Nutri-pharmacogenomics of warfarin anticoagulation therapy: VKORC1 genotype-dependent influence of dietary vitamin K intake

Warfarin is the most widely prescribed oral anticoagulant, but large interindividual variations exist in the dose required to achieve comparable therapeutic effects. Several clinical and genetic variables have been identified that influence warfarin dosing. However, interactions between genotype and nutrition remain uncertain in terms of dietary vitamin K intake. To investigate genotype–nutrient interactions in warfarin anticoagulation therapy, 202 consecutive outpatients (M/F = 142/60, mean age, 69 years) undergoing treatment with warfarin were enrolled. Prevalent single nucleotide polymorphisms in VKORC1 and CYP2C9 were genotyped, and dietary vitamin K intake during the week preceding the blood sampling was quantitatively estimated by a dietitian-assisted questionnaire. Patients were classified according to low, medium, or high vitamin K intake. The mean daily warfarin dose in subjects with a VKORC1-1639 A/A genotype was significantly smaller than that with a -1639A/G genotype (2.74 vs. 3.91 mg/day, respectively, p < 0.0001). Dose requirements did not differ between subjects with a CYP2C9 *1/*3 genotype versus a CYP2C9 *1/*1 genotype. In subjects with a variant VKORC1-1639 G allele, the mean daily warfarin dose was significantly attenuated by low vitamin K intake compared with medium and high intake after adjustment for covariates (3.4 vs. 5.0 vs. 4.0 mg/day, respectively, p = 0.028). No such genotype effects were observed in homozygous patients for the VKORC1-1639 A allele. The results of the present study suggest that the capacity of dietary vitamin K intake to influence warfarin dose requirements during anticoagulation therapy is VKORC1 genotype-dependent, at least in part.     

Dependency of phenprocoumon dosage on polymorphisms in the VKORC1 and CYP2C9 genes

Objectives Polymorphisms in the vitamin K epoxide–reductase-complex-1 (VKORC1) and the cytochrome-P450-isozyme (CYP2C9) genes account for therapeutic responses to vitamin K antagonists (VKA). This study aimed to investigate the prevalence of VKORC1 and CYP2C9 polymorphisms among patients under phenprocoumon and its influence on the VKA dosage. Methods Patients under phenprocoumon were screened for the polymorphisms −1639G > A and 3730G > A in the VKORC1 gene and 430C > T and 1075A > C in the CYP2C9 gene by means of a StripAssay. Baseline clinical and laboratory parameters were registered. Results Among 53 patients (28 females, mean age 72.5 years), VKORC1 polymorphisms were found in 34 [−1639G > A: homozygote (n = 11), heterozygote (n = 23)] and 28 [3730G > A: homozygote (n = 7), heterozygote (n = 21)] patients. Thirteen patients were compound heterozygote. CYP2C9 polymorphisms were found in 12 [430G > T: homozygote (n = 1), heterozygote (n = 11)] and 7 [1075A > C: homozygote (n = 0), heterozygote (n = 7)] patients. Seventeen patients had at least one VKORC1 and one CYP2C9 polymorphism. Mean phenprocoumon dosage per week to achieve therapeutic anticoagulation was lower (higher) in patients with than without the VKORC1 polymorphism −1639G > A (3730G > A) or the CYP2C9 polymorphisms. Despite the presence of VKORC1 or CYP2C9 polymorphisms, mean International Normalized Ratio was not significantly different between patients with and without polymorphisms. Conclusions Though VKORC1 and CYP2C9 polymorphisms influence the phenprocoumon dosage necessary to achieve therapeutic anticoagulation, anticoagulation is therapeutic if carefully monitored.     

