian randomization (MR) analysis at a summarized level to illuminate the potential causal relationship between the two variables.

METHODS

This study utilized genetic variance in cirrhosis and inflammatory cytokines from a genome-wide association study (GWAS) of European descent. The MR-PRESSO outlier test, Cochran's Q test, and MR-Egger regression were applied to assess outliers, heterogeneity, and pleiotropy. The inverse variance weighted method and multiple sensitivity analyses were used to evaluate causalities. Furthermore, the validation set was used for simultaneous data validation.

RESULTS

The inflammatory cytokine monocyte chemoattractant protein 3 (MCP-3) was supposedly associated with a greater risk of cirrhosis. And cirrhosis was significantly correlated with increased levels of hepatocyte growth factor (HGF).

CONCLUSIONS

This study suggests that MCP-3 might be associated with the etiology of cirrhosis, while several inflammatory cytokines could potentially play a role in its downstream development. Additionally, the progression of cirrhosis was associated with elevated levels of HGF, suggesting a possible role for liver repair functions.

A Mendelian analysis of the causality between inflammatory cytokines and digestive tract cancers

PURPOSE

In this study, we performed a two-sample Mendelian randomization (MR) analysis to assess the causality between inflammatory cytokines and the risk of digestive tract cancers (DTCs). Furthermore, we conducted a molecular docking study to predict the therapeutic mechanisms of traditional Chinese medicine (TCM) compounds in the treatment of DTCs.

METHODS

In our MR analysis, genetic variations associated with eight types of DTCs were utilized, which were sourced from a large publicly available genome-wide association study dataset (7929 cases and 1 742 407 controls of European ancestry) and inflammatory cytokines data from a genome-wide association study summary of 8293 European participants. Inverse-variance weighted method, MR-Egger, and weighted median were performed to analyze and strengthen the final results. We investigated the effects of 41 inflammatory molecules on 8 types of DTCs. Subsequently, the effect of DTCs on positive inflammatory factors was analyzed by means of inverse MR. Molecular docking was exploited to predict therapeutic targets with TCM compounds.

RESULTS

Interleukin-7, interleukin-16, macrophage colony-stimulating factor, monokine induced by interferon-gamma, and vascular endothelial growth factor may be significantly associated with various types of DTCs. Five TCM compounds (baicalin, berberine, curcumin, emodin, and salidroside) demonstrated better binding energies to both interleukin-7 and vascular endothelial growth factor than carboplatin.

CONCLUSION

This study provides strong evidence to support the potential causality of some inflammatory cytokines on DTCs and indicates the potential molecular mechanism of TCM compounds in the treatment of DTCs. Key message What is already known on this topic  The increasing evidence indicates that inflammatory cytokines are implicated in the pathogenesis of digestive tract cancers (DTCs). Nevertheless, the causal relationship between inflammatory cytokines and DTCs remains indistinct. Additionally, certain traditional Chinese medicine compounds have been demonstrated to treat DTCs by influencing inflammatory factors, yet their underlying potential mechanisms remain ambiguous. What this study adds  In this study, Mendelian randomization analysis was performed for the first time regarding the causality between human inflammatory cytokines and eight types of DTCs, which revealed that inflammatory factors may play different roles in different types of DTCs. Moreover, molecular docking of key inflammatory factors was implemented, indicating the targets for drug actions. How this study might affect research, practice, or policy  This research has the potential to reveal the causality between 41 inflammatory factors and 8 DTCs, offering novel perspectives for the prevention and management strategies of DTCs. Additionally, it indicates the targets for the actions of traditional Chinese medicine on the key inflammatory factors of these cancers.

