Objective To explore the causal relationship between breast cancer and rotator cuff injury using bidirectional two-sample Mendelian randomization. Methods Instrumental variables for breast cancer and rotator cuff injury were extracted from published genome-wide association study data. The positive study used breast cancer as the exposure and rotator cuff injury as the outcome, with single nucleotide polymorphisms (SNPs) closely associated with both breast cancer and rotator cuff injury as genetic instrumental variables. The reverse study used rotator cuff injury as the exposure and breast cancer as the outcome, with SNPs closely associated with both breast cancer and rotator cuff injury as genetic instrumental variables. Bidirectional MR analysis was conducted using five models: inverse variance weighted (IVW), simple model, weighted median, weighted model, and MR-Egger to assess the causal relationship between breast cancer and rotator cuff injury. Cochran Q test was used to detect heterogeneity, MR-Egger to detect horizontal pleiotropy, and leave-one-out method for sensitivity analysis to ensure the robustness of the results. Results A total of 51 SNPs closely associated with breast cancer were included in the forward study. The results indicated a positive causal association between breast cancer and an increased risk of rotator cuff injury [IVW: odds ratio=1.08, 95% confidence interval (1.02, 1.12), P=0.014], with no evidence of heterogeneity in the causal relationship between breast cancer and rotator cuff injury (P>0.05). Horizontal pleiotropy test results showed no horizontal pleiotropy in the SNPs (P>0.05). Leave-one-out test results did not detect any SNP with a large impact on the results. In the reverse study, a total of 3 SNPs related to rotator cuff injury were included as instrumental variables. There was no strong evidence that rotator cuff injury had a causal effect on breast cancer incidence [IVW: odds ratio=0.95, 95% confidence interval (0.86, 1.05), P=0.334]. Conclusions There is a potential causal association between breast cancer and rotator cuff injury. Therefore, it is suggested to increase the screening for rotator cuff injury in breast cancer patients.
Objective To explore the causal association between obstructive sleep apnea (OSA) and venous thromboembolism (VTE). Methods Using the summary statistical data from the FinnGen biological sample library and IEU OpenGWAS database, the relationship between OSA and VTE, including deep vein thrombosis (DVT) and pulmonary embolism, was explored through Mendelian randomization (MR) method, with inverse variance weighted (IVW) as the main analysis method. Results The results of univariate MR analysis using IVW method showed that OSA was associated with VTE and pulmonary embolism (P<0.05), with odds ratios and 95% confidence intervals of 1.204 (1.067, 1.351) and 1.352 (1.179, 1.544), respectively. There was no correlation with DVT (P>0.05). Multivariate MR analysis showed that after adjustment for confounding factors (smoking, diabetes, obesity and cancer), OSA was associated with VTE, DVT and pulmonary embolism (P<0.05), with odds ratios and 95% confidence intervals of 1.168 (1.053, 1.322), 1.247 (1.064, 1.491) and 1.158 (1.021, 1.326), respectively. Conclusion OSA increases the risk of VTE, DVT, and pulmonary embolism.
Objective To explore the relationship between the gut microbiome (GM) and psoriasis using a two-sample two-way Mendelian randomization (MR) approach. Methods The forward analysis uses the gut microbiota as the exposure factor, and its genetic data are derived from the genome-wide association study dataset published by the MiBioGen consortium. Psoriasis was used as the outcome variable, and its genetic data were obtained from the UK Biobank. The reverse MR analysis, on the other hand, took psoriasis as the exposure and the specific gut microbiota taxonomic units identified in the forward analysis as the outcome variable. MR analysis was conducted using maximum likelihood, MR Egger regression, weighted median, inverse variance weighting (IVW), and weighted models to study the causal relationship between the gut microbiota and psoriasis. Then, sensitivity analyses including horizontal pleiotropy test, Cochran’s Q test, and leave-one-out analysis were used to evaluate the reliability of the results. Results A total of 51 single nucleotide polymorphisms from 5 fungi were included in the forward study. The forward IVW analysis results showed that, the class Mollicutes [odds ratio (OR)=1.003, 95% confidence interval (CI) (1.001, 1.006), P=0.004], genus Lachnospiraceae FCS020 group [OR=1.003, 95%CI (1.000, 1.006), P=0.041], and phylum Tenericutes [OR=1.003, 95%CI (1.001, 1.006), P=0.004] were causally associated with an increased risk of psoriasis. The family Victivallaceae [OR=0.998, 95%CI (0.997, 1.000), P=0.005] and order Pasteurellales [OR=0.998, 95%CI (0.996, 1.000), P=0.047] were also linked to a decreased risk of psoriasis. The results of the sensitivity analysis were robust. There was no evidence of a reverse causal relationship from psoriasis to the identified bacterial taxa found in the results of reverse MR analysis results. Conclusions The abundance of three species, class Mollicutes, genus Lachnospiraceae and phylum Tenericutes, may increase the risk of psoriasis. The abundance of two species, family Victivallaceae and order Pasteurellales may reduce the risk of psoriasis. These results provide new directions for the prevention and treatment of psoriasis in the future, but further research is needed to explore how the aforementioned microbiome affects the progression of psoriasis.
