Recently, the importance of the third β-propeller domain has been emphasized by the successful generation of two novel mouse models, the Lrp4 Arg1170Gln knock-in mouse and the Lrp4 Arg1170Trp knock-in mouse, both recapitulating the sclerosteosis phenotype observed in human patients [16,17]. Here, LRP4 is linked to sclerosteosis.