Investigating the Genetic Association of 40 Biochemical Indicators with Parkinson's Disease

The mechanisms of Parkinson's disease (PD) are not fully understood, which hinders the development of effective therapies. Research indicates that lower levels of biochemical indicators like bilirubin, vitamin D, and cholesterol may elevate the risk of PD. However, clinical studies on abnormal levels of biochemical indicators in PD patients' circulation are inconsistent, leading to ongoing debate about their association with PD. Here, we investigate the genetic correlation between 40 biochemical indicators and PD using a bidirectional two-sample Mendelian randomization (MR) approach to uncover potential causal relationships. Data from genome-wide association studies (GWAS) were utilized, with genetic variations from specific lineages serving as instrumental variables (IVs). The methodology followed the STROBE-MR checklist and adhered to the three principal assumptions of MR. Statistical analyses employed methods including inverse variance weighting (IVW), MR-Egger, weighted median, and weighted mode. Biochemical indicators including albumin, C-reactive protein (CRP), and sex hormone-binding globulin (SHBG) showed significant associations with PD risk. Elevated levels of albumin (OR = 1.246, 95% CI 1.006-1.542, P = 0.043) and SHBG (OR = 1.239, 95% CI 1.065-1.439, P = 0.005) were linked to higher PD risk. Conversely, increased CRP levels (OR = 0.663, 95% CI 0.517-0.851; P = 0.001) could potentially lower PD risk. The robustness of the results was confirmed through various MR analysis techniques, including assessments of directional pleiotropy and heterogeneity using MR-Egger intercept and MR-PRESSO methods. This study systematically reveals, for the first time at the genetic level, the relationship between 40 biochemical indicators and PD risk. Our research verifies the role of inflammation in PD and provides new genetic evidence, further advancing the understanding of PD pathogenesis. The study shows a positive correlation between albumin and SHBG with PD risk and a negative correlation between CRP and PD risk. This study identifies for the first time that SHBG may be involved in the onset of PD and potentially worsen disease progression.

Causal relationship between lymphocyte subsets and the risk of sepsis: A Mendelian randomization study

Recent empirical research posits a link between lymphocyte subgroups and both the incidence and prognosis of sepsis. Nevertheless, the potential influence of multiple confounding variables obscures any clear causative correlation. Utilizing a 2-sample Mendelian randomization approach, we conducted a meta-analysis of lymphocyte subgroups. In a genome-wide association study, flow cytometry was applied to a lymphocyte subgroup comprising 3757 Sardinians to identify genes influenced by blood immune cells. The sepsis meta-analysis data were sourced from the UK Biobank database, including 11,643 treatment groups and 47,841 control groups. Inverse variance-weighted, Mendelian randomization-Egger regression, weighted median, simple mode, and weighted mode methods were deployed to ascertain the causative relationship between lymphocyte subgroup and sepsis. Cochran Q test, the Mendelian randomization-Egger intercept test, and funnel plots were leveraged to assess the robustness of study findings. The inverse variance-weighted analysis disclosed that the absolute count of CD4 regulatory T cells (CD4 Treg AC) within the lymphocyte subgroup has a causative link to an elevated risk of sepsis, with an odds ratio of 1.08 and a 95% confidence interval of 1.02 to 1.15 (P = .011). Compared to individuals not subjected to this factor, those exposed to CD4 Treg AC have a marginally elevated sepsis risk by approximately 0.08%. No causative relationships were observed between sepsis risk and the absolute counts of other lymphocyte subgroups such as CD8+ T cells, CD4+ CD8dim T cells, natural killer T cells, B cells (B cell absolute count), and HLA DR+ natural killer cells. The 2-sample Mendelian randomization study indicated a causal relationship between the level of CD4 Treg AC and the increased risk of sepsis. The elevation in circulating lymphocyte subgroups suggests higher susceptibility to sepsis, affirming the immune susceptibility inherent to this condition. The findings from our study may propose potential targets for diagnosis and intervention of sepsis.

