SLC34A1 and hypercalcemia, infantile, 2: Pathogenic variants in the SLC34A1 gene, which encodes the sodium-phosphate cotransporter NaPi-IIa, lead to a spectrum of renal tubular disorders, including infantile hypercalcemia type 2, nephrolithiasis/osteoporosis-hypophosphatemia type 2, and Fanconi renotubular syndrome type 2.