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Introduction: Warfarin is an anticoagulant whose efficacy depends on reaching and maintaining an INR (International Normalized Ratio) within therapeutic ranges. Up to 60% of interindividual dose-response variability can be explained by pharmacogenes, in this regard there are no studies in Peru. We studied the effect of the CYP4F2 gene on the dose of warfarin in Peruvian patients. Material and Methods: A descriptive and ambispective observational study was carried out with patients seen in the Grau ESSALUD Hospital Hematology Service, Lima, Peru, selected by non-probabilistic convenience sampling. The inclusion criteria were patients anticoagulated for more than three months and with stable doses of warfarin (same dose for at least three outpatient visits and with an INR in therapeutic ranges of 2.5-3.5). Analysis of the CYP4F2 gene was performed by taking a DNA sample from peripheral blood. Results: 70 patients with a mean age of 69.6 + 13.4, male 38 (54.39%) and female 32 (45.7%) entered the study. The mean dose of warfarin was 31.6 + 15.2 mg/week. The genotypic frequency of the CYP4F2 gene, rs2108622 variant (C>T) was 55 (78%), 13 (19%) and 2 (3%) of CC, CT, TT, respectively. No deviation from the Hardy-Weinberg equilibrium was found in the variants studied (p=0.56). Mean warfarin doses/week of the CC, CT, TT genotypes were 30.34 + 11.98; 36.4 + 25.6 and 36.25 + 1.8 mg/week, respectively (p=0.397). Conclusion: In conclusion, it appears that CYP4F2 gene genotypes do not have a significant effect on warfarin dose. [ABSTRACT FROM AUTHOR]

The allele and genotype frequency distribution at polymorphic loci rs1799853 (430C>T) and rs1057910 (A1075C) of the CYP2C9 gene, rs2108622 (1347C>T) of the CYP4F2 gene, and rs9923231 (1639G>A) of the VKORC1 gene in the Buryat population was examined. The study involved 197 volunteers living in the Republic of Buryatia: 124 woman and 73 men, average age of 57.51 ± 10.88 years. Genetic typing of DNA samples was performed by polymerase chain reaction (RT-PCR). The frequency of the minor alleles *2 and *3 of the CYP2C9 gene was 2.03 and 3.05%, respectively. The frequency of the allele T of the CYP4F2 gene was 31.22%; the frequency of the allele A of the VKORC1 gene was 85.28%. The obtained results could be used in the prognosis of pharmacotherapy of warfarin in the population Buryat population. [ABSTRACT FROM AUTHOR]

Background: Age‐related macular degeneration (AMD) is the leading cause of blindness in the elderly individuals. The etiology of AMD includes environmental and genetic factors. Methods: We aimed to determine the association between CETP (rs5882; rs708272; rs3764261; rs1800775; rs2303790), AGER (rs1800624; rs1800625), and CYP4F2 (rs1558139) gene polymorphisms and development of atrophic AMD. About 52 patients with atrophic AMD and 800 healthy control subjects were evaluated. The genotyping of single‐nucleotide polymorphisms in CETP, AGER, and CYP4F2 was carried out using the real‐time‐PCR method. Results: Genetic risk models in the analysis of CETP rs5882 revealed statistically significant variables with increased risk of atrophic AMD in the codominant (p <.001), dominant (p <.001), recessive (p <.001), and additive (p <.001) models with the highest 25.4‐fold increased risk of atrophic AMD in the codominant model (p <.001). The AGER rs1800625 was associated with a highly increased risk of atrophic AMD in the codominant (p <.001), recessive (p <.001), and additive (p <.001) genetic models. Conclusion: We identified two polymorphisms with a higher risk of atrophic AMD (CETP rs5882 and AGER rs1800625). [ABSTRACT FROM AUTHOR]

This study aimed to explore whether the polymorphisms of CYP4F2 and CYP3A5 are correlated with the risk of lung cancer development. A case–control study was conducted among 510 patients with pathologically confirmed lung cancer as the case group and 504 healthy individuals as the control group. Four single-nucleotide polymorphisms of the CYP4F2 and CYP3A5 genes were genotyped, and their correlations with the risk of lung cancer were examined using Chi-square test and logistic regression analysis. Stratified analysis found that the rs3093105 and rs3093106 loci of CYP4F2 gene were significantly associated with lower risk of lung cancer (P = 0.012, OR 0.64, 95% CI 0.45–0.91). The correlation was related to patients' age and sex and pathological type of lung cancer. Similarly, the rs10242455 loci of CYP3A5 gene showed a statistical significance between the case group and the control group (P = 0.018, OR 0.71, 95% CI 0.53–0.94), which also was associated with reduced risk of squamous cell lung cancer in the dominant and additive models (dominant: OR 0.66, 95% CI 0.46–0.94, P = 0.021; additive: OR 0.71, 95% CI 0.53–0.95, P = 0.023). CYP4F2 and CYP3A5 gene polymorphisms are associated with the reduced risk of non-small cell lung cancer, and its correlation is related to patients' age and sex and pathological type of lung cancer. [ABSTRACT FROM AUTHOR]

