Mendelian randomization: use of genetics to enable causal inference in observational studies

Identification of potential drug targets for pelvic organ prolapse using a proteome-wide Mendelian randomization approach

Pelvic organ prolapse (POP) significantly impacts patients' quality of life, and current treatment options remain limited due to high recurrence rates, making the exploration of new therapeutic targets essential. Using data from the FinnGen cohort, we performed a proteome-wide Mendelian randomization (PW-MR) analysis. Through PW-MR and Bayesian colocalization analyses, we identified EFEMP1 and MFAP4 as potential key drug targets, with EFEMP1 potentially exerting a protective effect, whereas MFAP4 may be associated with an increased risk of POP. To further support these findings, we analysed single-cell RNA sequencing data to evaluate the expression patterns of EFEMP1 and MFAP4 in different cell populations. The analysis revealed that EFEMP1 and MFAP4 are specifically enriched in cell types involved in tissue remodelling and fibrosis. Findings of phenome-wide association studies indicated that the risk of side effects for these targets may be low, suggesting the safety of treatment focused on these targets. Preliminary molecular docking analysis findings suggested that EFEMP1 and MFAP4 may have strong binding affinities with candidate drugs, further supporting the feasibility of EFEMP1 and MFAP4 as drug targets. In conclusion, our findings indicate that EFEMP1 and MFAP4 are promising therapeutic targets for POP, providing important insights for the development of safe and effective treatments.

Effects of Klotho in epilepsy: An umbrella review of observational and mendelian randomization studies

BACKGROUND

Klotho is a geroprotective protein which has been recognized for its anti-aging properties. Pre-clinical evidence suggested that boosting Klotho might hold therapeutic potential in ageing and disease. Epilepsy is a neurological disorder characterized by its recurrent seizures. The complex interplay between Klotho and epilepsy has not been elucidated. The main objective was to investigate the role of Klotho in epilepsy with combination of observational and mendelian randomization (MR) studies.

METHODS

The observational data set comprised 13,766 adults who were aged 20-80 years from the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2016. We used weighted multivariable-adjusted logistic regression models to examine the association between Klotho and epilepsy. We also applied MR to discern if a causal link is present between Klotho and epilepsy.

RESULTS

In NHANES study, the incidence of epilepsy tended to decline with an increase of Klotho levels after covariate adjustments. Klotho was identified to have causal effects on epilepsy. MR analyses revealed that higher transformed Klotho (by rank-based inverse normal transformation) levels were correlated with a higher likelihood of developing generalized epilepsy, lesion-negative focal epilepsy, and focal epilepsy, indicating that higher Klotho concentrations were associated with reduced risks of epilepsy. The sensitivity analyses upheld these consistent relationships.

CONCLUSIONS

Our research, encompassing comprehensive NHANSE analysis and MR methods, revealed that an increase in Klotho levels was associated with a reduced risk of epilepsy, suggesting that increasing or restoring Klotho might play a protective role and offer new anti-aging therapeutic potential in epilepsy.

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

BACKGROUND

Numerous 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.

METHODS

A 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.

RESULTS

IVW 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.

CONCLUSIONS

Our 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.

Hypertension and 28-day mortality in sepsis patients: An observational and mendelian randomization study

BACKGROUND

Predicting and reducing the 28-day mortality in sepsis remains a challenge in this research field.

OBJECTIVE

This study aimed to explore the association between hypertension and 28-day mortality in sepsis.

METHODS

This study is a cross-sectional approach with Mendelian Randomization (MR). We used GWAS data for hypertension as the exposure and 28-day mortality in sepsis as the outcome and employed the main inverse variance weighted method along with other supplementary MR techniques to verify the causal association between hypertension and 28-day mortality in sepsis. We used sensitivity analyses to ensure the robustness of the research findings. Finally, we utilized clinical data from the Medical Information Mart for Intensive Care-IV database to assess the risk association between hypertension and 28-day mortality in sepsis using difference analysis and multivariate logistic regression analysis.

RESULTS

According to MR, hypertension increased the 28-day mortality in sepsis in both two datasets (FinnGen: odds ratio [OR] = 1.61, 95 % confidence interval [CI] = 1.15-2.26, p = 0.006; Medical Research Council-Integrative Epidemiological Unit: OR = 160, 95 % CI = 2.76-9250, p = 0.014). In our observational study, we included a total of 2012 sepsis patients, of which 60.5 % were male, and the average age was 55.4 years. By applying univariate and multivariate logistic regression models (univariate analysis p = 0.02, multivariate analysis p = 0.02), we observed a significantly increased risk of 28-day mortality due to hypertension in sepsis patients.

CONCLUSION

This study confirmed the causal relationship between hypertension and the 28-day mortality in sepsis.

Exploring modifiable risk factors: insights from Mendelian randomization analyses of gastric cancer in East Asian populations

BACKGROUND

The incidence of gastric cancer (GC) shows strong geographic variation, with the highest incidence occurring in East Asia. Epidemiological studies have linked lifestyle, diet, and inflammatory factors to the risk of GC. However, their causal relationship is subject to debate due to the potential presence of bias. Addressing these uncertainties is vital for guiding effective preventive strategies.

METHODS

We used genetic variants as instruments via two-sample univariate and multivariate Mendelian randomization analyses to examine the relationships between 40 potentially modifiable risk factors and gastric cancer in 6563 patients with gastric cancer and 195,745 controls. These population data came from a genome-wide association study of people of Asian ancestry and were obtained from BioBank Japan.

RESULTS

Our multivariable Mendelian randomization analyses provided suggestive evidence of a potential association between genetically predicted concentrations of serum hemoglobin (ORSD 0.62 [95% CI 0.41 ~ 0.93]; p = 0.02), lactate dehydrogenase (LDH) (ORSD 0.30 [95% CI 0.16 ~ 0.56]; p < 0.001) and alkaline phosphatase (ALP) (ORSD 0.80 [95% CI 0.73 ~ 0.88]; p < 0.001) and a decreased risk of GC. Furthermore, our study revealed a causal link between type 2 diabetes mellitus (T2DM) (ORSD 0.83, 95% CI = 0.73 ~ 0.93, p value = 0.002) and GC incidence.

CONCLUSIONS

This analysis identified several potential modifiable factors for gastric cancer, including hemoglobin, LDH, ALP and T2DM. These findings should be considered when formulating strategies for the primary prevention of GC, thereby informing evidence-based public health policies.

Investigating the causal relationship between the plasma lipidome and cholangiocarcinoma mediated by immune cells: a mediation Mendelian randomization study

The plasma lipidome and immune cells are instrumental in shaping the health profile of an organism, and their influence on diseases is profound. However, the intricate interactions between cholangiocarcinoma (CCA) and these physiological components have yet to be comprehensively explored. Employing Mendelian randomization (MR), our study delved into the causal links among immune cells, the lipidome, and CCA. The research design meticulously considered both the direct associations and the mediating roles of immune cells within the complex interplay between the lipidome and CCA. Our analysis uncovered significant correlations between the levels of Sphingomyelin (d34:1), Phosphatidylcholine (0-16:0, 22:5) and Sterol ester (27:1/16:0) and CCA. Moreover, we have pinpointed various immune cells that play a mediating role in the impact of the lipidome on CCA. For example, Sphingomyelin (d34:1) can impact CCA through the IgD on IgD+ CD38- unswitched memory (unsw mem) B cell (B cell panel), IgD on unsw mem (B cell panel) and Naive CD4+ %CD4+ (maturation stages of T cell). The proportion of mediating effects further sheds light on the intricate interplay among the lipidome, immune cells, and their cumulative influence on CCA. Our study illuminates the intricate relationship among the lipidome, immune cells, and CCA. These findings suggest that the lipidome could serve as a promising and potentially effective therapeutic target in the treatment of CCA.

Frailty and the Risk of Age-Related Macular Degeneration: A Prospective Cohort and Mendelian Randomization Study

BACKGROUND

Both frailty and age-related macular degeneration (AMD) are related to aging and may share some common mechanisms. We aimed to examine the observational and causal association between frailty and the risk of AMD.

METHODS

We included 320 810 participants free of AMD at baseline from the UK Biobank. Frailty phenotypes were defined according to 5 components: weight loss, exhaustion, slow gait speed, low grip strength, and low physical activity. Cox proportional hazard models were used to evaluate the association between frailty phenotype and the risk of AMD. A causal relationship between frailty phenotype and AMD was examined using 2-sample Mendelian randomization (MR) analysis.

RESULTS

During a median follow-up of 12.81 years, 7 222 AMD cases were documented. After adjusting for confounding factors, compared with nonfrail participants, both pre-frail and frail participants were significantly associated with an increased risk of AMD (hazard ratio [HR] 1.17, [95% confidence interval {CI}: 1.11, 1.23] for pre-frailty and HR 1.55 [95% CI: 1.40, 1.73] for frailty). With each 1-point increase in frailty phenotype score, the risk of AMD increased by 14%. Results from the 2-sample MR analysis supported the potential causal effect of frailty phenotype on AMD.

CONCLUSIONS

Our findings suggested that frailty assessment may help identify at-risk populations and serve as a potential strategy for early prevention and management of AMD.

Causal associations between socioeconomic status and prostate cancer using two-sample Mendelian randomization study

Prostate cancer (PCa) is a common form of malignancy among men. The associations between socioeconomic status (SES) indicators and PCa risks remain incompletely elucidated. Through two-sample Mendelian randomization (MR), this research seeks to assess the causal links between 4 genetically predicted SES indicators-average total household income before tax, the Townsend deprivation index at recruitment, unemployed status and college or university degree in the household-and PCa. Genetic variants were extracted from publicly available genome-wide association studies (GWAS) under stringent threshold as instrumental variables (IVs). We employed the inverse variance weighted (IVW), weighted median, weighted mode and MR-Egger to estimate the causal effect, with sensitivity analyses such as Cochran's Q tests, MR-Egger, MR-PRESSO and leave-one-out performed to detect potential heterogeneity and pleiotropy. Our MR analysis revealed a causal association between unemployment and prostate cancer (OR: 3.07, 95%CI:1.12-8.42, P = 0.03). No causal associations were identified between other SES components and prostate cancer. The MR-PRESSO suggested 2 outliers in the association between college or university degree in household and prostate cancer, which rendered the association significant after outliers were removed. The heterogeneity and pleiotropy are unlikely to affect our causal estimate. Our results indicated that unemployment poses a potential risk factor for the incidence of PCa. The findings highlight the necessity for further exploration into the underlying etiology of PCa.

