Extracellular bone matrix phosphoprotein osteopontin (OPN) has been recently implicated in disease models of hypophosphatemia (Barros et al., 2013; Liu et al., 2006; Boukpessi et al., 2017), hyperphosphatemia (Yuan et al., 2014), and/or hypophosphatasia (Harmey et al., 2006; Narisawa et al., 2013; Yadav et al., 2014). Here, SPP1 is linked to hypophosphatasia.