CYP24A1 and hypercalcemia disease: In humans, inactivating mutations in CYP24A1 is now recognized as a major cause of idiopathic infantile hypercalcemia (IIH), a syndrome marked by severe hypercalcemia, hypercalciuria, and nephrocalcinosis, decreased PTH, low 24,25(OH)2D, and inappropriately normal to high 1,25(OH)2D [51].