Serum APN levels were similar between groups with stable or unstable CAD (APN 9.20±5.88 vs 9.47±6.23 μg/mL, P=0.738, and HMW APN 5.31±3.72 vs 5.91±4.16 μg/mL, P=0.255), even after stratification by the number of arteries involved (single-vessel vs multivessel disease: APN 9.39±5.76 vs 9.26±6.27 μg/mL, P=0.871; HMW APN 5.29±3.79 vs 5.83±4.04 μg/mL, P=0.306) and DJS score (APN, P=0.718; HMW APN, P=0.276). This evidence concerns the gene ANPEP and coronary artery disorder.