The association between serum albumin levels and metabolic syndrome based on the NHANES and two sample Mendelian randomization study

Previous studies have shown that serum albumin levels are associated with a greater risk of metabolic syndrome (MetS). However, it is unclear whether this association is causal or only influenced by confounding factors, so further investigation is needed to determine the causal relationships. Researchers selected participants with serum albumin, metabolic syndrome, and related covariates from the National Health and Nutrition Examination Survey (NHANES) database for a total of 14,036 individuals, including 5483 individuals with MetS and 8553 individuals without MetS. The association of serum albumin levels with metabolic syndrome and its components was estimated using weighted multivariable logistic regression, with its nonlinearity being examined by restricted cubic spline (RCS) regression. Bidirectional two-sample Mendelian randomization (MR) analysis was performed using Genome-Wide Association Study (GWAS) data on serum albumin and MetS to assess the causal relationship between serum albumin levels and MetS and its components. The primary MR analyses were performed via an inverse variance weighting (IVW) approach. In addition, several sensitivity analyses were performed to assess the robustness of the results. The STROBE-MR checklist for the reporting of MR studies was used in this study. After confounder adjustment, when the serum albumin levels were analyzed as a continuous variable, the multivariable logistic analysis revealed a significant association between it and metabolic syndrome (OR: 1.032, 95% CI: 1.012-1.052). When the serum albumin levels were used as categorical variables, the adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for metabolic syndrome across higher serum albumin levels quartiles were 0.981 (0.842-1.143), 1.290 (1.115-1.492), and 1.244 (1.064-1.454) compared to the lowest quartile, respectively. In the forward MR study, the IVW method revealed that genetic predicted increased levels of serum albumin were positively correlated with metabolic syndrome (OR: 1.149, 95% CI: 1.016-1.299) and its components, including hypertension (OR: 1.130, 95% CI: 1.013-1.260) and triglycerides (OR: 1.343, 95% CI: 1.209-1.492). In the reverse MR study, the IVW method showed no significant causal relationship between MetS, hypertension, fasting blood glucose and HDL-C with serum albumin levels. The results from the NHANES and MR analysis have revealed a causal relationship between serum albumin levels and both metabolic syndrome and hypertension, indicating that elevated levels of serum albumin are a risk factor for these conditions. Our results provide new biomarkers for preventive and therapeutic strategies for metabolic syndrome.

The effects of coagulation factors on the risk of autoimmune diseases: A Mendelian randomization study

The objective of this study was to investigate the potential causal relationship between coagulation factors and autoimmune diseases (ADs). We employed Mendelian randomization to investigate the associations between selected 7 coagulation factors and 10 ADs, leveraging genetic variants as instrumental variables to assess causal relationships between exposures of interest and outcomes. Within the scope of this investigation, coagulation factors were designated as the exposure source, while ADs were observed to manifest as the consequent outcome. Our analysis using the inverse-variance weighted (IVW) method revealed that Factor VIII (FVIII) (P = .0067) exhibited significant causal associations with a reduced risk of multiple sclerosis. In contrast, fibrinogen (P = .0004) was associated with an increased risk of multiple sclerosis. The analysis also indicated that activated partial thromboplastin time (P = .0047) was implicated in elevating the risk of urticaria. The results also showed that protein C (P = .0188) was inversely associated with the risk of systemic lupus erythematosus. The results unveiled a significant positive correlation between fibrinogen (P = .0318) and the risk of rheumatoid arthritis. Similarly, Factor VII (P = .0119), FVIII (P = .0141), and von Willebrand Factor (P = .0494) were also found to be positively associated with the risk of inflammatory bowel disease. The IVW analysis demonstrated a causal relationship between von Willebrand Factor (P = .0316) and FVIII (P = .0408) and a decreased risk of primary sclerosing cholangitis. IVW results confirmed that protein C (P = .0409) had a protective effect on vitiligo. No significant associations were found between psoriatic arthritis, rosacea, and the 7 coagulation factors in this study. This is of significant importance for advancing the prevention, diagnosis, and treatment of ADs.

Association of cardiovascular disease on cancer: observational and mendelian randomization analyses

Extensive research is needed to examine the association between cardiovascular disease (CVD) and cancer. The observational study is based on data collected from the 2005-2018 National Health and Nutrition Examination Survey (NHANES). To assess the connection between CVDs and cancer, we used a weighted multivariable logistic regression analysis with as many confounding factors as feasible included in the model. By employing Mendelian randomization (MR), the unbiased causal relationship between CVDs and cancers was ascertained. The primary analytical approach employed the Inverse Variance Weighted methodology. In cross-sectional study, a positive correlation was observed between CVD and cancer (Model 3, Odds ratio 1.26, 95% confidence interval 1.01 ~ 1.57, p = 0.040). However, MR analysis indicated a negative causal relationship between certain subtypes of CVD and specific cancers, with effect sizes for coronary heart disease and lung cancer (β = - 4.759, p = 0.002), breast cancer (β = - 2.684, p = 0.026), colorectal cancer (β = - 4.581, p = 0.042), liver cancers (β = - 19.264, p = 0.028), and stroke with prostate cancer (β = - 0.299, p = 0.017), with no evidence of a positive correlation. Results from the reverse MR causal analysis revealed a positive correlation between prostate cancer and angina pectoris. An observational study linked CVDs risk to cancer risk. MR analysis has shown that the expected incidence of CVDs can reduce the probability of developing certain forms of cancer. Further investigation is required to examine the clinical correlations and underlying processes between these two illnesses.

The role of moderate to vigorous physical activity level and number of treatments/medications in mediating the effect of body mass index on diabetic nephropathy: a Mendelian randomization study

BACKGROUND

Body mass index (BMI) is associated with diabetic nephropathy (DN). However, the mediator factors in the BMI-DN effects remain unclear.

METHODS

Univariate and multivariate Mendelian randomization (MR) analysis were performed to estimate the association between six lifestyles (moderate to vigorous physical activity levels, years of schooling, BMI, nap during day, number of treatments/medications taken and coffee intake) and DN. MR Egger, Weighted median, Simple mode, and Weighted mode was supplemental methods to Inverse variance weighted. Sensitivity analysis included heterogeneity test, horizontal pleiotropy test, and Leave-One-Out. Additionally, mediation MR was conducted to evaluate the mediating role of lifestyles between BMI and DN. Finally, functional enrichment analysis based on the mediation MR results was performed.

RESULTS

univariate and multivariate Mendelian randomization (MR) analysis were performed to estimate the association between six lifestyles (moderate to vigorous physical activity levels, years of schooling, BMI, nap during day, number of treatments/medications taken and coffee intake) and DN. MR Egger, Weighted median, Simple mode, and Weighted mode was supplemental methods to Inverse variance weighted. Sensitivity analysis included heterogeneity test, horizontal pleiotropy test, and Leave-One-Out. Additionally, mediation MR was conducted to evaluate the mediating role of lifestyles between BMI and DN. Finally, functional enrichment analysis based on the mediation MR results was performed.

CONCLUSION

our results supported mediation role of vigorous physical activity level and number of treatments/medications in BMI-DN effects.

Exploring Genetic Drug Targets in Acne Vulgaris: A Comprehensive Proteome-Wide Mendelian Randomization Study

BACKGROUND

Acne vulgaris presents a substantial clinical challenge due to its complex pathophysiology and significant impact on quality of life. Identification of novel therapeutic targets for acne using genetic tools can guide the development of more effective treatments.

METHODS

Utilizing a dataset comprising 35 559 Icelandic individuals, we performed proteomic analyses to quantify 4709 circulating proteins. We integrated these data with acne-specific genome-wide association studies (GWAS) encompassing 34 422 acne patients and 364 991 controls. Mendelian randomization (MR) analyses employed the TwoSampleMR tool and Summary-data-based Mendelian Randomization (SMR) to estimate the causal effects of identified proteins on acne risk. Colocalization analyses assessed the likelihood of shared genetic etiology between protein levels and acne using the "coloc" R package.

RESULTS

Our proteome-wide MR analysis initially identified 128 proteins potentially associated with acne risk. Following multiple testing corrections using the Benjamini-Hochberg method, fatty acid synthase (FASN) and tissue inhibitor of metalloproteinases 4 (TIMP4) remained significantly associated with acne risk. FASN exhibited a protective effect against acne (OR = 0.768, 95% CI: 0.676-0.872, p = 4.685E-05), while TIMP4 was associated with an increased risk (OR = 1.169, 95% CI: 1.103-1.241, p = 1.956E-07). Colocalization analysis supported a shared genetic basis for these protein-acne associations, with posterior probabilities indicating strong evidence of shared causal variants.

CONCLUSION

Our findings highlight the utility of integrative genomic approaches in identifying potential therapeutic targets for acne. FASN and TIMP4, in particular, demonstrate strong potential as targets for therapeutic intervention, pending further validation through clinical research. These results offer a foundation for targeted acne treatment development, aligning with personalized medicine principles.

Relationship between serum neurofilament light chain protein and depression: A nationwide survey and Mendelian randomization study

BACKGROUND

Investigating the link between serum neurofilament protein (sNfL) levels and depression remains an area of limited understanding. This study explores the correlation in US adults and employs Mendelian randomization (MR) to ascertain causality.

METHODS

Our cross-sectional study analyzed data from participants aged 20 and above in the National Health and Nutrition Examination Survey (2013-2014). We employed a weighted multiple logistic regression model to examine the relationship between ln (sNfL) and depression. Restricted cubic splines (RCS) were used to visualize non-linear relationships. Stratified analyses examined associations between ln(sNfL) and depression in different subgroups. Subsequently, we conducted a two-sample bidirectional Mendelian randomization (MR) to assess the causal relationship between sNfL and depression. The inverse variance-weighted (IVW) method was utilized as the primary analysis.

RESULTS

Among 1765 participants (mean age 45.19 years; 49.37 % male), 166 had depression with a Patient Health Questionnaire (PHQ-9) score ≥ 10. After adjusting for covariates, a positive correlation remained between sNfL and depression (OR 1.511, 95 % CI: 1.050-2.175). RCS curves indicated a non-linear association, with a turning point at 2.76 pg/ml. Stratified analyses revealed positive correlations in specific subgroups, with interactions involving age, race, family income, recreational activity, and ln(sNfL). MR using IVW found no significant causal relationship between sNfL and depression genetically (OR = 0.956, 95 % CI: 0.878-1.042), with reverse analysis yielding similar results (OR = 0.897, 95 % CI: 0.756-1.065).