Background: Chronic obstructive pulmonary disease (COPD) is a complex pulmonary disease. Cytochrome P450 family 4 subfamily F member 2 (CYP4F2) belongs to cytochrome P450 superfamily of enzymes responsible for metabolism, its single nucleotide polymorphisms (SNPs) were reported to be involved in metabolism in the development of many diseases. The study aimed to assess the relation between CYP4F2 SNPs and COPD risk in the Hainan Han population.Method: We genotyped five SNPs in CYP4F2 in 313 cases and 508 controls by Agena MassARRAY assay. The association between CYP4F2 SNPs and COPD risk were assessed by χ2 test and genetic models. Besides, logistic regression analysis was introduced into the calculation for odds ratio (OR) and 95% confidence intervals (CIs).Results: Allele model analysis indicated that rs3093203 A was significantly correlated with an increased risk of COPD. Also, rs3093193 G and rs3093110 G were associated with a reduced COPD risk. In the genetic models, we found that rs3093203 was related to an increased COPD risk, while rs3093193 and rs3093110 were related to a reduced risk of COPD. After gender stratification, rs3093203, rs3093193 and rs3093110 showed the association with COPD risk in males. With smoking stratification, rs3093144 was significantly associated with an increased risk of COPD in smokers. CYP4F2 SNPs were significantly associated with COPD risk.Conclusions: Our findings illustrated potential associations between CYP4F2 polymorphisms and COPD risk. However, large-scale and well-designed studies are needed to determine conclusively the association between the CYP4F2 SNPs and COPD risk. [ABSTRACT FROM AUTHOR]

Purpose: To find an association of relative expression of hsa-miR-24-3p and hsa-miR-34a-5p molecules and CYP4F2 enzyme activity in blood plasma of stable angina pectoris (AP) patients'. Materials and Methods: MiRNA gene expression analysis was performed on total RNA extracted from blood plasma, using quantitative real-time polymerase chain reaction. CYP4F2 enzyme levels were determined using commercial ELISA kit. In total, 32 AP and 15 control samples were examined. Results: The relative expression of hsa-miR-24-3p and hsa-miR-34a-5p was upregulated by 4.4 (p = 0.0001) and 3.8 (p = 0.005) -fold in AP patient's blood plasma compared to control subjects. CYP4F2 enzyme level in blood plasma were 2.1 (p = 0.001) times lower in AP patients. Circulating hsa-miR-24-3p was negatively associated with CYP4F2 enzyme level (Spearman correlation coefficient rank r= −0.32; p = 0.03). Moreover, patients that were taking atorvastatin, had 1.5 (p = 0.04) times higher hsa-miR-24-3p expression in blood plasma. Conclusions. Our data suggest that hsa-miR-24-3p might have an effect on CYP4F2 activity during atherosclerosis. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate whether cytochrome P450 (CYP)4F2 is involved in the exposure of vitamin K1 through a drug interaction study with ketoconazole, a CYP4F2 inhibitor, and a pharmacogenetic study with CYP4F2*3. Twenty‐one participants with different CYP4F2*3 polymorphisms were enrolled (8 for *1/*1, 7 for *1/*3, and 6 for *3/*3). All participants were treated twice daily for 5 days with 200 mg of ketoconazole or placebo. Finally, a single dose of 10 mg vitamin K1 was administered, plasma levels of vitamin K1 were measured, and its pharmacokinetics was assessed. Ketoconazole elevated the plasma levels of vitamin K1 and increased the average area under the concentration‐time curve (AUCinf) and peak concentration by 41% and 40%, respectively. CYP4F2*3 polymorphism also affected plasma levels of vitamin K1 and its pharmacokinetics in a gene dose–dependent manner. The average AUCinf value was 659.8 ng·h/mL for CYP4F2*1/*1, 878.1 ng·h/mL for CYP4F2*1/*3, and 1125.2 ng·h/mL for CYP4F2*3/*3 (P =.010). This study revealed that ketoconazole and CYP4F2*3 polymorphism substantially increased the exposure of vitamin K1 in humans. These findings provide a plausible explanation for variations in warfarin dose requirements resulting from interindividual variations in vitamin K1 exposure due to CYP4F2‐related drug interactions and genetic polymorphisms. [ABSTRACT FROM AUTHOR]

