Physical activity and risks of breast and colorectal cancer: a Mendelian randomisation analysis

Causal relationship between iron status and preeclampsia-eclampsia: a Mendelian randomization analysis

BACKGROUND

Preeclampsia/eclampsia is a severe pregnancy-related disorder associated with hypertension and organ damage. While observational studies have suggested a link between maternal iron status and preeclampsia/eclampsia, the causal relationship remains unclear. The aim of this study was to investigate the genetic causality between iron status and preeclampsia/eclampsia using large-scale genome-wide association study (GWAS) summary data and Mendelian randomization (MR) analysis.

METHODS

Summary data for the GWAS on preeclampsia/eclampsia and genetic markers related to iron status were obtained from the FinnGen Consortium and the IEU genetic databases. The "TwoSampleMR" software package in R was employed to test the genetic causality between these markers and preeclampsia/eclampsia. The inverse variance weighted (IVW) method was primarily used for MR analysis. Heterogeneity, horizontal pleiotropy, and potential outliers were evaluated for the MR analysis results.

RESULTS

The random-effects IVW results showed that ferritin (OR = 1.11, 95% CI: .89-1.38, p = .341), serum iron (OR = .90, 95% CI: .75-1.09, p = .275), TIBC (OR = .98, 95% CI: .89-1.07, p = .613), and TSAT (OR = .94, 95% CI: .83-1.07, p = .354) have no genetic causal relationship with preeclampsia/eclampsia. There was no evidence of heterogeneity, horizontal pleiotropy, or possible outliers in our MR analysis (p > .05).

CONCLUSIONS

Our study did not detect a genetic causal relationship between iron status and preeclampsia/eclampsia. Nonetheless, this does not rule out a relationship between the two at other mechanistic levels.

Insulin-related traits and prostate cancer: A Mendelian randomization study

Investigating the causal relationship between insulin secretion and prostate cancer (PCa) development is challenging due to the multifactorial nature of PCa, which complicates the isolation of the specific impact of insulin-related factors. We conducted a Mendelian randomization (MR) study to investigate the associations between insulin secretion-related traits and PCa. We used 36, 60, 56, 23, 48, and 49 single nucleotide polymorphisms (SNPs) as instrumental variables for fasting insulin, insulin sensitivity, proinsulin, and proinsulin in nondiabetic individuals, individuals with diabetes, and individuals receiving exogenous insulin, respectively. These SNPs were selected from various genome-wide association studies. To clarify the causal relationship between insulin-related traits and PCa, we utilized a multivariable MR analysis to adjust for obesity and body fat percentage. Additionally, two-step Mendelian randomization was conducted to assess the role of insulin-like growth factor 1 (IGF-1) in the relationship between proinsulin and PCa. Two-sample MR analysis revealed strong associations between genetically predicted fasting insulin, insulin sensitivity, proinsulin, and proinsulin in nondiabetic individuals and the development of PCa. After adjustment for obesity and body fat percentage using multivariable MR analysis, proinsulin remained significantly associated with PCa, whereas other factors were not. Furthermore, two-step MR analysis demonstrated that proinsulin acts as a negative factor in prostate carcinogenesis, largely independent of IGF-1. This study provides evidence suggesting that proinsulin may act as a negative factor contributing to the development of PCa. Novel therapies targeting proinsulin may have potential benefits for PCa patients, potentially reducing the need for unnecessary surgical treatments.

Association between circulating unsaturated fatty acid and preeclampsia: a two-sample Mendelian randomization study

OBJECTIVE

In recent years, several studies have reported an association between unsaturated fatty acids (UFAs) and the risk of developing preeclampsia; however, its exact causal effect is unclear. This study assessed the causal association between circulating UFAs and preeclampsia.

METHODS

A two-sample Mendelian randomization (MR) study using publicly available genome-wide association study (GWAS) summary data for circulating UFA s (N = 114,999) and preeclampsia (N = 118,291) was performed. Single nucleotide polymorphisms (SNPs) significantly associated with exposure was selected as instrumental variables (IVs). The inverse variance weighted (IVW) test was used as the primary method for estimating causality in MR analysis, while MR pleiotropy residual sum and outlier (MR-PRESSO) and MR-Egger regression methods were used to assess horizontal pleiotropy. Cochran's Q test was used to evaluate heterogeneity among SNPs, and leave-one-out sensitivity analysis was used to determine the effect of individual SNPs on the results of the MR analysis. Bonferroni correction was used as a correction for multiple corrections.

RESULTS

Two-sample MR analysis suggested that the ratio of monounsaturated fatty acids (MUFAs) to total fatty acids (OR 1.150, 95% CI 1.006-1.315, p = 0.041), the ratio of polyunsaturated fatty acids (PUFAs) to total fatty acids (OR 0.805, 95% CI 0.658-0.986, p = 0.036) and the ratio of PUFAs to MUFAs (OR 0.807, 95% CI 0.694-0.938, p = 0.005) were causally associated with preeclampsia. After Bonferroni correction, the causal association between the ratio of polyunsaturated to MUFAs and preeclampsia remained statistically different.

CONCLUSIONS

This MR analysis provides evidence for a genetic causal association between circulating UFAs and preeclampsia.

Dyslipidemia characterized by low density lipoprotein cholesterol and risk of preterm Birth: A Mendelian randomization study

BACKGROUND

Preterm birth is the leading cause of neonatal mortality worldwide, and dyslipidemia is associated with preterm birth in observational studies. We use Mendelian randomization (MR) analyses to uncover the causal association between blood lipid levels and preterm birth.

METHODS

We extracted uncorrelated (R2 < 0.001) single-nucleotide polymorphisms strongly associated (p < 5 × 10-8) with blood lipids from genome wide association studies of FinnGen database and UK Biobank participants. Inverse variance weighted method was the main MR analysis. Sensitivity analyses including genetic pleiotropy, heterogeneity, and directionality of causality were conducted.

RESULTS

The study included 115,082 participants with lipid measurements, 8,507 patients with preterm birth. Increasing apolipoprotein B (odds ratio (OR), 1.12[95 % CI, 1.02-1.23]; p = 0.019), low-density lipoprotein cholesterol (OR, 1.11[95 % CI, 1.00-1.22]; p = 0.040), non-high-density lipoprotein cholesterol (OR, 1.12[95 % CI, 1.01-1.24]; p = 0.026), remnant cholesterol (OR, 1.11[95 % CI, 1.00-1.23]; p = 0.047) and total free cholesterol (OR, 1.11[95 % CI, 1.01-1.23]; p = 0.037) were associated with increased risk of preterm delivery. Moreover, triglycerides in low-density lipoprotein were causally associated with the risk of PTB. Our sensitivity analysis yielded robust results, uncovering no evidence of horizontal pleiotropy or reverse causal relationships.

CONCLUSION

Our investigation unveils the adverse impact of dyslipidemia on preterm birth, with a particular emphasis on the detrimental effect of elevated low-density lipoprotein cholesterol.

Investigating the causal relationship between major depressive disorder and benign prostatic hyperplasia: a bidirectional Mendelian randomisation study

BACKGROUND

Evidence from various cohort studies indicate a potential association between depressive disorder and benign prostatic hyperplasia (BPH), yet findings are inconsistent. This study employs bidirectional two-sample Mendelian randomisation (MR) analysis to explore the causal relationship between BPH and major depressive disorder (MDD).

METHODS

Genetic variants strongly associated with MDD were extracted as instrumental variables conducted by the Psychiatric Genomics Consortium (PGC). Two sets of genetic variants associated with BPH were extracted from the recent FinnGen and Medical Research Council-Integrative Epidemiology Unit Consortium of BPH as the discovery and replication stages, respectively. Bidirectional MR analysis employed methods such as inverse variance weighted, MR-Egger, weighted median, maximum likelihood, and weighted mode. The inverse variance weighted method was primarily used to evaluate the causal relationship.

RESULTS

MR analysis in both the discovery and replication stages showed a significant causal relationship between MDD and the risk of BPH (discovery stages, odds ratio (OR) = 1.1146, 95% CI 1.0058-1.2353, P = 0.03852; replication stage, OR: 1.0042, 95% CI 1.0019-1.0065, P = 0.0004). No causal relationship was found between BPH and MDD risk in the reverse MR analysis.

CONCLUSIONS

Our findings highlight a significant association between MDD and an increased risk of BPH development. Further investigation is needed to elucidate the underlying mechanisms linking depression and BPH.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Circulating inflammatory cytokines and sarcopenia-related traits: a mendelian randomization analysis

Objective

To explore the causal relationships between 91 circulating inflammatory cytokines and sarcopenia-related traits (low hand grip strength, appendicular lean mass, and usual walking pace) by Mendelian randomized analysis.

Methods

Independent genetic variations of inflammatory cytokines and sarcopenia-related traits were selected as instrumental variables from publicly available genome-wide association studies (GWAS). The MR analysis was primarily conducted using the inverse variance-weighted (IVW) method. Sensitivity analyses included Steiger filtering and MR PRESSO, with additional assessments for heterogeneity and pleiotropy.

Results

The IVW method indicated a causal relationship between Vascular Endothelial Growth Factor A (VEGF-A) and low hand grip strength (OR = 1.05654, 95% CI: 1.02453 to 1.08956, P = 0.00046). Additionally, Tumor Necrosis Factor-beta (TNF-β) was found to have a causal relationship with appendicular lean mass (ALM) (β = 0.04255, 95% CI: 0.02838 to 0.05672, P = 3.96E-09). There was no evidence suggesting a significant causal relationship between inflammatory cytokines and usual walking pace.

Conclusion

Our research substantiated the causal association between inflammatory cytokines, such as VEGF-A and TNF-β, and sarcopenia. This finding may provide new avenues for future clinical treatments.

Gastroesophageal Reflux Disease and Preterm Birth: Univariate and Multivariate Mendelian Randomization

Background

Observational studies have established a connection between Gastroesophageal reflux disease (GERD) and preterm birth (PTB). Nevertheless, these correlations can be affected by residual confounding or reverse causality, resulting in ambiguity regarding the connection. The objective of this study was to assess the relationship between genetically predicted GERD and PTB.

Methods

Initially, we performed bidirectional univariate Mendelian randomization (UVMR) analysis utilizing publicly accessible genome-wide association studies (GWAS) data. The primary analytical approach employed to determine the causal impact between GERD and PTB is the inverse variance weighted technique (IVW). Subsequently, we utilized multivariate Mendelian randomization (MVMR) to adjust for potential factors that could influence the results, such as body mass index (BMI), maternal smoking around birth, educational attainment, household income, and Townsend deprivation index (TDI). Furthermore, we performed a sequence of comprehensive sensitivity analyses to assess the reliability of our MR findings.

Results

The UVMR analysis results showed a significant correlation between GERD and PTB (odds ratio [OR]: 1.810; 95% confidence interval [CI]: 1.344-2.439; P=9.60E-05) in the IVW model, and the Weighted median method (OR=1.591, 95% CI=1.094-2.315, P=0.015) revealed consistent results. The inverse MR findings suggest no causal link between PTB and the incidence of GERD. In addition, the sensitivity analysis did not detect heterogeneity or horizontal pleiotropy, and the "leave-one-out" examination confirmed that the causal estimation is unlikely to be influenced by the single nucleotide polymorphisms (SNPs) effect. The MVMR analysis demonstrated that the causal association between GERD and PTB still existed after considering BMI, maternal smoking around birth, educational attainment, household income, and TDI (OR=1.921, 95% CI=1.401-2.634, P=5.08E-05).

