Increased RANKL/OPG ratio (or decreased OPG/RANKL ratio) is also related to local osteoclastogenic activity and bone resorption in several pathologies such as periodontitis [14], rheumatoid arthritis [32], multiple myeloma [33], osteoporosis [34] and COPD [35, 36]. The gene discussed is TNFSF11; the disease is periodontitis.