Evidence of the association between asthma and lung cancer risk from mendelian randomization analysis

Asthma and lung cancer are both significant public health concerns worldwide. Previous observational studies have indicated a potential link between asthma and an increased risk of lung cancer, whereas the causal relationship remains uncertain. We aimed to investigate the potential causal relationship between asthma and lung cancer risk utilizing Mendelian randomization (MR) design.The present study employed a two-sample MR analysis utilizing summary statistics from genome-wide association studies (GWAS) with European descent of asthma and lung cancer. The MR analysis was performed using inverse variance weighting (IVW), supplemented with MR-Egger regression and weighted median method to investigate the potential causality between asthma and lung cancer. Furthermore, Sensitivity analyses were also conducted to ensure the reliability of the findings. The MR analysis showed that genetically predicted asthma had suggestive causal association with the elevated risk of lung cancer [odds ratio (OR), 1.05 (95%Cl,1.01-1.09), P = 0.01]. The consistent direction of effects observed in the three methods further supported this finding. In addition, sensitivity analyses demonstrated the reliability of the results. This study provided potential evidence supporting a causal association between asthma and lung cancer. These findings highlighted the importance of early detection and prevention strategies for lung cancer in individuals with asthma. Further research was needed to elucidate the underlying mechanisms linking asthma and lung cancer.

Immune cell traits and causal relationships with cholecystitis: a mendelian randomization analysis

Cholecystitis, characterized by inflammation of the gallbladder, is intricately linked to immune cells and the cytokines they produce. Despite this association, the specific contributions of immune cells to the onset and progression of cholecystitis remain to be fully understood. To delineate this relationship, we utilized the Mendelian randomization (MR) method to scrutinize the causal connections between 731 immune cell phenotypes and cholecystitis. By conducting MR analysis on 731 immune cell markers from public datasets, this study seeks to understand their potential impact on the risk of cholecystitis. It aims to elucidate the interactions between immune phenotypes and the disease, aiming to lay the groundwork for advancing precision medicine and developing effective treatment strategies for cholecystitis. Taking immune cell phenotypes as the exposure factor and cholecystitis as the outcome event, this study used single nucleotide polymorphisms (SNPs) closely associated with both immune cell phenotypes and cholecystitis as genetic instrumental variables. We conducted a two-sample MR analysis on genome-wide association studies (GWAS) data. Our research thoroughly examined 731 immune cell markers, to determine potential causal relationships with susceptibility to cholecystitis. Sensitivity analyses were performed to ensure the robustness of our findings, excluding the potential impacts of heterogeneity and pleiotropy. To avoid reverse causality, we conducted reverse MR analyses with cholecystitis as the exposure factor and immune cell phenotypes as the outcome event. Among the 731 immune phenotypes, our study identified 21 phenotypes with a causal relationship to cholecystitis (P < 0.05). Of these, eight immune phenotypes exhibited a protective effect against cholecystitis (odds ratio (OR) < 1), while the other 13 immune phenotypes were associated with an increased risk of developing cholecystitis (OR > 1). Additionally, employing the false discovery rate (FDR) method at a significance level of 0.2, no significant causal relationship was found between cholecystitis and immune phenotypes. Our research has uncovered a significant causal relationship between immune cell phenotypes and cholecystitis. This discovery not only enhances our understanding of the role of immune cells in the onset and progression of cholecystitis but also establishes a foundation for developing more precise biomarkers and targeted therapeutic strategies. It provides a scientific basis for more effective and personalized treatments in the future. These findings are expected to substantially improve the quality of life for patients with cholecystitis and mitigate the impact of the disease on patients and their families.

Causal effects of pediatric asthma on psychiatric disorders: a bidirectional Mendelian randomization study

BACKGROUND

Previous studies have suggested a potential link between pediatric asthma and psychiatric disorders. However, the causal relationship between pediatric asthma and psychiatric disorders is unclear. Therefore, we used Mendelian randomization to explore causal relationships between pediatric asthma and depression, anxiety disorders, and attention deficit and hyperactivity disorder (ADHD).