Conclusion

This study presents evidence indicating that genetically predicted GERD can heighten the risk of PTB. Therefore, it is advisable to perform focused screening for pregnant women with GERD in order to find the initial signs of PTB and promptly apply intervention strategies to extend the duration of pregnancy.

Causal influence of immune factors on the risk of diabetic retinopathy: a mendelian randomization study

OBJECTIVES

Diabetic retinopathy (DR) is a prevalent microvascular complication in diabetic patients. Various mechanisms have been implicated in the pathogenesis of DR. Previous studies have observed the relationship between immune factors and DR, but the causal relationship has not been determined.

METHODS

We conducted a two-sample Mendelian randomization (MR) analysis of 731 immune cells and DR, using publicly available genome-wide association study (GWAS) summary statistics, to evaluate potential causal relationships between them. Four types of immune traits were included in the analysis through flow cytometry. GWAS statistics for DR were obtained from the Finngen database, which performed GWAS on 190,594 European individuals (Ncase = 14,584, Ncontrol = 176,010) to assess genetically predicted DR. The primary method used to perform causality analysis was inverse variance weighting (IVW).

RESULTS

Following false discovery rate (FDR) correction, 11MFI-DR, 5AC-DR, 5RC-DR, and 1MP-DR reached a significant causal association level (PFDR < 0.05). Notably, all AC traits exhibited potential associations with a decreased risk of DR(OR < 1), while a majority of MFI traits, along with the singular MP trait, exhibited potential associations with an increased risk of DR (OR > 1). The highest proportion of T-cell subsets in the final results.

CONCLUSION

This study elucidates that the progression of DR is intricately influenced by immune responses, thereby confirming the immunological susceptibility of DR. Our findings may offer new targets for diagnosing and treating DR, as well as aid in developing therapeutic strategies from an immunological standpoint.

Gut microbiota, circulating inflammatory proteins and sepsis: a bi-directional Mendelian randomization study

Background

Gut microbiota is closely related to the occurrence and development of sepsis. However, the causal effects between the gut microbiota and sepsis, and whether circulating inflammatory proteins act as mediators, remain unclear.

Methods

Gut microbiota, circulating inflammatory proteins, and four sepsis-related outcomes were identified from large-scale genome wide association studies (GWAS) summary data. Inverse Variance Weighted (IVW) was the primary statistical method. Additionally, we investigated whether circulating inflammatory proteins play a mediating role in the pathway from gut microbiota to the four sepsis-related outcomes.

Results

There were 14 positive and 15 negative causal effects between genetic liability in the gut microbiota and four sepsis-related outcomes. Additionally, eight positive and four negative causal effects were observed between circulating inflammatory proteins and the four sepsis-related outcomes. Circulating inflammatory proteins do not act as mediators.

Conclusions

Gut microbiota and circulating inflammatory proteins were causally associated with the four sepsis-related outcomes. However, circulating inflammatory proteins did not appear to mediate the pathway from gut microbiota to the four sepsis-related outcomes.

Bidirectional Mendelian randomization to explore the causal relationships between the gut microbiota and male reproductive diseases

Gut bacteria might play an important role in male reproductive disorders, such as male infertility and sperm abnormalities; however, their causal role is unclear. Herein, Mendelian randomization (MR)-Egger, weighted median, inverse variance weighting, Simple mode, and Weighted mode were used to test the causal relationship between gut microbes and male reproductive diseases. The MR results were validated using various metrics. The MR results were also consolidated using reverse causality speculation, conducted using two-way MR analysis and Steiger filtering. Biological function was analysed using enrichment analyses. The results suggested that eight intestinal microflorae were causally associated with male infertility. The Eubacterium oxidoreducens group was associated with an increased risk of male infertility, while the family Bacteroidaceae was negatively associated with male reproductive diseases. Eight intestinal microflorae were causally associated with abnormal spermatozoa. The family Streptococcaceae was associated with a high risk of abnormal spermatozoa, whereas the family Porphyromonadaceae was associated with a low risk of abnormal spermatozoa. No pleiotropy was observed, this study identified a high correlation between the gut flora and the likelihood of male reproductive diseases. Future research will attempt to advance microbial-focused treatments for such diseases.

Discrepancies between general and central obesity in arterial stiffness: observational studies and Mendelian randomization study

BACKGROUND

Obesity has been linked to arterial stiffness, while no consensus was reached on the association. We aimed to clarify the association of general and central obesity with arterial stiffness by combining observational studies and Mendelian randomization (MR) study.

METHODS

Two cross-sectional studies were performed in UK Biobank and Fuqing Cohort, respectively. Two-sample MR study was conducted using summary data of GWASs from GIANT consortium and UK Biobank. General obesity and central obesity were measured using body mass index (BMI) and waist circumference (WC), respectively. Arterial stiffness was measured by arterial stiffness index (ASI) in UK Biobank or branchial-ankle pulse wave velocity (baPWV) in Fuqing Cohort.

RESULTS

Two observational studies found a consistent positive association of BMI and WC with arterial stiffness when adjusting for age, sex, education, smoking, alcohol drinking, physical activity, and LDL cholesterol. However, when additionally adjusting for metabolic traits (i.e., systolic blood pressure, diastolic blood pressure, blood glucose, triglycerides, high-density lipoprotein cholesterol, and WC or BMI), the association with BMI changed to be inverse. As compared to the lowest quintile group, the adjusted ORs across groups of second to fifth quintile were 0.93, 0.90, 0.83, and 0.72 in UK Biobank and 0.88, 0.65, 0.63, and 0.50 in Fuqing Cohort. In contrast, the positive relationship with WC remained stable with the adjusted ORs of 1.23, 1.46, 1.60, and 1.56 in UK Biobank and 1.35, 1.44, 1.77, and 1.64 in Fuqing Cohort. MR analyses provided supportive evidence of the negative association with BMI (OR = 0.97, 95%CI = 0.94-1.00) and the positive association with WC (OR = 1.14, 95%CI = 1.08-1.20).

CONCLUSIONS

Observational and genetic analyses provide concordant results that central obesity is independently related to arterial stiffness, while the role of general obesity depends on metabolic status.

Unraveling the association between gut microbiota and chemotherapy efficacy: a two-sample Mendelian randomization study

Emerging evidence has underscored the complex link between gut microbiota and chemotherapy efficacy; however, establishing causality remains elusive due to confounding factors. This study, leveraging bidirectional two-sample Mendelian randomization (MR) analyses, explores the casual relationship between gut microbiota and chemotherapy efficacy. Utilizing genome-wide association study (GWAS) data from the MiBioGen consortium for gut microbiota and IEU Open GWAS for chemotherapy efficacy, we employed genetic variants as instrumental variables (IVs). The inverse variance weighted (IVW) method, weighted median estimator (WME), and MR-Egger regression method were applied, with sensitivity analyses ensuring robustness. Furthermore, we conducted reverse MR analyses between chemotherapy efficacy and identified significant gut microbial taxa. The results indicated that genus Butyricicoccus (OR = 3.7908, 95% CI: 1.4464-9.9350, P = 0.01), Dorea (OR = 3.3295, 95% CI: 1.2794-8.6643, P = 0.01), Hungatella (OR = 2.6284, 95% CI: 1.0548-6.5498, P = 0.04), and Turicibacter (OR = 2.5694, 95% CI: 1.0392-6.3526, P = 0.04) were positively associated with chemotherapy efficacy using the IVW method. Conversely, family Porphyromonadaceae (OR = 0.2283, 95% CI: 0.0699-0.7461, P = 0.01) and genus Eggerthella (OR = 0.4953, 95% CI: 0.2443-1.0043, P = 0.05) exhibited negative associations. WME demonstrated consistent results with IVW method only for genus Eggerthella (OR = 0.3343, 95% CI: 0.1298-0.8610, P = 0.02). No significant heterogeneity or horizontal pleiotropy was observed. Reverse MR analyses revealed no significant causal effect of chemotherapy on identified gut microbiota. This study sheds light on the intricate relationship between gut microbiota, with a particular emphasis on the genus Eggerthella, and chemotherapy efficacy, offering valuable insights for refining cancer treatment strategies.IMPORTANCEGlobal advancements in cancer treatment, particularly in chemotherapy, have notably decreased mortality rates in recent years. However, the correlation between gut microbiota and chemotherapy efficacy remains elusive. Our study, emphasizing the role of genus Eggerthella, represented a crucial advance in elucidating this intricate interplay. The identified associations offer potential therapeutic targets, contributing to global efforts for enhanced treatment precision and improved patient outcomes. Furthermore, our findings hold promise for personalized therapeutic interventions, shaping improved strategies in the ever-evolving landscape of cancer treatment.

Assessment of causal association between the socio-economic status and osteoporosis and fractures: a bidirectional Mendelian randomization study in European population

The correlation between socio-economic status (SES) and bone-related diseases garners increasing attention, prompting a bidirectional Mendelian randomization (MR) analysis in this study. Genetic data on SES indicators (average total household income before tax, years of schooling completed, and Townsend Deprivation Index at recruitment), femoral neck bone mineral density (FN-BMD), heel bone mineral density (eBMD), osteoporosis, and five different sites of fractures (spine, femur, lower leg-ankle, foot, and wrist-hand fractures) were derived from genome-wide association summary statistics of European ancestry. The inverse variance weighted method was employed to obtain the causal estimates, complemented by alternative MR techniques, including MR-Egger, weighted median, and MR-pleiotropy residual sum and outlier (MR-PRESSO). Furthermore, sensitivity analyses and multivariable MR were performed to enhance the robustness of our findings. Higher educational attainment exhibited associations with increased eBMD (β: .06, 95% confidence interval [CI]: 0.01-0.10, P = 7.24 × 10-3), and reduced risks of osteoporosis (OR: 0.78, 95% CI: 0.65-0.94, P = 8.49 × 10-3), spine fracture (OR: 0.76, 95% CI: 0.66-0.88, P = 2.94 × 10-4), femur fracture (OR: 0.78, 95% CI: 0.67-0.91, P = 1.33 × 10-3), lower leg-ankle fracture (OR: 0.79, 95% CI: 0.70-0.88, P = 2.05 × 10-5), foot fracture (OR: 0.78, 95% CI: 0.66-0.93, P = 5.92 × 10-3), and wrist-hand fracture (OR: 0.83, 95% CI: 0.73-0.95, P = 7.15 × 10-3). Material deprivation appeared to increase the risk of spine fracture (OR: 2.63, 95% CI: 1.43-4.85, P = 1.91 × 10-3). A higher FN-BMD level positively affected increased household income (β: .03, 95% CI: 0.01-0.04, P = 6.78 × 10-3). All these estimates were adjusted for body mass index, type 2 diabetes, smoking initiation, and frequency of alcohol intake. The MR analyses show that higher educational levels is associated with higher eBMD, reduced risk of osteoporosis and fractures, while material deprivation is positively related to spine fracture. Enhanced FN-BMD correlates with increased household income. These findings provide valuable insights for health guideline formulation and policy development.