The Influence of CYP2C9 and VKORC1 Gene Polymorphisms on the Response to Warfarin in Egyptians

Warfarin is the most commonly used drug for chronic prevention of thromboembolic events, it also ranks high among drugs that cause serious adverse events. The variability in dose requirements has been attributed to inter-individual differences in medical, personal, and genetic factor. Cytochrome P-450 2C9 is the principle enzyme that terminates the anticoagulant effect of warfarin by catalyzing the conversion of the pharmacologically more potent S-enantiomer to its inactive metabolites. Warfarin exerts its effect by inhibition of vitamin K epoxide reductase. This protein is encoded by vitamin K epoxide reductase complex subunit 1 gene (VKORC1). The current study aimed to investigate the pharmacogenetic effect of CYP2C9 and VKORC1 gene polymorphisms on the patients response to warfarin. One hundred cases starting warfarin treatment and 20 healthy controls were enrolled. The mean daily dose of warfarin was calculated from patient’s medical records. For each patient, less than 10 % variability in warfarin dose and a target international normalized ratio (INR) within the therapeutic target range were required for at least 3 months for one of the following indications (deep vein thrombosis, pulmonary embolism, cerebrovascular stroke and myocardial infarction) prior to inclusion in the study. Tetraprimer amplification refractory mutation system PCR was performed to determine CYP2C9*2, CYP2C9*3, and the VKORC1 1639 G > A genetic polymorphisms. Plasma warfarin determination was performed using rapid fluorometric assay. Plasma warfarin concentration ranged from 2.19 to 10.98 μg/ml with a median 3.52 μg/ml. Supratherpeutic INR was observed in 11 % of the cases. Thromboembolic complications occurred in 7 % of the cases and 8 % of cases experienced major bleeding. High maintenance dose (>7 mg/day) was associated with the combined non VKORC1*2 and homozygous wild type CYP2C9 (CYP2C9*1*1) alleles, while low maintenance dose was associated with the Variant (AG + AA)/Wild (*1/*1). (p value <0.001). CYP2C9 variant was a risk factor for supratherapeutic INR in the multivariate logistic regression model. Thromboembolic complication and incidence of supratherapeutic INR were observed in patients carrying combined VKORC1 Variant (AG + AA) and CYP2C9 Variant (*2/*3). Data from our study suggest that together with clinical factors, VKORC1 and CYP2C9 polymorphisms are important contributors to warfarin dosing and may help predict adverse effects in Egyptian patients.     

Association of VKORC1 −1639 G > A polymorphism with carotid intima-media thickness in type 2 diabetes mellitus

Aims

Media calcification is a predictor of cardiovascular mortality in type 2 diabetes mellitus (T2DM). Undercarboxylation of some vitamin K-dependent proteins, due to genetic polymorphisms of VKORC1, can lead to calcification. We examined a potential association between VKORC1 −1639 G > A polymorphism and T2DM and, also, the association of this polymorphism with carotid intima-media thickness (cIMT).

Methods

VKORC1 −1639 G > A polymorphism was determined in 299 T2DM patients and 328 controls of Caucasian origin using PCR-RFLP. cIMT was measured in a subgroup of 118 T2DM patients.

Results

The frequency of VKORC1 genotypes between diabetic and nondiabetic subjects differed significantly (p = 0.01). VKORC1 genotype was associated with T2DM in an adjusted model (OR 1.36, p = 0.009). A statistically significant difference was observed in the maximum value of cIMT among different genotypes. VKORC1 −1639 G > A polymorphism was an independent predictor of cIMT (p = 0.029) after adjusting for established risk factors.

Conclusions

The association between VKORC1 −1639 G > A polymorphism and risk of T2DM could be due to the higher prevalence of calcification in T2DM patients. This is supported by the independent association between VKORC1 −1639 G > A polymorphism and maximum cIMT in T2DM patients which is likely due to atherosclerosis characterized by increased calcification.     

Pharmacogenetic tests could be helpful in predicting of VKA maintenance dose in elderly patients at treatment initiation

Several studies have linked mutations in the genes encoding cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex 1 (VKORC1) to a reduced VKA dose requirement and an increased risk of bleeding. Nevertheless, implementation of genotyping as a routine practice is still controversial. Our study was conducted in order to investigate the impact of genetic factors, presence of VKORC1-c.1639A, CYP2C*2 and CYP2C*3 among outpatients referred to Anticoagulation Service due to extremely unstable anticoagulant therapy. From 2008 to 2011, 68 patients, mean age 65.9, were included in the study. They were referred from primary care physicians due to inability to sustain the therapeutic range in the period of initiation of anticoagulant therapy. Genotyping results showed that 17 (25 %) of them were carriers of both CYP2C9 and VKORC1 variant alleles, 38 (55.9 %) were carriers of VKORC1 c.1639AA, 6 (8.8 %) were carriers of CYP2C9 variant alleles, while 7 (10.3 %) of them were carriers of wild type alleles. INR control upon admission showed that 34 (50 %) of them were over-anticoagulated, while 12 (17.6 %) of them had subsequent bleeding complications. Among over-anticoagulated patients, 32 were carriers of mutated alleles in both CYP2C9 and VKORC1 gene or VKORC1 alone, while 2 of patients carried wild type alleles. In addition to presence of CYP2C9 or VKORC 1 alleles, older age was an important factor related to a lower dose and risk for over-anticoagulation. Genotype (CYP2C9/VKORC1) and age are the most important factors that could predispose an extreme response and subsequent bleeding complications during the initiation of VKA.     

