Pathway

Defective CYP27B1 causes VDDR1B

Vitamin D3 (cholecalciferol), synthesised in human skin by ultraviolet radiation action on 7-dehydrocholesterol, does not possess any biological activity. Vitamin D hormonal activity requires hydroxylation at the 25 and 1-alpha positions by cytochrome P450 enzymes CYP2R1 and CYP27B1 respectively.

Vitamin D 25-hydroxylase (CYP2R1) catalyses the hydroxylation of vitamin D3 to calcidiol (CDL). Subsequent 1-alpha-hydroxylation of CDL produces calcitriol (CTL). CTL binds and activates the nuclear vitamin D receptor, with subsequent regulation of physiologic events such as calcium homeostasis, cellular differentiation and proliferation.

Defects in CYP2R1 can cause rickets, vitamin D-dependent 1B (VDDR1B; MIM:600081), a disorder caused by a selective deficiency of the active form of vitamin D (CTL) resulting in defective bone mineralization and clinical features of rickets.

Summary from Reactome (R-HSA-5579027), read 2026-09-23.

REACT:R-HSA-5579027Reactome

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What the reference databases state

Statements

1 statement

1 statement · 1 reference database · Subject: Defective CYP27B1 causes VDDR1B · Sources: Reactome

Order

CYP2R1 participates in Defective CYP27B1 causes VDDR1BProteinReactome R-HSA-5579027Inferred only