The presence of nephrocalcinosis or nephrolithiasis in a patient prior to initiation of therapy, suggests diseases associated with hypercalciuria such as HHRH (NaPi 2C defects), Dent disease 1(CLCN5 defect) or hypophosphatemia and nephrocalcinosis (NaPi2a defects). The gene discussed is SLC34A1; the disease is hereditary hypophosphatemic rickets with hypercalciuria.