MR-Egger Methods Research Articles

Assessing the causal relationship between gut microbiota and prostate cancer: A two-sample Mendelian randomization study

BackgroundNumerous studies indicate that the gut microbiome is closely associated with prostate cancer (PCa), however, owing to various confounding factors, the causal relationship between gut microbiota and PCa remains unclear. MethodsA 2-sample Mendelian randomization (MR) analysis utilized genome-wide association study (GWAS) data on the gut microbiota of 18,340 participants and GWAS summary statistics on PCa involving 46,3010 participants. Inverse variance weighted (IVW) served as the primary method, complemented by the MR-Egger method, weighted median method (WME), simple mode method (SM), and weighted mode method (WM). Finally, to confirm the robustness of the results, heterogeneity test, pleiotropy test, and leave-one-out sensitivity test were conducted. ResultsIVW analysis revealed that 12 specific gut microbial taxa were potentially causally associated with PCa; the genera Victivallis, Akkermansia, Odoribacter, Butyrivibrio, and the families Enterobacteriaceae, Verrucomicrobiaceae, as well as the orders Verrucomicrobiales, Enterobacteriales and the class Verrucomicrobiae, were found to be positively associated with PCa risk. Conversely, the genera Eubacterium ruminantium group, Candidatus Soleaferrea, and RuminococcaceaeUCG003 were negatively associated with PCa risk. ConclusionsOur MR study's results support a genetically predicted causal relationship between the gut microbiota and PCa, and we identified 12 specific gut microbial taxa. These findings could offer new targets for PCa screening and treatment.

Causal effects of neuroticism on postpartum depression: a bidirectional mendelian randomization study.

Postpartum depression (PPD) brings adverse and serious consequences to both new parents and newborns. Neuroticism affects PPD, which remains controversial for confounding factors and reverse causality in cross-sectional research. Therefore, mendelian randomization (MR) study has been adopted to investigate their causal relationship. This study utilized large-scale genome-wide association study genetic pooled data from three major databases: the United Kingdom Biobank, the European Bioinformatics Institute, and the FinnGen databases. The causal analysis methods used inverse variance weighting (IVW). The weighted median, MR-Egger method, MR-PRESSO test, and the leave-one-out sensitivity test have been used to examine the results' robustness, heterogeneity, and horizontal pleiotropy. The fixed effect model yielded the results of meta-analysis. In the IVW model, a meta-analysis of the MR study showed that neuroticism increased the risk of PPD (OR, 1.17; 95% CI, 1.11-1.25, p < 0.01). Reverse analysis showed that PPD could not genetically predict neuroticism. There was no significant heterogeneity or horizontal pleiotropy bias in this result. Our study suggests neuroticism is the risk factor for PPD from a gene perspective and PPD is not the risk factor for neuroticism. This finding may provide new insights into prevention and intervention strategies for PPD according to early detection of neuroticism.

Relationship between serum vitamin D levels and thyroid- and parathyroid-related diseases: a Mendelian randomisation study.

Previous studies have indicated an association between vitamin D and thyroid- and parathyroid-related diseases. However, it remains unclear whether it is a cause of the disease, a side effect of treatment or a consequence of the disease. The Mendelian randomisation (MR) study strengthens the causal inference by controlling for non-heritable environmental confounders and reverse causation. In this study, a two-sample bidirectional MR analysis was conducted to investigate the causal relationship between serum vitamin D levels and thyroid- and parathyroid-related diseases. Inverse variance weighted, weighted median and MR-Egger methods were performed, the Cochran Q test was used to evaluate the heterogeneity and the MR-PRESSO and MR-Egger intercepts were utilised to assess the possibility of pleiotropy. The Bonferroni-corrected significance threshold was 0·0038. At the Bonferroni-corrected significance level, we found that vitamin D levels suggestively decreased the risk of benign parathyroid adenoma (OR = 0·244; 95 % CI 0·074, 0·802; P = 0·0202) in the MR analyses. In the reverse MR study, a genetically predicted risk of thyroid cancer suggestively increased the risk of elevated vitamin D (OR = 1·007; 95 % CI 1·010, 1·013; P = 0·0284), chronic thyroiditis significantly increased the risk of elevated vitamin D (OR = 1·007; 95 % CI 1·002, 1·011; P = 0·0030) and thyroid nodules was significantly decreased the vitamin D levels (OR = 0·991; 95 % CI 0·985, 0·997; P = 0·0034). The findings might be less susceptible to horizontal pleiotropy and heterogeneity (P > 0·05). This study from a gene perspective indicated that chronic thyroiditis and thyroid nodules may impact vitamin D levels, but the underlying mechanisms require further investigation.

Exploring the correlation among genetic variants, cholecystectomy and gut microbiome: A Mendelian randomization study.