Association between gut microbiota and diabetic microvascular complications: a two-sample Mendelian randomization study

Background

Gut microbiota (GM) homeostasis in the human body is closely associated with health, which can be used as a regulator for preventing the onset and progression of disease. Diabetic microvascular complications bring about not only a huge economic burden to society, but also miserable mental and physical pain. Thus, alteration of the GM may be a method to delay diabetic microvascular complications.

Objective

A two-sample Mendelian randomization (MR) analysis was conducted to reveal the causal inference between GM and three core diabetic microvascular complications, namely, diabetic kidney disease (DKD), diabetic retinopathy (DR), and diabetic neuropathy (DNP).

Methods

First, genome-wide association study (GWAS) summary statistics for GM from the MiBioGen consortium and three main diabetic microvascular complications acquired from the FinnGen research project were assessed. Second, a forward MR analysis was conducted to assess the causality of GM on the risk of DKD, DR, and DNP. Third, a series of sensitivity studies, such as heterogeneity tests, pleiotropy evaluations, and leave-one-out analyses, were further conducted to assess the accuracy of MR analysis. Finally, Steiger tests and reverse MR analyses were performed to appraise the possibility of reverse causation.

Results

A total of 2,092 single-nucleotide polymorphisms related to 196 bacterial traits were selected as instrumental variables. This two-sample MR analysis provided strongly reasonable evidence that 28 genetically predicted abundance of specific GM that played non-negligible roles in the occurrence of DKD, DR, and DNP complications were causally associated with 23 GM, the odds ratio of which generally ranged from 0.9 to 1.1. Further sensitivity analysis indicated low heterogeneity, low pleiotropy, and high reliability of the causal estimates.

Conclusion

The study raised the possibility that GM may be a potential target to prevent and delay the progression of diabetic microvascular complications. Further experiments of GM therapy on diabetic microvascular complications are warranted to clarify their effects and specific mechanisms.

Circulating Proteins and IgA Nephropathy: A Multiancestry Proteome-Wide Mendelian Randomization Study

Key Points

Background

The therapeutic options for IgA nephropathy are rapidly evolving, but early diagnosis and targeted treatment remain challenging. We aimed to identify circulating plasma proteins associated with IgA nephropathy by proteome-wide Mendelian randomization studies across multiple ancestry populations.

Methods

In this study, we applied Mendelian randomization and colocalization analyses to estimate the putative causal effects of 2615 proteins on IgA nephropathy in Europeans and 235 proteins in East Asians. Following two-stage network Mendelian randomization, multitrait colocalization analysis and protein-altering variant annotation were performed to strengthen the reliability of the results. A protein–protein interaction network was constructed to investigate the interactions between the identified proteins and the targets of existing medications.

Results

Putative causal effects of 184 and 13 protein–disease pairs in European and East Asian ancestries were identified, respectively. Two protein–disease pairs showed shared causal effects across them (CFHR1 and FCRL2). Supported by the evidence from colocalization analysis, potential therapeutic targets were prioritized and four drug-repurposing opportunities were suggested. The protein–protein interaction network further provided strong evidence for existing medications and pathways that are known to be therapeutically important.

Conclusions

Our study identified a number of circulating proteins associated with IgA nephropathy and prioritized several potential drug targets that require further investigation.

Gastroesophageal reflux disease increases the risk of rheumatoid arthritis: a bidirectional two-sample Mendelian randomization study

Rheumatoid arthritis (RA) is a common autoimmune disease, and some observational studies have indicated an association between Gastroesophageal Reflux Disease (GERD) and RA. However, the causal relationship between the two remains uncertain. We used Mendelian randomization (MR) to assess the causal relationship between GERD and RA. Two-sample Mendelian randomization analysis was performed using pooled data from large-scale genome-wide association studies. In addition, we performed multivariate MR analyses to exclude confounding factors between GERD and RA, including smoking quantity, drinking frequency, BMI, depression, and education attainment. The MR results for GERD on RA suggested a causal effect of the genetic susceptibility of GERD on RA (discovery dataset, IVW, odds ratio [OR] = 1.41, 95% confidence interval [CI] 1.22-1.63, p = 2.81 × 10-6; validation dataset, IVW, OR = 1.38, 95% CI 1.23-1.55, P = 1.76 × 10-8). Multivariate MR analysis also supports this result. But the results of the reverse MR analysis did not reveal compelling evidence that RA can increase the risk of developing GERD. Our bidirectional Two-Sample Mendelian randomization analysis and multivariate MR analysis provide support for the causal effect of GERD on RA. This discovery could offer new insights for the prevention and treatment of RA.

Causality of inflammatory bowel disease and seborrheic keratosis: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Previous studies have revealed a potential link between inflammatory bowel disease (IBD) and seborrheic keratosis (SK). However, whether this association is causal or confounded remains unknown.

METHODS

We conducted this two-sample Mendelian randomization (TSMR) analysis to clarify bidirectional causality between IBD, including its two primary conditions Crohn's disease (CD) and ulcerative colitis (UC), and SK. The summary genetic data of IBD, CD, UC and SK were obtained from accessible genome-wide association studies (GWAS). This TSMR study was primarily performed using inverse-variance weighted (IVW) method, complemented by MR-Egger, weighted median (WM), Bayesian weighted MR (BWMR), MR-robust adjusted profile score (MR-RAPS), MR-pleiotropy residual sum and outlier (MR-PRESSO), and radial IVW MR analyses with modified second-order weights (IVW [Mod 2nd]) methods. Assessment of sensitivity and identification of potential outliers were subsequently conducted to aid interpretation of results.

RESULTS

The forward MR results showed that IBD [odds ratio (OR) = 1.068, 95% confidence interval (CI) = 1.010-1.129, p = 0.020) and its subtype CD (OR = 1.088, 95%CI = 1.038-1.139, p < 0.001) increased the risk of SK. However, the occurrence of SK could not be affected by UC (OR = 1.090, 95%CI = 0.977-1.216, p = 0.123). In the reverse analysis, no causal relationship between SK and IBD (OR = 0.905, 95%CI = 0.813-1.008, p = 0.069), UC (OR = 0.959, 95%CI = 0.860-1.068, p = 0.443), and CD (OR = 0.933, 95%CI = 0.846-1.029, p = 0.165) was identified.

CONCLUSION

These findings demonstrate that IBD and its subtype CD could increase the incidence of SK in European populations, whereas SK does not affect IBD occurrence.

Causality between Sarcopenia and Depression: A Bidirectional Mendelian Randomization Study

BACKGROUND

Numerous observational studies have suggested a correlation between sarcopenia and depression, but the nature of this relationship requires further investigation.

METHODS

This study employed bidirectional Mendelian randomization to explore this connection. Data from genome-wide association studies were used, encompassing measures of sarcopenia and mental factors, including depression and emotional states. The initial analysis concentrated on the impact of depression on sarcopenia, and then it examined the reverse relationship. The same methodology was applied to emotional data for validation.

RESULTS

The results indicated a reciprocal causation between sarcopenia and depression, even when emotional state data were considered. Various emotions can impact sarcopenia, and in turn, sarcopenia can affect emotions, except subjective well-being. These findings highlight a cyclic deterioration between sarcopenia and depression, with a link to negative emotions and a partially ameliorative effect of subjective well-being on sarcopenia.

CONCLUSIONS

In summary, this study sheds light on the interplay between psychiatric factors and sarcopenia, offering insights into intervention and prevention strategies.

Rheumatoid arthritis and adverse pregnancy outcomes: a bidirectional two-sample mendelian randomization study

BACKGROUND

There is growing evidence of bidirectional associations between rheumatoid arthritis and adverse pregnancy outcomes (APOs) in observational studies, but little is known about the causal direction of these associations. Therefore, we explored the potential causal relationships between rheumatoid arthritis and APOs using a bidirectional two-sample Mendelian randomization (MR) in European and Asian populations.

METHODS

We conducted a bidirectional two-sample Mendelian randomization analysis using available summary statistics from released genome-wide association studies. Summary statistics for instrument-outcome associations were retrieved from two separate databases for rheumatoid arthritis and adverse pregnancy outcomes, respectively. The inverse-variance weighted method was used as the primary MR analysis, and cML-MA-BIC was used as the supplementary analysis. MR-Egger, MR pleiotropy residual sum and outlier (MR-PRESSO), and Cochran Q statistic method were implemented as sensitivity analyses approach to ensure the robustness of the results.

RESULTS

Our study showed that a higher risk of rheumatoid arthritis in the European population was associated with gestational hypertension (OR: 1.04, 95%CI: 1.02-1.06), pre-eclampsia (OR: 1.06, 95%CI: 1.01-1.11), fetal growth restriction (OR: 1.08, 95%CI: 1.04-1.12), preterm delivery (OR:1.04, 95%CI: 1.01-1.07). Furthermore, we found no evidence that APOs had causal effects on rheumatoid arthritis in the reverse MR analysis. No association between rheumatoid arthritis and APOs was found in East Asian population. There was no heterogeneity or horizontal pleiotropy.

CONCLUSIONS

This MR analysis provides the positive causal association from rheumatoid arthritis to gestational hypertension, pre-eclampsia, fetal growth restriction and preterm delivery genetically. It highlights the importance of more intensive prenatal care and early intervention among pregnant women with rheumatoid arthritis to prevent potential adverse obstetric outcomes.

Genetically predicted small dense low-density lipoprotein cholesterol and ischemic stroke subtype: multivariable Mendelian randomization study

Purpose

Small dense low-density lipoprotein cholesterol (S-LDL-C) has been suggested as a particularly atherogenic factor for ischemic stroke (IS) in observational studies, but the causality regarding the etiological subtype remains unclear. This study aims to explore the causal effects of small dense low-density lipoprotein cholesterol (S-LDL-C), medium (M-LDL-C) and large (L-LDL-C) subfractions on the lifetime risk of ischemic stroke (IS) and main subtypes using two-sample Mendelian randomization (TSMR) design.

Methods

We identified genetic instruments for S-LDL-C, M-LDL-C and L-LDL-C from a genome-wide association study of 115 082 UK Biobank participants. Summary-level data for genetic association of any ischemic stroke (AIS), large artery stroke (LAS), small vessel stroke (SVS) and cardioembolic stroke (CES) were obtained from MEGASTROKE consortium. Accounting for the pleiotropic effects of triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C), we conducted multivariable TSMR analysis.

Results

In univariable TSMR, we found a causal association between genetically predicted S-LDL-C and LAS (IVW-FE: odds ratio (OR) = 1.481, 95% confidence interval (CI): 1.117-1.963, P = 0.006, q = 0.076) but not AIS, SVS or CES. No causal effects were observed for M-LDL-C or L-LDL-C in terms of AIS and IS subtype. In multivariable analysis, the causal association between S-LDL-C and LAS remained significant (IVE-MRE: OR = 1.329, 95% CI: 1.106-1.597, P = 0.002).

Conclusions

Findings supported a causal association between S-LDL-C and LAS. Further studies are warranted to elucidate the underlying mechanism and clinical benefit of targeting S-LDL-C.

