Causal association between blood metabolites and abdominal aortic calcification: A bidirectional Mendelian randomization study.

Previous studies have reported correlations between metabolic factors and abdominal aortic calcification (AAC). However, the causal relationship between blood metabolites and AAC remains to be fully explored. We employed bidirectional two-sample Mendelian randomization (MR) to investigate the potential causal relationships between 486 blood metabolites and AAC. The inverse variance weighted method was primarily utilized for MR analysis, and the MR-Egger, weighted median, and Robust Adjusted Profile Score methods were used for supplementary analysis. Sensitivity analyses were conducted using Radial MR, MR-PRESSO, Cochran Q test, MR-Egger intercept, and leave-one-out analysis to evaluate the heterogeneity and pleiotropy. Furthermore, the Steiger test and linkage disequilibrium score regression were used to assess genetic correlation and directionality. Multivariable MR analysis was performed to evaluate the direct effect of metabolites on AAC. Through rigorous screening, we identified 6 metabolites with presumed causal effects on AAC: 4-methyl-2-oxopentanoate (effect size [ES] 0.46, 95% confidence interval [CI]: 0.10-0.82), erythrose (ES -0.35, 95% CI: -0.59 to -0.11), 10-undecenoate (11:1n1) (ES 0.14, 95% CI: 0.03-0.25), 1-myristoylglycerophosphocholine (ES 0.31, 95% CI: 0.11-0.50), glycerol 2-phosphate (ES 0.20, 95% CI: 0.04-0.37), and the unidentified metabolite X-11469 (ES 0.19, 95% CI: 0.08-0.30). Multivariable MR analysis revealed that genetically predicted erythrose, 10-undecenoate, 1-myristoylglycerophosphocholine, and X-11469 could directly affect AAC independent of other metabolites. Reverse MR analysis revealed an alteration in 12 blood metabolites due to AAC, including caffeine, 1,7-dimethylurate, arachidonic acid, and 1-arachidonoylglycerophosphocholine. This study provides evidence supporting a causal relationship between metabolites and AAC. These findings help elucidate the underlying biological mechanisms of AAC and may offer insights into screening, prevention, and treatment approaches.