CONCLUSIONS

This cross-sectional study highlights a significant correlation between ln(sNfL) and depression. However, MR results indicate no causal relationship between sNfL and depression.

Association of dementia with the 28-day mortality of sepsis: an observational and Mendelian randomization study

Background

Observational research suggests that individuals with dementia who have sepsis face a higher likelihood of death. However, whether there is a causal relationship between the two remains unknown.

Methods

We analyzed data from patients diagnosed with sepsis and dementia, extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. To examine the correlation between dementia and 28-day mortality in sepsis, we utilized Cox proportional hazards models. Following this, we performed a Mendelian randomization (MR) study with two samples to investigate the potential link between dementia and mortality within 28 days in sepsis.

Results

This study included a total of 22,189 patients diagnosed with sepsis, among whom 1,346 cases (6.1%) had dementia. After adjusting for multiple confounding factors, dementia was associated with an increased risk of 28-day mortality in sepsis (HR = 1.25, 95% CI = 1.12-1.39, p < 0.001). In the MR analysis, there appeared to be a causal relationship between genetically predicted dementia with Lewy bodies (DLB) (OR = 1.093, 95% CI = 1.016-1.177, p = 0.017) and 28-day mortality in sepsis. However, there was no evidence of causality between any dementia (OR = 1.063, 95% CI = 0.91-1.243, p = 0.437), Alzheimer's disease (AD) (OR = 1.126, 95% CI = 0.976-1.299, p = 0.103), vascular dementia (VD) (OR = 1.008, 95% CI = 0.93-1.091, p = 0.844), and the risk of 28-day mortality in sepsis.

Conclusion

In the observational analysis, dementia was associated with an increased risk of 28-day mortality in septic patients. However, in the MR analysis, only DLB was associated with increased 28-day mortality in septic patients, with no observed correlation for other dementia subtypes.

Frailty increases depression risk independently of cognitive decline: Insights from Mendelian randomization and cross-sectional analysis

BACKGROUND

Frailty, cognitive decline, and depression are common syndromes among the elderly and are closely interconnected. However, it is still unclear whether the impact of frailty on depression depends on the role of cognitive decline.

METHOD

We conducted the Mendelian randomization (MR) analysis based on the instrumental variables (IVs) from the genome-wide association study (GWAS) databases, and we also performed a cross-sectional study consisting of 1362 older adults aged ≥65 for validation.

RESULTS

The results of the multivariable MR analysis showed that frailty significantly increased the risk of depression, even after controlling for the influence of cognitive performance. Conversely, after controlling for frailty, the effect of cognitive performance on depression risk was noticeably reduced. In the cross-sectional study, frailty mediated 24.04 % of the relationship between cognition and depression, and cognition mediated 7.63 % of the relationship between frailty and depression.

CONCLUSIONS

We provide evidence that frailty could increase depression risk independently of cognitive decline. Further research with a larger sample size is necessary.

Potentially causal association between immunoglobulin G N-glycans and cardiometabolic diseases: Bidirectional two-sample Mendelian randomization study

BACKGROUND

Observational studies support that altered immunoglobulin G (IgG) N-glycosylation and inflammatory factors are associated with cardiometabolic diseases (CMDs); nevertheless, the causality between them remains unclear.

METHODS

Two-sample Mendelian randomization (MR) analyses were conducted to systematically investigate the bidirectional causality between IgG N-glycans and nine CMDs in both East Asians and Europeans.

RESULTS

In the forward MR analysis, the univariable MR analysis presented suggestive causality of 14 and eight genetically instrumented IgG N-glycans with CMDs in East Asians and Europeans, respectively; the multivariable MR analysis showed that ten and 11 pairs of glycan-CMD associations were identified in East Asian and European populations, respectively. In the reverse MR analysis, based on East Asians and Europeans, the univariable MR analysis presented suggestive causality of seven and 12 genetically instrumented CMDs with IgG N-glycans, respectively; the multivariable MR analysis presented that six and five CMD-glycan causality were found in East Asian and Europeans, respectively.

CONCLUSIONS

The comprehensive MR analyses provide suggestive evidence of bidirectional causality between IgG N-glycans and CMDs. This work helps to understand the molecular mechanism of the occurrence/progression of CMDs, optimize existing and develop new strategies to prevent CMDs, and contribute to the early identification of high-risk groups of CMDs.

The Effect of Circulating Inflammatory Proteins on Endometriosis: A Mendelian Randomization Study

Background

Endometriosis is a complex gynecological condition in which endometrial fragments are implanted outside the uterus, causing pain and infertility. Although immune mediators play a vital role in endometriosis, their exact etiology remains elusive. Using Mendelian randomization (MR), this study aimed to assess the causal relationship between inflammatory proteins and endometriosis.

Methods

Genetic variants associated with inflammatory proteins were filtered from a genome-wide protein quantitative trait locus study under stringent thresholds. These variants were used as instrumental variables (IVs) to evaluate the causal effects of these inflammatory proteins on endometriosis. A two-sample MR analysis was performed with endometriosis from the UK Biobank as the outcome, and a sensitivity analysis was performed to mitigate potential confounding factors. Analyses were replicated in an independent endometriosis cohort from the FinnGen, followed by a meta-analysis of MR results from both cohorts. Finally, we assessed the causality between inflammatory proteins and the endometriosis subtypes.

Results

Independent MR analysis revealed that the genetically higher levels of CXCL5 were linked to a lower chance of having endometriosis. The causal link remained significant in the meta-analysis. Furthermore, the causality of CXCL5 expression has been identified in ovarian and pelvic peritoneal endometriosis.

Conclusion

Our MR analysis indicated that CXCL5 was associated with a decreased risk of endometriosis, suggesting that CXCL5 might have a protective effect against endometriosis. This enhances our understanding of the involvement of chemokines in endometriosis pathology and provides insights for future studies to explore the detailed mechanisms underlying CXCL5 in endometriosis.

Genetically Predicted Sleep Traits and Sensorineural Hearing Loss: A Mendelian Randomization Study

OBJECTIVE

Observational studies suggest a potential association between sleep characteristics, sensorineural hearing loss (SNHL), and sudden SNHL (SSNHL), but causal evidence is scarce. We sought to clarify this issue using two-sample Mendelian randomization analysis.

METHODS

The inverse-variance weighted (IVW) method was performed as primary analysis to assess bidirectional causal associations between sleep traits (chronotype, sleep duration, insomnia, daytime sleepiness, and snoring) and SNHL/SSNHL using publicly available Genome-Wide Association Studies summary data from two large consortia (UK Biobank and FinnGen). Sensitivity analyses, including Mendelian randomization (MR)-Egger, Mendelian randomization pleiotropy residual sum and outlier, weight median, Cochran's Q test, leave-one-out analysis, and potential pleiotropy analysis, were conducted to ensure robustness.

RESULTS

IVW analysis found suggestive associations of morning chronotype (odds ratio [OR] = 1.08, 95% confidence interval [CI] = 1.01-1.16, p = 0.031) and daytime sleepiness (OR = 1.88, 95% CI = 1.24-2.87, p = 0.003) with SNHL onset. Additionally, morning chronotype was nominally associated with SSNHL onset using IVW method (OR = 1.37, 95% CI = 1.10-1.71, p = 0.006). However, there was no evidence for the causal effect of SNHL and SSNHL on different sleep traits (all p > 0.05). Sensitivity analysis showed that the results were stable.

CONCLUSION

Within the MR limitations, morning chronotype and daytime sleepiness were underlying causal contributors to the burden of SNHL, indicating that optimal sleep might facilitate the prevention and development of SNHL.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:4723-4729, 2024.

Hyperthyroidism, hypothyroidism, thyroid stimulating hormone, and dementia risk: results from the NHANES 2011-2012 and Mendelian randomization analysis

Introduction

As the world ages, dementia places a heavy burden on society and the economy, but current methods of diagnosing dementia are still limited and there are no better therapies that target the causes of dementia. The purpose of this work is to explore the relationship between thyroid disease, thyroid stimulating hormone (TSH) concentrations, free tetraiodothyronine (FT4) concentrations and cognitive function.

Methods

This study utilized cognitive function and thyroid data from the 2011-2012 National Health and Nutrition Examination Survey (NHANES) to assess the relationship between different groups of TSH and FT4 concentrations and cognitive function using weighted logistic regression and restricted cubic spline (RCS), and then used two-sample Mendelian Randomization (MR) to assess the causal relationship between hyperthyroidism, hypothyroidism, TSH and FT4 concentrations with dementia.

Results

Our analysis of the 2011-2012 NHANES data showed that the individuals with low TSH concentrations had higher Alzheimer's Disease Word List Registry Consortium1 (CERAD1) and CERAD.delay.recall scores than individuals with high TSH concentrations, and individuals with low FT4 concentrations had higher CERAD3 and Animal Fluency Test scores than individuals with high FT4 concentrations. Our results also showed a non-linear relationship between serum TSH and FT4 concentrations and the Animal Fluency Test. The TSH concentrations within the range of 1.703 to 3.145 mIU/L exhibit a positive correlation with Animal Fluency Test, whereas concentrations outside this range are negatively correlated with Animal Fluency Test. The FT4 concentrations exhibited a positive correlation with Animal Fluency Test to the left of the FT4 concentrations inflection point (0.849 ng/L), whereas to the right of this inflection point, correlation was negative. MR analysis results further indicate that genetic predisposition to hyperthyroidism may be associated with a reduced risk of dementia and vascular dementia(VaD). Conversely, genetic predisposition to hypothyroidism appears to be linked with an increased risk of dementia and VaD. Additionally, genetic predisposition to elevated TSH concentrations may be correlated with a heightened risk of risk of Alzheimer's disease (AD).

Conclusion

This study provides evidence of a nonlinear relationship between TSH and FT4 concentrations and cognitive function, with hyperthyroidism decreasing the risk of dementia and VaD, hypothyroidism increasing the risk of dementia and VaD, and elevated serum TSH concentrations increasing the risk of AD. Furthermore, prioritizing early detection, diagnosis, and treatment through the assessment of thyroid function in individuals at high risk for developing dementia is of paramount importance. This strategy has the potential to significantly contribute to the prevention and deceleration of dementia progression.