This Mendelian randomization (MR) study aims to explore the relationship between gut microbiota and the occurrence of cholelithiasis, as well as the impact of cholecystectomy on the gut microbiota. This study leverages data on exposures and outcomes from the GWAS database, employing the inverse variance weighting (IVW) method to obtain primary causal estimates. Heterogeneity is assessed using Cochran Q and Rücker Q tests through both IVW and MR-Egger methods. Pleiotropy is evaluated using the Egger-intercept method, while sensitivity analyses are conducted via leave-one-out tests. Additionally, the F-statistic is calculated to assess the presence of weak instrument bias. Finally, the MR-PRESSO method is utilized to validate the findings concerning the relationship between gut microbiota and the incidence of cholelithiasis, as well as the impact of cholecystectomy on gut microbiota composition. The genera Butyricicoccus (ID: 2055), Solibacillus (ID: 11348), Anaerotruncus (ID: 2054), Allisonella (ID: 2174), and Howardella (ID: 2000) have been found to decrease the genetically predicted probability of cholelithiasis. Reverse MR analysis indicates that the occurrence of cholelithiasis reduces the levels of gut microbiota such as Blautia (ID: 1992), Anaerofilum (ID: 2053), Howardella (ID: 2000), Butyricicoccus (ID: 2055), Solibacillus (ID: 11348), Allisonella (ID: 2174), Anaerotruncus (ID: 2054), and Firmicutes (ID: 1672). Additionally, the genera Odoribacter (ID: 952), and Holdemanella (ID: 2157) increase the genetically predicted risk of cholecystectomy. Reverse MR results show that post-cholecystectomy reduces the levels of gut microbiota such as Blautia (ID: 1992), Butyricicoccus (ID: 2055), Alistipes (ID: 11296), Oxalobacteraceae (ID: 2966), and Ruminococcaceae UCG010 (ID: 11367). Conversely, post-cholecystectomy increases the levels of gut microbiota such as Odoribacter (ID: 952), an unknown family (ID: 1000001214), an unknown genus (ID: 1000001215), Aeromonadales (ID: 1591), Holdemanella (ID: 2157), Phascolarctobacteria (ID: 1589), and Eggerthella (ID: 819). All study results show no horizontal pleiotropy, and the MR-PRESSO validation results are consistent with the MR analysis findings. This study elucidates the relationship between gut microbiota and the occurrence of cholelithiasis, as well as the impact of cholecystectomy on the gut microbiota. These findings have clinical significance for diagnosing disease onset and understanding digestive function changes following gallbladder removal, providing theoretical support for further investigation into the molecular mechanisms underlying cholelithiasis.

Causality between ankylosing spondylitis and urolithiasis in European Populations: A Mendelian randomization analysis

BackgroundAnkylosing spondylitis (AS) is an inflammatory condition affecting the spine. Observational studies have suggested a heightened risk of urolithiasis in AS patients. However, due to the inherent limitations of observational research, the causal relationship between the two remains to be determined. ObjectiveUtilizing the Mendelian randomization analysis approach, this study sought to explore the causal link between AS and urolithiasis. MethodsData from genome-wide association studies were employed for analysis. Mendelian randomization analyses were conducted using the IVW, MR-Egger, Weighted Median, and Weighted Mode methods. Heterogeneity tests, sensitivity analyses, and pleiotropy analyses were also performed. ResultsThe causality between AS and urolithiasis was supported by the IVW (P=.02), Weighted Median (P=.006), and Weighted Mode (P=.01) methods. The MR-Egger method (P=.07) did not support this causal relationship, yet its directionality was consistent with the other three methods. None of the four analysis methods supported a reverse causal relationship between AS and urolithiasis. ConclusionOur study demonstrates a causal relationship between AS and urolithiasis, with no evidence of reverse causality. Given the increased risk of urolithiasis in AS patients, it is crucial to implement preventive strategies and early detection. Stone composition analysis should also be incorporated into clinical practice for these patients, as it can provide essential insights into the metabolic and genetic factors contributing to stone formation, thus improving diagnostic accuracy and treatment outcomes. Future studies are needed to further validate these findings and explore the detailed mechanisms involved.