Association between levels of sex hormones and risk of multiple sclerosis: a mendelian randomization study

BACKGROUND

This research aimed to examine the causal connections between multiple sclerosis (MS) and a range of sex hormone-related traits, such as bioavailable testosterone (BT), sex hormone-binding globulin (SHBG), testosterone, and estradiol (E2).

METHODS

A bidirectional two-sample Mendelian randomization (MR) analysis using summary statistics from genome-wide association studies (GWAS) was conducted to investigate the relationship between sex hormone-related traits and MS. Moreover, the Inverse-variance weighted (IVW) method was employed as the primary analysis approach.

RESULTS

The MR analysis, using the IVW method, found a significant correlation between genetically determined SHBG levels and MS (OR = 1.634, 95% CI: 1.029-2.599, p = 0.038). Similarly, the reverse MR analysis suggested a causal link between MS and SHBG (OR = 1.005, 95% CI: 1.001-1.009, P = 0.003). However, no association was observed between MS risk and E2, testosterone, or BT levels.

CONCLUSION

Our MR analysis demonstrated that genetically predicted higher SHBG may be positively correlated with the risk of MS. Moreover, the role of SHBG in MS could be further investigated.

Investigation of the causal relationship between breast cancer and thyroid cancer: a set of two-sample bidirectional Mendelian randomization study

PURPOSE

A potential association between breast (BC) and thyroid cancer (TC) has been observed. We investigated if the relationship between BC and TC is causal using bidirectional Mendelian randomization (MR) in Asian and European populations.

METHODS

BC-linked single nucleotide polymorphisms (SNPs) were acquired from a genome-wide association study (GWAS) conducted by the Breast Cancer Association Consortium and Biobank Japan. The most recent TC GWAS data were obtained from the FinnGen Project and National Biobank of Korea. We assessed the potential causal relationship between BC and TC using various MR methods, including inverse-variance-weighting (IVW). Sensitivity, heterogeneity, and pleiotropic tests were performed to assess reliability.

RESULTS

We found a bidirectional causal association between BC and TC within Europeans (IVW, TC on BC: odds ratio [OR] 1.090, 95% confidence interval [CI]: 1.012-1.173, P = 0.023; BC on TC: OR 1.265, 95% CI: 1.158-1.381, P < 0.001). A one-way causal relationship between BC susceptibility and TC risk was found in Asians (IVW BC on TC: OR 2.274, 95% CI: 2.089-2.475, P < 0.001). Subsequently, we identified a noteworthy bidirectional causal relationship between estrogen receptor (ER)-positive BC and TC (IVW, TC on ER-positive BC: OR 1.104, 95% CI: 1.001-1.212, P = 0.038; ER-positive BC on TC: OR 1.223, 95%CI: 1.072-1.395, P = 0.003), but not ER-negative BC and TC in Europeans.

CONCLUSION

We revealed a reciprocal causal association between ER-positive BC and TC. These findings establish a theoretical framework for the simultaneous surveillance and treatment of BC and TC.

Integrating Mendelian randomization and single-cell RNA sequencing to identify therapeutic targets of baicalin for type 2 diabetes mellitus

Background

Alternative and complementary therapies play an imperative role in the clinical management of Type 2 diabetes mellitus (T2DM), and exploring and utilizing natural products from a genetic perspective may yield novel insights into the mechanisms and interventions of the disorder.

Methods

To identify the therapeutic target of baicalin for T2DM, we conducted a Mendelian randomization study. Druggable targets of baicalin were obtained by integrating multiple databases, and target-associated cis-expression quantitative trait loci (cis-eQTL) originated from the eQTLGen consortium. Summary statistics for T2DM were derived from two independent genome-wide association studies available through the DIAGRAM Consortium (74,124 cases vs. 824,006 controls) and the FinnGen R9 repository (9,978 cases vs. 12,348 controls). Network construction and enrichment analysis were applied to the therapeutic targets of baicalin. Colocalization analysis was utilized to assess the potential for the therapeutic targets and T2DM to share causative genetic variations. Molecular docking was performed to validate the potency of baicalin. Single-cell RNA sequencing was employed to seek evidence of therapeutic targets' involvement in islet function.

Results

Eight baicalin-related targets proved to be significant in the discovery and validation cohorts. Genetic evidence indicated the expression of ANPEP, BECN1, HNF1A, and ST6GAL1 increased the risk of T2DM, and the expression of PGF, RXRA, SREBF1, and USP7 decreased the risk of T2DM. In particular, SREBF1 has significant interaction properties with other therapeutic targets and is supported by strong colocalization. Baicalin had favorable combination activity with eight therapeutic targets. The expression patterns of the therapeutic targets were characterized in cellular clusters of pancreatic tissues that exhibited a pseudo-temporal dependence on islet cell formation and development.

Conclusion

This study identified eight potential targets of baicalin for treating T2DM from a genetic perspective, contributing an innovative analytical framework for the development of natural products. We have offered fresh insights into the connections between therapeutic targets and islet cells. Further, fundamental experiments and clinical research are warranted to delve deeper into the molecular mechanisms of T2DM.

The role of coffee and potential mediators in subclinical atherosclerosis: insights from Mendelian randomization study

Background and aims

Coffee contains many bioactive compounds, and its inconsistent association with subclinical atherosclerosis has been reported in observational studies. In this Mendelian randomization study, we investigated whether genetically predicted coffee consumption is associated with subclinical atherosclerosis, as well as the role of potential mediators.

Methods

We first conducted a two-sample Mendelian randomization analysis to examine the causal effect of coffee and its subtypes on subclinical atherosclerosis inferred from coronary artery calcification (CAC). Next, the significant results were validated using another independent dataset. Two-step Mendelian randomization analyses were utilized to evaluate the causal pathway from coffee to subclinical atherosclerosis through potential mediators, including blood pressure, blood lipids, body mass index, and glycated hemoglobin. Mendelian randomization analyses were performed using the multiplicative random effects inverse-variance weighted method as the main approach, followed by a series of complementary methods and sensitivity analyses.

Results

Coffee, filtered coffee, and instant coffee were associated with the risk of CAC (β = 0.79, 95% CI: 0.12 to 1.47, p = 0.022; β = 0.66, 95% CI: 0.17 to 1.15, p = 0.008; β = 0.66, 95% CI: 0.20 to 1.13, p = 0.005; respectively). While no significant causal relationship was found between decaffeinated coffee and CAC (β = -1.32, 95% CI: -2.67 to 0.04, p = 0.056). The association between coffee and CAC was validated in the replication analysis (β = 0.27, 95% CI: 0.07 to 0.48, p = 0.009). Body mass index mediated 39.98% of the effect of coffee on CAC (95% CI: 9.78 to 70.19%, p = 0.009), and 5.79% of the effect of instant coffee on CAC (95% CI: 0.54 to 11.04%, p = 0.030).

Conclusion

Our study suggests that coffee other than decaffeinated coffee increases the risk of subclinical atherosclerosis inferred from CAC. Body mass index mediated 39.98 and 5.79% of the causal effects of coffee and instant coffee on CAC, respectively. Coffee should be consumed with caution, especially in individuals with established cardiovascular risk factors, and decaffeinated coffee appears to be a safer choice.

Role of blood metabolites in mediating the effect of gut microbiome on the mutated-RAS/BRAF metastatic colorectal cancer-specific survival

BACKGROUND

Recent studies have linked alterations in the gut microbiome and metabolic disruptions to the invasive behavior and metastasis of colorectal cancer (CRC), thus affecting patient prognosis. However, the specific relationship among gut microbiome, metabolite profiles, and mutated-RAS/BRAF metastatic colorectal cancer (M-mCRC) remains unclear. Furthermore, the potential mechanisms and prognostic implications of metabolic changes induced by gut microbiome alterations in patients with M-mCRC still need to be better understood.

METHODS

We conducted Mendelian randomization (MR) to evaluate the causal relationship of genetically predicted 196 gut microbiome features and 1400 plasma metabolites/metabolite ratios on M-mCRC-specific survival. Additionally, we identified significant gut microbiome-metabolites/metabolite ratio associations based on M-mCRC. Metabolite information was annotated, and functional annotation and pathway enrichment analyses were performed on shared proteins corresponding to significant metabolite ratios, aiming to reveal potential mechanisms by which gut microbiome influences M-mCRC prognosis via modulation of human metabolism.

RESULTS

We identified 11 gut microbiome features and 49 known metabolites/metabolite ratios correlated with M-mCRC-specific survival. Furthermore, we identified 17 gut microbiome-metabolite/metabolite ratio associations specific to M-mCRC, involving eight lipid metabolites and three bilirubin degradation products. The shared proteins corresponding to significant metabolite ratios were predominantly localized within the integral component of the membrane and exhibited enzymatic activities such as glucuronosyltransferase and UDP-glucuronosyltransferase, crucial in processes such as glucuronidation, bile secretion, and lipid metabolism. Moreover, these proteins were significantly enriched in pathways related to ascorbate and aldarate metabolism, pentose and glucuronate interconversions, steroid hormone biosynthesis, and bile secretion.

CONCLUSION

Our study offers novel insights into the potential mechanisms underlying the impact of the gut microbiome on the prognosis of M-mCRC. These findings serve as a meaningful reference for exploring potential therapeutic targets and strategies in the future.

Novel prognostic alternative splicing events in colorectal Cancer: Impact on immune infiltration and therapy response

OBJECTIVE

This study aims to comprehensively analyze alternative splicing (AS) features in colorectal cancer (CRC) using integrative multi-omics and to elucidate their relationship with the CRC immune microenvironment.

METHODS

Transcriptomic data, clinical information, and Percent Spliced In (PSI) values of AS events for CRC patients were obtained from The Cancer Genome Atlas (TCGA) and TCGA SpliceSeq databases. Differentially expressed AS events were identified. Univariate Cox analysis was used to pinpoint prognosis-related AS events. A prognostic risk model was developed and validated using multivariate Cox analysis, patient survival analysis, and the area under the receiver operating characteristic (ROC) curve (AUC). Gene Set Enrichment Analysis (GSEA), immune infiltration, immunotherapy, chemotherapy sensitivity analyses, and regulatory relationships between AS events and splicing factors (SFs) were conducted. Single-cell sequencing was used to study the distribution of key factors. siRNA and overexpression vectors were utilized to silence/overexpress BCAS1 in CRC cells and evaluate their effects on cell growth, migration, and invasion. Furthermore, the interaction between BCAS1 and ANO7 pre-mRNA was investigated using RIP-PCR.

RESULTS

82 prognosis-related AS events were identified in CRC patients. A 15-AS prognostic model was constructed, which correlated with immune cell infiltration and showed differences in immunotherapy and chemotherapy sensitivity. BCAS1 was identified as a potential regulator of the ANO7|58341|AT splicing event in CRC. Single-cell sequencing analysis revealed the distribution of BCAS1 and ANO7 in cancer stem cells. In vitro experiments demonstrated that overexpression of BCAS1 and silencing of ANO7 inhibit the proliferation, migration, and invasion of CRC cells. Moreover, BCAS1 suppresses the progression of CRC by modulating ANO7 alternative splicing.

CONCLUSION

This study provides new insights into the role of alternative splicing in colorectal cancer, particularly the potential regulatory action of BCAS1 on the ANO7|58341|AT splicing event. It also identifies the impact of alternative splicing on the tumor microenvironment and potential implications for immunotherapy, highlighting its relevance for the in-depth study and treatment of CRC.

