Determination of genetic correlation between tobacco smoking and coronary artery disease

Backgrounds Tobacco smoking is an important risk factor for coronary artery disease (CAD), but the genetic mechanisms linking smoking to CAD remain largely unknown. Methods We analyzed summary data from the genome-wide association study (GWAS) of the UK Biobank for CAD, plasma lipid concentrations ( n = 184,305), and smoking ( n = 337,030) using different biostatistical methods, which included LD score regression and Mendelian randomization (MR). Results We identified SNPs shared by CAD and at least one smoking behavior, the genes where these SNPs are located were found to be significantly enriched in the processes related to lipoprotein metabolic, chylomicron-mediated lipid transport, lipid digestion, mobilization, and transport. The MR analysis revealed a positive correlation between smoking cessation and decreased risk for CAD when smoking cessation was considered as exposure ( p = 0.001), and a negative correlation between the increased risk for CAD and smoking cessation when CAD was considered as exposure ( p = 2.95E-08). This analysis further indicated that genetic liability for smoking cessation increased the risk of CAD. Conclusion These findings inform the concomitant conditions of CAD and smoking and support the idea that genetic liabilities for smoking behaviors are strongly associated with the risk of CAD.