Causal association between mental disorders and cerebrovascular diseases: Evidence from Mendelian randomization study

Background and objectiveObservational studies have suggested that mental disorders and cerebrovascular diseases (CVDs) may be risk factors for each other, but genetic evidence of a causal relationship is still lacking. We used Mendelian randomization (MR) studies to explore the causal relationship between mental disorders and CVDs from the genetic perspective. MethodsTo investigate the causal association between major depressive disorder (MDD), anxiety, attention deficit/hyperactivity disorder (ADHD), bipolar disorder and schizophrenia five kinds of mental disorders and CVDs using two-sample two-way MR analysis based on publicly available genome-wide association study (GWAS) data. We used as instrumental variables (IVs) single-nucleotide polymorphisms (SNPs) that were strongly associated with mental disorders and CVDs. IVW method was used as the main analysis method, and MR-IVW, MR-Egger methods, MR-PRESSO test, leave-one-out analysis and funnel plot were used for sensitivity analysis. We further conducted a meta-analysis to summarize the currently available MR analyses. ResultsThe results of forward MR study showed that there was a significant causal relationship between ADHD and AS (any stroke) (p(AS) = 0.001, OR (95%CI) =1.118 (1.047–1.195)), any ischemic stroke (AIS) (p(AIS) = 0.004, OR (95%CI) =1.118(1.035–1.206)) and large artery stroke (LAS) (p(LAS) = 0.026, OR (95%CI): 1.206(1.023–1.422)). No heterogeneity, pleiotropy and outliers were found in sensitivity analysis. The reverse MR study showed that IA (intracranial aneurysm) (p(IA) = 0.033, OR (95%CI) = 1.123(1.009–1.249)) and UIA (unruptured intracranial aneurysm) (p(UIA) = 0.015, OR (95%CI) =1.040(1.008–1.074)) were risk factors for schizophrenia. Sensitivity analysis showed no pleiotropy, but there was heterogeneity. After excluding outliers, MR analysis showed that IA and UIA were still risk factors for schizophrenia. Our meta-analyses found statistical significance in causal relationships between ADHD and LAS (OR (95%CI) =1.18 (1.06–1.32), p = 0.003), IA and schizophrenia (OR (95%CI) =1.05 (1.02–1.08), p = 0.002) and UIA and schizophrenia (OR (95%CI) =1.03 (1.01–1.06), p = 0.010). ConclusionThe MR study and meta-analysis suggest that genetically predicted ADHD is a risk factor for LAS, and IA and UIA increase the risk of schizophrenia. The result has implications for the development of feasible prevention strategies in the future.

Causal associations between intermediate very-low-density lipoprotein cholesterol-to-total lipids ratio and peptic ulcer: A bidirectional Mendelian randomization study.

Previous epidemiologic investigations have consistently demonstrated a strong association between the ratio of cholesterol to total lipids in medium very-low-density lipoprotein (VLDL) and the occurrence of peptic ulcers (PU). However, the precise causal relationship between these factors remains ambiguous. Consequently, this study aims to elucidate the potential correlation between the ratio of cholesterol to total lipids in medium VLDL and the incidence of peptic ulcer. To investigate the ratio of cholesterol to total lipids in medium very-low-density lipoprotein (VLDL) association with PU via genetic methods, guiding future clinical research. Genome-wide association study (GWAS) datasets for the ratio of cholesterol to total lipids in intermediate VLDL and peptic ulcer were retrieved from the IEU OpenGWAS project (https://gwas.mrcieu.ac.uk). For the forward Mendelian randomization (MR) analysis, 72 single nucleotide polymorphisms (SNPs) were identified as instrumental variables. These SNPs were selected based on their association with the ratio of cholesterol to total lipids in intermediate VLDL, with peptic ulcer as the outcome variable. Conversely, for the inverse MR analysis, no SNPs were identified with peptic ulcer as the exposure variable and the ratio of cholesterol to total lipids in intermediate VLDL as the outcome. All MR analyses utilized inverse variance weighted (IVW) as the primary analytical method. Additionally, weighted median and MR-Egger methods were employed as supplementary analytical approaches to assess causal effects. Egger regression was used as a supplementary method to evaluate potential directional pleiotropy. Heterogeneity and multiplicity tests were conducted using the leave-one-out method to evaluate result stability and mitigate biases associated with multiple testing. The genetically predicted ratio of cholesterol to total lipids in medium VLDL was significantly associated with an elevated risk of peptic ulcer (IVW: OR = 2.557, 95%CI = 1.274-5.132, P = 0.008). However, no causal association of peptic ulcer with the ratio of cholesterol to total lipids in medium VLDL was observed in the inverse Mendelian randomization analysis. In conclusion, our study reveals a significant association between the ratio of cholesterol to total lipids in medium VLDL and an elevated risk of peptic ulcers. However, further validation through laboratory investigations and larger-scale studies is warranted to strengthen the evidence and confirm the causal relationship between these factors.

