CYP24A1

CYP24A1 encodes 25-hydroxyvitamin D 24-hydroxylase, a mitochondrial cytochrome P450 enzyme expressed mainly in the kidney and intestine that initiates the breakdown of active vitamin D metabolites (25-hydroxyvitamin D and 1,25-dihydroxyvitamin D) into inactive forms such as calcitroic acid. By controlling how quickly vitamin D is degraded, CYP24A1 activity influences circulating vitamin D levels and downstream intestinal calcium absorption, linking it to variation in normal-range blood calcium status. Loss-of-function variants in CYP24A1 cause impaired vitamin D catabolism and are a known cause of idiopathic infantile hypercalcemia.