DMP1 and autosomal recessive hypophosphatemic rickets: Dentin matrix protein 1 (DMP-1) is expressed predominantly in odontoblasts in tooth and osteocytes in bone.(1–3) Deletion of murine Dmp1 causes striking defects in tooth and bone during postnatal development in C57/B6 or CD-1 background mice.(4,5) Recently, we and others have demonstrated that DMP1 mutations result in autosomal recessive hypophosphatemic rickets (ARHR) in humans similar to the phenotype of Dmp1 null mice.