Genetic evidence causally linking gastroesophageal reflux disease to cholecystitis: a two-sample mendelian randomization study

BackgroundGastroesophageal reflux disease (GERD) and cholecystitis share overlapping symptoms, including belching, acid reflux, and heartburn. Despite this, the causal relationship between these two conditions remains unclear. This study aimed to investigate the causal link between GERD and cholecystitis using a Mendelian randomization (MR) approach.MethodsA two-sample MR analysis was conducted using the inverse variance weighted (IVW), weighted median, weighted mode, and MR-Egger method to assess the causal effects of GERD on the cholecystitis risk. Genome-wide association studies (GWASs) on GERD (N cases = 129080; N controls = 473524) and cholecystitis (N cases = 1930; N controls =359264) were obtained from the IEU Open GWAS project. Various techniques were employed to assess pleiotropy and heterogeneity.ResultsSeventy-seven single nucleotide polymorphisms from GERD GWASs were selected as instrumental variables (IVs). The primary IVW method revealed a significant association between GERD and an increased risk of cholecystitis (odds ratio = 1.004; 95% confidence interval = 1.003–1.005, p = 2.68 × 10− 9). The absence of heterogeneity and pleiotropy in the data supports the reliability of the results.ConclusionsGERD was positively associated with the risk of cholecystitis. This study provides insights into potential avenues for the development of prevention strategies and treatment options for cholecystitis in patients with GERD. These findings contribute to our understanding of the complex interplay between GERD and cholecystitis.

Mendelian randomization identifies causal associations between GWAS-associated bacteria and their metabolites and rheumatoid arthritis.

Accumulating evidence suggests that an imbalance of gut microbiota is commonly observed in patients with rheumatoid arthritis (RA). However, it remains unclear whether gut microbiota dysbiosis is a cause or consequence of RA, and the mechanisms by which gut dysbiosis contributes to RA have not been fully understood. This study aimed to investigate the causal relationship between gut microbiota and metabolites with RA. A two-sample Mendelian randomization analysis was performed to estimate the causality of gut microbiota and metabolites on RA. A genome-wide association study (GWAS) of 211 gut microbiota and 217 metabolites was used as the exposure, whereas RA was treated as the outcome. Inverse variance weighted (IVW) was regarded as the primary approach for calculating causal estimates. MR Egger method, Weighted median method, Simple mode method, and weighted mode method were used for sensitive analysis. Metabolic pathway analysis was performed via the web-based Metaconflict 5.0. Additionally, an animal study was undertaken to evaluate the results inferred by Mendelian randomization. This study indicated that six gut microbiota taxa (RuminococcaceaeUCG013, Erysipelotrichia, Erysipelotrichaceae, Erysipelotrichales, Clostridia, and Veillonellaceae) were estimated to exert a positive impact on RA. Conversely, seven gut microbiota taxa (Oxalobacter, Cyanobacteria, RuminococcaceaeUCG002, LachnospiraceaeUCG010, Christensenellaceae, Oxalobacteraceae, Anaerostipes) were estimated to exert a negative impact on RA. Three metabolites, namely indole-3-propionate (IPA), glycine and sphingomyelin (SM 16:1), were found to be linked to lower RA risk, while five metabolites (argininosuccinate, CE 20_4, TAG 58_8, PC 40_6, and LPC 20_4) were linked to higher RA risk. Additionally, four metabolic pathways were identified by metabolic pathway analysis. The collagen-induced arthritis (CIA) rats exhibited a higher relative abundance of Class_Clostridia and a lower abundance of Genus_Lachnospiraceae (p < 0.05) than the healthy controls. This study identified causal associations between specific gut microbiota, metabolites, and RA. These findings support the significant role of gut microbiota and metabolites in RA pathogenesis.

Exploring the mechanisms and relationship between body mass index and asthma: findings from Mendelian randomization

Background The mechanism linking BMI and asthma remains unclear. Method Mendelian Randomization (MR) analysis was conducted using summary-level GWAS data from the FinnGen Biobank and the Open GWAS project. The analysis considering potential variables as mediators, including blood cell counts, blood pressure, and blood biomarkers. Three commonly used MR methods—the inverse-variance-weighted (IVW) method, weighted median (WM) method, and MR-Egger method—were employed to infer causal links. A two-step approach was used in mediation analysis to evaluate the causal links among BMI, candidate mediators, and asthma. Result Elevated BMI demonstrated a substantial correlation with increased asthma risk. Thirteen biomarkers mediated the relationship between BMI and asthma, mainly including leukocyte count (5.070%), apolipoprotein A levels (7.395%), cystatin C levels (5.345%), urate levels (9.057%), diastolic blood pressure (7.365%), and albumin levels (10.888%). These factors collectively explained over 50% of the increased asthma risk associated with BMI elevation. Additionally, eosinophil count and C-reactive protein were also identified as important mediators using the WM method. Conclusion This study highlights the complex relationship between obesity, blood biomarkers, and asthma risk. Additional studies are required to validate these results and investigate causal relationships in various populations.