Association Between Serum Galectin-3 and Parkinson's Disease: A Two-Sample Mendelian Randomization Study

BACKGROUND

Parkinson's disease (PD) is a prevalent neurodegenerative disorder with poor prognosis. Observational studies have demonstrated a significant correlation between serum galectin-3 and PD, suggesting a potential role of galectin-3 as a biomarker for PD. However, it is still unclear whether galectin-3 contributes to the risk of the disease.

METHODS

A two-sample Mendelian randomization (MR) approach was used in this study. Genetic instruments for serum galectin-3 level were selected from a genome-wide association study (GWAS), including 30,931 European individuals. Summary-level statistics for PD were derived from another published GWAS, including 33,674 cases and 449,056 controls. Primary analysis was conducted using the inverse-variance weighting (IVW) method. Weighted median, MR-Egger, simple mode, weighted mode, and MR-pleiotropy residual sum and outlier (MR-PRESSO) methods were used as complementary analyses. To detect heterogeneity, Cochran's Q statistic and leave-one-out analysis were used. For testing potential horizontal pleiotropy, the MR-Egger intercept test and MR-PRESSO global test were conducted.

RESULTS

MR analysis using IVW model (OR 1.112, 95% CI 1.025-1.206, p = 0.010), weighted median (OR 1.135, 95% CI 1.037-1.242, p = 0.006), weighted mode (OR 1.142, 95% CI 1.038-1.257, p = 0.030), and MR-PRESSO (OR 1.112, 95% CI 1.046-1.182, p = 0.012) presented a consistent result, indicating that increased serum galectin-3 was associated with a higher risk of PD. No heterogeneity or horizontal pleiotropy was detected in the analyses.

CONCLUSIONS

The study shows a suggestive association between galectin-3 and PD. Increasing serum galectin-3 was associated with an increase in PD risk. Galectin-3 may play an important role in the causal pathway to PD.

Causal relationships between vitamin E and multiple kidney diseases: evidence from trans-ethnic Mendelian randomization study

PURPOSE

The association between vitamin E and the risk of kidney disease is well documented in observational studies, but the role of vitamin E in kidney disease remain inconclusive. Here, we evaluated the causal effect of vitamin E on the risk of multiple kidney diseases, including chronic kidney disease, membranous nephropathy, diabetic nephropathy, IgA nephropathy, and dialysis.

METHODS

We conducted a two-sample Mendelian randomization analysis from large-scale trans-ancestry genome-wide association studies to determine whether there was a significant causal relationship between vitamin E and multiple kidney diseases in European, American, and Asian ancestry. Instrumental genetic variants associated with vitamin E were selected, and summary statistic-based methods of inverse variance weighted, MR Egger, weighted median, simple mode, and weighted mode methods were conducted. Pleiotropy and sensitivity were assessed.

RESULTS

We obtained 87 instrumental genetic variants in European ancestry and found no causal relationship between vitamin E and chronic kidney disease, membranous nephropathy, diabetic nephropathy, IgA nephropathy, and dialysis with no heterogeneity and pleiotropy. We obtained 18 instrumental genetic variants in Asian ancestry and vitamin E had no causal relationship with membranous nephropathy, diabetic nephropathy, and IgA nephropathy with no heterogeneity and pleiotropy. In African ancestry, 25 instrumental genetic variants were obtained and no causal relationship was identified with no heterogeneity and pleiotropy.

CONCLUSION

Our study first suggested plausible non-causal associations between vitamin E and multiple kidney diseases among different ancestry.

Association between inflammatory factors and melanoma: a bidirectional Mendelian randomization study

PURPOSE

This study performed a bidirectional Mendelian randomization (MR) analysis to elucidate the causal relationships of C-reactive protein and 41 inflammatory regulators with melanoma, including data from UK Biobank, Cardiovascular Risk in Young Finns Study, and Cohorts for Inflammation Work Group.

METHODS

We selected the inverse variance weighting (IVW) to merge the estimated causal effects of multiple SNPs into a weighted average. To evaluate the heterogeneities of IVW, the Cochran Q statistic, and I2 index were used. What's more, several sensitivity analyses were employed, including IVW, MR-Egger, weighted median, and Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO).

RESULTS

With SNPs reaching P < 5 × 10-8, the analyses findings revealed that IL-16 had a significant positively association with genetically risk of melanoma (ORIVW: 1.05; 95% CI: 1.03-1.07; P < 0.001), and high levels of MCP1 (ORIVW: 1.13; 95% CI: 1.03-1.23; P = 0.01) were suggestively associated with melanoma susceptibility. What's more, TNF-β (ORIVW: 1.07; 95% CI: 1.01-1.13; P = 0.02) and IL-8 (ORIVW: 1.08, 95% CI: 1.01-1.16; P = 0.03) were demonstrated a positive association with the risk of melanoma under a less stringent cut-off (P < 5 × 10-6). Conversely, we found a facilitative effect of melanoma susceptibility on IP-10 and inhibitory effects on IL-6, IL-1b, and GRO-α.

CONCLUSION

The genetic evidence that we have uncovered indicates a potential association between the levels of specific inflammatory markers (IL-16, IL-8, MCP-1, and TNF-β) and the risk of melanoma. Further research is imperative to translate these findings into clinical applications.

Association between retinal nerve fiber layer thickness and psychiatric disorders: a mendelian randomization study

BACKGROUND

Retinal nerve fiber layer thickness, as a new visual indicator that may help diagnose mental disorders, is gaining attention from researchers. However, the causal relationship between retinal nerve fiber layer thickness and mental disorders is still to be effectively proved.

METHODS

A bidirectional Two-sample Mendelian randomization analysis was utilized to analyse aggregated data from large-scale genome-wide association studies, we selected genetic loci for retinal nerve fiber layer thickness in independent retinal abnormalities and three prevalent psychiatric disorders (schizophrenia, depression, bipolar disorder) as instrumental variables. The Two-sample Mendelian randomization analysis was mainly performed by inverse variance weighting and weighted median method. The Cochran Q test and leave-one-out sensitivity were used to ensure the robustness of the results. The Mendelian random polymorphism residuals and outliers were used to detect single nucleotide polymorphism outliers, and MR-Egger intercept test was used to test single nucleotide polymorphism horizontal pleiotropy.

RESULTS

IVW showed that retinal nerve fiber layer thickness was positively associated with schizophrenia (OR = 1.057, 95%CI: 1.000-1.117, P < 0.05), in the study of bipolar disorder, MR analysis also suggested a positive causal relationship between retinal nerve fiber layer thickness and bipolar disorder (OR = 1.025, 95%CI: 1.005-1.046, P < 0.05), which indicated possible causal relationships between retinal nerve fiber layer thickness and these two diseases. Depression (OR = 1.000143, 95%CI: 0.9992631-1.001024, P = 0.74) indicated no significant causal association. No reverse causal effects of psychiatric disorders on retinal nerve fiber layer thickness were found.

CONCLUSIONS

A statistically significant causal relationship between retinal nerve fiber layer thickness and schizophrenia and bipolar disorder has been supported by genetic means, indicating RNFL has potential to aid in the diagnosis of schizophrenia and bipolar disorder.

Causal role of circulating inflammatory cytokines in cardiac diseases, structure and function

BACKGROUND

Inflammation is implicated in cardiovascular disease (CVD) pathogenesis, but causal roles of specific circulating inflammatory cytokines remain unclear. Mendelian randomization (MR) studies are well-poised to provide etiological insights beyond constraints of conventional research.

METHODS

We conducted a large-scale MR study to investigate potential causal relationships of 91 inflammatory proteins with CVD outcomes and cardiac remodeling using summary-level genetic data. Outcomes included coronary artery disease, myocardial infarction, stroke, atrial fibrillation, heart failure, abdominal aortic aneurysm, deep vein thrombosis of lower extremities, pulmonary embolism, cardiac structure and functional parameters. Inverse-variance weighted analysis was undertaken as the primary analysis, with several sensitivity analyses applied.

RESULTS

Hepatocyte growth factor (HGF) demonstrated a causal relationship with increased susceptibility to both any stroke (OR 1.111; 95 % CI 1.044 - 1.183; P = 9.50e-04) and ischemic stroke (OR 1.121; 95 % CI 1.047 - 1.200; P = 1.04e-03). Programmed cell death 1 ligand 1 (PD-L1) was negatively associated with atrial fibrillation risk (OR 0.936, 95 % CI 0.901 - 0.973; P = 7.69e-04). CCL20, CDCP1, Flt3L and IL-10RA were identified as causal coronary artery disease risk factors, while LIF and ST1A1 had protective effects. IL-4 and LIF-R demonstrated causal links with right heart functional changes.

CONCLUSIONS

Our MR study nominates specific circulating inflammatory cytokines as potential targets for CVD treatment and prevention. Further research into mechanisms and clinical translation are warranted.

Association of dietary intake and serum concentration of omega-3 fatty acids on celiac disease: evidence from observational study and Mendelian randomization

OBJECTIVE

The association between omega-3 fatty acids (O3FA) and celiac disease lacks sufficient investigation.

METHODS

Utilizing data gleaned from the 2009 to 2014 National Health and Nutrition Examination Survey (NHANES), this research comprises a sample of 13 403 adults, each aged 20 years and above. We conducted a multivariable logistic regression analysis to assess the association between dietary intake of O3FA and celiac disease. Subsequently, a two-sample Mendelian randomization was performed to estimate the unconfounded causal relationship between serum O3FA and celiac disease. The principal analytical strategy utilized the inverse-variance weighted methodology.

RESULTS

In this cross-sectional study, 48 occurrences (0.36%) of celiac disease were encompassed. In the multivariable model, there was no association between dietary intake of O3FA and cases of celiac disease (odds ratio: 1.12, 95% confidence interval: 0.47-2.66, P  = 0.792). However, serum levels of O3FA determined by genetic assay were correlated with celiac disease (inverse-variance weighted, β = 0.2439, P  = 0.0287), with no evidence of horizontal pleiotropy ( P  = 0.3689).

CONCLUSION

The dietary consumption of O3FA did not exhibit an association with the risk of celiac disease in this cross-sectional investigation. However, a correlation between celiac disease and serum levels of O3FA was observed in the Mendelian randomization. Further investigations, including human clinical trials, are warranted.

The interplay between systemic inflammatory factors and endometriosis: A bidirectional mendelian randomization study

OBJECTIVE

To utilize vast genetic data to reveal the interplay between 41 systemic inflammatory factors and endometriosis.