Purpose: Large inter-individual differences in warfarin maintenance dose are mostly due to the effect of genetic polymorphisms in multiple genes, including vitamin K epoxide reductase complex 1 (VKORC1), cytochromes P450 2C9 (CYP2C9), and cytochrome P450 4F2 (CYP4F2). Thus, several algorithms for predicting the warfarin dose based on pharmacogenomics data with clinical characteristics have been proposed. Although these algorithms consider these genetic polymorphisms, the formulas have different coefficient values that are critical in this context. In this study, we assessed the mutual validity among these algorithms by specifically considering racial differences. Methods: Clinical data including actual warfarin dose (AWD) of 125 Japanese patients from our previous study (Eur J Clin Pharmacol 65(11):1097–1103, 2009) were used as registered data that provided patient characteristics, including age, sex, height, weight, and concomitant medications, as well as the genotypes of CYP2C9 and VKORC1. Genotyping for CYP4F2*3 was performed by the PCR method. Five algorithms that included these factors were selected from peer-reviewed articles. The selection covered four populations, Japanese, Chinese, Caucasian, and African-American, and the International Warfarin Pharmacogenetics Consortium (IWPC). Results: For each algorithm, we calculated individual warfarin doses for 125 subjects and statistically evaluated its performance. The algorithm from the IWPC had the statistically highest correlation with the AWD. Importantly, the calculated warfarin dose (CWD) using the algorithm from African-Americans was less correlated with the AWD as compared to those using the other algorithms. The integration of CYP4F2 data into the algorithm did not improve the prediction accuracy. Conclusion: The racial difference is a critical factor for warfarin dose predictions based on pharmacogenomics. [ABSTRACT FROM AUTHOR]

Objective: To investigate the association between the CYP4F2 gene rs1558139 and rs2108622 polymorphisms and hypertension. Materials and Methods: In this meta-analysis, we searched databases for case–control studies published before May 2018 examining the associations between two polymorphic sites of the CYP4F2 gene (rs1558139 and rs2108622) and hypertension. The fixed or random effects model chosen was selected according to the heterogeneity of the studies to calculate the pooled odds ratios (OR) and corresponding 95% confidence intervals (95% CI). Results: Six articles in total were analyzed in this study; three investigated the rs1558139 polymorphism and six investigated the rs2108622 polymorphism. The pooled OR and 95% CI using the dominant model for rs1558139, and both the homozygous model and the recessive model of rs2108622 were statistically significant giving values of 0.83 (0.71–0.96), 0.83 (0.71–0.98), and 1.24 (1.07–1.44), respectively. The pooled OR and 95% CI of the rs1558139 polymorphism in the subgroup analysis based on gender were 1.25 (1.08–1.45) and 0.98 (0.85–1.13), whereas the results for the rs2108622 polymorphism were 1.03 (0.86–1.24) and 0.91 (0.72–1.14). Conclusion: Our meta-analysis demonstrates that the rs1558139 and rs2108622 single nucleotide polymorphisms of the CYP4F2 gene are associated with hypertension, with a particularly strong link between the rs1558139 polymorphism in males. [ABSTRACT FROM AUTHOR]

[Display omitted] 20-Hydroxyeicosatetraenoic acid (20-HETE) is a lipid mediator and one of the major arachidonic acid metabolites whose formation is mainly catalyzed by the enzymes cytochrome P450 (CYP) 4F2 and CYP4A11. Several studies have suggested that 20-HETE is involved in the pathogenesis of renal diseases, including diabetic nephropathy and autosomal dominant polycystic kidney disease, and we previously reported compound 1 as a dual inhibitor of CYP4A11/4F2 with therapeutic potential against renal fibrosis. Subsequent studies revealed that compound 1 , the dual CYP4A11/4F2 inhibitor, however, exhibited low selectivity over another CYP4F subtype, CYP4F22, which catalyzes ω -hydroxylation of ultra-long-chain fatty acids (ULCFAs); ULCFAs are important for the formation of acylceramides, which play a role in skin barrier formation. Therefore, we sought to develop a CYP4A11/4F2 inhibitor that would show greater CYP4A11/4F2 selectivity against CYP4F22, to avoid potential dermatological side effects. We re-evaluated a series of compounds from our 20-HETE program and identified pyrazolylpyridine derivatives containing a carboxylic acid group showing only weak CYP4F22 inhibition. Subsequent optimization studies from these derivatives led to identification of compound 15 , which showed CYP4A11/4F2 inhibition with improved selectivity against CYP4F22. Compound 15 inhibited 20-HETE production in both human and rat renal microsomes and did not inhibit ω -hydroxylation of ULCFAs in human keratinocytes. Compound 15 also significantly inhibited renal 20-HETE production after oral administration. [ABSTRACT FROM AUTHOR]