A cause-effect relationship between uterine diseases and breast cancer: A bidirectional Mendelian randomization study

ObjectiveTo explore the cause-effect relationship between uterine diseases (UDs) and breast cancer (BC) and underlying mechanism of the cause-effect relationship, enhance understanding of the association between BC and UDs. MethodsA two-sample bidirectional Mendelian randomization (MR) analysis was conducted. We obtained summary statistics data from GWAS for BC, endometriosis, endometrial cancer (EC), uterine leiomyoma (UL), uterine polyps (UP), and cervical cancer (CC). Independent SNPs were selected as instrumental variables (IVs) for each disease. The inverse variance weighted (IVW) method was primary used for estimating the causal association between UDs and BC. To further evaluate the consistency and dependability of the results, we also utilized the weighted median, weighted mode, simple mode, and MR-Egger methods, along with sensitivity analyses. Furthermore, a supplementary analysis focusing on the variants linked to BC and UDs was conducted. This involved identifying corresponding genes and subsequently performing KEGG/GO analyses to investigate potential molecular mechanisms. ResultsThe results indicated significant associations between genetic susceptibility to endometriosis, EC, and UL with BC risk. The odds ratios (ORs) were as follows: endometriosis at 0.963 (95 % CI, 0.942–0.984; p = 7.11e-5), EC at 1.056 (95 % CI, 1.033–1.081; p = 2.39e-6), and UL at 1.027 (95 % CI, 1.006–1.048; p = 0.010). Conversely, the predisposition to BC inferred from genetic factors was markedly correlated with an elevated risk of EC indicated by an OR of 1.066 (95 % CI, 1.019–1.116; p = 0.006), and was correlated with UP risk (OR, 1.001,95 % CI, 1.000–1.002; p = 0.001).Sensitivity analyses provided weak evidence for these effects, suggesting that the study's outcomes are consistent and trustworthy. Further analysis of the genetic variants associated with BC, and these related genes are enriched in Cellular senescence, GnRH secretion, Phosphatidylinositol signaling system, and so on. ConclusionThis study corroborates the existence of a reciprocal causal relationship between BC and EC, as well as highlighting the substantial correlations between a genetic susceptibility to UL and endometriosis with BC. BC may exert their influence on EC and UP through Cellular senescence, GnRH secretion, and other pathways. These discoveries offer fresh perspectives on the genetic pathogenesis of BC and UDs, and can guide future experimental studies. Additionally, they lay down a groundwork for the development of tailored preventative and therapeutic strategies moving forward.

Causal relationship between genetically determined plasma metabolites and stroke: A two sample Mendelian randomization study

IntroductionThis study investigates the causal relationship between plasma metabolites and stroke. MethodThe primary analytical approach employed was the inverse variance weighted (IVW) method, complemented by the weighted median (WM) and MR Egger methods for Additionally, validation of the identified plasma metabolites was performed using the Steiger test and LD linkage disequilibrium score. Furthermore, the main results were confirmed through data from the UK Biobank. ResultThe IVW analysis revealed the most notable negative association found in X-17335 levels (OR [95 % CI]: 0.82 [0.72, 0.94]). On the other hand, the strongest positive effect was seen in the 5′-homophase (AMP) to phase ratio (OR [95 % CI]: 1.17 [1.03, 1.32]). Moving on to the validation dataset, the most significant positive effect was observed in the 13 HODE+9-HODE levels (OR [95 % CI]: 0.996 [0.993, 0.999]), whereas the most significant negative effect was seen in the Dihydroxide levels (OR [95 % CI]: 1.004 [1.00, 1.007]). Notably, Alpha ketoglutarate levels exhibited strong causal effects in both datasets (OR 0.908 [0.841, 0.981], p = 0.0144). Enrichment analysis highlighted the association of Alpha ketoglutarate levels with five plasma metabolites in metabolic pathways relevant to stroke, specifically Arginine biosynthesis, Butanoate metabolism, Citrate cycle (TCA cycle), Alanine, aspartate, and glutamate metabolism, and Lipid acid metabolism, all linked to oxoglutaric acid. ConclusionThe discovery dataset showed the most significant positive effect of the 5′-homophase (AMP) to phase ratio, while the validation dataset revealed the most significant positive effect of the 13 HODE+9-HODE levels. Additionally, alpha ketoglutarate may offer a potential protective effect on stroke by influencing five metabolic pathways that intersect with Oxoglutaric acid during the progression of the condition.

Mendelian randomization did not support the causal effect of diabetes on aortic diseases.