DESIGN

Bidirectional Mendelian randomization study.

MAINS OUTCOME MEASURES

This study obtained believable genetic instrumental variables for systemic inflammatory factors. The effect of systemic inflammatory factors on different endometriosis phenotypes, and the effect of endometriosis on the concentrations of systemic inflammatory factors were investigated.

RESULTS

In this mendelian randomization study, we found 20 causal relationships involving 18 systemic inflammatory factors and it was shown that Monocyte chemotactic protein-1, Macrophage inflammatory protein-1a, Granulocyte colony-stimulating factor, Macrophage migration inhibitory factor, Interleukin-4, Interleukin-5, Interleukin-8, Interleukin-9, Interleukin-12p70, Interleukin-16, and Interleukin-17 may be the upstream causes of endometriosis (P<0.05). Additionally, if the definition of exposure in the mendelian randomization was endometriosis, it could suggestively cause an increase in Eotaxin, cutaneous T-cell attracting chemokine, and Interferon gamma-induced protein 10 levels, and a decrease in growth-regulated oncogene-alpha, Interleukin-2 receptor, alpha subunit, platelet-derived growth factor BB, and Interleukin-18 (P<0.05). Reverse causality was not observed between a single systemic inflammatory factor and endometriosis.

CONCLUSIONS

Our findings indicate that several systemic inflammatory factors may act as the initiator at the onset of endometriosis. Additionally, several other inflammatory factors are far more probable to involved downstream during disease development.

Causal relationship between immune cells and risk of myocardial infarction: evidence from a Mendelian randomization study

Background

Atherosclerotic plaque rupture is a major cause of heart attack. Previous studies have shown that immune cells are involved in the development of atherosclerosis, but different immune cells play different roles. The aim of this study was to investigate the causal relationship between immunological traits and myocardial infarction (MI).

Methods

To assess the causal association of immunological profiles with myocardial infarction based on publicly available genome-wide studies, we used a two-sample mendelian randomization (MR) approach with inverse variance weighted (IVW) as the main analytical method. Sensitivity analyses were used to assess heterogeneity and horizontal pleiotropy.

Results

A two-sample MR analysis was conducted using IVW as the primary method. At a significance level of 0.001, we identified 47 immunophenotypes that have a significant causal relationship with MI. Seven of these were present in B cells, five in cDC, four in T cells at the maturation stage, six in monocytes, five in myeloid cells, 12 in TBNK cells, and eight in Treg cells. Sensitivity analyses were performed to confirm the robustness of the MR results.

Conclusions

Our results provide strong evidence that multiple immune cells have a causal effect on the risk of myocardial infarction. This discovery provides a new avenue for the development of therapeutic treatments for myocardial infarction and a new target for drug development.

Insights into preeclampsia: a bioinformatics approach to deciphering genetic and immune contributions

Background

Preeclampsia (PE) is a global pregnancy concern, characterized by hypertension with an unclear etiology. This study employs Mendelian randomization (MR) and single-cell RNA sequencing (scRNA-seq) to clarify its genetic and molecular roots, offering insights into diagnosis and treatment avenues.

Methods

We integrated PE-specific genome-wide association study (GWAS) data, expression and protein quantitative trait loci (eQTL and pQTL) data, and single-cell data from peripheral blood mononuclear cells (PBMCs). We identified highly variable genes using single-cell information and employed MR to determine potential causality. We also combined pQTL and GWAS data, discerned genes positively associated with PE through scRNA-seq, and leveraged the Enrichr platform to unearth drug-gene interactions.

Results

Our scRNA-seq pinpointed notable cell type distribution variances, especially in T helper cells (Th cells), between PE and control groups. We unveiled 591 highly variable genes and 6 directly PE-associated genes. Although MR revealed correlations with PE risk, pQTL analysis was inconclusive due to data constraints. Using DSigDB, 93 potential therapeutic agents, like Retinoic acid targeting core genes (IFITM3, NINJ1, COTL1, CD69, and YWHAZ), emerged as prospective multi-target treatments.

Conclusion

Utilizing MR and scRNA-seq, this study underscores significant cellular disparities, particularly in Th cells, and identifies crucial genes related to PE. Despite some limitations, these genes have been revealed in PE's underlying mechanism. Potential therapeutic agents, such as Retinoic acid, suggest promising treatment pathways.

[Exploring the Causal Relationship Between Coagulation Function and Gestational Diabetes Mellitus Through Mendelian Randomization]

Objective

To explore the causal association between coagulation function, including von Willebrand factor (vWF), a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS13), activated partial thromboplastin time (aPTT), coagulation factor Ⅷ (FⅧ), coagulation factor Ⅺ (FⅪ), coagulation factor Ⅶ (FⅦ), coagulation factor Ⅹ (FⅩ), endogenous thrombin potential (ETP), plasminogen activator inhibitor-1 (PAI-1), protein C, and plasmin, and gestational diabetes mellitus (GDM) using two-sample two-way Mendelian randomization (MR), and to provide genetic evidence for the association between coagulation function and the pathogenesis of GDM.

Methods

The IEU OpenGWAS database was accessed using the R package TwoSampleMR (v 0.5.6) to obtain the statistical data of the genome-wide association study (GWAS) summary of GDM. MR analysis of the causal association between 11 coagulation function and GDM was performed by the inverse-variance weighted method (IVW), the MR-Egger method, and the weighted median method (WM).

Results

In this study, the GWAS summary statistics of GDM (covering 5 687 cases and 117 892 controls) were used for MR analysis. It was found that there was a causal relationship between the predicted plasma FⅧ level and the risk for GDM (IVW: [odds ratio, OR]=0.28, 95% confidence interval [CI]: 0.10-0.75, P<0.001; WM: OR=0.30, 95% CI: 0.09-0.98, P<0.001). There was no causal relationship between other coagulation function and the risk for GDM (P>0.05).

Conclusion

There is a significant causal relationship between the plasma FⅧ level and the risk for GDM. This finding highlights the complex interaction between coagulation function and glucose metabolism during pregnancy, but further research on this finding is warranted.

Association between dietary zinc intake and epilepsy: findings from NHANES 2013-2018 and a Mendelian randomization study

Background

The association between dietary zinc intake and epilepsy remains unclear. This study aimed to investigate the relationship between zinc intake from the diet and epilepsy, employing Mendelian randomization (MR) to explore potential causal links between zinc and epilepsy.

Methods

The cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2013 and 2018. Among the 4,434 participants included, 1.5% (67/4,434) reported having epilepsy. Restricted cubic spline models and logistic regression models were employed to examine the relationships between dietary zinc intakes and epilepsy. Subsequently, a 2-sample Mendelian randomization (MR) analysis was conducted using the inverse variance weighted (IVW) approach as the primary analysis.

Results

In the restricted cubic spline (RCS) analysis, the relationship between dietary zinc consumption and epilepsy displayed an L-shaped curve (nonlinear, p = 0.049). After multivariate adjustments, the adjusted odds ratios for epilepsy in T2 (5.0-11.0 mg/day) and T3 (≥11.0 mg/day) were 0.49 (95% confidence interval [CI]: 0.26-0.92, p = 0.026) and 0.60 (95% CI: 0.31-1.17, p = 0.132), respectively, compared to the lowest dietary zinc consumption tertile (T1, ≤5.0 mg/day). The IVW method indicated that genetically predicted zinc intake per standard-deviation increase was inversely associated with three types of epilepsy, including all types of epilepsy (OR = 1.06, 95% CI: 1.02-1.11, p = 0.008), generalized epilepsy (OR = 1.13, 95% CI: 1.01-1.25, p = 0.030), and focal epilepsy (documented hippocampal sclerosis) (OR = 1.01, 95% CI: 1.00-1.02, p = 0.025).

Conclusion

Our findings suggest that a daily zinc intake ranging from 5.0 to 11.0 mg is associated with the lowest risk of epilepsy. Furthermore, Mendelian randomization (MR) studies provide additional support for the existence of a causal relationship between zinc and epilepsy.

Plasma metabolites as mediators in immune cell-pancreatic cancer risk: insights from Mendelian randomization

Background

Immune cells play a crucial role in the development and progression of pancreatic cancer, yet the causal relationship remains uncertain due to complex immune microenvironments and conflicting research findings. Mendelian randomization (MR), this study aims to delineate the causal relationships between immune cells and pancreatic cancer while identifying intermediary factors.

Methods

The genome-wide association study (GWAS) data on immune cells, pancreatic cancer, and plasma metabolites are derived from public databases. In this investigation, inverse variance weighting (IVW) as the primary analytical approach to investigate the causal relationship between exposure and outcome. Furthermore, this study incorporates MR-Egger, simple mode, weighted median, and weighted mode as supplementary analytical approaches. To ensure the reliability of our findings, we further assessed horizontal pleiotropy and heterogeneity and evaluated the stability of MR results using the Leave-one-out method. In conclusion, this study employed mediation analysis to elucidate the potential mediating effects of plasma metabolites.

Results

Our investigation revealed a causal relationship between immune cells and pancreatic cancer, highlighting the pivotal roles of CD11c+ monocytes (odds ratio, ORIVW=1.105; 95% confidence interval, 95%CI: 1.002-1.218; P=0.045), HLA DR+ CD4+ antigen-presenting cells (ORIVW=0.920; 95%CI: 0.873-0.968; P=0.001), and HLA DR+ CD8br T cells (ORIVW=1.058; 95%CI: 1.002-1.117; P=0.041) in pancreatic cancer progression. Further mediation analysis indicated that oxalate (proportion of mediation effect in total effect: -11.6%, 95% CI: -89.7%, 66.6%) and the mannose to trans-4-hydroxyproline ratio (-19.4, 95% CI: -136%, 96.8%) partially mediate the relationship between HLA DR+ CD8br T cells and pancreatic cancer in nature. In addition, our analysis indicates that adrenate (-8.39%, 95% CI: -18.3%, 1.54%) plays a partial mediating role in the association between CD11c+ monocyte and pancreatic cancer, while cortisone (-26.6%, 95% CI: 138%, -84.8%) acts as a partial mediator between HLA DR+ CD4+ AC and pancreatic cancer.

Conclusion

This MR investigation provides evidence supporting the causal relationship between immune cell and pancreatic cancer, with plasma metabolites serving as mediators. Identifying immune cell phenotypes with potential causal effects on pancreatic cancer sheds light on its underlying mechanisms and suggests novel therapeutic targets.

