Von Kossa/van Gieson staining (Fig. 2C) revealed characteristics of osteomalacia in Phospho1−/− mice: widespread excessive osteoid (OV/BV = 3.96% in Phospho1−/− mice versus 0.06% in WT mice, p = .0001) and increased width of osteoid at the surfaces of both trabecular and cortical bone. The gene discussed is PHOSPHO1; the disease is osteomalacia.