ObjectiveTo conduct a Mendelian randomization (MR) analysis to elucidate the potential causal relationship between sarcopenia (SA) and knee osteoarthritis (KOA). MethodsThree SA-related traits were selected as exposure factors from the summary data of the genome-wide association studies database (IEU GWAS). KOA and hospital-diagnosed osteoarthritis of the knee (osteoarthritis of the knee hospital diagnosed) were chosen as outcome factors. The inverse variance-weighted (IVW) method was employed as the primary analytical approach to evaluate the causal relationship between SA and KOA. Heterogeneity tests, sensitivity analyses, and pleiotropy analyses were conducted to validate the reliability of the results. ResultsThe MR results indicated a substantial causal relationship between genetically predicted appendicular muscle mass (OR=1.079, 95%CI 1.015 to 1.147, P=0.015 5), walking speed (OR=0.157, 95%CI 0.101 to 0.248, P<0.001). No significant causal relationship was found between grip strength and KOA (OR=1.318, 95%CI 0.933 to 1.859, P=0.116 6), and the sensitivity analysis results did not exhibit horizontal pleiotropy. ConclusionSA may have a causal relationship with KOA, and appendicular muscle mass and walking speed may be risk factors for the occurrence and development of KOA.
Objective To analyze whether there is a causal association between psoriasis and Alzheimer disease (AD) by a two-sample two-way Mendelian randomization (MR) method. Methods In the forward study, the single nucleotide polymorphisms (SNPs) associated with psoriasis were obtained from the comprehensive statistical data of the genome-wide association study database as the instrumental variables, and AD as the outcome; in the reverse study, the SNPs associated with AD were taken as instrumental variables, and psoriasis as the outcome. Using two-sample two-way MR analysis, the odds ratio (OR) value and 95% confidence interval (CI) of regression models, namely inverse variance weighted (IVW) method, MR-Egger regression method, weighted median method, simple pattern method, and weighted pattern method, were used to evaluate the causal relationship between psoriasis and AD. Cochran’s Q test was used to assess the heterogeneity of genetic instrumental variables, MR-Egger intercept method was used to test the horizontal pleiotropy of the assessment, “leave-one-out” method was used to assess the sensitivity of a SNP to the effect of causality, and the symmetry of funnel plot was observed to assess bias. Results A total of 19 SNPs associated with psoriasis were included as instrumental variables in the forward study. The IVW analysis of the forward study showed that there was a causal correlation between psoriasis and AD [OR=1.032, 95%CI (1.014, 1.051), P<0.001], and MR-Egger regression method [OR=1.042, 95%CI (1.012, 1.073), P=0.013], weighted median [OR=1.048, 95%CI (1.023, 1.074), P<0.001], and weighted model [OR=1.046, 95%CI (1.020, 1.073), P=0.002] all supported this result. Heterogeneity test (IVW result: Q=13.752, P=0.745; MR-Egger regression result: Q=13.134, P=0.727), MR-Egger intercept method (Egger intercept=–0.004, P=0.442), the results of “leave-one-out” method and funnel plot showed that the results of MR analysis were reliable. A total of 127 AD-related SNPs were included as instrumental variables in the reverse study. In reverse research, there was no evidence to support the AD could increase the risk of psoriasis (P>0.05). Heterogeneity test (IVW result: Q=232.496, P<0.001; MR-Egger regression result: Q=232.119, P<0.001) suggested heterogeneity, but MR-Egger intercept method (Egger intercept=0.003, P=0.652), the results of “leave-one-out” method and funnel plot showed that the results of MR analysis were reliable. Conclusion There is a causal association between psoriasis and AD, and psoriasis may increase the risk of AD.