Metformin treatment reduces the incidence of osteoporosis: a two-sample Mendelian randomized study

It remains unclear whether the association between metformin and osteoporosis (OP) risk is causal. This two-sample Mendelian randomization (MR) study suggests a causal relationship between metformin treatment and a decrease in OP and fracture incidence, as well as an increase in bone mineral density (BMD) in the lumbar spine, femoral neck, and heel. Nonetheless, no significant causal effect is observed on forearm BMD.

PURPOSE

We utilize a MR approach to investigate the association between metformin treatment and the risk of OP.

METHODS

Metformin treatment was selected as exposures. Outcomes included OP; BMD at the forearm (FA), femoral neck (FN), and lumbar spine (LS); estimated heel bone mineral density (eBMD); and fracture. Summary statistics for exposures and outcomes were obtained from corresponding genome-wide association studies. Inverse variance-weighted (IVW) analysis was mainly applied; the weighted median (WM), penalized weighted median (PWM), maximum likelihood (ML), and MR-Egger regression (MR-Egger) method were also used to obtain robust estimates. A series of sensitivity analyses including Cochran's Q test, MR-Egger regression, leave-one-out analysis, and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) were used to detect pleiotropy or heterogeneity.

RESULTS

In the main analysis, IVW estimates demonstrated that metformin treatment had a definite causal effect on the risk of OP (odds ratio (OR): 0.859, 95% CI: 0.774-0.953, P = 0.004), LS-BMD (OR: 1.063, 95% CI: 1.023-1.105, P = 0.002), FN-BMD (OR: 1.034, 95% CI: 1.000-1.069, P = 0.049), eBMD (OR: 1.035, 95% CI: 1.023-1.047, P ≤ 0.001), and fracture(OR: 0.958, 95% CI: 0.928-0.989, P = 0.008). However, it did not have an effect on FA-BMD(OR: 1.050, 95% CI: 0.969-1.138, P = 0.237).

CONCLUSIONS

This study indicated that metformin treatment is significantly associated with a reduction in the risk of OP, fracture and higher LS-BMD, FN-BMD, and eBMD. However, there was no significant association with FA-BMD.

Periodontitis and thyroid function: A bidirectional Mendelian randomization study

BACKGROUND AND OBJECTIVE

Previous studies suggest interaction between periodontitis and thyroid function, while the causality has not yet been established. We applied the Mendelian randomization (MR) method to assess bidirectional causal association between periodontitis and thyroid-related traits, including free thyroxine (FT4), thyroid stimulating hormone (TSH), hypothyroidism, hyperthyroidism and autoimmune thyroid disease (AITD).

METHODS

Genetic instruments were extracted from large-scale genome-wide association studies on normal-range FT4 (N = 49 269) and TSH (N = 54 288) levels, TSH in full range (N = 119 715); hypothyroidism (discovery/replication cohorts: N = 53 423/334 316), hyperthyroidism (discovery/replication cohorts: N = 51 823/257 552), AITD (N = 755 406) and periodontitis (N = 45 563). Here, the inverse variance weighted (IVW) method was applied as the primary analysis, and robustness of results were assessed by several pleiotropic-robust methods. Results were adjusted for Bonferroni correction thresholds with significant p < .004 (0.05/13) and suggestive p between .004 and .05.

RESULTS

The IVW analysis revealed a suggestively causal linkage between genetic predisposition to periodontitis and the increased risk of hypothyroidism (discovery cohort: odds ratio [OR] = 1.24, 95% confidence interval [CI] = 1.05-1.46, p = .012; replication cohort: OR = 1.06, 95% CI = 1.01-1.11, p = .011). No evidence was found for supporting the impact of periodontitis on hyperthyroidism and AITD risks (associated p ≥ .209), as well as thyroid-related traits on periodontitis risk (associated p ≥ .105). These findings were robust and consistent through sensitivity analysis with other MR models.

CONCLUSION

This bidirectional MR reveals periodontitis should not be attributed to variations in thyroid function but it has potential causal effect on hypothyroidism risk, which provides a better understanding of the relationship between periodontitis and thyroid function, and potential evidence for the clinical intervention of hypothyroidism. Further investigations are warranted to elucidate the nature and underlying mechanisms of this finding.

Causal association of gastroesophageal reflux disease with chronic sinusitis and chronic disease of the tonsils and adenoids

BACKGROUND

Exploring bidirectional causal associations between gastroesophageal reflux disease (GERD) and chronic disease of the tonsils and adenoids and chronic sinusitis, respectively.

METHODS

We first conducted a TSMR (two-sample mendelian randomization) study using the results of the inverse variance weighting method as the primary basis and bidirectional MR to rule out reverse causation. Subsequently, MVMR (multivariate MR) analysis was performed to identify phenotypes associated with SNPs and to explore the independent effect of GERD on two outcomes. Finally, we calculated MR-Egger intercepts to assess horizontal polytropy and Cochran's Q statistic to assess heterogeneity and ensure the robustness of the study.

RESULTS

For each standard deviation increase in genetically predicted GERD rate, there was an increased risk of chronic disease of the tonsils and adenoids (OR 1.162, 95% CI 1.036-1.304, P: 1.06E-02) and of developing chronic sinusitis (OR 1.365, 95% CI 1.185-1.572, P: 1.52E-05), and there was no reverse causality. Causality for TSMR was obtained on the basis of IVW (inverse variance weighting) and appeared to be reliable in almost all sensitivity analyses, whereas body mass index may be a potential mediator of causality between GERD and chronic sinusitis.

CONCLUSION

There is a causal association between GERD and chronic disease of the tonsils and adenoids and chronic sinusitis, respectively, and the occurrence of GERD increases the risk of developing chronic disease of the tonsils and adenoids and chronic sinusitis.

Exploring Genetic Associations of 3 Types of Risk Factors With Ischemic Stroke: An Integrated Bioinformatics Study

BACKGROUND

Ischemic stroke (IS) is a major cause of disability and mortality worldwide. Increasing evidence suggests a strong association between blood pressure, blood glucose, circulating lipids, and IS. Nonetheless, the genetic association of these 3 risk factors with IS remains elusive.

METHODS

We screened genetic instruments related to blood pressure, blood glucose, and circulating lipids and paired them with IS genome-wide association study data to conduct Mendelian randomization analysis. Positive Mendelian randomization findings were then subjected to colocalization analysis. Subsequently, we utilized the Gene Expression Omnibus data set to perform differential expression analysis, aiming to identify differentially expressed associated genes. We determined the importance scores of these differentially expressed associated genes through 4 machine learning models and constructed a nomogram based on these findings.

RESULTS

The combined results of the Mendelian randomization analysis indicate that blood pressure (systolic blood pressure: odds ratio [OR], 1.02 [95% CI, 1.01-1.02]; diastolic blood pressure: OR, 1.03 [95% CI, 1.03-1.04]) and some circulating lipids (low-density lipoprotein cholesterol: OR, 1.06 [95% CI, 1.01-1.12]; apoA1: OR, 0.95 [95% CI, 0.92-0.98]; apoB: OR, 1.05 [95% CI, 1.01-1.09]; eicosapentaenoic acid: OR, 2.36 [95% CI, 1.41-3.96]) have causal relationships with the risk of IS onset. We identified 73 genes that are linked to blood pressure and circulating lipids in the context of IS, and 16 are differentially expressed associated genes. FURIN, MAN2A2, HDDC3, ALDH2, and TOMM40 were identified as feature genes for constructing the nomogram that provides a quantitative prediction of the risk of IS onset.

CONCLUSIONS

This study indicates that there are causal links between blood pressure, certain circulating lipids, and the development of IS. The potential mechanisms underlying these causal relationships involve the regulation of lipid metabolism, blood pressure, DNA repair and methylation, cell apoptosis and autophagy, immune inflammation, and neuronal protection, among others.

Identifying depression's genetic role as a precursor to sepsis and increased mortality risk: Comprehensive insights from mendelian randomization analysis

BACKGROUND

Previous retrospective studies have shown a correlation between depression and increased risk of infections, including a moderate rise in sepsis likelihood associated with severe depression and anxiety. To investigate the potential causal links between depression, sepsis, and mortality risks, while considering confounding factors, we employed a Mendelian randomization (MR) approach.

METHODS

In this two-sample Mendelian randomization study, we analyzed data from a large-scale genome-wide association study on depression, involving 807,553 European individuals (246,363 cases, 561,190 controls). We extracted SNP associations with sepsis and 28-day mortality from UK Biobank GWAS outcomes. The correlation analysis primarily employed the inverse-variance weighted method, supplemented by sensitivity analyses for heterogeneity and pleiotropy assessment.

RESULTS

Our analysis revealed a potential causal link between depression and an increased risk of sepsis (OR = 1.246, 95% CI: 1.076-1.442, P = 0.003), but no causal association was found with sepsis-induced mortality risk (OR = 1.274, 95% CI: 0.891-1.823, P = 0.184). Sensitivity analyses confirmed the robustness of these findings.

CONCLUSIONS

We identified a potential causal association between depression and heightened sepsis risk, while no link was found with sepsis-induced mortality. These findings suggest that effective management of depression could be important in preventing sepsis.

Relationship between plasma brain-derived neurotrophic factor levels and neurological disorders: An investigation using Mendelian randomisation

Background

Altered brain-derived neurotrophic factor (BDNF) concentrations have been detected in the central nervous system tissues and peripheral blood. These alterations are associated with a series of neurological disorders.

Objective

To investigate the potential causal relationships between genetically determined plasma BDNF levels and various neurological diseases using a two-sample Mendelian randomisation study.

Methods

We selected single nucleotide polymorphisms strongly related to plasma BDNF levels as instrumental variables. Within the Mendelian randomisation framework, we used summary-level statistics for exposure (plasma BDNF levels) and outcomes (neurological disorders).

