Removal of Xbp1 had a profound effect on the phenotype of EDM5 mice, which is a disease predominantly affecting chondrocytes undergoing proliferation, but in contrast, deletion of Xbp1 had no effect on the severity of MCDS, a disease of the hypertrophic zone of the growth plate [31]. The gene discussed is XBP1; the disease is Schmid metaphyseal chondrodysplasia.