The effect of CYP2C9, VKORC1 and CYP4F2 polymorphism and of clinical factors on warfarin dosage during initiation and long-term treatment after heart valve surgery

The dosage of warfarin is restricted due to its narrow therapeutic index, so, the required dose must be adapted individually to each patient. Variations in warfarin dosage are influenced by genetic factors, the changes in patient diet, anthropometric and clinical parameters. To determine whether VKORC1 G3730A and CYP4F2 G1347A genotypes contribute to warfarin dosage in patients during initiation and long-term anticoagulation treatment after heart valve surgery. From totally 307 patients, who underwent heart valve surgery, 189 patients (62 %) who had been treated with warfarin more than 3 months, were included into the study. A hierarchical stepwise multivariate linear regression model showed, that during initiation clinical factors can explain 17 % of the warfarin dose variation. The addition of CYP2C9 and VKORC1 G-1639A genotype raises the accuracy about twice—to 32 %. The CYP4F2 G1347A genotype can add again about 2–34 %. During long-term treatment clinical factors explain about 26 % of warfarin dose variation. If the CYP2C9 *2, *3, VKORC1*2 alleles are detected, model can explain about 49 % in dose variation. The *3 allele of VKORC1 raises the accuracy by 1–50 %. The carriers of CYP4F2 A1347A genotype required higher daily warfarin doses during initiation of warfarin therapy after heart valve surgery than comparing to G/G and G/A carriers, but during the longer periods of warfarin use, the dosage of warfarin depended significantly on VKORC1 *3 allele (G3730A polymorphism) and on the thyroid stimulating hormone level in the blood plasma.     

Appraisal of current vitamin K dosing algorithms for the reversal of over-anticoagulation with warfarin: the need for a more tailored dosing regimen

Warfarin is the most commonly prescribed oral anticoagulant in the UK for the treatment and prevention of thromboembolic disorders. Vitamin K administration is an effective way of reversing excessive anticoagulation. Over-anticoagulated patients present with a wide range of international normalized ratio (INR) values and may respond differently to a fixed dose of vitamin K. Current dosing algorithms for vitamin K administration in the non-urgent treatment of over-anticoagulation do not take this variability in response into account. Consequently, over a third of over-anticoagulated patients still remain outside their target INR 24 h after treatment. Such patients are therefore prone to either haemorrhage (if the patient is still over-anticoagulated) or thromboembolism (if the INR reversal is over-corrected). A number of factors such as patient age, body weight, co-morbidity, frailty, warfarin daily dose and CYP2C9 and VKORC1 polymorphism could affect response to vitamin K and thus the rate and extent of INR reversal. There is a need for a more individualized approach to the reversal of over-anticoagulation in asymptomatic or mildly haemorrhagic patients in order to improve the safety of warfarin therapy.     

Influence of warfarin dose-associated genotypes on the risk of hemorrhagic complications in Chinese patients on warfarin