Observational studies revealed paradoxically inverse associations between diabetes and aortic diseases (aortic aneurysm or aortic dissection), yet the causality remains to be determined. To investigate the causal associations between diabetes and aortic diseases using Mendelian randomization (MR) analyses. Summary-level data for exposures (type 1 diabetes, type 2 diabetes, fasting glucose, fasting insulin, glycated hemoglobin) and outcomes (aortic dissection and aortic aneurysm) were obtained from public genome-wide association study data. The principal analysis was the inverse-variance weighted (IVW) method. Sensitivity analyses were also carried out, including weighted median, MR-Egger, and multivariable MR methods. According to IVW results, type 1 diabetes (odds ratio [OR]: 0.99; 95% confidence interval [CI] 0.93-1.07; P = 0.87), type 2 diabetes (OR: 0.97; 95% CI 0.77-1.20; P = 0.75), fasting glucose (OR: 1.16; 95% CI 0.48-2.84; P = 0.74), fasting insulin (OR: 2.75; 95% CI 0.53-14.26; P = 0.23), or glycated hemoglobin (OR: 0.33; 95% CI 0.09-1.17; P = 0.09) had no causal effect on aortic dissection. Similarly, type 1 diabetes, type 2 diabetes, fasting glucose, fasting insulin, or glycated hemoglobin had no causal effect on aortic aneurysm. Sensitivity analyses revealed consistent results. MR-Egger method and funnel plot yielded no indication of directional pleiotropy. Diabetes had no causal associations with aortic dissection or aortic aneurysm. The observed inverse associations in previous cohort studies may be explained by confounding factors or reverse causation.

Association between air pollutants and four major mental disorders: Evidence from a Mendelian randomization study

BackgroundExisting epidemiological studies have indicated a correlation between air pollutants and the occurrence of mental disorders. However, it is difficult to estimate the causal relationship between the two because of the limitations of traditional epidemiological research. In our study, we aimed to extensively explore the causal relationship between five types of air pollutants and four types of mental disorders. MethodsBased on the IEU OPEN GWAS database, we performed a two-sample MR analysis. The primary analysis method utilized was the inverse variance weighted (IVW) method, supplemented by the MR-Egger method and the weighted median method. Additionally, we conducted sensitivity analyses with the Cochran's Q statistic method, the leave-one-out method, and the MR-Egger intercept. We chose at least 4 GWAS datasets for each of the four psychiatric diseases and conducted a meta-analysis of our results of the MR analysis. ResultsThe meta-analysis's findings demonstrated a causal link between depression and PM2.5 (OR=1.020, 95 %CI: (1.010,1.030), P=0.001). PM10 and schizophrenia are also causally related (OR=1.136, 95 %CI: (1.034,1.248), P=0.008). Nitrogen oxides and bipolar disorder have a causal relationship (OR=1.002, 95 %CI: (1.000,1.003), P=0.022). Nitrogen oxides and schizophrenia have a high causal association (OR=1.439, 95 %CI: (1.183,1.752), P<0.001). ConclusionThis study observed a causal association between increased concentrations of PM2.5, PM10, and nitrogen oxides and the occurrence of depression, schizophrenia, and bipolar disorder. Our research findings have certain guiding implications for treating and preventing mental disorders.

Association between blood mitochondrial DNA copy number and mental disorders: A bidirectional two-sample mendelian randomization study

BackgroundMitochondria is essential for cellular energy production, oxidative stress, and apoptosis. Mitochondrial DNA (mtDNA) encodes essential proteins for mitochondrial function. Although several studies have explored the association between changes in mtDNA copy number (mtDNA-CN) and risk of mental disorders, the results remain debated. This study used a bidirectional two-sample Mendelian randomization (MR) analysis to examine the genetic causality between mtDNA-CN and mental disorders. MethodsGenome-wide association study (GWAS) data for mtDNA-CN were sourced from UK biobank, involving 383,476 European cases. GWAS data for seven mental disorders—attention deficit/hyperactivity disorder, autism spectrum disorder (ASD), schizophrenia, bipolar disorder, major depressive disorder, anxiety, and obsessive-compulsive disorder—were primarily obtained from the Psychiatric Genomics Consortium. Causal associations were assessed using inverse variance weighting, with sensitivity analyses via the weighted median and MR-Egger methods. Reverse MR considered the seven mental disorders as exposures. All analyses were replicated with additional mtDNA-CN GWAS data from 465,809 individuals in the Heart and Ageing Research in Genomic Epidemiology consortium and the UK Biobank. ResultsForward MR observed a 27 % decrease in the risk of ASD per standard deviation increase in genetically determined blood mtDNA-CN (OR = 0.73, 95%CI: 0.58–0.92, p = 0.002), with no causal effects on other disorders. Additionally, reverse MR did not indicate a causal association between any of the mental disorders and mtDNA-CN. Validation analyses corroborated these findings, indicating their robustness. ConclusionsOur study supports the potential causal association between mtDNA-CN and the risk of ASD, suggesting that mtDNA-CN could serve as a promising biomarker for early screening of ASD.

