CYP24A1

CYP24A1 is an enzyme that in humans is encoded by the CYP24A1 gene. This enzyme plays a crucial role in the metabolism of vitamin D, by initiating the degradation of 1,25-dihydroxyvitamin D3 (the active form of vitamin D), thus regulating vitamin D levels in the body. The CYP24A1 gene is located on chromosome 20 (20q13.2) in humans.

The enzyme encoded by CYP24A1 is part of the cytochrome P450 family, a group of enzymes that are involved in the oxidation of organic substances. Specifically, CYP24A1 is involved in the hydroxylation and oxidation of the active vitamin D metabolites, converting them into less active forms. This process is essential for maintaining the balance of vitamin D in the body, which is crucial for various bodily functions including calcium absorption and bone health.

Mutations in the CYP24A1 gene have been associated with several medical conditions. For instance, loss-of-function mutations can lead to hypercalcemia (elevated calcium levels in the blood) and hypercalciuria (elevated calcium levels in the urine), conditions that are often grouped under the term "idiopathic infantile hypercalcemia". This is due to the reduced breakdown of 1,25-dihydroxyvitamin D3, leading to increased vitamin D activity and calcium absorption.

Conversely, gain-of-function mutations in CYP24A1 can lead to reduced vitamin D levels, potentially contributing to conditions such as osteomalacia (softening of the bones) in adults and rickets in children, due to impaired bone mineralization.

The regulation of CYP24A1 expression is complex and involves various factors including parathyroid hormone, calcium, and phosphorus levels in the body, as well as the presence of 1,25-dihydroxyvitamin D3 itself. Understanding the regulation and function of CYP24A1 is important for developing treatments for conditions related to vitamin D metabolism and calcium homeostasis.

Research into CYP24A1 and its role in vitamin D metabolism has also implications beyond bone health, including potential roles in the immune system, cancer prevention, and the regulation of cell growth and differentiation.