This study was designed to evaluate the effect of the warfarin dose-associated genotypes, CYP2C9*3 (rs1057910), VKORC1 ?1639 G/A (rs9923231), and CYP4F2 1347 C/T (rs2108622), on hemorrhagic complications in Han Chinese patients. Consecutively recruited patients requiring more than 1 year of warfarin treatment were followed from the initiation of warfarin anticoagulation for at least 3 months. CYP2C9*3, VKORC1 ?1639 G/A, and CYP4F2 1347 C/T were genotyped by sequencing. The association between genotypes and warfarin hemorrhagic complications was evaluated using Cox proportional hazard regression, adjusted for demographic and clinical factors. Of 312 eligible patients obtaining stable warfarin anticoagulation in 3 months, 11 major and 69 minor hemorrhages occurred over 147 person-years. The CYP2C9*3 genotype conferred an increased risk of all [hazard ratio (HR) 3.07, 95 % confidence interval (CI) 1.57–6.01] and minor hemorrhage (HR 3.28, 95 % CI 1.62–6.65), but not major hemorrhage (HR 0.44, 95 % CI 0.04–4.72). CYP2C9*3 also conferred an increased risk of over-anticoagulation with international normalization ratio (INR) ≥4 (HR 2.92, 95 % CI 1.08–7.85). VKORC1 ?1639 G/A, and CYP4F2 rs2108622 did not confer significant increase in risk for hemorrhage or over-anticoagulation. Kaplan–Meier curves showed that time to all hemorrhagic events was significantly shorter for patients with CYP2C9*3 genotype than non-carriers (P = 0.001), but not for patients with VKORC1 ?1639 G/A or CYP4F2 rs2108622 genotype (P = 0.3 and 0.2). CYP2C9*3 may be the main genetic factor in hemorrhagic complications in Chinese patients under warfarin anticoagulation.     

The impact of CYP2C9 and VKORC1 genetic polymorphism and patient characteristics upon warfarin dose requirements in an adult Turkish population

In this study, we investigated the contribution of vitamin K epoxide reductase (VKORC1) and cytochrome P450 2C9 (CYP2C9) genotypes, age, and body surface area (BSA) on warfarin dose requirements and in an adult Turkish population. Blood samples were collected from 100 Turkish patients with stable warfarin dose requirements and an international normalized ratio (INR) of the prothrombin time within the therapeutic range. Genetic analyses for CYP2C9 genotypes (*2 and *3 alleles) and VKORC1 −1639 G>A polymorphism were performed and venous INR determined. The mean warfarin daily dose requirement was higher in CYP2C9 homozygous wild-type patients, compared to those with the variant *3 allele (P < 0.05), similar to those with the variant *2 allele (P > 0.05) and highest in patients with the VKORC1 −1639 GG genotype compared to those with the GA genotype and the AA genotype (P < 0.01). The time to therapeutic INR was longer in CYP2C9 homozygous wild-type patients compared with those with the variant *2 and *3 alleles (P < 0.01), and longer in patients with the VKORC1 (position −1639) GG genotype compared with those with the GA genotype and the AA genotype (P < 0.01). The multivariate regression model including the variables of age (R ² = 4.4%), BSA (R ² = 27.4%), CYP2C9 (R ² = 8.1%), and VKORC1 genotype (R ² = 34.1%) produced the best model for estimating warfarin dose (R ² = 60.4%). VKORC1 genotype and CYP2C9 polymorphism affect daily dose requirements and time to therapeutic INR in Turkish patients receiving warfarin for anticoagulation.     

Cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase (VKORC1) genotypes as determinants of acenocoumarol sensitivity

The aim of the study is to explore the contribution of genetic factors related either to drug metabolism (cytochrome P450 2C9) or to drug target (vitamin K epoxide reductase) to variability in the response to acenocoumarol among 222 healthy volunteers after a single oral dose. Associations between a pharmacodynamic index (reduction in factor VII activity and international normalized ratio [INR] change) and several genetic polymorphisms (VKORC1: -4931T>C, -4451C>A, -2659G>C, -1877A>G, -1639G>A, 497C>G, 1173C>T, and CYP2C9*3) were investigated using haplotype and univariate analyses. VKORC1 haplotypes were associated with the pharmacologic response, and this association can be explained only by the effect of the -1639G>A polymorphism (or alternatively by 1173C>T, which is in complete association with it). Indeed, it explains about one third of the variability of the pharmacologic response (37% of factor VII decrease and 30% of INR change). Moreover, the previously observed effect of the CYP2C9*3 allele is independent of the VKORC1 gene effect. These 2 polymorphisms account for up to 50% of the interindividual variability. The simple genotyping of 2 single-nucleotide polymorphisms (SNPs), VKORC1 -1639G>A or 1173C>T and the CYP2C9*3 polymorphisms, could thus predict a high risk of overdose before initiation of anticoagulation with acenocoumarol, and provide a safer and more individualized anticoagulant therapy.     