Correlation between inflammatory cytokines and the likelihood of developing multiple types of digestive system cancers: A Mendelian randomization study

ObjectiveInflammatory cytokines have been linked to digestive system cancers, yet their exact causal connection remains uncertain. Consequently, we conducted a Mendelian randomization (MR) analysis to gauge how inflammatory cytokines are linked to the risk of five prevalent digestive system cancers (DSCs). MethodsWe collected genetic variation data for 41 inflammatory cytokines from genome-wide association studies (GWAS), and the results data for five common diseases from the Finnish database. Our primary analytical approach involved employing the inverse-variance weighted, residual sum (IVW) method, complemented by the MR-Egger method, the weighted median method, simple mode analysis, and weighted mode analysis as supplementary analytical techniques. Furthermore, we conducted multiple sensitivity analyses. ResultsTumor necrosis factor-related apoptosis-inducing ligand (TRAIL), macrophage colony-stimulating factor (M-CSF), and interleukin (IL)-18 showed a negative association with the risk of hepatocellular carcinoma. Conversely, TRAIL was inversely linked to the risk of gastric cancer, while IL-16 exhibited a positive correlation with gastric cancer risk. Stem cell factor (SCF) acted as a protective factor against pancreatic cancer. For colorectal cancer, IL-7, IL-9, IL-13, and vascular endothelial growth factor (VEGF) were identified as risk factors. Notably, our results did not indicate a significant correlation between inflammatory cytokines and the risk of esophageal cancer. ConclusionOur research unveils potential connections between 41 inflammatory cytokines and the risk of five common DSCs through a MR analysis. These associations offer valuable insights that could aid in the development of diagnostic biomarkers and the identification of novel therapeutic targets for DSCs.

Association between rheumatoid arthritis and chronic respiratory diseases in a Japanese population: A Mendelian randomization study.

Past observational studies have documented an association between rheumatoid arthritis (RA) and chronic respiratory diseases. Undertaking the approach of Mendelian randomization (MR) analysis, this research aims to delve deeper into the probability of a causal connection between RA and chronic respiratory diseases. Collated genome-wide association study data covering RA with 4199 cases against 208,254 controls, asthma comprising 8216 cases versus 201,592 controls, and chronic obstructive pulmonary disease (COPD) detailing 3315 cases in contrast to 201,592 controls were derived from the repository of the Japanese Biobank. A selection of 10 RA-related, 8 asthma-related, and 4 COPD-related single nucleotide polymorphisms notable for their statistical significance (P < 5 × 10-8) were identified as instrumental variables. The primary analytical technique was the inverse variance-weighted (IVW) method, alongside the MR-Egger protocol, weighted median, and weighted mode to reinforce the validity and solidity of the principal results. For scrutinizing possible implications of horizontal pleiotropy, we harnessed the MR-Egger intercept examination and the Mendelian Randomization Pleiotropy REsidual Sum and Outlier test. Employing the inverse variance-weighted technique, we established a positive correlation between genetic predispositions for RA and actual occurrences of asthma (odds ratios [OR] = 1.14; 95% confidence intervals [CI]: 1.04-1.24; P = .003). This correlation remained strong when testing the results utilizing various methods, including the MR-Egger method (OR = 1.32; 95% CI: 1.09-1.60; P = .023), the weighted median (OR = 1.16; 95% CI: 1.06-1.26; P < .001), and the weighted mode (OR = 1.21; 95% CI: 1.11-1.32; P = .002). Furthermore, our findings from the inverse variance-weighted method also demonstrated a positive association between genetically predicted RA and COPD (OR = 1.12; 95% CI: 1.02-1.29; P = .021). However, no such link was discerned in supplementary analyses. In a shifted perspective-the reverse MR analysis-no correlation was identified between genetically predicted instances of asthma (IVW, P = .717) or COPD (IVW, P = .177) and RA. The findings confirm a causal correlation between genetically predicted RA and an elevated risk of either asthma or COPD. In contrast, our results offer no support to the presumed causal relationship between genetic susceptibility to either asthma or COPD and the subsequent development of RA.

Novel insights into causal effects of maternal nonalcoholic fatty liver disease on adverse pregnancy outcomes: evidence from Human Genetics and Mendelian Randomization Study.