Purpose: Interpatient variation of warfarin dose requirements may be explained by genetic variations and general and clinical factors. In this scenario, diverse population-calibrated dosing algorithms, which incorporate the main warfarin dosing influencers, have been widely proposed for predicting supposed warfarin maintenance dose, in order to prevent and reduce adverse events. The aim of the present study was to evaluate the impact of the inclusion of ABCB1 c.3435C>T and CYP4F2 c.1297G>A polymorphisms as additional covariates in a previously developed pharmacogenetic-based warfarin dosing algorithm calibrated for the Brazilian population.Methods: Two independent cohorts of patients treated with warfarin (n = 832 and n = 133) were included for derivation and replication of the algorithm, respectively. Genotyping of ABCB1 c.3435C>T and CYP4F2 c.1297G>A polymorphisms was performed by polymerase chain reaction followed by melting curve analysis and TaqMan® assay, respectively. A multiple linear regression was performed for the warfarin stable doses as a dependent variable, considering clinical, general, and genetic data as covariates.Results: The inclusion of ABCB1 and CYP4F2 polymorphisms was able to improve the algorithm’s coefficient of determination (R2) by 2.6%. In addition, the partial determination coefficients of these variants revealed that they explained 3.6% of the warfarin dose variability. We also observed a marginal improvement of the linear correlation between observed and predicted doses (from 59.7 to 61.4%).Conclusion: Although our study indicates that the contribution of the combined ABCB1 and CYP4F2 genotypes in explaining the overall variability in warfarin dose is not very large, we demonstrated that these pharmacogenomic data are statistically significant. However, the clinical relevance and cost-effective impact of incorporating additional variants in warfarin dosing algorithms should be carefully evaluated. [ABSTRACT FROM AUTHOR]

Aims: Previous trials on the effectiveness of genotype‐guided warfarin dosing vs. conventional dosing have been inconclusive. We conducted a systematic review and meta‐analysis of randomized trials comparing genotype‐guided to conventional dosing strategies. Methods: PubMed and the Cochrane Library were searched up to 23 October 2017. Results: A total of 76 and 94 entries were retrieved were retrieved from PubMed and the Cochrane Library, respectively. A total of 2626 subjects in the genotype‐guided dosing (mean age 63.3 ± 5.8 years; 46% male) and 2604 subjects in the conventional dosing (mean age 64.7 ± 6.1 years; 46% male) groups (mean follow‐up duration 64 days) from 18 trials were included. Compared with conventional dosing, genotype‐guided dosing significantly shortened the time to first therapeutic international normalized ratio (INR) (mean difference 2.6 days, standard error 0.3 days; P < 0.0001; I2 0%) and time to first stable INR (mean difference 5.9 days, standard error 2.0 days; P < 0.01; I2 94%). Genotype‐guided dosing also increased the time in therapeutic range (mean difference 3.1%, standard error 1.2%; P < 0.01; I2 80%) and reduced the risks of both excessive anticoagulation, defined as INR ≥4 [risk ratio (RR) 0.87; 95% confidence interval (CI) 0.78, 0.98; P < 0.05; I2: 0%), and bleeding (RR 0.82; 95% CI 0.69, 0.98; P < 0.05; I2 31%). No difference in thromboembolism (RR 0.84; 95% CI 0.56, 1.26; P = 0.40; I2 0%) or mortality (RR 1.16; 95% CI 0.46, 2.91; P = 0.76; I2 0%) was observed between the two groups. Conclusions: Genotype‐guided warfarin dosing offers better safety with less bleeding compared with conventional dosing strategies. No significant benefit on thromboembolism or mortality was evident. [ABSTRACT FROM AUTHOR]

This study aims to investigate in in vivo and in vitro models of nonalcoholic fatty liver disease (NAFLD) the enzymatic metabolism of α-tocopherol (vitamin E) and its relationship to vitamin E-responsive genes with key role in the lipid metabolism and detoxification of the liver. The experimental models included mice fed a high-fat diet combined or not with fructose (HFD+F) and HepG2 human hepatocarcinoma cells treated with the lipogenic agents palmitate, oleate or fructose. CYP4F2 protein, a cytochrome P-450 isoform with proposed α-tocopherol ω-hydroxylase activity, decreased in HFD and even more in HFD+F mice liver; this finding was associated with increased hepatic levels of α-tocopherol and decreased formation of the corresponding long-chain metabolites α-13-hydroxy and α-13-carboxy chromanols. A decreased expression was also observed for PPAR-γ and SREBP-1 proteins, two vitamin E-responsive genes with key role in lipid metabolism and CYP4F2 gene regulation. A transient activation of CYP4F2 gene followed by a repression response was observed in HepG2 cells during the exposure to increasing levels of the lipogenic and cytotoxic agent palmitic acid; such gene repression effect was further exacerbated by the co-treatment with oleic acid and α-tocopherol and was also observed for PPAR-γ and the SREBP isoforms 1 and 2. Such gene response was associated with increased uptake and ω-hydroxylation of α-tocopherol, which suggests a minor role of CYP4F2 in the enzymatic metabolism of vitamin E in HepG2 cells. In conclusion, the liver metabolism and gene response of α-tocopherol are impaired in experimental NAFLD. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate the contributions of non-genetic and genetic factors on the variability of stable warfarin doses in Thai patients. Methods: A total of 250 Thai patients with stable warfarin doses were enrolled in the study. Demographics and clinical data, e.g., age, body mass index, indications for warfarin and concomitant medications, were documented. Four single nucleotide polymorphisms in the VKORC1 − 1639G > A, CYP2C9*3, CYP4F2 rs2108622, and UGT1A1 rs887829 genes were detected from gDNA using TaqMan allelic discrimination assays. Results: The patients with variant genotypes of VKORC1 − 1639G > A required significantly lower warfarin stable weekly doses (SWDs) than those with wild-type genotype ( p < 0.001). Similarly, the patients with CYP2C9*3 variant allele required significantly lower warfarin SWDs than those with homozygous wild-type ( p = 0.006). In contrast, there were no significant differences in the SWDs between the patients who carried variant alleles of CYP4F2 rs2108622 and UGT1A1 rs887829 as compared to wild-type allele carriers. Multivariate analysis, however, showed that CYP4F2 rs2108622 TT genotype accounted for a modest part of warfarin dose variability (1.2%). In contrast, VKORC1 − 1639G > A, CYP2C9*3, CYP4F2 rs2108622 genotypes and non-genetic factors accounted for 51.3% of dose variability. Conclusions: VKORC1 − 1639G > A, CYP2C9*3, and CYP4F2 rs2108622 polymorphisms together with age, body mass index, antiplatelet drug use, amiodarone use, and current smoker status explained 51.3% of individual variability in stable warfarin doses. In contrast, the UGT1A1 rs887829 polymorphism did not contribute to dose variability. [ABSTRACT FROM AUTHOR]

