In mammals, the dominant renal apical transporters are type II Na+/Pi cotransporters NaPi-IIa (SLC34A1) and NaPi-IIc (SLC34A3) in proximal tubule brush border, and loss-of-function in either gene causes renal Pi wasting and hypophosphatemic disease in humans (e.g., SLC34A3-related HHRH; SLC34A1-related proximal tubular Pi-leak phenotypes) [322,323,324]. Here, SLC34A3 is linked to hereditary hypophosphatemic rickets with hypercalciuria.