Polymorphisms in VKORC1 have more impact than CYP2C9 polymorphisms on early warfarin International Normalized Ratio control and bleeding rates

Poor warfarin control with resultant high International Normalized Ratios (INRs) and bleeding events is most common during the first months of treatment. The effects of genetic polymorphisms at the vitamin K epoxide reductase [VKORC1] and cytochrome P450 2C9 [CYP2C9] loci have been increasingly acknowledged as contributory factors of enhanced warfarin sensitivity. In our prospective, blinded study, 557 patients (49·1% male, mean age 65·4 years, range 18-91 years) commencing warfarin (target INR 2·5) were genotyped and monitored through the first 3 months of anticoagulation. Homozygosity for the -1639 G>A single nucleotide functional promoter polymorphism of the VKORC1 gene (genotype AA; 14·5% of cases) was associated with a significantly shortened time to therapeutic INR ≥ 2 (P < 0·01), reduced stable warfarin dose (P < 0·01), and an increased number of INRs > 5 (P < 0·001) and occurrence of bleeding events (P < 0·01) during the first month, as compared to the GG genotype. CYP2C9 genetic variations *2 and *3 were not associated with significant effect on these factors. Neither VKORC1 nor CYP2C9 polymorphisms influenced these parameters beyond the first month of treatment. These findings imply possible benefits of assessing VKORC1 polymorphisms prior to anticoagulation, particularly as a low dose induction regime in VKORC1 AA individuals appears to reduce the incidence of high INRs.     

An evaluation of nine genetic variants related to metabolism and mechanism of action of warfarin as applied to stable dose prediction

Warfarin anticoagulation is complicated by the highly variable inter-individual response. Approximately 50% of the dose variability arises from clinical factors and variants in two genes, CYP2C9 (*2 and *3 variants) and VKORC1 -1173 C > T. We tested variants in five additional genes (EPHX1, PROC, APOE, CYP4F2, CALU and a new variant in VKORC1 in an attempt to further reduce the variability in predicted stable warfarin dose. Consecutive consenting outpatients requiring anticoagulation on stable warfarin dose (target INR 2–3) were genotyped; the association of SNP genotypes with stable warfarin dose was evaluated using the test of linear contrasts in analysis of variance (ANOVA). Study participants were 71 ± 13 years, 53% female, 85 ± 23 kg, body mass index 29 ± 7 kg/m². Genotypes were in Hardy–Weinberg equilibrium with the exception of VKORC1 -1639. Weekly stable dosages were 31.7 ± 13.9 mg/week; median: 30 mg/week, range: 11–70 mg/week. Significant associations with dose were seen for VKORC1 -1639 (P < 0.001), CYP2C9*2 (P = 0.005) and *3 (P = 0.003), the CYP4F2 SNP (P-trend = 0.00037), and VKORC1 3730 (p-trend = 0.042). In linear regression, age, sex, weight, and CYP2C9 *2 and *3 and VKORC1-1639 genotype explained 42% of variance. The addition of CYP4F2 genotype to the regression model increased the degree of variance explained to 47%. Addition of VKORC1 SNP -1639 to a model eliminated the association of VKORC1 3730 with warfarin dose (P-trend = 0.74), but -1639 remained highly significant. No impact on dose was observed for the other tested genetic variants.     

CYP2C9与VKORC1基因变异对华法林初始抗凝治疗反应性的影响

目的 探讨细胞色素P450酶2C9基因(CYP2C9)与维生素K环氧化物还原酶复合物1基因( VKORC1)多态性对中国汉族人华法林初始抗凝治疗反应性的影响.方法 入选2000-2008年广东省人民医院瓣膜置换术后长期口服华法林抗凝治疗的中国汉族患者798例,通过文献检索,选取与华法林药动学和药效学可能相关的CYP2C...     

Interaction of vitamin K antagonists with heparin affect monitoring by activated clotting times

Background

Unfractionated heparin is recommended during atrial fibrillation (AF) ablation to achieve activated clotting time (ACT) above 250–300 s to prevent clot. Many patients on therapeutic international normalised ratio (INR) undergo AF ablation procedures; however, it is unknown whether they require less heparin to achieve similar ACT levels.