CYP4F11, together with CYP4F2, plays an important role in the synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE) from arachidonic acid. We identified 21 variants by whole exome sequencing, including 4 non-synonymous variants in Korean subjects. The proteins of the wild-type CYP4F11 and the four coding variants (C276R, D315N, D374Y, and D446N) were expressed in Escherichia coli DH5α cells and purified to give cytochrome P450-specific carbon monoxide difference spectra. Wild-type CYP4F2 was also expressed and purified to compare its activity with the CYP4F11 wild-type. Wild-type CYP4F11 exhibited the highest maximal clearance for erythromycin N -demethylase activity followed by the variants D374Y, D446N, C276R, and D315N. In particular, the CYP4F11 D315N protein showed about 50% decrease in intrinsic clearance compared to the wild type. The ability of wild-type CYP4F11 and the variants to synthesize 20-HETE from arachidonic acid was similar; the CYP4F11 D315N variant, however, showed only 68% of wild-type activity. Furthermore, the ability of CYP4F2 to synthesize 20-HETE was 1.7-fold greater than that of CYP4F11. Overall, our results suggest that the metabolism of CYP4F11 substrates may be reduced in individuals carrying the CYP4F11 D315N genetic variant and individuals carrying the common D446N CYP4F11 variant likely exhibit comparable 20-HETE synthesis as individuals expressing wild-type CYP4F11. [ABSTRACT FROM AUTHOR]

The rs2108622 genetic variant in CYP4F2 gene is associated with cardiovascular diseases and response to warfarin treatment. Objective: To determine the frequency of CYP4F2rs2108622 alleles and genotypes among Jordanian population. Methods: The genomic DNA was extracted from 90 healthy Jordanian volunteers and the frequency of CYP4F2 rs2108622 was determined by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism assays (RFLP). Results: The frequency (95% confidence interval) of rs2108622 C and T allele was 0.55 (0.48-0.62) and 0.45 (0.38- 0.52), respectively. The CYP4F2rs2108622 genotype frequencies among healthy Jordanian volunteers were wild CC (0.27, 95% CI 0.18-0.36), heterozygote CT (0.55, 95% CI 0.45-0.65) and homozygote TT (0.18, 95% CI 0.10-0.26). The frequency of rs2108622C>T was high among the Jordanian population which was similar to Middle Eastern populations but higher than European Caucasians, Africans and Asians. Conclusion: Jordanian ethnic population has high frequency of CYP4F2rs2108622 genetic variant which may play a major role in the predisposition to cardiovascular diseases and inter-individual variation in warfarin response among Jordanians. [ABSTRACT FROM AUTHOR]

The expression of CYP4F2, a form of cytochrome P-450 with proposed role in α-tocopherol and long-chain fatty acid metabolism, was explored in HepG2 and HepaRG human hepatocytes during ethanol toxicity. Cytotoxicity, ROS production, and JNK and ERK1/2 kinase signaling increased in a dose and time-dependent manner during ethanol treatments; CYP4F2 gene expression decreased, while other CYP4F forms, namely 4F11 and 12, increased along with 3A4 and 2E1 isoforms. α-Tocopherol antagonized the cytotoxicity and CYP4F2 gene repression effect of ethanol in HepG2 cells. Ethanol stimulated the tocopherol-ω-hydroxylase activity and the other steps of vitamin E metabolism, which points to a minor role of CYP4F2 in this metabolism of human hepatocytes. PPAR-γ and SREBP-1c followed the same expression pattern of CYP4F2 in response to ethanol and α-tocopherol treatments. Moreover, the pharmacological inhibition of PPAR-γ synergized with ethanol in decreasing CYP4F2 protein expression, which suggests a role of this nuclear receptor in CYP4F2 transcriptional regulation. In conclusion, ethanol toxicity modifies the CYP expression pattern of human hepatic cells impairing CYP4F2 transcription and protein expression. These changes were associated with a lowered expression of the fatty acid biosynthesis regulators PPAR-γ and SREBP-1c, and with an increased enzymatic catabolism of vitamin E. CYP4F2 gene repression and a sustained vitamin E metabolism appear to be independent effects of ethanol toxicity in human hepatocytes. [ABSTRACT FROM AUTHOR]

