The Wnt pathway was found to be involved in bone biology in 2001-2002 with the discovery of a (G171V) mutation in the lipoprotein receptor-related protein 5 (LRP5) that resulted in high bone mass and another mutation that completely inactivated Lrp5 function and resulted in osteoporosis pseudoglioma syndrome (OPPG).
Both disuse stimuli induced significant bone loss in WT mice, but Lrp5 A214V and G171V were partially or fully protected from the bone loss that normally results from disuse.
Like the previously reported mutation (G171V) that causes the high-bone-mass phenotype, all mutations are located in the aminoterminal part of the gene, before the first epidermal growth factor-like domain.