Association between body fat distribution and asthma in adults: results from the cross-sectional and bidirectional Mendelian randomization study

Background

Many studies define obesity based on body mass index (BMI) and explore its relationship with adult asthma. However, BMI only considers height and weight, ignoring other factors such as body fat, which may have a greater impact on health. We investigated the relationship between body fat distribution and adult asthma using both a cross-sectional study and bidirectional Mendelian randomization (MR) analysis.

Methods

Weighted logistic regression models were used to examine the relationship between body fat distribution measurements and adult asthma in the cross-sectional study from National Health and Nutrition Examination Survey (NHANES) 2011-2018. Restricted cubic spline (RCS) curves were employed to explore the dose-response relationship between them. The inverse-variance weighted (IVW) method was used as the main method of MR analysis to explore the causal effect of exposure on outcome.

Results

After adjusting for all covariates, weighted logistic regression analysis indicated that fat mass in the left arm, left leg, right arm, right leg, trunk, and total body is associated with an increased risk of developing adult asthma (p < 0.05). RCS curves showed that all six fat mass indicators exhibit a J-shaped relationship with adult asthma. Forward MR analysis found a causal effect of six fat mass indicators on the increased risk of adult asthma (p < 0.05). However, reverse MR did not reveal any causal effect of adult asthma on these six fat mass indicators (p > 0.05).

Conclusion

Our study supports a positive correlation and a unidirectional causality between body fat distribution measurements and the risk of adult asthma. Further studies are needed to validate our findings.

Allergic diseases and Meniere's disease: a bidirectional Mendelian randomization

OBJECTIVES

Allergic diseases and Meniere's disease found to have a possible link in observational study. However, the potential causal relationship between the two is unclear. Therefore, we aimed to explore the causal relationship between allergic diseases and Meniere's disease using a new data analysis technique called bidirectional Mendelian randomization study.

METHOD

Summary-level statistics for Meniere's disease and three allergic diseases (asthma, allergic rhinitis, eczema/dermatitis) were obtained from large-scale genome-wide association studies. The inverse variance weighted method was used as the primary measure, supplemented by MR-Egger regression and the weighted median method. To ensure the reliability of the conclusions, Cochran's Q, MR-Egger intercept, MR-PRESSO test, leave-one-out test, and MR Steiger test were used.

RESULTS

Inverse-variance weighted method showed asthma (p = 0.008, OR = 3.908, 95% CI 1.424-10.724, adjust_p = 0.024), allergic rhinitis (p = 0.026, OR = 24.714, 95% CI 1.479-412.827, adjust_p = 0.026) and eczema/dermatitis (p = 0.019, OR = 3725.954, 95% CI 3.795 to 3,658,399.580, adjust_p = 0.029) all had a significant effect on Meniere's disease. Reverse Mendelian randomization studies have shown that Meniere's disease does not increase the risk of three allergic diseases. Sensitivity analysis showed no horizontal pleiotropy and heterogeneity for each trait.

CONCLUSION

Our Mendelian randomization analysis supports a positive causal relationship between three allergic diseases (asthma, allergic rhinitis, eczema/dermatitis) and Meniere's disease. This suggests that physicians should pay more attention to the Meniere's patient's allergy history and consider allergy avoidance as part of their treatment plan.

LEVEL OF EVIDENCE

Mendelian Randomized (MR) studies are second only to randomized controlled trials in terms of the level of evidence.

Trans-ancestry analysis in over 799,000 individuals yields new insights into the genetic etiology of colorectal cancer

BACKGROUND

Recent studies have demonstrated the relevance of circulating factors in the occurrence and development of colorectal cancer (CRC); however, the causal relationship remains unclear.

METHODS

Summary-level data for CRC were obtained from the UK Biobank (5,657 cases and 372,016 controls), FinnGen cohort (3,022 cases and 215,770 controls), and BioBank Japan Project (BBJ, 7,062 cases and 195,745 controls). Thirty-two peripheral markers with consistent definitions were collected from the three biobanks. Mendelian randomization (MR) was used to evaluate the causal effect of circulating factors on CRC. The effects from the three consortiums were combined using trans-ancestry meta-analysis methods.

RESULTS

Our analysis provided compelling evidence for the causal association of higher genetically predicted eosinophil cell count (EOS, odds ratio [OR], 0.8639; 95% confidence interval [CI] 0.7922-0.9421) and red cell distribution width (RDW, OR, 0.9981; 95% CI, 0.9972-0.9989) levels with a decreased risk of CRC. Additionally, we found suggestive evidence indicating that higher levels of total cholesterol (TC, OR, 1.0022; 95% CI, 1.0002-1.0042) may increase the risk of CRC. Conversely, higher levels of platelet count (PLT, OR, 0.9984; 95% CI, 0.9972-0.9996), total protein (TP, OR, 0.9445; 95% CI, 0.9037-0.9872), and C-reactive protein (CRP, OR, 0.9991; 95% CI, 0.9983-0.9999) may confer a protective effect against CRC. Moreover, we identified six ancestry-specific causal factors, indicating the necessity of considering patients' ancestry backgrounds before formulating prevention strategies.

CONCLUSIONS

MR findings support the independent causal roles of circulating factors in CRC, which might provide a deeper insight into early detection of CRC and supply potential preventative strategies.

Relationships of omega-3 and omega-6 polyunsaturated fatty acids with esophageal diseases: a two-sample Mendelian randomization analysis

Introduction

Omega-3 polyunsaturated fatty acids (PUFAs) have been widely studied and used as nutritional supplements because of their anti-inflammatory effects. Previous studies have shown an association between polyunsaturated fatty acids such as omega-3 and omega-6 PUFAs with the development of malignant tumors. However, the relationships of omega-3 and omega-6 PUFAs with esophageal diseases have not been characterized.

Methods

Mendelian randomization (MR) is a statistical method for identifying instrumental variables (IVs) from genome-wide association study (GWAS) data, and is associated with little confounding by environmental or other disease-related factors. We used genome-wide association study (GWAS) data from previously published studies on circulating concentrations of omega-3, omega-6, docosahexaenoic acid (DHA) and linoleic acid (LA), as well as esophageal cancer and other esophageal diseases, which were downloaded from the IEU OpenGwas database (https://gwas.mrcieu.ac.uk/) and the GWAS Catalog database (https://www.ebi.ac.uk/). The inverse variance-weighted approach was used as the principal analysis, and the MR-Egger and weighted median methods were used alongside. A series of sensitivity analyses were used to ensure the robustness of the causality estimates.

Results

We found that the circulating omega-3 PUFAs concentration was positively associated with esophageal cancer (p = 8 × 10-4), and circulating DHA concentration (the main component of omega-3 in food), was also positively associated with esophageal cancer (p = 2 × 10-2), but no significant association was found between circulating omega-6 PUFAs and esophageal cancer (p = 0.17), and circulating LA concentration (the main component of omega-6 in food), was also no significant associated with esophageal cancer (p = 0.32). We found no significant relationships of circulating omega-3 and omega-6 PUFAs concentration with four other esophageal diseases.

Conclusion

This study indicates that higher levels of circulating omega-3 PUFAs and DHA concentrations may be a risk factor for the development of esophageal cancer. Conversely, an increased omega-6/omega-3 ratio may serve as a protective factor against esophageal cancer. These findings have significant implications for the clinical application of omega-3 PUFAs and the prevention and treatment of esophageal cancer.

Causal effects of genetic birth weight and gestational age on adult esophageal diseases: Mendelian randomization study

BACKGROUND

Few studies have investigated the association between gestational age, birth weight, and esophageal cancer risk; however, causality remains debated. We aimed to establish causal links between genetic gestational age and birth weight traits and gastroesophageal reflux disease (GERD), Barrett's esophagus (BE), and esophageal adenocarcinoma (EA). Additionally, we explored if known risk factors mediate these links.

AIM

To analyze of the relationship between gestational age, birth weight and GERD, BE, and EA.

METHODS

Genetic data on gestational age and birth weight (n = 84689 and 143677) from the Early Growth Genetics Consortium and outcomes for GERD (n = 467253), BE (n = 56429), and EA (n = 21271) from genome-wide association study served as instrumental variables. Mendelian randomization (MR) and mediation analyses were conducted using MR-Egger, weighted median, and inverse variance weighted methods. Robustness was ensured through heterogeneity, pleiotropy tests, and sensitivity analyses.

RESULTS

Birth weight was negatively correlated with GERD and BE risk [odds ratio (OR) = 0.78; 95% confidence interval (CI): 0.69-0.8] and (OR = 0.75; 95%CI: 0.60-0.9), respectively, with no significant association with EA. No causal link was found between gestational age and outcomes. Birth weight was positively correlated with five risk factors: Educational attainment (OR = 1.15; 95%CI: 1.01-1.31), body mass index (OR = 1.06; 95%CI: 1.02-1.1), height (OR = 1.12; 95%CI: 1.06-1.19), weight (OR = 1.13; 95%CI: 1.10-1.1), and alcoholic drinks per week (OR = 1.03; 95%CI: 1.00-1.06). Mediation analysis showed educational attainment and height mediated the birth weight-BE link by 13.99% and 5.46%.

CONCLUSION

Our study supports the protective role of genetically predicted birth weight against GERD, BE, and EA, independent of gestational age and partially mediated by educational attainment and height.

Causal association between telomere length and female reproductive endocrine diseases: a univariable and multivariable Mendelian randomization analysis

BACKGROUND

The relationship between leukocyte telomere length (LTL) and female reproductive endocrine diseases has gained significant attention and research interest in recent years. However, there is still limited understanding of the exact impacts of LTL on these diseases. Therefore, the primary objective of this study was to investigate the genetic causal association between LTL and female reproductive endocrine diseases by employing Mendelian randomization (MR) analysis.

METHODS

Instruments for assessing genetic variation associated with exposure and outcome were derived from summary data of published genome-wide association studies (GWAS). Inverse-variance weighted (IVW) was utilized as the main analysis method to investigate the causal relationship between LTL and female reproductive endocrine diseases. The exposure data were obtained from the UK Biobanks GWAS dataset, comprising 472,174 participants of European ancestry. The outcome data were acquired from the FinnGen consortium, including abnormal uterine bleeding (menorrhagia and oligomenorrhea), endometriosis (ovarian endometrioma and adenomyosis), infertility, polycystic ovary syndrome (PCOS), premature ovarian insufficiency (POI) and premenstrual syndrome (PMS). Furthermore, to account for potential confounding factors such as smoking, alcohol consumption, insomnia, body mass index (BMI) and a history of pelvic inflammatory disease (PID), multivariable MR (MVMR) analysis was also conducted. Lastly, a series of pleiotropy tests and sensitivity analyses were performed to ensure the reliability and robustness of our findings. P < 0.0063 was considered to indicate statistically significant causality following Bonferroni correction.