Results

We observed suggestive evidence of a relation between higher plasma BDNF levels and less risk of nontraumatic intracranial haemorrhage (nITH) (odds ratio [OR] = 0.861, 95 % confidence interval [CI]: 0.774-0.958, P = 0.006, PFDR = 0.078), epilepsy (OR = 0.927, 95 % CI: 0.880-0.976, P = 0.004, PFDR = 0.078), focal epilepsy (OR = 0.928, 95 % CI: 0.874-0.986, P = 0.016, PFDR = 0.139), and non-lesional focal epilepsy (OR = 0.981, 95 % CI: 0.964-0.999, P = 0.041, PFDR = 0.267). Combined with the UK Biobank dataset, the association of plasma BDNF levels with nITH remained significant (OR = 0.88, 95 % CI: 0.81-0.96, P < 0.01). The combined analysis of three consortium datasets demonstrated a considerable impact of plasma BDNF on epilepsy (OR = 0.94, 95 % CI: 0.90-0.98, P < 0.01) and a suggestive impact on focal epilepsy (OR = 0.94, 95 % CI: 0.89-0.99, P = 0.02). However, there was no apparent correlation between plasma BDNF levels and other neurological disorders or related subtypes.

Conclusions

Our study supports a possible causal relationship between elevated plasma BDNF levels and a reduced risk of nITH, epilepsy, and focal epilepsy.

Serum urate levels and neurodegenerative outcomes: a prospective cohort study and mendelian randomization analysis of the UK Biobank

BACKGROUND

Previous studies on the associations between serum urate levels and neurodegenerative outcomes have yielded inconclusive results, and the causality remains unclear. This study aimed to investigate whether urate levels are associated with the risks of Alzheimer's disease and related dementias (ADRD), Parkinson's disease (PD), and neurodegenerative deaths.

METHODS

This prospective study included 382,182 participants (45.7% men) from the UK Biobank cohort. Cox proportional hazards models were used to assess the associations between urate levels and risk of neurodegenerative outcomes. In the Mendelian randomization (MR) analysis, urate-related single-nucleotide polymorphisms were identified through a genome-wide association study. Both linear and non-linear MR approaches were utilized to investigate the potential causal associations.

RESULTS

During a median follow-up period of 12 years, we documented 5,400 ADRD cases, 2,553 PD cases, and 1,531 neurodegenerative deaths. Observational data revealed that a higher urate level was associated with a decreased risk of ADRD (hazard ratio [HR]: 0.93, 95% confidence interval [CI]: 0.90, 0.96), PD (HR: 0.87, 95% CI: 0.82, 0.91), and neurodegenerative death (HR: 0.88, 95% CI: 0.83, 0.94). Negative linear associations between urate levels and neurodegenerative events were observed (all P-values for overall < 0.001 and all P-values for non-linearity > 0.05). However, MR analyses yielded no evidence of either linear or non-linear associations between genetically predicted urate levels and the risk of the aforementioned neurodegenerative events.

CONCLUSION

Although the prospective cohort study demonstrated that elevated urate levels were associated with a reduced risk of neurodegenerative outcomes, MR analyses found no evidence of causality.

Uterine leiomyoma causes an increase in systolic blood pressure: a two-sample Mendelian randomization study

Objectives

Hypertension and hypertensive disorders of pregnancy (HDP) are common diseases in women at different stages, which affect women's physical and mental health, and the impact of the latter on the offspring cannot not be ignored. Observational studies have investigated the correlation between uterine leiomyoma (UL) and the above conditions, but the relationship remains unclear. In this study, we employed two-sample Mendelian randomization (MR) analysis to assess the association between UL and hypertension, HDP, as well as blood pressure.

Methods

We collected genetic association data of UL (35,474 cases), hypertension (129,909 cases), HDP (gestational hypertension with 8,502 cases, pre-eclampsia with 6,663 cases and eclampsia with 452cases), systolic blood pressure (SBP) and diastolic blood pressure (DBP) (both 757,601 participants) from published available genome-wide association studies (GWAS). The single nucleotide polymorphisms (SNPs) associated with UL phenotype were used as instrumental variables, and hypertension, three sub-types of HDP, SBP and DBP were used as outcomes. The inverse-variance weighted (IVW) method was employed as the primary method of causal inference. Heterogeneity was assessed using Cochran's Q test, and sensitivity analyses were conducted using MR-Egger regression and MR pleiotropy residual sum and outlier (MR-PRESSO) tests to evaluate the pleiotropy of instrumental variables. PhenoScanner search was used to remove confounding SNP. Robustness and reliability of the results were assessed using methods such as the weighted median and weighted mode.

Results

The IVW analysis revealed a positive correlation between genetically predicted UL and SBP [odds ratio (OR)= 1.67, 95% confidence interval (CI):1.24~2.25, P = 0.0007], and no statistical association was found between UL and hypertension, HDP, or DBP. The MR-Egger regression suggested that the above causal relationships were not affected by horizontal pleiotropy. The weighted median method and weighted model produced similar results to the IVW.

Conclusion

Based on large-scale population GWAS data, our MR analysis suggested a causal relationship between UL and SBP. Therefore, women with UL, especially pregnant women, should pay attention to monitoring their blood pressure levels. For patients with hypertension who already have UL, interventions for UL may serve as potential therapeutic methods for managing blood pressure.

Genetic insights into the relationship between immune cell characteristics and ischemic stroke: A bidirectional Mendelian randomization study

BACKGROUND AND PURPOSE

Ischemic stroke, a major contributor to global disability and mortality, is underpinned by intricate pathophysiological mechanisms, notably neuroinflammation and immune cell dynamics. Prior research has identified a nuanced and often paradoxical link between immune cell phenotypes and ischemic stroke susceptibility. The aim of this study was to elucidate the potential causal links between the median fluorescence intensity (MFI) and morphological parameters (MP) of 731 immune cell types and ischemic stroke risk.

METHODS

By analyzing extensive genetic datasets, we conducted comprehensive Mendelian randomization (MR) analyses to discern the genetic correlations between diverse immune cell attributes (MFI and MP) and ischemic stroke risk.

RESULTS

Our study identified key immune cell signatures linked to ischemic stroke risk. Both B cells and T cells, among other immune cell types, have a bidirectional influence on stroke risk. Notably, the regulatory T-cell phenotype demonstrates significant neuroprotective properties, with all odds ratio (OR) values and confidence intervals (CIs) being less than 1. Furthermore, CD39 phenotype immune cells, particularly CD39+ CD8+ T cells (inverse variance weighting [IVW] OR 0.92, 95% CI 0.87-0.97; p = 0.002) and CD39+ activated CD4 regulatory T cells (IVW OR 0.93, 95% CI 0.90-0.97; p < 0.001), show notable neuroprotection against ischemic stroke.

CONCLUSION

This investigation provides new genetic insights into the interplay between various immune cells and ischemic stroke, underscoring the complex role of immune processes in stroke pathogenesis. These findings lay a foundation for future research, which may confirm and expand upon these links, potentially leading to innovative immune-targeted therapies for stroke prevention and management.

The effect of androgens on the risk of endometriosis sub-phenotypes and ovarian neoplasms: A Mendelian randomization study

Endometriosis is a complex gynecological pathology with a broad spectrum of symptoms, affecting around 10% of reproductive-aged women. Ovarian cancer (OC) is a heterogeneous disease for which we lack effective diagnostic and therapeutic strategies. The etiology and pathogenesis of both diseases remain ambiguous. Androgens in endometriosis could have a distinct role beyond serving as estrogen sources, whereas in the case of serous OC could be important in the formation of precursor lesions which ultimately lead to tumor formation. Here we performed two-sample Mendelian randomization (MR) analysis to examine the causal relationship between the androgen precursor - dehydroepiandrosterone sulphate (DHEAS), bioactive androgen - testosterone (T), androgen metabolite - androsterone sulphate, steroid hormone binding globulin (SHBG) and albumin and the risk of endometrioses of various sub-phenotypes and ovarian neoplasms across the benign-borderline-malignant spectrum. Stringent quality control procedures were followed to select eligible instrumental variables that were strongly associated with the selected exposures, sensitivity analyses were performed to assess the heterogeneities, horizontal pleiotropy, and stabilities of SNPs in endometriosis and ovarian neoplasms. We discovered an inverse association between genetically predicted levels of all androgens and risk of endometriosis, the same trend was most evident in the ovarian sub-phenotype. Total T levels were also inversely associated with peritoneal sub-phenotype of endometriosis. Likewise, T was causally associated with decreased risk of clear-cell OC, an endometriosis-associated OC subtype, and with malignant serous OC of both low- and high-grade, but with higher risk of their counterpart of low malignant potential. These findings support further investigation of androgen's action at a molecular level in ovary-associated endometriotic lesions, clear cell ovarian tumors and serous precursor lesions.

Causal role of immune cells in psoriasis: a Mendelian randomization analysis

Background

A growing body of evidence has shown that immune cells are linked to psoriasis. It is, however, still unclear if these associations reflect a relationship of cause and effect.

Objective

We employed a two-sample Mendelian randomization (MR)-based study to elucidate the probable causative connection between immune cells and psoriasis.

Methods

Summary information for psoriasis (Ncase = 5,427, Ncontrol = 479,171) was obtained from the European Bioinformatics Institute. Summarized statistical information on 731 immune cell features, including morphological parameters (MP; n = 32), relative cell number (n = 192), median fluorescence intensity (MFI) of surface antigens (n = 389), and absolute cell number (n = 118), was obtained from the genome-wide association studies (GWAS) catalog. The research consisted of forward MR analysis, in which immune cell traits were used as the exposure factor, and psoriasis was the outcome, as well as reverse MR analysis, in which psoriasis was used as the exposure factor, and immune cell traits were the outcome. We ran numerous sensitivity analyses to ascertain the study results for robustness, heterogeneity, and potential multiple-biological effects.

Result

This research determined a probable causative connection between immune cells and psoriasis. In particular, we identified 36 distinct types of immune cells that are potentially causally linked to psoriasis.

Conclusion

Our findings indicate strong causal correlations between 36 immunological phenotypes and psoriasis, thus, directing future clinical trials.

Causal relationship between genetically predicted type 2 diabetes mellitus and male infertility

Background

Diabetes mellitus (DM) stands as the most prevalent endocrine abnormality affecting the physiological systems and organs and impairing the male reproductive functions. Type 2 Diabetes Mellitus (T2DM), accounting for about 90-95% of DM, is closely associated with male infertility. However, the magnitude of the causal relationships between T2DM and male infertility remains unclear. The current investigation was to explore the causal relationship between T2DM and male infertility utilizing the Mendelian Randomization (MR) analysis.

Methods

A two-sample MR (2SMR) analysis was conducted to investigate the causal relationship between T2DM and male infertility in the European population from the genome-wide association study (GWAS) summary data that was publicly accessible. GWAS for T2DM and male infertility were extracted from the IEU Open GWAS Project database, with the resulting data encompassing 680 cases and 72,799 controls as the outcome data. Five MR methods were employed for the 2SMR analyses, namely the MR-Egger, weighted median estimation (WME), weighted mode (WM), inverse-variance weighted (IVW), and simple mode. The primary analytical technique utilized in this study was the IVW method, and a multivariate MR analysis was executed to examine the potential mediating influences of T2DM on male infertility.