METHODS

Genome-wide association studies (GWAS) meta-analyses with the largest possible sample size and independent individuals from European ancestry were selected. The genetic data for depression and anxiety are from FinnGen consortium, while the genetic data for ADHD is from the Psychiatric Genomics Consortium. Inverse variance weighted (IVW) was the main analysis method. The heterogeneity of the instrumental variables (IVs) was assessed using IVW, and the horizontal pleiotropy of the IVs was assessed using MR-Egger.

RESULT

The IVW results showed a significant causal relationship between pediatric asthma and depression (OR = 1.08, 95% CI = 1.02-1.15; p = 0.013). However, there is no evidence to suggest a causal relationship between pediatric asthma, anxiety, and ADHD. Reverse MR suggests a significant causal relationship (OR = 1.27, 95% CI [1.14-1.41], p = 9.64E - 06) between ADHD and pediatric asthma using the IVW method.

CONCLUSIONS

Our findings suggest a causal relationship between pediatric asthma and an increased risk of depression. Additionally, we found that ADHD is significantly associated with a higher risk of pediatric asthma.

Effects of Iron, Copper, Zinc, and Magnesium on Chronic Widespread Pain: A Two-Sample Mendelian Randomization

Background: Chronic widespread pain (CWP) affects approximately 10% of the adult population globally, causing significant physical and psychological distress. Micronutrients, such as iron, copper, zinc, and magnesium, are essential in various physiological functions, and their imbalances may impact pain perception and chronic pain conditions. Methods: This study used Mendelian randomization (MR) to investigate the causal relationships between micronutrient levels and CWP. Data were obtained from genome-wide association studies (GWASs) for iron, copper, zinc, and magnesium, and CWP data were sourced from large-scale GWASs with 461,857 European participants. Genetic variants were used as instrumental variables to infer causal relationships, minimizing confounding factors. Results: MR analysis revealed a significant association between higher iron levels and an increased risk of CWP (IVW, OR 1.01, 95% CI: 1.00-1.01, p = 0.029). This finding was supported by the weighted median and MR-Egger methods. No significant associations were found for copper, zinc, and magnesium levels. Conclusions: These results suggest that iron levels may influence pain perception and chronic pain conditions. Balanced iron levels are crucial for managing chronic pain. Regular monitoring and personalized treatment plans could benefit individuals with CWP. Further research is needed to understand the mechanisms linking micronutrient levels to chronic pain and to develop targeted therapeutic interventions.

Cathepsins and neurological diseases: a Mendelian randomization study

Background

The causal relationship between cathepsins and neurological diseases remains uncertain. To address this, we utilized a two-sample Mendelian randomization (MR) approach to assess the potential causal effect of cathepsins on the development of neurological diseases.

Methods

This study conducted a two-sample two-way MR study using pooled data from published genome-wide association studies to evaluate the relationship between 10 cathepsins (B, D, E, F, G, H, L2, O, S, and Z) and 7 neurological diseases, which included ischemic stroke, cerebral hemorrhage, Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, and epilepsy. The analysis employed various methods such as inverse variance weighting (IVW), weighted median, MR Egger regression, MR pleiotropy residual sum and outlier, Cochran Q statistic, and leave-one-out analysis.

Results

We found a causal relationship between cathepsins and neurological diseases, including Cathepsin B and Parkinson's disease (IVW odds ratio (OR): 0.89, 95% confidence interval (CI): 0.83, 0.95, p = 0.001); Cathepsin D and Parkinson's disease (OR: 0.80, 95%CI: 0.68, 0.95, p = 0.012); Cathepsin E and ischemic stroke (OR: 1.05, 95%CI: 1.01, 1.09, p = 0.015); Cathepsin O and ischemic stroke (OR: 1.05, 95%CI: 1.01, 1.10, p = 0.021). Reverse MR analyses revealed that multiple sclerosis and Cathepsin E (OR: 1.05, 95%CI: 1.01, 1.10, p = 0.030). There is currently no significant relationship has been found between other cathepsins and neurological diseases.

