Osteoprotegerin (OPG) protects the skeleton from excessive bone resorption by binding to receptor activator of nuclear factor-κB ligand (RANKL) and preventing it from binding to its receptor, receptor activator of nuclear factor-κB. However, conflicting results have been obtained about association of serum level of OPG or RANKL with coronary artery disease (CAD). This evidence concerns the gene TNFRSF11B and coronary artery disorder.