Background: Several studies have demonstrated an association between body mass index (BMI) and warfarin therapeutic dose, but none evaluated the association of BMI with the clinically important outcome of major bleeding in a community setting. To address this evidence gap, we conducted a case-control study to evaluate the association between BMI and major bleeding risk among patients receiving warfarin.Methods: We used a case-control study design to evaluate the association between obesity (BMI >30.0 kg/m2) and major bleeding risk among 265 cases and 305 controls receiving warfarin at Group Health, an integrated healthcare system in Washington State. Multivariate logistic regression was used to adjust for potential confounders derived from health plan records and a self-report survey. In exploratory analyses we evaluated the interaction between genetic variants potentially associated with warfarin bleeding (CYP2C9, VKORC1, and CYP4F2) and obesity on the risk of major bleeding.Results: Overall, the sample was 55% male, 94% Caucasian, and mean age was 70 years. Cases and controls had an average of 3.4 and 3.7 years of warfarin use, respectively. Obese patients had significantly lower major bleeding risk relative to non-obese patients (odds ratio [OR] 0.60, 95% confidence interval [CI] 0.39-0.92). The OR was 0.56 (95% CI 0.35-0.90) in patients with ≥1 year of warfarin use, and 0.78 (95% CI 0.40-1.54) in patients with <1 year of warfarin use. An exploratory analysis indicated a statistically significant interaction between CYP4F2*3 genetic status and obesity (P = .049), suggesting a protective effect of obesity on the risk of major bleeding among those wild type for CYP4F2*3, but not among variants.Conclusions: Our findings suggest that BMI is an important clinical factor in assessing and managing warfarin therapy. Future studies should confirm the major bleeding associations, including the interaction between obesity and CYP4F2*3 status identified in this study, and evaluate potential mechanisms. [ABSTRACT FROM AUTHOR]

Cytochrome 4F2 (CYP4F2) is a major arachidonic acid-metabolizing enzyme which produces 20-Hydroxyeicosatetraenoic acid (20-HETE). It is found that 20-HETE is involved in the pathophysiology of many diseases, including diabetes mellitus. The genetic variants of CYP4F2 can affect its enzymatic activity as well as the 20-HETE production. Our aim with this paper was to find out the genotype frequency of CYP4F2 rs2108622 C>T , the major functional variant in the CYP4F2 gene, among a sample of type II diabetes (TIIDM) and its effects on diabetes complications and lipid profile. The CYP4F2 rs2108622 variant was genotyped among 90 healthy volunteers and 90 TIIDM patients that attending the University of Jordan Hospital, using the DNA Sanger sequencing method. The data of lipid profile and diabetes complications were obtained from the electronic records available in the hospital. We found that the frequency of CYP4F2 rs2108622C>T variant is significantly (P = 0.02) lower among TIIDM patients in comparison to healthy subjects using both co-dominant and dominant genotyping models. In addition, the CYP4F2 rs2108622 T/T genotype was significantly (P = 0.02) more frequent among TIIDM patients with retinopathy complications (OR=4.36, CI: 1.32–14.37). Lastly, the CYP4F2 rs2108622C>T variant was not associated (P > 0.05) with the glycaemic and lipid profile of patients. It can be concluded from this study that the frequency of CYP4F2 rs2108622 T/T genotype is lower among TIIDM, but this genotype is associated with an increased risk of retinopathy complications in patients of Jordanian origin. Further studies with a larger sample size are needed to validate the findings of this study. • CYP4F2 rs210622 allele is more frequent among type 2 diabetic patients. • CYP4F2 rs210622 allele is associated with retinopathy complication of diabetes. • CYP4F2 rs210622 allele is not associated with the lipid profile among diabetic patients. [ABSTRACT FROM AUTHOR]

