RESEARCH ARTICLE Confirmation of warfarin r t

Full list of author information is available at the end of the articleBackground Vitamin K hydroquinone is an essential cofactor for the posttranslational modification of vitamin K-dependent (VKD) proteins by the endoplasmic membrane enzyme γ-glutamyl-carboxylase (GGCX) [1]. VKD proteins com-prise clotting factors II, VII, IX and X, protein C, S and Z as well as osteocalcin, matrix Gla protein, growth arrest-specific protein (gas6) and four transmembrane proteins (PRGP1, PRGP2, TMG3, TMG4) [2,3]. For these proteins, γ-carboxylation is essential in order to attain their full biological activity state. During each carboxyl-ation step, vitamin K hydroquinone is oxidised to vitamin K epoxide which is in turn reduced by vitamin K epoxide reductase (VKOR) [4]. The gene encoding vitamin K epoxide reductase complex subunit 1 (VKORC1) was iden-tified in 2004 by two independent working groups [5,6]