Osteoclast differentiation through the RANK/RANKL/OPG system seems to be a pathwaywith implications in the regulation of bone destruction in PD patients.32 SNPs in theRANK gene have been implicated in different human diseases,including Paget's Disease, rheumatoid arthritis and osteoporosis.33,45,47. This evidence concerns the gene TNFRSF11A and osteoporosis.