Observational studies have associated nonalcoholic fatty liver disease (NAFLD) with adverse pregnancy events, but findings show heterogeneity, leaving the causal direction and mediating pathways unclear. We aimed to investigate the causal relation between NAFLD and various pregnancy events, and to elucidate the underlying mediating pathways while determining the proportion of this correlation that is mediated through these pathways. A genome-wide association study involving over 6 million participants employing Mendelian randomization (MR) and mediation analysis was performed. The study used genetically predicted NAFLD as exposures and cardiometabolic traits as mediators, with various adverse pregnancy events as outcomes. The main analysis was performed using the inverse variance weighted (IVW) approach, while sensitivity analyses included the weighted median, weighted mode, MR-Egger, and MR-PRESSO methods. Mediation analyses were performed using a two-step MR framework. In this MR cohort study, NAFLD was found to be strongly associated with elevated risks of GDM (P = 0.019 for the discovery dataset, P < 0.001 for the discovery dataset) and HDPs, including any HDP (P < 0.001 for the both datasets), gestational hypertension (P = 0.007 for the discovery dataset, P < 0.001 for the discovery dataset), and pre-eclampsia or eclampsia (P = 0.040 for the discovery dataset, P < 0.001 for the discovery dataset). However, no significant associations were found with hemorrhage in early pregnancy, postpartum hemorrhage, preterm birth, or offspring birthweight for both datasets. Cardiometabolic traits played a significant mediating role in these associations, rather than solely acting as confounding factors. This study provided evidence supporting a correlation between NAFLD and a higher risk of adverse pregnancy events and introduces some new insights. These findings may inform preventions and interventions for remediating adverse pregnancy outcomes attributable to NAFLD.

Causal associations between Helicobacter Pylori infection and the risk and symptoms of Parkinson's disease: a Mendelian randomization study.

Increasing evidence suggests an association between Helicobacter pylori (HP) infection and Parkinson's disease (PD) and its clinical manifestations, but the causal relationship remain largely unknown. To investigate the causal relationship between HP infection and PD risk, PD symptoms, and secondary parkinsonism, we conducted two-sample Mendelian randomization (MR). We obtained summary data from genome-wide association studies for seven different antibodies specific to HP proteins and five PD-related phenotypes. The inverse-variance weighted (IVW), weighted median, weighted mode, and MR-Egger methods were used to assess the causal relationships. Sensitivity analyses were performed to examine the stability of the MR results and reverse MR analysis was conducted to evaluate the presence of reverse causality. Genetically predicted HP antibodies were not causally associated with an increased risk of PD. However, HP cytotoxin-associated gene-A (CagA) and outer membrane protein (OMP) antibody level were causally associated with PD motor subtype (tremor to postural instability/gait difficulty score ratio; β = -0.16 and 0.46, P = 0.002 and 0.048, respectively). HP vacuolating cytotoxin-A (VacA) antibody level was causally associated with an increased risk of PD dementia [odds ratio (OR) = 1.93, P = 0.040]. Additionally, HP OMP antibody level was identified as a risk factor for drug-induced secondary parkinsonism (OR = 2.08, P = 0.033). These results were stable, showed no evidence of heterogeneity or directional pleiotropy, and no evidence of a reverse causal relationship. Our findings indicate that HP infection does not increase the risk of PD, but contributes to PD motor and cognitive symptoms. Different types of HP antibodies affect different symptoms of PD. Eradication of HP infection may help modulate and improve symptoms in PD patients.

Micronutrients and Allergic Diseases: A Mendelian Randomization Study

Introduction: Previous studies have indicated a controversy regarding the association between dietary micronutrient concentrations and the risk of allergic diseases. In this study, we employed Mendelian randomization (MR) analysis using data from two samples to investigate the causal relationship between circulating micronutrient concentrations and three allergic diseases. Methods: In this study, we considered 16 circulating micronutrients as exposure variables (beta carotene, calcium, copper, folate, iron, lycopene, magnesium, phosphorus, selenium, vitamin A1, vitamin B6, vitamin B12, vitamin C, vitamin D, vitamin E, and zinc); and three common allergic diseases (allergic asthma [AA], atopic dermatitis [AD], and allergic rhinitis [AR]) as outcomes. The inverse variance weighted (IVW) method was primarily applied for MR analysis, supplemented by MR-Egger and weighted-median methods to corroborate the IVW results; and sensitivity analysis was conducted to ensure the robustness of the MR assumptions. Results: Our results revealed that an increase in serum phosphorus and zinc concentrations may diminish the risk of AA, while for AD an increase in serum zinc concentration may reduce the risk, but an increase in serum vitamin C concentration may elevate the risk. As for AR, an increase in serum phosphorus and selenium concentrations appeared to be associated with a reduced risk. We did not find evidence for an association between other micronutrients and the risk of allergic diseases. Conclusion: Our study indicates that an increase in serum phosphorus and zinc concentrations may reduce the risk of AA, while an increase in serum zinc concentration may reduce the risk of AD, but an increase in serum vitamin C concentration may elevate the risk of AD. An increase in serum phosphorus and selenium concentrations is associated with a reduced risk of AR. This provides additional support for research on the effects of micronutrients on allergic diseases.