Conclusion

Our study reveals a causal relationship between Cathepsins B, D, E, and O and neurological diseases, offering valuable insights for research aimed at improving the diagnosis and treatment of such conditions.

Artificial Sweetener and the Risk of Adverse Pregnancy Outcomes: A Mendelian Randomization Study

The relationship between the intake of artificial sweetener (AS) and adverse pregnancy outcomes is under-researched, and existing studies yield inconsistent conclusions. A Mendelian randomization (MR) approach was employed to investigate the causal relationship between the intake of AS and adverse pregnancy outcomes. Instrumental variables related to the exposure phenotype were selected for analysis. The analysis was conducted using genome-wide association study summary data from public datasets. The inverse variance weighted, MR-Egger, weighted median, simple mode, and weighted mode methods were used to evaluate the causal relationship between exposure and outcomes. Sensitivity analysis and multivariable Mendelian randomization enrolling body mass index, type 2 diabetes mellitus, and fasting glucose were employed to further validate the consistency and robustness of the results. In univariable MR, the intake of AS added to tea was associated with an increased risk of ectopic pregnancy [OR = 1.821 (1.118-2.967), p = 0.016]. In multivariable MR adjusting for body mass index and type 2 diabetes mellitus, the intake of AS added to cereal was linked to a reduced risk of ectopic pregnancy [OR = 0.361 (0.145-0.895), p = 0.028] and premature rupture of membranes [OR = 0.116 (0.019-0.704), p = 0.019], while the intake of artificial sweetener added to coffee was associated with an increased risk of placenta previa [OR = 1.617 (1.042-2.510), p = 0.032]. No causal relationship was identified between the intake of artificial sweetener and other adverse pregnancy outcomes. The consumption of artificial sweetener during pregnancy warrants careful consideration.

Associations between Disc Hemorrhage and Primary Open-Angle Glaucoma Based on Genome-Wide Association and Mendelian Randomization Analyses

Background/Objectives: We aimed to investigate the genetic loci related to disc hemorrhage (DH) and the relationship of causation between DH and primary open-angle glaucoma (POAG) using a genome-wide association study (GWAS) in East Asian individuals. Methods: The GWAS included 8488 Koreans who underwent ocular examination including fundus photography to determine the presence of DH and POAG. We performed a GWAS to identify significant single-nucleotide polymorphisms (SNPs) associated with DH and analyzed the heritability of DH and genetic correlation between DH and POAG. The identified SNPs were utilized as instrumental variables (IVs) for two-sample Mendelian randomization (MR) analysis. The POAG outcome dataset was adopted from Biobank Japan data (n = 179,351). Results: We found that the rs62463744 (TMEM270;ELN), rs11658281 (CCDC42), and rs77127203 (PDE10A;LINC00473) SNPs were associated with DH. The SNP heritability of DH was estimated to be 6.7%, with an absence of a genetic correlation with POAG. MR analysis did not reveal a causal association between DH and POAG for East Asian individuals. Conclusions: The novel loci underlying DH in the Korean cohort revealed SNPs in the ELN, CCDC41, and LINC00473 genes. The absence of a causal association between DH and POAG implies that DH is a shared risk factor, rather than an independent culprit factor, and warrants further investigation.

Genetic insights into dietary patterns, liposome mediation, and osteoporosis risk: a Mendelian randomization study

Background

This study examines the indirect causal relationships between dietary habits and osteoporosis, mediated through liposomes, utilizing a two-sample Mendelian randomization (MR) approach. The research leverages genetic variations as instrumental variables to explore the genetic influences on dietary habits, liposomes, and osteoporosis, aiming to unravel the complex interplay between diet, lipid metabolism, and bone health.

