The importance of the Wnt pathway in bone homeostasis is further underlined by the isolation of bone disease-related mutations of Wnt co-receptor LRP5, with loss-of-function mutations in LRP5 associated with low bone mass in osteoporosis-pseudoglioma syndrome whereas gain-of-function was found to be associated with high bone mass [39]–[41]. Here, LRP5 is linked to osteoporosis.