ABSTRACT: Genetic variants of the enzyme that metabolizes warfarin, cytochrome P-450 2C9 (CYP2C9) and of a key pharmacologic target of vitamin K antagonists, vitamin K epoxide reductase (VKORC1), contribute to differences in patients' responses to coumarin derivatives. The role of these variants in fluindione response is unknown. Our aim was to assess whether genetic factors contribute to the variability in the response to fluindione.
Four hundred sixty-five patients with a venous thromboembolic event treated by fluindione for at least 3 months with a target international normalized ratio (INR) of 2.0 to 3.0 were studied. VKORC1, CYP2C9, CYP4F2 and EPHX1 genotypes were assessed. INR checks, fluindione doses and bleeding events were collected.
VKORC1 genotype had a significant impact on early anticoagulation (INR value ≥2 after the first two intakes) (P < 0.0001), on the time required to reach a first INR within the therapeutic range (P < 0.0001) and on the time to obtain a first INR value > 4 (P= 0.0002). The average daily dose of fluindione during the first period of stability was significantly associated with the VKORC1 genotype: 19.8 mg (±5.5) for VKORC1 CC, 14.7mg (±6.2) for VKORC1 CT and 8.2mg (±2.5) for VKORC1 TT (P < 0.0001). CYP2C9, CYP4F2 and EPHX1 genotypes did not significantly influence the response to fluindione.
VKORC1 genotype strongly affected anticoagulation induced by fluindione whereas CYP2C9, CYP4F2 and EPHX1 genotypes seemed less determining.
British Journal of Clinical Pharmacology 08/2011; 73(3):428-36. · 2.96 Impact Factor
ABSTRACT: Venous thromboembolism (VTE) is a multifactorial disease, caused by interacting environmental and genetic risk factors. Gene-centric genotyping strategy is one of the approaches to explore unexplained associations between risk factors and VTE. It was the objective of this study to evaluate, using a gene-centric genotyping strategy, polymorphisms in genes involved in the following pathways: coagulation cascade process, renin-angiotensin or adrenergic systems, lipid metabolism, platelet aggregation. Allele frequency was compared between 677 cases with idiopathic VTE and their matched controls. After Bonferroni adjustment, four single nucleotide polymorphisms (SNPs) were significantly associated with VTE: Factor XI rs925451 polymorphism, factor XI rs2289252 polymorphism, factor II rs1799963 (G20210A) polymorphism and factor V Leiden rs6025. An additive mode of inheritance fitted best both factor XI polymorphisms. In this hospital-based case-control study, two polymorphisms located on the factor XI gene were significantly associated with VTE. Other newly investigated polymorphisms with potentially false negatives may warrant further analyses.
Thrombosis and Haemostasis 03/2010; 103(6):1161-9. · 5.04 Impact Factor
ABSTRACT: The vitamin K epoxide reductase complex subunit 1 (VKORC1) recycles endogenous vitamin K, a cofactor for vitamin K-dependent coagulation factor synthesis. Common polymorphisms in VKORC1, the gene coding for VKORC1, have been found to affect the dose response to vitamin K antagonists, and to confer an increased risk of vascular diseases in a Chinese population. The aim of this study was to evaluate the association between the VKORC1 1173C > T polymorphism and venous thromboembolism (VTE).
We report the results of a case-control study designed to evaluate interactions between acquired and inherited risk factors of VTE. We studied 439 cases hospitalized with a first venous thromboembolic event that was not related to a major acquired risk factor for VTE, and 439 matched controls. The VKORC1 1173C > T polymorphism was selected for genotyping as the tagging single-nucleotide polymorphism for previously identified VKORC1 haplotypes.
The relationship between VTE and the VKORCI 1173C > T polymorphism was consistent with a recessive model. The frequency of the VKORCI TT genotype was lower in cases than in controls. The odds ratio (OR) (95% CI) was 0.62 (0.41-0.94) for the TT genotype as compared to CT/CC genotypes. Adjustment on cardiovascular diseases, body mass index, factor V (FV) and prothrombin gene mutations did not alter the results.
In this case-control study, the frequency of the VKORCI TT genotype was lower in patients with VTE than in matched controls. The clinical consequence of these results remains to be determined, but gives new perspectives for exploration of the role of VKORCI polymorphism in the pathogenesis of VTE.
Journal of Thrombosis and Haemostasis 11/2007; 5(10):2020-4. · 5.73 Impact Factor