RESULTS

Our univariable MR analysis demonstrated that longer LTL was causally associated with an increased risk of menorrhagia (IVW: odds ratio [OR]: 1.1803; 95% confidence interval [CI]: 1.0880-1.2804; P = 0.0001) and ovarian endometrioma (IVW: OR: 1.2946; 95%CI: 1.0970-1.5278; P = 0.0022) at the Bonferroni significance level. However, no significant correlation was observed between LTL and oligomenorrhea (IVW: OR: 1.0124; 95%CI: 0.7350-1.3946; P = 0.9398), adenomyosis (IVW: OR: 1.1978; 95%CI: 0.9983-1.4372; P = 0.0522), infertility (IVW: OR: 1.0735; 95%CI: 0.9671-1.1915; P = 0.1828), PCOS (IVW: OR: 1.0633; 95%CI: 0.7919-1.4278; P = 0.6829), POI (IVW: OR: 0.8971; 95%CI: 0.5644-1.4257; P = 0.6459) or PMS (IVW: OR: 0.7749; 95%CI: 0.4137-1.4513; P = 0.4256). Reverse MR analysis indicated that female reproductive endocrine diseases have no causal effect on LTL. MVMR analysis suggested that the causal effect of LTL on menorrhagia and ovarian endometrioma remained significant after accounting for smoking, alcohol consumption, insomnia, BMI and a history of PID. Pleiotropic and sensitivity analyses also showed robustness of our results.

CONCLUSION

The results of our bidirectional two-sample MR analysis revealed that genetically predicted longer LTL significantly increased the risk of menorrhagia and ovarian endometrioma, which is consistent with the findings from MVMR studies. However, we did not notice any significant effects of LTL on oligomenorrhea, adenomyosis, infertility, PCOS, POI or PMS. Additionally, reproductive endocrine disorders were found to have no impact on LTL. To enhance our understanding of the effect and underlying mechanism of LTL on female reproductive endocrine diseases, further large-scale studies are warranted in the future.

Asthma and risk of adverse pregnancy outcomes: A Mendelian randomization study

Background

Multiple empirical investigations have indicated a connection between asthma and adverse pregnancy outcomes (APOs). Nevertheless, the effects of asthma on APOs remain uncertain.

Methods

We performed bi-directional Univariable Mendelian randomization (UVMR) analyses using combined information obtained from genome-wide association studies (GWAS) data that is publicly accessible. The principal approach used to analyze the causal association between asthma or age when diagnosed and APOs was the inverse variance weighted (IVW) method. The two types of data regarding exposure originate from the IEU Open GWAS project, which includes 56,167 and 47,222 European asthma patients, respectively. The data of four APOs were acquired via the GWAS dataset of the FinnGen collaboration. In addition, we implemented multivariable Mendelian randomization (MVMR), controlling for confounding factors such as smoking status, frequent drinking, body mass index (BMI), and live birth quantity. Furthermore, we executed several meticulous sensitivity studies to ascertain the reliability of our MR results.

Results

Following the implementation of the Bonferroni adjustment, the UVMR assessment revealed that in the IVW model, asthma was significantly linked to an elevated risk of spontaneous abortion (SA) (odds ratio [OR]: 1.115; 95 % confidence interval [CI]: 1.031-1.206; P = 0.006) and gestational diabetes mellitus (GDM) (OR: 1.125; 95 % CI: 1.037-1.220; P = 0.005). However, there was no causal correlation between asthma and preterm birth (PTB) (OR: 0.979; 95 % CI: 0.897-1.068; P = 0.629) or preeclampsia (PE) (OR: 1.059; 95 % CI: 0.951-1.179; P = 0.297). After adjusting for confounding factors, including smoking status, frequent drinking, BMI, and live birth quantity, the MVMR analysis shows a statistically significant causal relationship between asthma and SA or GDM. Furthermore, our investigation's findings did not reveal a substantial correlation between the age of asthma onset based on genetics and the likelihood of SA or GDM. The inverse MR outcomes indicate a lack of causal connection linking APOs to the incidence of asthma. The validity of these findings were verified by sensitivity analyses.

Conclusions

The evidence provided by this study proves that genetically determined asthma is linked to a higher likelihood of SA and GDM. Further research is required to examine potential pathways. However, no conclusive evidence has been found to support the increased risk of SA and GDM in early asthma diagnosis or the interaction between asthma and PTB or PE, indicating that confounding factors may affect the results of previous observational studies.

Advances in Diet and Physical Activity in Breast Cancer Prevention and Treatment

There is currently a growing interest in diets and physical activity patterns that may be beneficial in preventing and treating breast cancer (BC). Mounting evidence indicates that indeed, the so-called Mediterranean diet (MedDiet) and regular physical activity likely both help reduce the risk of developing BC. For those who have already received a BC diagnosis, these interventions may decrease the risk of tumor recurrence after treatment and improve quality of life. Studies also show the potential of other dietary interventions, including fasting or modified fasting, calorie restriction, ketogenic diets, and vegan or plant-based diets, to enhance the efficacy of BC therapies. In this review article, we discuss the biological rationale for utilizing these dietary interventions and physical activity in BC prevention and treatment. We highlight published and ongoing clinical studies that have applied these lifestyle interventions to BC patients. This review offers valuable insights into the potential application of these dietary interventions and physical activity as complimentary therapies in BC management.

Causal relationships between psychological disorders and functional gastrointestinal disorders: a bidirectional two-sample Mendelian randomization study

BACKGROUND AND AIMS

Observational studies have shown bidirectional associations between psychological disorders (e.g. depression and anxiety) and functional gastrointestinal disorders. However, whether the relationships are causal is uncertain. Here, we used a bidirectional two-sample Mendelian randomization method to investigate the association between psychological disorders and functional gastrointestinal disorders (FGIDs).

METHODS

We obtained genome-wide association study summary statistics for two common psychological disorders: depression (170 756 cases) and anxiety (31 977 cases), as well as for three common FGIDs: functional dyspepsia with 6666 cases, constipation with 26 919 cases, and irritable bowel syndrome (IBS) with 7053 cases. These summary statistics were retrieved from several publicly available genome-wide association study databases. The inverse variance weighted method was used as the main Mendelian randomization method.

RESULTS

Inverse variance weighted Mendelian randomization analyses showed statistically significant associations between genetically predicted depression and risk of functional dyspepsia [odds ratio (OR): 1.40, 95% confidence interval (CI): 1.08-1.82], constipation (OR: 1.28, 95% CI: 1.13-1.44), and IBS (OR: 1.51, 95% CI: 1.37-1.67). Genetically predicted anxiety was associated with a higher risk of IBS (OR: 1.13, 95% CI: 1.10-1.17) instead of functional dyspepsia and constipation. In addition, genetically predicted IBS instead of functional dyspepsia and constipation was associated with a higher risk of depression (OR: 1.33, 95% CI: 1.12-1.57) and anxiety (OR: 2.05, 95% CI: 1.05-4.03).

CONCLUSION

Depression is a causal risk factor for three common FGIDs. A bidirectional causal relationship between IBS and anxiety or depression was also identified.

Relationship between Sjogren's syndrome and gastroesophageal reflux: A bidirectional Mendelian randomization study

The clinical incidence of sjogren's syndrome combined with gastroesophageal reflux disease is high. Existing observational studies have shown inconsistent results in the association between gastroesophageal reflux disease (GERD) and Sjogren's syndrome (SS).We observed that the symptoms of SS patients also improved after receiving GERD-related treatment. Therefore, we aimed to investigate the relationship between GERD and SS through a bidirectional two-sample Mendelian randomization (MR) study. Independent SNPs associated with GERD and SS were selected from a genome-wide association study (GWAS) as instrumental variables to conduct a bidirectional two-sample Mendelian analysis of GERD and SS. Genetic data were obtained from two databases for the following two outcomes: Gastroesophageal reflux (IEU Open GWAS) [sample size = 602,604 (patients = 129,080; nonpatients = 473,524)] and SS (FinnGen) [sample size = 392,423 (patients = 2,495; nonpatients = 389,928)]. Statistical methods for the MR analysis included the inverse-variance weighting method, weighted median, simple mode and weighted mode, as well as heterogeneity and sensitivity analyses using the Cochran Q statistic, MR‒Egger regression, outlier detection methods (MR-PRESSO). In addition, Steiger Test was conducted to test the direction of causality. MR analysis showed a positive correlation between GERD and SS risk [odds ratio (OR) = 1.3279 (95% confidence interval 1.0312-1.7099, P = 0.0280)]. However, in contrast, no significant causal effect of SS on GERD was observed [OR = 1.0024 (95% CI 0.9651-1.0412; P = 0.8995)]. This bidirectional two-sample Mendelian randomization study confirmed a causal relationship between SS and GERD, and suggested that GERD is a risk factor for SS, while SS does not affect GERD.

Association of lipid-lowering drugs with risk of sarcopenia: a drug target mendelian randomization study and meta-analysis

BACKGROUND

Lipid-lowering drugs are widely used among the elderly, with some studies suggesting links to muscle-related symptoms. However, the causality remains uncertain.

METHODS

Using the Mendelian randomization (MR) approach, we assessed the causal effects of genetically proxied reduced low-density lipoprotein cholesterol (LDL-C) through inhibitions of hydroxy-methyl-glutaryl-CoA reductase (HMGCR), proprotein convertase subtilisin/kexin type 9 (PCSK9), and Niemann-Pick C1-like 1 (NPC1L1) on sarcopenia-related traits, including low hand grip strength, appendicular lean mass, and usual walking pace. A meta-analysis was conducted to combine the causal estimates from different consortiums.

RESULTS

Using LDL-C pooled data predominantly from UK Biobank, genetically proxied inhibition of HMGCR was associated with higher appendicular lean mass (beta = 0.087, P = 7.56 × 10- 5) and slower walking pace (OR = 0.918, P = 6.06 × 10- 9). In contrast, inhibition of PCSK9 may reduce appendicular lean mass (beta = -0.050, P = 1.40 × 10- 3), while inhibition of NPC1L1 showed no causal impact on sarcopenia-related traits. These results were validated using LDL-C data from Global Lipids Genetics Consortium, indicating that HMGCR inhibition may increase appendicular lean mass (beta = 0.066, P = 2.17 × 10- 3) and decelerate walking pace (OR = 0.932, P = 1.43 × 10- 6), whereas PCSK9 inhibition could decrease appendicular lean mass (beta = -0.048, P = 1.69 × 10- 6). Meta-analysis further supported the robustness of these causal associations.

CONCLUSIONS

Genetically proxied HMGCR inhibition may increase muscle mass but compromise muscle function, PCSK9 inhibition could result in reduced muscle mass, while NPC1L1 inhibition is not associated with sarcopenia-related traits and this class of drugs may serve as viable alternatives to sarcopenia individuals or those at an elevated risk.

Mendelian randomization of circulating proteome identifies IFN-γ as a druggable target in aplastic anemia

BACKGROUND

Aplastic anemia (AA) is a kind of bone marrow failure (BMF) characterized by pancytopenia with hypoplasia/aplasia of bone marrow. Immunosuppressive therapy and bone marrow transplantation are effective methods to treat severe aplastic anemia. However, the efficacy is limited by complications and the availability of suitable donors. This study aimed to determine whether any circulating druggable protein levels may have causal effects on AA and provide potential novel drug targets for AA.