Results

Following were the odds ratios (ORs) and associated 95% CIs derived from IVW (fixed effects), MR-Egger, WM, WME, and simple mode approaches: 0.824 (95% CI 0.703-0.966), 0.726 (95% CI 0.527-1.001), 0.827 (95% CI 0.596-1.150), 0.841 (95% CI 0.654-1.082), and 0.875 (95% CI 0.544-1.405), respectively. The outcomes of the heterogeneity tests were P=0.378 and P=0.384, respectively, implying no heterogeneity. Egger-intercept outcomes were P=0.374, highlighting the absence of pleiotropy. The stability of the results was affirmed through the leave-one-out analysis. Notably, all F-values surpassed 10, indicating the absence of weak bias attributed to instrument variables(IVs).

Conclusions

This research furnishes evidence supporting a causal association between T2DM and male infertility. These insights offer a foundation for future investigations aiming to establish the association between genetically predicted T2DM and male infertility. These outcomes suggest the significance of active monitoring and proactive measures for preventing infertility in male individuals with T2DM. Furthermore, careful consideration is required for individuals of reproductive age to prevent and treat T2DM.

The causal impact of saturated fatty acids on rheumatoid arthritis: a bidirectional Mendelian randomisation study

Objective

The causal relationship between saturated fatty acids (SFAs) and rheumatoid arthritis (RA) remains poorly understood. This study aimed to determine whether SFAs are causally related to RA using Mendelian randomisation (MR) analyses.

Methods

Genome-wide association study (GWAS) summary data for RA (ukb-d-M13_RHEUMA) and SFAs (met-d-SFA) were obtained from the Integrative Epidemiology Unit OpenGWAS database. A bidirectional MR analysis was performed using a suite of algorithms, namely the MR-Egger, weighted median, simple mode, weighted mode, and inverse-variance weighted (IVW) algorithms, all integrated using the "MR" function. The robustness of the MR findings was further evaluated through sensitivity analyses, including heterogeneity, horizontal pleiotropy, and leave-one-out tests.

Results

The IVW algorithm in the forward MR analysis indicated a causal link between SFAs and RA (p = 0.025), identifying SFAs as a risk factor for RA (odds ratio = 1.001). Sensitivity analyses indicated no significant heterogeneity, horizontal pleiotropy, or severe bias, reinforcing the credibility of the forward MR results. However, the reverse MR analysis revealed that RA does not causally affect SFA levels (p = 0.195), and this finding was supported by corresponding sensitivity analyses.

Conclusion

The findings of this study substantiate the positive causal effect of SFAs on the incidence of RA through bidirectional MR analysis, thereby offering a consequential direction for future research on the diagnosis and treatment of RA.

Visceral adipose tissue and osteoarthritis, a two-sample Mendelian randomized study

Background

The relationship between visceral adipose tissue and osteoarthritis is not clear. The purpose of our study was to explore the relationship between visceral adipose tissue and osteoarthritis.

Methods

We used a two-sample Mendelian randomization method to select single-nucleotide polymorphisms (SNPs) significantly associated with visceral adipose tissue as instrumental variables to explore the relationship between visceral adipose tissue and all osteoarthritis, hand osteoarthritis, hip osteoarthritis, knee osteoarthritis, and spine osteoarthritis. The reliability of the results was tested using sensitivity analysis.

Results

Our findings indicated that visceral adipose tissue was associated with all osteoarthritis, hip osteoarthritis, knee osteoarthritis, and spine osteoarthritis (all osteoarthritis: OR = 1.399, 95% CI: 1.335-1.467, p = 7.95e-44; hip osteoarthritis: OR = 1.399, 95% CI: 1.284-1.524, p = 1.41e-14; knee osteoarthritis: OR = 1.794, 95% CI: 1.662-1.937, p = 1.33e-50; and spine osteoarthritis: OR = 1.445, 95% CI: 1.314-1.589, p = 2.89e-14). Sensitivity analysis demonstrated the reliability of these results.

Conclusion

Our study suggests that genetically predicted visceral adipose tissue is associated with osteoarthritis. Reducing the accumulation of visceral adipose tissue could potentially have an impact on the incidence of osteoarthritis.

The Associations Among Gut Microbiota, Branched Chain Amino Acids, and Parkinson's Disease: Mendelian Randomization Study

Background

In experimental and observational studies, the characteristics of gut microbiota have been associated with Parkinson's disease (PD), among which metabolic pathways played an important role. However, the causality remained unclear.

Objective

Herein, we aimed to determine the potential impact of gut microbiota and gut microbiota-derived metabolites on PD risk using a Mendelian randomization (MR) approach.

Methods

We included as exposures gut microbial taxa abundance and gut-derived metabolites (branched chain amino acids [BCAAs]), with PD as the outcome. In addition, we explored whether BCAAs act as a mediating factor in the pathway from gut microbiota to PD.

Results

We found evidence of a causality of 15 microbial taxa and PD before and after sensitivity analyses, but not after multiple testing correction. There was significant association between BCAAs levels and the risk of PD, especially isoleucine (OR = 0.995, 95% CI 0.992-0.999, p = 0.004, pFDR = 0.012). In addition, the causality of gut microbiota and BCAAs was also explored that the increased g_Coprococcus abundance can result in the decrease in isoleucine level (OR = 1.046; 95% CI, 1.009-1.085; p = 0.016).

Conclusions

Our findings indicated suggestive association between gut microbiota and its metabolites and PD. Furthermore, higher BCAAs levels were associated with the decreased PD risk. This study may provide new targets for PD treatment, such as dietary BCAAs supplementation.

Association Between Endometritis and Endometrial Polyp: A Mendelian Randomization Study

Background

Endometrial polyps (EPs) are one of the most common intrauterine benign tumors, and are an important cause of uterine bleeding and female infertility. Previous studies have suggested that endometritis may contribute to the onset of EPs. This study aims to reveal the causal effect of endometritis on EPs by a two-sample Mendelian randomization (MR) study.

Methods

Utilizing summarized statistics from genome-wide association studies (GWAS) in the European population, we conducted a Mendelian randomization study. In order to select suitable instrumental variables (IVs) that were significantly related to the exposures, a number of quality control approaches were used. For endometritis, 2144 cases and 111,858 controls were included, while for EPs, 2252 cases and 460,758 controls. Utilizing the inverse variance weighted (IVW) as the primary analysis, the data were subjected to a two-sample MR analysis, and the weighted median (WM) technique and MR-Egger regression were carried out additionally. The sensitivity analysis revealed neither heterogeneity nor horizontal pleiotropy.

Results

Four independent single nucleotide polymorphisms (SNPs) from endometritis GWAS as IVs were selected. The IVW data did not agree to a causal association between endometritis and EPs (β=1.11e-04, standard error [SE] =4.88e-04, P = 0.82). Directional pleiotropy did not affect the outcome, according to the MR-Egger regression (intercept = 0.09, P = 0.10); Additionally, it showed no causation association between endometritis and EPs (β= -3.28e-03, SE = 3.54e-03, P = 0.45). Similar results were obtained using the weighted-median method (β=8.56e-05, SE=5.97e-04, P = 0.89). No proof of heterogeneity and horizontal pleiotropy between IV estimates was discovered.

Conclusion

In conclusion, by large scale genetic data, the results of this MR analysis provided suggestive evidence that the presence of endometritis is not associated with higher EPs risk.

Association of autoimmune diseases with the occurrence and 28-day mortality of sepsis: an observational and Mendelian randomization study

BACKGROUND

Observational studies have indicated a potential association between autoimmune diseases and the occurrence of sepsis, with an increased risk of mortality among affected patients. However, whether a causal relationship exists between the two remains unknown.

METHODS

In the Mendelian randomization (MR) study, we accessed exposure Genome-wide association study (GWAS) data from both the MRC Integrative Epidemiology Unit (MRC-IEU) and the FinnGen consortium. GWAS data for sepsis and its 28-day mortality were obtained from MRC-IEU. We employed univariable, multivariable, and reverse MR analyses to explore potential associations between autoimmune disorders and sepsis and its 28-day mortality. Additionally, a two-step mediation MR analysis was performed to investigate indirect factors possibly influencing the relationship between autoimmune disorders and sepsis. Afterward, we conducted an observational analysis to further explore the relationship between autoimmune disease and occurrence as well as 28-day mortality of sepsis using a real-world database (the MIMIC-IV database). A cohort of 2537 patients diagnosed with autoimmune disease were extracted from the database for analysis. Multivariable logistic regression models were used to confirm the association between autoimmune diseases and the occurrence of sepsis, as well as the 28-day mortality associated with sepsis.

RESULTS

In univariable MR analysis, there appeared to be causal relationships between genetically predicted type 1 diabetes (OR = 1.036, 95% CI = 1.023-1.048, p = 9.130E-09), rheumatoid arthritis (OR = 1.077, 95% CI = 1.058-1.097, p = 1.00E-15) and sepsis, while a potential causal link was observed between celiac disease and sepsis (OR = 1.013, 95% CI = 1.002-1.024, p = 0.026). In a subsequent multivariable MR analysis, only rheumatoid arthritis was found to be independently associated with the risk of sepsis (OR = 1.138, 95% CI = 1.044-1.240, p = 3.36E-03). Furthermore, there was no causal link between autoimmune disorders and 28-day mortality from sepsis. In reverse MR analysis, sepsis was suggested to potentially trigger the onset of psoriasis (OR = 1.084, 95% CI = 1.040-1.131, p = 1.488E-04). In the real-world observational study, adjusting for multiple confounders, rheumatoid arthritis (OR = 1.34, 95% CI = 1.11-1.64, p = 0.003) and multiple sclerosis (OR = 1.31, 95% CI = 1.03-1.68, p = 0.02) were associated with a higher risk of sepsis. In addition, we did not find that autoimmune diseases were associated with 28-day mortality from sepsis.

CONCLUSION

Both in observational and MR analysis, only rheumatoid arthritis is highly correlated with occurrence of sepsis. However, autoimmune disease was not associated with an increased 28-day mortality in patient with sepsis. Sepsis may increase the risk of developing psoriasis.