VKORC1

Vitamin K epoxide reductase complex subunit 1 is an enzyme that in humans is encoded by the VKORC1 gene.

Vitamin K is essential for blood clotting but must be enzymatically activated. This enzymatically activated form of vitamin K is a reduced form required for the carboxylation of glutamic acid residues in some blood-clotting proteins. The product of this gene encodes the enzyme that is responsible for reducing vitamin K 2,3-epoxide to the enzymatically activated form. Fatal bleeding can be caused by vitamin K deficiency and by the vitamin K antagonist warfarin, and it is the product of this gene that is sensitive to warfarin. In humans, mutations in this gene can be associated with deficiencies in vitamin-K-dependent clotting factors. In humans and rats it has also been associated with warfarin resistance - but these mutations are rare except in Ethiopian and certain Jewish populations. Two pseudogenes have been identified on chromosome 1 and the X chromosome. Two alternatively spliced transcripts encoding different isoforms have been described.