SLC34A1 and hereditary hypophosphatemic rickets: Unlike NaPi-IIb, expression of the other two members of the Slc34 family (NaPi-IIa/Slc34a1 and NaPi-IIc/Slc34a3) is rather restricted to kidney23,24, and their mutations in humans associate with several hypophosphatemic syndromes, including infantile hypercalcemia type 2 (HCINF2: OMIM 616963)25,26 and hereditary hypophosphatemic rickets with hypercalciuria (HHRH: OMIM 609826)27–29, respectively.