Methods

The study utilized genome-wide association studies (GWAS) data for liposomes from Finnish individuals and osteoporosis-related data, alongside dietary factors from the OpenGWAS database. Instrumental variables were selected based on genetic variants associated with these factors, using a strict significance level and linkage disequilibrium threshold. Statistical analysis employed the Inverse Variance Weighted method, weighted median, and mode-based methods within the R environment, complemented by sensitivity analyses to ensure the robustness of the causal inferences.

Results

Findings revealed significant causal relationships between specific dietary components (white rice, cereal, and non-oily fish) and osteoporosis risk, both directly and mediated through changes in liposome levels. Notably, white rice consumption was associated with an increased risk of osteoporosis, while cereal and non-oily fish intake showed protective effects. Further, certain liposomes were identified as mediators in these relationships, suggesting a link between diet, lipid profiles, and bone health.

Conclusion

The study highlights the significant impact of dietary habits on osteoporosis risk, mediated through liposomes. These findings underscore the importance of considering lipidomic profiles in dietary guidance and suggest potential targets for preventing osteoporosis through nutritional interventions.

Causal relationships between cerebral cortical structure and preeclampsia: insights from bidirectional Mendelian randomization and colocalization analysis

Preeclampsia, a multifaceted condition characterized by high blood pressure during pregnancy, is linked to substantial health risks for both the mother and the fetus. Previous studies suggest potential neurological impacts, but the causal relationships between cortical structural changes and preeclampsia remain unclear. We utilized genome-wide association study data for cortical thickness (TH) and surface area (SA) across multiple brain regions and preeclampsia. Bidirectional Mendelian randomization (MR) analyses were conducted to assess causality, followed by co-localization analyses to confirm shared genetic architecture. Increased cortical TH in the inferior parietal and supramarginal regions, and an enlarged SA in the postcentral region, were significantly associated with higher preeclampsia risk. Conversely, preeclampsia was linked to increased SA in the supramarginal and middle temporal gyri, and decreased SA in the lingual gyrus. Co-localization analyses indicated distinct genetic determinants for cortical structures and preeclampsia. Our findings reveal bidirectional influences between cortical structural features and preeclampsia, suggesting neuroinflammatory and vascular mechanisms as potential pathways. These insights underscore the importance of considering brain structure in preeclampsia risk assessment and highlight the need for further research into neuroprotective strategies.

Comprehensive analysis of aging-related gene expression patterns and identification of potential intervention targets

PURPOSE

This study aims to understand the molecular mechanisms underlying the aging process and identify potential interventions to mitigate age-related decline and diseases.

METHODS

This study utilized the GSE168753 dataset to conduct comprehensive differential gene expression analysis and co-expression module analysis. Machine learning and Mendelian randomization analyses were employed to identify core aging-associated genes and potential drug targets. Molecular docking simulations and mediation analysis were also performed to explore potential compounds and mediators involved in the aging process.

RESULTS

The analysis identified 4164 differentially expressed genes, with 1893 upregulated and 2271 downregulated genes. Co-expression analysis revealed 21 modules, including both positively and negatively correlated modules between older age and younger age groups. Further exploration identified 509 aging-related genes with distinct biological functions. Machine learning and Mendelian randomization analyses identified eight core genes associated with aging, including DPP9, GNAZ, and RELL2. Molecular docking simulations suggested resveratrol, folic acid, and ethinyl estradiol as potential compounds capable of attenuating aging through modulation of RELL2 expression. Mediation analysis indicated that eosinophil counts and neutrophil count might act as mediators in the causal relationship between genes and aging-related indicators.

CONCLUSION

This comprehensive study provides valuable insights into the molecular mechanisms of aging and offers important implications for the development of anti-aging therapeutics. Key Messages What is already known on this topic - Prior research outlines aging's complexity, necessitating precise molecular targets for intervention. What this study adds - This study identifies novel aging-related genes, potential drug targets, and therapeutic compounds, advancing our understanding of aging mechanisms. How this study might affect research, practice, or policy - Findings may inform targeted therapies for age-related conditions, influencing future research and clinical practices.