Background: Warfarin is a widely prescribed anticoagulant with narrow therapeutic window for thromboembolic events. Warfarin displays large individual variability in dose requirements. The purpose of this study is to assess the contribution of patient-specific and genetic risk factors to dose requirements of patients on either high or low warfarin maintenance dose in Ghana. Blood samples were collected from 141 (62 males, 79 females) Ghanaian patients on stable warfarin dose to determine their INR. Influence of patient specific factors and gene variations within VKORC1, CYP2C9 and CYP4F2 were determined in patients on either high or low warfarin maintenance dose. Results: One hundred and forty-one patients took part in the study with 79 (56%) participants being Female. The median age of the study participants was 48 years [IQR: 34-58]. The median duration for patients to be on warfarin therapy was 24 months [IQR: 10-72]. Majority of the study participants (80.9%, n = 114) did not have any side effects to warfarin. CYP2C9*2 and CYP2C9*3 variant alleles were not detected. VKORC1 variant allele was observed at 6% and CYP4F2 variant allele was observed at 41%. Duration of patients on warfarin therapy was marginally associated with high warfarin dose (adjusted OR = 1.01 [95% CI 1.00-1.02], p = 0.033) while the odds of heterozygous individuals (G/A) for VKORC1 gene to have high warfarin dose compared to persons with homozygous (G/G) (adjusted OR = 0.06 [95% CI 0.01-0.63], p = 0.019). Age, gender, diagnosis, presence of side effects and other medications were not associated with warfarin dose (p = 0.05). Conclusion: This study provides data on VKORC1 and CYP4F2 variants among an indigenous African population. Duration of patients on warfarin therapy was marginally associated with high warfarin dose. CYP2C9*2 and *3 variants were not detected and may not be the most important genetic factor for warfarin maintenance dose among Ghanaians. [ABSTRACT FROM AUTHOR]

Background: Despite its shortcomings, warfarin is still the most commonly prescribed anticoagulant to prevent thromboembolism in children. In adults, numerous studies confirmed the robust relationship between warfarin maintenance doses and single nucleotide polymorphisms of cytochrome P450 2C9 (CYP2C9), vitamin K epoxide reductase (VKORC1), and cytochrome P450 4F2 (CYP4F2). However, their effect in children still remains to be determined. The primary objective of the present systematic review and meta-analysis is to assess the effect of genotypes of CYP2C9, VKORC1, and CYP4F2 on warfarin maintenance dose in children. Methods/design: A comprehensive literature review search using the OVID platform will be conducted by a specialized librarian, without language restrictions (i.e., MEDLINE/EMBASE/Cochrane Central Register of Controlled Trials), and all abstracts will be reviewed by two authors. Data abstraction from each eligible study will be extracted individually by two authors (MT and TK), and disagreements will be resolved through discussion with a third person (SI). Critical appraisal of the included analysis of the primary objective will follow the Newcastle-Ottawa Scale, in addition to the Strengthening the Reporting of Genetic Association study (STREGA) statement, and data reporting will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. For the meta-analysis, the presence vs. absence of each genetic polymorphism will be pursued, respectively, using a random effect model with effect size expressed as a mean difference plus 95 % confidence interval. Discussion: Our study will provide a comprehensive systematic review and meta-analysis on the potential effects of CYP2C9, VKORC1, or CYP4F2 on the warfarin maintenance dose in children, exploring the feasibility of the development of pharmacogenetic-guided warfarin dosing algorithm for children on oral vitamin K antagonists. Systematic review registration: The review has been registered with PROSPERO (registration number CRD42015016172). [ABSTRACT FROM AUTHOR]

Warfarin is an oral anticoagulant with significant interpatient variability in dosage. A large number of studies have confirmed that the individual warfarin dose is mainly affected by the cytochrome P450 complex subunit 2C9 and vitamin K epoxide reductase complex subunit 1. However, the association between cytochrome P450 4F2 (CYP4F2) gene polymorphisms and warfarin dosage in the Asian population remains controversial. To investigate the impact of the CYP4F2 polymorphism rs2108622 (p.V433M) on warfarin dose requirement, a systematic review and meta-analysis were conducted. According to the strict inclusion and exclusion criteria set, a comprehensive literature search was performed, and the studies published before August 5, 2015 were searched for in PubMed, EMBASE and the China National Knowledge Infrastructure databases. The references were checked by two independent reviewers. The association between the warfarin maintenance dose and CYP4F2 polymorphism was analyzed. Twenty-two studies were included in the meta-analysis. Compared with the CYP4F2 genotype CC, carriers of the CT and TT genotypes required a 9 [95% confidence interval (CI): 6.0-13.0] and 20% (95% CI, 13.0-27.0) higher warfarin dose, respectively. In the combined analysis, T carriers (CT+TT) required an 11% (95% CI, 8.0-14.0) higher warfarin dose compared to the CC genotype. In addition, there was a 10% (95% CI, 5.0-15.0) higher warfarin dose in TT carriers compared to the CT genotype (all P<0.05). The results of the meta-analysis suggest that the effects of the CYP4F2 polymorphism on individual warfarin dose have a statistically significant difference, and the effect degree is variable in the subgroups. Further studies are expected to explore whether the pharmacogenetics model including the CYP4F2 polymorphism can strengthen the prediction of warfarin dose. [ABSTRACT FROM AUTHOR]

