The product of VKORC1 is a rate-controlling enzyme in the vitamin cycle and is essential for the production of vitamin-K-dependent, γ-carboxylated proteins such as clotting factors II, VII, IX, X protein C, S, and Z. Thus, VKORC1 has broad implications for clotting, a property well-appreciated: even before the gene was identified, VKOR has long been the target of warfarin, a commonly prescribed anticoagulant used to prevent stroke and other thromboembolic events. This evidence concerns the gene VKORC1 and Stroke.