Methods

During AF ablation, the ACT was measured before and 10 min after administration of i.v. unfractionated heparin in patients with and without anticoagulation. The association of INR, heparin, pre-procedure ACT and body weight with ACT after heparin administration was tested using multivariable linear regression models.

Results

The subjects of this study were 149 patients undergoing AF ablation, among them 40 (27%) with subtherapeutic INR?<?2, 79 (53%) with an INR between 2 and 3, and 30 (20%) patients with INR?>?3. Baseline ACT was associated with INR (r?=?0.33, p?<?0.001). After a mean of 8,685?±?2,015 U (range, 5,000–15,000 IU) unfractionated heparin, univariate predictors of ACT were baseline INR (p?<?0.001), heparin dose (p?=?0.012) and baseline ACT (p?=?0.027). In the multivariable model, baseline INR (part r?=?0.64, p?<?0.001) and heparin dose (part r?=?0.33, p?<?0.001) strongly predicted post-heparin ACT. Estimated from the regression model, the heparin dose reductions by approximately one third in those with an INR of 2–3 and by at least two thirds in those with an INR above 3 may be favourable. Over the following 3 months, no thromboembolism and acute bleeding were observed.

Conclusion

The INR was the strongest predictor of post-heparin ACT, even more important than the heparin dose itself. The reduction of heparin dose by one third if INR is between 2–3 and by two thirds if INR is above 3 may be favourable.     

Prognostic predictive value of TLR4 polymorphisms in Han Chinese population with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiac disease and is an important cause of sudden death in patients of all ages. The aim of this study was to find out whether Toll-like receptor-4 (TLR4) polymorphism is associated with HCM. To explore the association between TLR4 gene polymorphisms and HCM, 486 HCM patients and 214 healthy controls were enrolled in a case–control study of Chinese Han population. Two single nucleotide polymorphisms (SNPs) in the promoter region of TLR4 gene, ?728G > C (rs11536865) and ?2081G > A (rs10983755), were genotyped by PCR restriction fragment length polymorphism (PCR-RFLP). The associations between TLR4 SNPs and overall survival (OS) of HCM patients were analyzed by the Kaplan–Meier estimation method and Cox proportional hazards regression analysis. Serum TLR4 level was determined by ELISA. Our results showed that the C allelic frequency of ?728G > C and A allelic frequency of ?2081G > A were higher in HCM patients than those in controls (P < 0.001). The ratios of genotype frequencies for both SNPs were associated with HCM susceptibility under three genetic models (P < 0.01). Two SNPs were also associated with the OS in HCM patients (P < 0.001). The CC genotype of ?728G > C and AA genotype of ?2081G > A were associated with poor prognosis of HCM (P < 0.001). Moreover, HCM patients had a higher serum TLR4 level compared with the controls (242.6 pg/ml versus 135.7 pg/ml, P = 0.027). In addition, significant associations were observed between CC genotype of ?728G > C or AA genotype of ?2081G > A and plasma TLR4 level (P < 0.01). The results of this study indicated that TLR4 polymorphisms may be a genetic susceptibility factor for HCM in the Han Chinese population.     

Pharmacogenetics of warfarin: regulatory, scientific, and clinical issues

Using pharmacogenetics-based therapy, clinicians can estimate the therapeutic warfarin dose by genotyping patients for single nucleotide polymorphisms (SNPs) that affect warfarin metabolism or sensitivity. SNPs in the cytochrome P450 complex (CYP2C9) affect warfarin metabolism: patients who have the CYP2C9*2 and/or CYP2C9*3 variants metabolize warfarin slowly and are more likely to have an elevated International Normalized Ratio INR or to hemorrhage during warfarin initiation than patients without these variants. SNPs in vitamin K epoxide reductase (VKORC1) correlate with warfarin sensitivity. Patients who are homozygous for a common VKORC1 promoter polymorphism, −1639 G>A (also designated as VKOR 3673, haplotype A, or haplotype*2), are warfarin sensitive and typically require lower warfarin doses. By providing an estimate of the therapeutic warfarin dose, pharmacogenetics-based therapy may improve the safety of anticoagulant therapy. To improve drug safety, the FDA updates labels of previously approved drugs as new clinical and genetic evidence accrues. The labels of medical products serve to inform prescribers and patients about potential ways to improve the benefit/risk ratio and/or optimize doses of medical products. On August 16, 2007, the FDA updated the label of warfarin to include information on pharmacogenetic testing and to encourage, but not require, the use of this information in dosing individual patients initiating warfarin therapy. The FDA completed the label update in August 2007. Disclosure: A portion of this article was adapted from an education handout that Dr. Gage has retained copyright of: Gage, B.F. (2006). Pharmacogenetics-based coumarin therapy. Hematology Am Soc Hematol Educ Program: 467–473. Dr. Gage has served as a consultant to Bristol-Myers Squibb. Funding: NIH R01 HL074724.     