METHODS

Genetic variants strongly associated with circulating druggable protein levels to perform Mendelian randomization (MR) analyses were used. The effect of these druggable protein levels on AA risk was measured using the summary statistics from a large-scale proteomic genome-wide association study (GWAS) and FinnGen database ( https://www.finngen.fi/en/access_results ). Multivariable MR analyses were performed to statistically adjust for potential confounders, including platelet counts, reticulocyte counts, neutrophil counts, and proportions of hematopoietic stem cells.

RESULTS

The data showed that higher level of circulating IFN-γ levels was causally associated with AA susceptibility. The causal effects of circulating IFN-γ levels on the AA were broadly consistent, when adjusted for platelet counts, reticulocyte counts, neutrophil counts and proportions of hematopoietic stem cells.

CONCLUSIONS

High levels of circulating IFN-γ levels might increase the risk of AA and might provide a potential novel target for AA.

Association of Ideal Cardiovascular Health in Youth with Cancer Risk in Adulthood: A Cardiovascular Risk in Young Finns Study

BACKGROUND

Lifestyle factors may affect cancer risk. This study aimed to identify whether the American Heart Association ideal cardiovascular health (ICH) score and its individual variables in youth are associated with subsequent cancer incidence.

METHODS

This study comprised participants of the Cardiovascular Risk in Young Finns Study free of cancer at the analysis baseline in 1986 (n = 1,873). The baseline age was 12 to 24 years, and the follow-up occurred between 1986 and 2018.

RESULTS

Among 1,873 participants (mean age 17.3 ± 4.1 years; 53.4% females at baseline), 72 incident cancer cases occurred during the follow-up (mean follow-up time 31.4 ± 3.4 years). Baseline ICH score was not associated with future cancer risk (HR, 0.96; 95% confidence interval, 0.78-1.12 per 1-point increment). Of individual ICH score variables, ideal physical activity (PA) was inversely associated with cancer incidence [age- and sex-adjusted HR, 0.45 (0.23-0.88) per 1-category change (nonideal/ideal)] and remained significant in the multivariable-adjusted model, including body mass index, smoking, diet, and socioeconomic status. A continuous PA index at ages 9 to 24 years and moderate-to-vigorous PA in youth were also related to decreased cancer incidence (P < 0.05). Body mass index, smoking, diet, total cholesterol, glucose, and blood pressure were not related to cancer risk. Of the dietary components, meat consumption was associated with cancer incidence (P = 0.023).

CONCLUSIONS

These findings indicate that higher PA levels in youth are associated with a reduced subsequent cancer incidence, whereas the American Heart Association's ICH score in youth does not.

IMPACT

This finding supports efforts to promote a healthy lifestyle and encourages PA during childhood, yielding a subsequent healthier life.

Recreational physical activity and breast cancer risk by menopausal status and tumor hormone receptor status: results from the Nurses' Health Studies

PURPOSE

Physical activity is associated with lower breast cancer risk, especially in postmenopausal women. Associations in premenopausal women are less well established.

METHODS

We evaluated recreational physical activity and breast cancer risk in the Nurses' Health Study (NHS) and NHSII (187,278 women; n = 12,785 breast cancers; follow-up: NHS = 1986-2016, NHSII = 1989-2017) by menopausal status and estrogen (ER) and progesterone (PR) receptor status. Physical activity was evaluated as updated cumulative average of metabolic equivalent of task (MET)-h/week. Cox proportional hazards models were used to estimate multivariable hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

Recreational physical activity was inversely associated with breast cancer risk in pre- and postmenopausal women. Higher activity levels were associated with lower risk of ER+/PR + breast cancer in both pre- and postmenopausal women (e.g., total recreational activity, ≥ 27 vs < 3 MET-h/week, premenopausal HR = 0.83, 95%CI = (0.70-0.99), postmenopausal HR = 0.86 (0.78-0.95); pheterogeneity = 0.97). Results were attenuated with adjustment for current body mass index (BMI) among postmenopausal, but not premenopausal, women (e.g., ≥ 27 vs < 3 MET-h/week, premenopausal HR = 0.83 (0.69-0.98); postmenopausal HR = 0.95 (0.85-1.05); pheterogeneity = 0.99). In analyses of moderate-vigorous activity and breast cancer risk, no heterogeneity by menopausal status was observed (phet ≥ 0.53; e.g., ≥ 27 vs < 3 MET-h/week, ER+/PR+, premenopausal HR = 0.88 (0.69-1.11); postmenopausal HR = 0.71 (0.58-0.88). No associations were observed for ER-/PR- disease.

CONCLUSIONS

Recreational physical activity was associated with lower breast cancer risk in both pre- and postmenopausal women, supporting recreational physical activity as an accessible, modifiable exposure associated with reduced breast cancer risk regardless of menopausal status.

Associations between type 1 diabetes and autoimmune skin diseases: Mendelian randomization analysis

Background

Type 1 diabetes mellitus (T1DM) may be associated with various autoimmune diseases, but the causal relationship between T1DM and autoimmune skin diseases is not yet clear.

Methods

The summary statistical data on T1DM and nine autoimmune skin diseases in European populations were extracted for mendelian randomization (MR) analysis. Subsequently, the analysis was replicated in East Asian populations. In the MR estimation, inverse variance-weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode methods were utilized. Outliers were excluded using MR-PRESSO, and horizontal pleiotropy was assessed with MR-Egger. Additionally, a multivariable MR analysis was conducted to investigate whether T1DM has an independent effect on autoimmune skin diseases after adjusting for potential confounders.

Results

In Europe, the MR estimated based on IVW method indicated a causal association between genetically determined T1DM and systemic lupus erythematosus (SLE) (OR = 1.38, 95%CI: 1.26-1.50, p＜0.01), rheumatoid arthritis (RA) (OR = 1.15, 95%CI: 1.05-1.25, p＜0.01), as well as multiple sclerosis (MS) (OR = 1.17, 95%CI: 1.01-1.36, p = 0.04), but there is no association between T1DM and atopic dermatitis (AD), vitiligo, lichen planus (LP), hidradenitis suppurativa (HS), alopecia areata (AA) and systemic sclerosis (SS). After adjusting for time spent watching television, body mass index, type 2 diabetes mellitus, and body fat percentage, we found a causal relationship between T1DM and SLE (OR = 1.29, 95%CI: 1.16-1.44, p < 0.01), RA (OR = 1.28, 95%CI: 1.20-1.38 p < 0.01) and MS (OR = 1.11, 95%CI: 1.04-1.18, p < 0.01). Then, no genetic causal association was found between TIDM and SLE, and AD in East Asia. These results didn't exhibit horizontal pleiotropy, and "leave-one-out" analysis demonstrated result stability.

Conclusion

Our MR research indicates a causal relationship between T1DM and SLE, RA, and MS in Europe. However, no causal relationship between T1DM and SLE has been observed in East Asia. Therefore, it is important to regularly monitor relevant immunological markers of SLE, RA, and MS in T1DM patients and take preventive measures.

Causal associations between psoriasis, eczema, urticaria, and mental illness: A bidirectional Mendelian randomization study of the European population

Observational studies have reported a relationship between multiple common dermatoses and mental illness. To assess the potential bidirectional causality between 3 skin disorders (psoriasis, eczema, and urticaria) and 4 psychiatric disorders (bipolar disorder, schizophrenia, major depressive disorder, and anxiety) in the European population, we used Mendelian randomization (MR) analysis, which provides definitive evidence for causal inference. Eligible single nucleotide polymorphisms were screened for dermatological and psychiatric disorders using a genome-wide association study database. We conducted bidirectional, 2-sample MR analysis using instrumental variables related to psoriasis, eczema, and urticaria as exposure factors, and bipolar disorder, schizophrenia, major depression, and anxiety as outcomes. Reverse MR analysis with bipolar disorder, schizophrenia, major depression, and anxiety as exposure and psoriasis, eczema, and urticaria as outcomes were also performed, and the causality was analyzed using inverse-variance weighting (IVW), MR-Egger, and weighted median methods. To thoroughly assess causality, sensitivity analyses were conducted using the IVW, MR-PRESSO, and MR-Egger methods. The results showed that bipolar disorder increased the incidence of psoriasis (odds ratio = 1.271, 95% confidence interval = 1.003-1.612, P = .047), heterogeneity test with Cochran Q test in the IVW showed P value > .05, (P = .302), the MR-Pleiotropy and MR-PRESSO (outlier methods) in the multiplicity test showed P value > .05, (P = .694; P = .441), and MR-Pleiotropy evidence showed no apparent intercept (intercept = -0.060; SE = 0.139; P = .694). Major depression increased the risk of eczema (odds ratio = 1.002, 95% confidence interval = 1.000-1.004, P = .024), heterogeneity test showed P value > .05, (P = .328), multiplicity detection showed P value > .05, (P = .572; P = .340), and MR-Pleiotropy evidence showed no apparent intercept (intercept = -0.099; SE = 0.162; P = .572). Sensitivity analyses of the above results were reliable, and no heterogeneity or multiplicity was found. This study demonstrated a statistically significant causality between bipolar disorder and psoriasis, major depression, and eczema in a European population, which could provide important information for physicians in the clinical management of common skin conditions.

Exploring causal correlations of inflammatory biomarkers in idiopathic normal-pressure hydrocephalus: insights from bidirectional Mendelian randomization analysis

Background and objective

Neuroinflammatory processes have been identified as playing a crucial role in the pathophysiology of various neurodegenerative diseases, including idiopathic normal-pressure hydrocephalus (iNPH). iNPH, defined as a common disease of cognitive impairment in older adults, poses major challenges for therapeutic interventions owing to the stringent methodological requirements of relevant studies, clinical heterogeneity, unclear etiology, and uncertain diagnostic criteria. This study aims to assess the relationship between circulating inflammatory biomarkers and iNPH risk using bidirectional two-sample Mendelian randomization (MR) combined with meta-analysis.

Methods

In our bidirectional MR study, genetic data from a genome-wide association study (GWAS) involving 1,456 iNPH cases and 409,726 controls of European ancestry were employed. Single-nucleotide polymorphisms (SNPs) associated with exposures served as instrumental variables for estimating the causal relationships between iNPH and 132 types of circulating inflammatory biomarkers from corresponding GWAS data. Causal associations were primarily examined using the inverse variance-weighted method, supplemented by MR-Egger, weighted median, simple mode, and weighted mode analyses. In the results, heterogeneity was assessed using the Cochran Q test. Horizontal pleiotropy was evaluated through the MR-Egger intercept test and the MR pleiotropy residual sum and outliers test. Sensitivity analysis was conducted through leave-one-out analysis. Reverse MR analyses were performed to mitigate bias from reverse causality. Meta-analyses of identical inflammatory biomarkers from both data sources strengthened the findings.

Results

Results indicated a genetically predicted association between Interleukin-16 (IL-16) [OR: 1.228, 95% CI: 1.049-1.439, p = 0.011], TNF-related apoptosis ligand (TRAIL) [OR: 1.111, 95% CI: 1.019-1.210, p = 0.017] and Urokinase-type plasminogen activator (uPA) [OR: 1.303, 95% CI: 1.025-1.658, p = 0.031] and the risk of iNPH. Additionally, changes in human Glial cell line-derived neurotrophic factor (hGDNF) [OR: 1.044, 95% CI: 1.006-1.084, p = 0.023], Matrix metalloproteinase-1 (MMP-1) [OR: 1.058, 95% CI: 1.020, 1.098, p = 0.003] and Interleukin-12p70 (IL-12p70) [OR: 0.897, 95% CI: 0.946-0.997, p = 0.037] levels were identified as possible consequences of iNPH.

