Genetic evidence that the human CYP2R1 enzyme is a key vitamin D 25-hydroxylase.
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Cheng JB, Levine MA, Bell NH, Mangelsdorf DJ, Russell DW
Genetic evidence that the human CYP2R1 enzyme is a key vitamin D 25-hydroxylase.
Proc Natl Acad Sci U S A. 2004 May 18;101(20):7711-5. Epub 2004 May 5.
- PubMed ID
- 15128933 [ View in PubMed]
- Abstract
The synthesis of bioactive vitamin D requires hydroxylation at the 1 alpha and 25 positions by cytochrome P450 enzymes in the kidney and liver, respectively. The mitochondrial enzyme CYP27B1 catalyzes 1 alpha-hydroxylation in the kidney but the identity of the hepatic 25-hydroxylase has remained unclear for >30 years. We previously identified the microsomal CYP2R1 protein as a potential candidate for the liver vitamin D 25-hydroxylase based on the enzyme's biochemical properties, conservation, and expression pattern. Here, we report a molecular analysis of a patient with low circulating levels of 25-hydroxyvitamin D and classic symptoms of vitamin D deficiency. This individual was found to be homozygous for a transition mutation in exon 2 of the CYP2R1 gene on chromosome 11p15.2. The inherited mutation caused the substitution of a proline for an evolutionarily conserved leucine at amino acid 99 in the CYP2R1 protein and eliminated vitamin D 25-hydroxylase enzyme activity. These data identify CYP2R1 as a biologically relevant vitamin D 25-hydroxylase and reveal the molecular basis of a human genetic disease, selective 25-hydroxyvitamin D deficiency.