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Introduction: Major depression disorder (MDD) has been associated with increased breast cancer risk in epidemiological studies; however, it is still unknown whether this association is causal or not. The aim of this study is to determine the causal relationship between MDD and breast cancer risk. Methods: Two‐sample Mendelian randomization (MR) analyses with 92 single‐nucleotide polymorphisms (SNPs) significantly associated with MDD as instrumental variables (IVs) were performed. Effects of these SNPs on breast cancer in women were estimated in the Breast Cancer Association Consortium (122,977 cases and 105,974 controls) using inverse variance weighted (IVW), weighted median and multivariable MR models. Heterogeneity and pleiotropy effects were assessed based on IVW and MR‐Egger regression model, respectively. Results: An 8.7% increased risk of overall breast cancer [odds ratio (OR) = 1.087; 95% confidence interval (CI) 1.011–1.170; P = 0.025] per log‐odds ratio increment of MDD risk based on the IVW model was noticed. Similar results were obtained with the multivariable MR model (OR = 1.118, 95% CI = 1.010–1.237; P = 0.031). An increment but not statistically significant causality association was noticed between MDD and risk of ER+ (OR = 1.098, 95% CI = 0.984–1.227; P = 0.093) or ER‐ (OR = 1.129, 95% CI = 0.982–1.297; P = 0.089) breast cancer under multivariable MR model. No significant pleiotropy effects were observed for the IVs in the two‐sample MR studies. Conclusions: The results suggested that a genetic predisposition of MDD is causally associated with overall breast cancer risk; however, the underlying biological mechanisms are worthy of further study. [ABSTRACT FROM AUTHOR]

Introduction and Aims. Bile acids play an essential role in the progression of nonalcoholic fatty liver disease (NAFLD). This study was aimed at investigating the association of the serum glycocholic acid- (GCA-) to-total bile acid (TBA) ratio with NAFLD in the general population. Materials and Methods. A total of 6708 subjects (2859 cases with NAFLD and 3849 controls) were enrolled in the development cohort and additional 1568 subjects (784 cases with NAFLD and 784 controls) in an independent validation cohort. Demographic characteristics and biochemical data were compared between subjects with NAFLD and controls. Multivariate logistic regression analysis was performed to determine the association of the GCA-to-TBA ratio with NAFLD. A novel model incorporating the GCA-to-TBA ratio was developed for screening NAFLD from the general population. Results. The serum TBA and GCA levels were significantly higher in subjects with NAFLD than in those without NAFLD (2.8 (2.0-4.2) μmol/L vs. 2.5 (1.8-3.7) μmol/L and 1.30 (1.10-1.53) μg/mL vs. 1.28 (1.08-1.50) μg/mL, respectively, all p ≤ 0.01), whereas the serum GCA-to-TBA ratio was significantly lower in subjects with NAFLD than in subjects without NAFLD (0.44 (0.33-0.60) vs. 0.48 (0.36-0.64), p ≤ 0.01). Logistic regression analysis showed that the GCA-to-TBA ratio was independently associated with NAFLD after adjustment for confounding factors (odds ratio: 0.81, 95% confidence interval (CI): 0.71-0.92, p ≤ 0.01). The area under the receiver operating characteristic curve of the novel developed GCA-to-TBA ratio score model in discriminating NAFLD was 0.84 (95% CI: 0.83-0.85) in the development cohort and was 0.91 (95% CI: 0.36-0.65) in the validation cohort. Conclusion. The serum GCA-to-TBA ratio is independently associated with NAFLD. A simple novel model incorporating the GCA-to-TBA ratio score has a good performance in discriminating NAFLD from the general population. [ABSTRACT FROM AUTHOR]