Pharmacodynamic resistance to warfarin associated with a Val66Met substitution in vitamin K epoxide reductase complex subunit 1

Summary

The gene encoding vitamin K epoxide reductase complex subunit 1 (VKORC1), a component of the enzyme that is the therapeutic target site for warfarin, has recently been identified. In order to investigate the relationship betweenVKORC1 and warfarin dose response, we studied theVKORC1 gene (VKORC1) in patients with warfarin resistance. From a study group of 820 patients, we identified 4 individuals who required more than 25 mg of warfarin daily for therapeutic anticoagulation.Three of these had serum warfarin concentrations within the therapeutic range of 0.7–2.3 mg/l and showed wild-type VKORC1 sequence. The fourth warfarin resistant individual had consistently high ( ≥ 5.7 mg/l) serum warfarin concentrations, yet had no clinically discernible cause for warfarin resistance. VKORC1 showed a heterozygous 196G→ A transition that predicted aVal66Met substitution in the VKORC1 polypeptide. This transition was also identified in 2 asymptomatic family members who had never received warfarin.These individuals had normal vitamin-K dependent coagulation factor activities and undetectable serum PIVKAII and vitamin K 1 2,3 epoxide suggesting that their basal vitamin K epoxide reductase activity was not adversely affected by the VKORC1 Val66Met substitution.The association between a nucleotide transition in VKORC1 and pharmacodynamic warfarin resistance supports the hypothesis that VKORC1 is the site of action of warfarin and indicates that VKORC1 sequence is an important determinant of the warfarin dose response.

Keywords

Warfarin resistance - vitamin K - vitamin K epoxide reductase - pharmacogenetics - coagulation factor

• References

• 1 Hirsh J, Fuster V, Ansell J. et al American Heart Association/ American College of Cardiology Foundation guide to warfarin therapy. Circulation 2003; 107: 1692-711.
• 2 James AH, Britt RP, Raskino CL. et al Factors affecting the maintenance dose of warfarin. J Clin Pathol 1992; 45: 704-6.
• 3 Palareti G, Leali N, Coccheri S. et al Bleeding complications of oral anticoagulant treatment: an inception- cohort, prospective collaborative study (ISCOAT). Italian Study on Complications of Oral Anticoagulant Therapy. Lancet 1996; 348: 423-8.
• 4 Gage BF, Eby C, Milligan PE. et al Use of pharmacogenetics and clinical factors to predict the maintenance dose of warfarin. Thromb Haemost 2004; 91: 87-94.
• 5 Suttie JW. The biochemical basis of warfarin therapy. Adv Exp Med Biol 1987; 214: 3-16.
• 6 Presnell SR, Stafford DW. The vitamin K-dependent carboxylase. Thromb Haemost 2002; 87: 937-46.
• 7 Rost S, Fregin A, Ivaskevicius V. et al Mutations in VKORC1 cause warfarin resistance and multiple coagulation factor deficiency type 2. Nature 2004; 427: 537-41.
• 8 Li T, Chang CY, Jin DY. et al Identification of the gene for vitamin K epoxide reductase. Nature 2004; 427: 541-4.
• 9 D’Andrea G, D’Ambrosio RL, Di Perna P. et al A polymorphism in VKORC1 gene is associated with an inter-individual variability in the dose-anticoagulant effect of warfarin. Blood 2004 Sep 9 [Epub ahead of print].
• 10 Shearer MJ. Assay of coumarin antagonists of vitamin K in blood by high-performance liquid chromatography. Methods Enzymol 1986; 123: 223-34.
• 11 Davidson KW, Sadowski JA. Determination of vitamin K compounds in plasma or serum by high-performance liquid chromatography using postcolumn chemical reduction and fluorimetric detection. Methods Enzymol 1997; 282: 408-21.
• 12 Belle M, Brebant R, Guinet R. et al Production of a new monoclonal antibody specific to human des-gamma-carboxyprothrombin in the presence of calcium ions. Application to the development of a sensitive ELISA-test. J Immunoassay 1995; 16: 213-29.
• 13 Kamali F, Edwards C, Butler TJ. et al The influence of (R)- and (S)-warfarin, vitamin K and vitamin K epoxide upon warfarin anticoagulation. Thromb Haemost 2000; 84: 39-42.
• 14 Diab F, Feffer S. Hereditary warfarin resistance. South Med J 1994; 87: 407-9.
• 15 O'Reilly RA, Aggeler PM, Hoag MS. et al Hereditary transmission of exceptional resistance to coumarin anticoagulant drugs. the first reported kindred. N Engl J Med 1964; 271: 809-15.
• 16 O'Reilly RA. Vitamin K in hereditary resistance to oral anticoagulant drugs. Am J Physiol 1971; 221: 1327-30.
• 17 Alving BM, Strickler MP, Knight RD. et al Hereditary warfarin resistance. Investigation of a rare phenomenon. Arch Intern Med 1985; 145: 499-501.
• 18 Warrier I, Brennan CA, Lusher JM. Familial warfarin resistance in a black child. Am J Pediatr Hematol Oncol 1986; 8: 346-7.
• 19 Hallak HO, Wedlund PJ, Modi MW. et al High clearance of (S)-warfarin in a warfarin-resistant subject. Br J Clin Pharmacol 1993; 35: 327-30.
• 20 Bentley DP, Backhouse G, Hutchings A. et al Investigation of patients with abnormal response to warfarin. Br J Clin Pharmacol 1986; 22: 37-41.
• 21 Kempin SJ. Warfarin resistance caused by broccoli. N Engl J Med 1983; 308: 1229-30.
• 22 Goodstadt L, Ponting CP. Vitamin K epoxide reductase: homology, active site and catalytic site. Trends Biochem Sci 2004; 29: 289-9.