Conclusion

Our MR study of inflammatory biomarkers and iNPH, indicated that IL-16, TRAIL, and uPA contribute to iNPH pathogenesis. Furthermore, iNPH may influence the expression of hGDNF, MMP-1, and IL-12p70. Therefore, targeting specific inflammatory biomarkers could be promising strategy for future iNPH treatment and prevention.

Assessment of circulating proteins in thyroid cancer: Proteome-wide Mendelian randomization and colocalization analysis

The causality between circulating proteins and thyroid cancer (TC) remains unclear. We employed five large-scale circulating proteomic genome-wide association studies (GWASs) with up to 100,000 participants and a TC meta-GWAS (nCase = 3,418, nControl = 292,703) to conduct proteome-wide Mendelian randomization (MR) and Bayesian colocalization analysis. Protein and gene expressions were validated in thyroid tissue. Through MR analysis, we identified 26 circulating proteins with a putative causal relationship with TCs, among which NANS protein passed multiple corrections (P BH = 3.28e-5, 0.05/1,525). These proteins were involved in amino acids and organic acid synthesis pathways. Colocalization analysis further identified six proteins associated with TCs (VCAM1, LGMN, NPTX1, PLEKHA7, TNFAIP3, and BMP1). Tissue validation confirmed BMP1, LGMN, and PLEKHA7's differential expression between normal and TC tissues. We found limited evidence for linking circulating proteins and the risk of TCs. Our study highlighted the contribution of proteins, particularly those involved in amino acid metabolism, to TCs.

Psychological distress and uterine fibroids: a bidirectional two-sample mendelian randomization study

BACKGROUND

Observational data indicates a connection between emotional discomfort, such as anxiety and depression, and uterine fibroids (UFs). However, additional investigation is required to establish the causal relationship between them. Hence, we assessed the reciprocal causality between four psychological disorders and UFs utilizing two-sample Mendelian randomization (MR).

METHODS

To evaluate the causal relationship between four types of psychological distress (depressive symptoms, severe depression, anxiety or panic attacks, mood swings) and UFs, bidirectional two-sample MR was employed, utilizing single nucleotide polymorphisms (SNPs) associated with these conditions. Both univariate MR (UVMR) and multivariate MR (MVMR) primarily applied inverse variance weighted (IVW) as the method for estimating potential causal effects. Complementary approaches such as MR Egger, weighted median, simple mode, and weighted mode were utilized to validate the findings. To assess the robustness of our MR results, we conducted sensitivity analyses using Cochran's Q-test and the MR Egger intercept test.

RESULTS

The results of our UVMR analysis suggest that genetic predispositions to depressive symptoms (Odds Ratio [OR] = 1.563, 95% Confidence Interval [CI] = 1.209-2.021, P = 0.001) and major depressive disorder (MDD) (OR = 1.176, 95% CI = 1.044-1.324, P = 0.007) are associated with an increased risk of UFs. Moreover, the IVW model showed a nominally significant positive correlation between mood swings (OR: 1.578; 95% CI: 1.062-2.345; P = 0.024) and UFs risk. However, our analysis did not establish a causal relationship between UFs and the four types of psychological distress. Even after adjusting for confounders like body mass index (BMI), smoking, alcohol consumption, and number of live births in the MVMR, the causal link between MDD and UFs remained significant (OR = 1.217, 95% CI = 1.039-1.425, P = 0.015).

CONCLUSIONS

Our study presents evidence supporting the causal relationship between genetic susceptibility to MDD and the incidence of UFs. These findings highlight the significance of addressing psychological health issues, particularly depression, in both the prevention and treatment of UFs.

The association between fatty acids and atherosclerotic diseases: A mendelian randomization study

BACKGROUND

The current observational studies have disputed the relationship between various fatty acids and atherosclerotic diseases, and the causal relationship between the two is still unclear.

METHODS

In this study, we utilized the available genome-wide association studies (GWAS) summary data on fatty acids and atherosclerotic diseases from the IEU OpenGWAS project. After identifying the appropriate single nucleotide polymorphisms (SNPs) as instrumental variables, we employed the MR-PRESSO outlier test to remove extreme values. Subsequently, we conducted a two-sample mendelian randomization (MR) analysis and performed sensitivity analyses to ensure the reliability of the results.

RESULTS

The results of MR analysis suggest that ratio of saturated fatty acids to total fatty acids is positively correlated with the incidence rate of coronary heart disease (OR = 1.341, 95% CI = 1.016-1.769, P value = 0.038), monounsaturated fatty acid levels is negatively correlated with the incidence of stroke (OR = 0.800, 95% CI = 0.642-0.996, P value = 0.046), and docosahexaenoic acid levels is negatively correlated with the incidence of peripheral artery disease (OR = 0.747, 95% CI = 0.572-0.976, P value = 0.033). All results showed no heterogeneity or pleiotropy, but leave-one-out tests showed that the analysis results of some fatty acids were driven by a single SNP.

CONCLUSIONS

This study highlights the existence of causal relationships between fatty acids and atherosclerotic diseases at the genetic level. These findings provide valuable insights for potential prevention measures and therapeutic targets for the three atherosclerotic diseases.

A causal relationship between particulate matter 2.5 and obesity and its related indicators: a Mendelian randomization study of European ancestry

Background

In recent years, the prevalence of obesity has continued to increase as a global health concern. Numerous epidemiological studies have confirmed the long-term effects of exposure to ambient air pollutant particulate matter 2.5 (PM2.5) on obesity, but their relationship remains ambiguous.

Methods

Utilizing large-scale publicly available genome-wide association studies (GWAS), we conducted univariate and multivariate Mendelian randomization (MR) analyses to assess the causal effect of PM2.5 exposure on obesity and its related indicators. The primary outcome given for both univariate MR (UVMR) and multivariate MR (MVMR) is the estimation utilizing the inverse variance weighted (IVW) method. The weighted median, MR-Egger, and maximum likelihood techniques were employed for UVMR, while the MVMR-Lasso method was applied for MVMR in the supplementary analyses. In addition, we conducted a series of thorough sensitivity studies to determine the accuracy of our MR findings.

Results

The UVMR analysis demonstrated a significant association between PM2.5 exposure and an increased risk of obesity, as indicated by the IVW model (odds ratio [OR]: 6.427; 95% confidence interval [CI]: 1.881-21.968; P FDR = 0.005). Additionally, PM2.5 concentrations were positively associated with fat distribution metrics, including visceral adipose tissue (VAT) (OR: 1.861; 95% CI: 1.244-2.776; P FDR = 0.004), particularly pancreatic fat (OR: 3.499; 95% CI: 2.092-5.855; PFDR =1.28E-05), and abdominal subcutaneous adipose tissue (ASAT) volume (OR: 1.773; 95% CI: 1.106-2.841; P FDR = 0.019). Furthermore, PM2.5 exposure correlated positively with markers of glucose and lipid metabolism, specifically triglycerides (TG) (OR: 19.959; 95% CI: 1.269-3.022; P FDR = 0.004) and glycated hemoglobin (HbA1c) (OR: 2.462; 95% CI: 1.34-4.649; P FDR = 0.007). Finally, a significant negative association was observed between PM2.5 concentrations and levels of the novel obesity-related biomarker fibroblast growth factor 21 (FGF-21) (OR: 0.148; 95% CI: 0.025-0.89; P FDR = 0.037). After adjusting for confounding factors, including external smoke exposure, physical activity, educational attainment (EA), participation in sports clubs or gym leisure activities, and Townsend deprivation index at recruitment (TDI), the MVMR analysis revealed that PM2.5 levels maintained significant associations with pancreatic fat, HbA1c, and FGF-21.

Conclusion

Our MR study demonstrates conclusively that higher PM2.5 concentrations are associated with an increased risk of obesity-related indicators such as pancreatic fat content, HbA1c, and FGF-21. The potential mechanisms require additional investigation.

The relationship between innate/adaptive immunity and gastrointestinal cancer : a multi-omics Mendelian randomization study

BACKGROUND

Innate/adaptive immunity is the key to anti-tumor therapy. However, its causal relationship to Gastrointestinal (GI) cancer remains unclear.

METHODS

Immunity genes were extracted from the MSigDB database. The Genome-wide association studies (GWAS) summary data of GI cancer were integrated with expression quantitative trait loci (eQTL) and DNA methylation quantitative trait loci (mQTL) associated with genes. Summary-data-based Mendelian randomization (SMR) and co-localization analysis were used to reveal causal relationships between genes and GI cancer. Two-sample MR analysis was used for sensitivity analysis. Single cell analysis clarified the enrichment of genes.

RESULTS

Three-step SMR analysis showed that a putative mechanism, cg17294865 CpG site regulating HLA-DRA expression was negatively associated with gastric cancer risk. HLA-DRA was significantly differentially expressed in monocyte/macrophage and myeloid cells in gastric cancer.

CONCLUSION

This study provides evidence that upregulating the expression level of HLA-DRA can reduce the risk of gastric cancer.

Causal Relationships Between Circulating Inflammatory Proteins and Obstructive Sleep Apnea: A Bidirectional Mendelian Randomization Study

Purpose

Clinical studies have demonstrated the intricate association between the onset and progression of obstructive sleep apnea (OSA) and the activation of the inflammatory cascade reaction. This study delves into investigating the causal links between 91 circulating inflammatory proteins (CIPs) and OSA through the application of Mendelian randomization (MR) techniques.

Methods

Utilizing genetic data on OSA sourced from the Finnish Biobank (FinnGen) Genome-wide Association Studies (GWAS) of the European population, alongside summary-level GWAS data of CIPs from 14,824 European participants, we conducted a bidirectional MR study.

Results

This study suggests that several factors may be associated with the risk of OSA. IL-17C (odds ratio (OR) = 1.090, p = 0.0311), CCL25 (OR = 1.079, p = 0.0493), FGF-5 (OR = 1.090, p = 0.0003), CD5 (OR = 1.055, p = 0.0477), and TNFSF14 (OR = 1.092, p = 0.0008) may positively correlate with OSA risk. Conversely, IL-20RA (OR = 0.877, p = 0.0107), CCL19 (OR = 0.933, p = 0.0237), MIP-1 alpha (OR = 0.906, p = 0.0042), Flt3L (OR = 0.941, p = 0.0019), CST5 (OR = 0.957, p = 0.0320), OPG (OR = 0.850, p = 0.0001), and TRAIL (OR = 0.956, p = 0.0063) may reduce the risk of OSA. Additionally, elevated levels of IL-10RA (OR = 1.153, p = 0.0478) were observed as a consequence of OSA. Conversely, OSA may potentially lead to decreased levels of CCL28 (OR = 0.875, p = 0.0317), DNER (OR = 0.874, p = 0.0324), FGF-21 (OR = 0.846, p = 0.0344), and CSF-1 (OR = 0.842, p = 0.0396).

Conclusion

Through this bidirectional MR study, we have identified 12 upstream regulatory proteins and 5 downstream effect proteins that are linked to OSA. These findings hold promise in providing potential therapeutic targets for the inflammatory mechanisms underlying OSA.