CD14 and IL6 polymorphisms are associated with a pro-atherogenic profile in young adults with acute myocardial infarction

This study investigated the relationship of polymorphisms in genes encoding CD14, IL-6 and TLR4 with metabolic, inflammatory and endothelial markers in young adults with acute myocardial infarction (AMI). Glucose, lipids, nitrate and inflammatory markers, flow mediated vasodilatation (FMV) and flow mediated by nitrate (FMN) were evaluated in 102 AMI and 108 non-AMI (control group) young individuals (<45 years). CD14 ?260C>T (rs2569190), IL6 ?174G>C (rs1800795) and TLR4 c.896A>G (rs4986790) and TLR4 c.1196C>T (rs4986791) polymorphisms were analyzed by PCR–RFLP. Minor allele frequencies of CD14, IL6 and TLR4 polymorphisms were similar between AMI and control groups (p > 0.05). In AMI group, individuals carrying IL6 ?174CC genotype had higher serum triglycerides, VLDL cholesterol and glucose compared to the IL6 ?174GG/GC genotype carriers (p < 0.05). Multiple logistic analysis showed that IL6 ?174CC genotype carriers had increased risk for hyperglycemia (>5.77 mmol/l) [OR: 6.75, 95 % CI: 1.80–24.40, p = 0.004] and hypertriglyceridemia (>2.68 mmol/l) [OR: 3.00, 95 % CI: 1.00–9.00, p = 0.043]. Moreover, CD14 ?260TT genotype was associated with reduced serum HDL cholesterol [OR: 3.10, 95 % CI: 1.00–9.01, p = 0.044] and apolipoprotein AI [OR: 3.20, 95 % CI: 1.00–9.70, p = 0.038] in AMI group. Relationship between CD14 and IL6 variants and altered inflammatory and endothelial (nitrate, FMV and FMN) markers was not found in both AMI and control groups. The IL6 ?174G>C and CD14 ?260C>T polymorphisms are likely to be associated with a pro-atherogenic profile but not with increased inflammatory markers and endothelial dysfunction in young AMI patients.     

Relation of the Fas and FasL gene polymorphisms with susceptibility to and severity of rheumatoid arthritis

To investigate associations of the Fas and FasL genes polymorphisms with rheumatoid arthritis (RA). One hundred patients with RA and age-, sex- and ethnically matched 101 controls were included. Four polymorphisms of Fas (-670 A>G rs1800682, -1377 G>A rs2234767) and FasL (IVS2nt-124 A>G rs5030772, -844 T>C rs763110) genes were typed from genomic DNA. Genotype distributions and allelic frequencies were compared between patients and control subjects. After the history and clinical examination of patients with RA, in terms of pain, fatigue and general health status were evaluated by visual analogue scale. Thereafter, erythrocyte sedimentation rate, C-reactive protein, blood count and rheumatoid factor levels were measured. The Disease Activity Score-28, Health Assessment Questionnaire and modified Sharp score were used to evaluate the disease activity, functional disability and radiological damage, and their relationships with the Fas and FasL gene polymorphisms were investigated. In patients with RA, CT and TT genotypes of FasL-844, polymorphism were twofold and 4.8-fold higher, and AA genotype of FasL IVS2nt-124 polymorphism was 3.4-fold higher than the control group (respectively, p = 0.05, p = 0.002, p = 0.039). T allele of FasL-844 polymorphism was more frequent in patients than controls (respectively, 52.5 vs. 41.4 %, p = 0.027). Any association was not detected between Fas (-670 A>G, -1377 G>A) and FasL (-844 T>C, IVS2nt-124 A>G) gene polymorphisms with the disease activity scores, functional disability and radiological damage. However, the Fas-670 A>G polymorphism was associated with drug therapy (p = 0.049). The distribution of GG genotype was higher compared to GA or AA genotypes in patients using triple disease-modifying antirheumatic drug therapy (71.4, 14.3 and 14.3 %, respectively). These findings suggest that the -844 T>C and IVS2nt-124 A>G polymorphisms in the FasL gene related with apoptosis may increase genetic susceptibility to RA in a Turkish population. In addition, the Fas-670 A>G gene polymorphism may be associated with disease progression. There is a need for further studies to clarify the genetic role of apoptosis in RA.     