ObjectiveA two-sample Mendelian randomization analysis was used to explore the causal associations between four basic body indices (basal metabolic rate, body fat percentage, BMI and hip circumference) and myasthenia gravis (MG). MethodsPooled gene-wide association study (GWAS) data were obtained from large publicly searchable databases, and four basic body indices were selected as the exposure factors and myasthenia gravis as the outcome factors, and single nucleotide polymorphisms (SNPs), which were strongly correlated with the phenotype of the exposure factors, were screened as the instrumental variables, and two-sample Mendelian randomization analyses were performed in order to assess the potential causal relationship between the exposure and the disease. ResultsInverse variance weighting (IVW) analysis showed that increased basal metabolic rate (OR=1.39, 95%CI 1.00 to 1.93, P=0.047), body fat percentage (OR=1.61, 95%CI 1.06 to 2.44, P=0.024), and hip circumference (OR=1.67, 95%CI 1.29 to 2.17, P<0.001) increased the risk of MG. But there was no significant causal relationship between BMI and MG. ConclusionBasal metabolic rate, body fat percentage and hip circumference have a positive causal relationship with MG, while BMI does not have a significant causal relationship with MG.
ObjectiveTo investigate the causal relationship between 731 kinds of immune cell phenotypes and positive-human epidermal growth factor receptor (HER+), negative-human epidermal growth factor receptor (HER–), negative-human epidermal growth factor receptor 2 (HER2–) breast cancer. MethodsGenome-wide association data using immune cell phenotype and breast cancer were used with inverse variance weighting as the primary analytical method; horizontal pleiotropy was tested using MR-PRESSO and outliers were corrected; in addition, the reliability of the obtained data was verified using Cochran’s Q test, Mendelian randomization (MR)- Egger regression and leave-one-out method were used to verify the reliability of the obtained data. ResultsFor HER+ breast cancer, CD3 on CD39+CD4+T cell [ OR=0.940, 95%CI (0.913, 0.968), P=0.019] was protective factor. For HER– breast cancer, no immune cell phenotype was found to be correlated with it. For HER2– breast cancer, CD3 on CD39+CD4+ T cell [OR=0.951, 95%CI (0.930, 0.973), P=0.014], CD3 on secreting CD4 regulatory T cell [OR=0.949, 95%CI (0.925, 0.974), P=0.023] were protective factors. ConclusionThere is a causal association between certain immune cell phenotypes and breast cancer, which may be predictive markers for early diagnosis of breast cancer and development of new immunotherapies.
ObjectiveExploring the potential causal effects and directions of insulin resistance (IR) and chronic airway inflammatory diseases, including asthma and chronic obstructive pulmonary disease (COPD), through two sample Mendelian randomization (MR). MethodsA total of 53 validated single nucleotide polymorphisms (SNPs) associated with IR were selected as instrumental variables. The inverse variance-weighted (IVW) method was used to model the causal association, and sensitivity analyses through leave-one-out analysis and pleiotropy testing were conducted to assess the relationship between IR and asthma and COPD. ResultsMR analysis revealed no significant causal effect of IR on asthma (IVW: OR=1.067, 95%CI 0.871 to 1.306, P=0.531) or COPD (IVW: OR=0.906, 95%CI 0.686 to 1.196, P=0.557). The results were consistent across sensitivity analyses and multiple pleiotropy tests, with no evidence of horizontal pleiotropy detected. ConclusionNo causal association was found between IR and the development of asthma or COPD. The relationship between these conditions may be influenced indirectly through complex interactions between metabolic and inflammatory pathways affecting disease progression.
Objective To investigate the potential causal relationship between specific oral microbiota and peptic ulcer disease (PUD) using a Mendelian randomization (MR) approach. Methods The genome-wide association study (GWAS) data from East Asian populations was utilized to perform a two-sample MR analysis to determine the causal relationship between oral microbiota and PUD. The MR analysis was primarily conducted using the inverse-variance weighted (IVW) method, supplemented by MR-Egger and weighted median methods. Heterogeneity and pleiotropy were assessed, and the leave-one-out method was employed to evaluate the stability of the MR results. Results There was a complex association between specific bacterial genera of the oral microbiota and PUD. Prevotella was found to potentially promote duodenal ulcers while exerting a protective effect against gastric ulcers. Campylobacter and Streptococcus demonstrated differing effects on gastric and duodenal ulcers. Furthermore, Fusobacterium and Haemophilus_A were positively associated with peptic ulcers, suggesting an increased risk of gastroduodenal ulcer development. Conclusion This study explores the causal relationship between oral microbiota and PUD, providing new insights into the prevention and treatment of PUD mediated by oral microbiota.
Objective To compare the balance of simple randomization, stratified blocked randomization and minimization. Methods Monte Carlo technique was employed to simulate the treatment allocation of simple randomization, stratified blocked randomization and minimization respectively, then the balance of treatment allocation in each group and the balance for every prognostic factor were compared. Results The simulation demonstrated that minimization provides the best performance to ensure balance in the number of patients between groups and prognostic factors. Balance in prognostic factors achieved with stratified blocked randomization was similar to that achieved with simple randomization. Conclusion Minimization offers the best balance in the number of patients and prognostic factors between groups.