PHEX and X-linked hypophosphatemic rickets: Subsequent quantification of growth plate thickness and osteoid volume confirmed that the skeletal phenotype of Hyp mice was not significantly altered by additional Thbs4-deficiency (Fig 3D), thereby demonstrating that increased Thbs4 expression by Phex-deficient osteoblasts is not involved in the pathogenesis of X-linked hypophosphatemic rickets.