Impact of CYP2C9*3, VKORC1-1639, CYP4F2rs2108622 genetic polymorphism and clinical factors on warfarin maintenance dose in Han-Chinese patients

To evaluate the impact of gene polymorphisms of Cytochrome P450 2C9 (CYP2C9), Vitamin K epoxide reductase complex subunit 1 (VKORC1) and Cytochrome P450 4F2 (CYP4F2) and clinical factors on warfarin maintenance dose in Han-Chinese patients from main land. DNA was extracted from 115 patients taking warfarin for more than 3 months with a stable international normalized ratio (INR) and genotyped for CYP2C9*3, VKORC1-1639 and CYP4F2 (rs2108622) polymorphisms using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Univariate analysis and multiple regression analysis were undertaken to assess the effect of genetic and clinical factors on the warfarin maintenance dose. Our study demonstrated that patients carrying CYP4F2 CT or TT allele needed a significantly higher warfarin dose compared to those carrying CC ((3.36 ± 0.14 mg/d vs. 2.77 ± 0.14 mg/d), P = 0.004). We also confirmed CYP2C9 *3 variant was related to lower warfarin dose (2.01 ± 0.23 mg/d) requirement compared to wild type (3.21 ± 0.11 mg/d) (P = 0.001). VKORC1-1639 AG genotype was associated with a higher maintenance dose compared to those with the AA genotype (4.06 ± 0.21 mg/d vs. 2.95 ± 0.11 mg/d, P < 0.001). The multiple linear regression model including VKORC1-1639G>A, CYP2C9, CYP4F2 and clinical factors (body surface area (BSA) and age) could explain 42 % of the variance in the warfarin maintenance dose. We developed a dose algorithm based on genetic polymorphism and clinical variables for Han-Chinese patients and evaluated its performance. CYP4F2 rs2108622 has a small but significant association with warfarin stable dose in Han-Chinese population.     

Timing of INR reversal using fresh-frozen plasma in warfarin-associated intracerebral hemorrhage

Rapid reversal of coagulopathy is recommended in warfarin-associated intracerebral hemorrhage (WAICH). However, rapid correction of the INR has not yet been proven to improve clinical outcomes, and the rate of correction with fresh-frozen plasma (FFP) can be variable. We sought to determine whether faster INR reversal with FFP is associated with decreased hematoma expansion and improved outcome. We performed a retrospective analysis of a prospectively collected cohort of consecutive patients with WAICH presenting to an urban tertiary care hospital from 2000 to 2013. Patients with baseline INR > 1.4 treated with FFP and vitamin K were included. The primary outcomes are occurrence of hematoma expansion, discharge modified Rankin Scale (mRS), and 30-day mortality. The association between timing of INR reversal, ICH expansion, and outcome was investigated with logistic regression analysis. 120 subjects met inclusion criteria (mean age 76.9, 57.5% males). Median presenting INR was 2.8 (IQR 2.3–3.4). Hematoma expansion is not associated with slower INR reversal [median time to INR reversal 9 (IQR 5–14) h vs. 10 (IQR 7–16) h, p = 0.61]. Patients with ultimately poor outcome received more rapid INR reversal than those with favorable outcome [9 (IQR 6–14) h vs. 12 (8–19) h, p = 0.064). We find no evidence of an association between faster INR reversal and either reduced hematoma expansion or better outcome.