Objective The p.V433M in cytochrome P450 4F2 (rs2108622, CYP4F2*3) is associated with a higher warfarin dose and lower risk of hemorrhage among European Americans. We evaluate the influence of CYP4F2*3 on warfarin dose, time to target international normalized ratio ( INR), and stable dose, proportion of time spent in target range ( PTTR), as well as the risk of overanticoagulation and hemorrhage among European and African Americans. Design CYP4F2*3 was genotyped in 1238 patients initiated on warfarin in a prospective inception cohort. Multivariable linear regression was used to assess warfarin dose and PTTR; proportional hazards analysis was performed to evaluate time to target INR and stable dose, overanticoagulation, and hemorrhage. Setting Two outpatient anticoagulation clinics. Participants A total of 1238 anticoagulated patients. Outcomes Warfarin dose (mg/day), time to target INR and stable dose, PTTR, overanticoagulation ( INR more than 4), and major hemorrhage. Results Minor allele frequency for the CYP4F2*3 variant was 30.3% among European Americans and 8.4% among African Americans. CYP4F2*3 was associated with higher dose among European Americans but not African Americans. Compared to CYP4F2*1/ *1, *1/ *3 was associated with a statistically nonsignificant increase in dose (4.5%, p=0.22) and *3/ *3 was associated with a statistically significant increase in dose (13.2%, p=0.02). CYP4F2 genotype did not influence time to target INR, time to stable dose, or PTTR in either race group. CYP4F2*3/ *3 was associated with a 31% lower risk of over anticoagulation (p=0.06). Incidence of hemorrhage was lower among participants with CYP4F2 *3/ *3 compared with *1/ *3 or *1/ *1 (incidence rate ratio = 0.45, 95% confidence interval 0.14-1.11, p=0.09). After controlling for covariates, CYP4F2 *3/ *3 was associated with a 52% lower risk of hemorrhage, although this was not statistically significant (p=0.24). Conclusion Possession of CYP4F2*3 variant influences warfarin dose among European Americans but not African Americans. The CYP4F2-dose, CYP4F2-overanticoagulation, and CYP4F2-hemorrhage association follows a recessive pattern with possession of CYP4F2*3/ *3 genotype likely demonstrating a protective effect. These findings need further confirmation. [ABSTRACT FROM AUTHOR]

Cytochrome P 450-derived long-chain metabolites are gaining increasing interest as bioactive intermediates of vitamin E. In this study we first report on the HPLC-ECD and GC–MS analysis in human serum of the earliest metabolite of this vitamin, namely α-(13'-hydroxy)-6-hydroxychroman (α-13'-OH). The two chromatographic procedure are sensitive enough (LOQ of 10 nM) to measure α-13'-OH after hexane extraction of 1 ml of sample obtained from healthy volunteers supplemented for 1-week with 1000 IU/d (671 mg/d) RRR -α-tocopherol. The observed concentrations ranged between 15 and 50 nM, with minor differences between fasting and 4-hr post-meal state. Baseline (non-supplemented state) levels of 7.2±1.6 nM were observed extracting higher volumes of serum. Biological effects of α-13'-OH investigated for the first time in RAW264.7 murine macrophages involved transcriptional control of inflammatory cytokines, and transcriptional and functional regulation of COX2 and iNOS enzymes in response to lipopolysaccharides. In conclusion, here we present the first quantitative evaluation of serum α-13'-OH also providing early evidence of the anti-inflammatory potential of this metabolite that is worth of further investigation in the area of functional and nutraceutical implications of vitamin E metabolism. [ABSTRACT FROM AUTHOR]

Background A high intake of omega-3 polyunsaturated fatty acids (ω-3 PUFAs), has been associated with reduced levels of blood pressure (BP). Their antihypertensive action may be due to the reduction of the ω-6/ω-3 ratio and the resulting competitive effect of ω-3 as compared to arachidonic acid (an ω-6 PUFA) as a substrate of cytochrome P450 (CYP450) enzymes involved in the production of vasoactive mediators. Some functional polymorphisms (SNPs), in genes which encode for the same enzymes, were associated with hypertension and ischemic stroke in the Malmö Diet and Cancer (MDC), a Swedish urban-based longitudinal study. The aim of this study was to evaluate the effect of the intake of different types of PUFAs on BP change over time (Δ-BP; mean follow-up 16.6 ± 1.5 years; n = 3.550 with complete phenotypic data), also considering the interaction with SNPs in genes involved in their metabolism via CYP450. Methods PUFA intakes were collected by a modified diet history method, and functional SNPs in CYP4F2 , CYP4A11 , CYP2J2 and EPHX2 were genotyped by Taqman. Result We did not find any overall association between ω-6 and ω-3 PUFA intakes, or their ratio, with Δ-BP but observed an interaction between CYP4F2 V433M genotype and total omega-3, α-linolenic acid and linoleic/α-linolenic ratio, so that a higher ω-3 PUFA intake was significantly associated with a more pronounced BP decrease over time in subjects with the 433VV genotype (−0.041 ± 0.018 mmHg/year; p = 0.024; p -interaction = 0.031) Conclusions Our data do not support a major role of ω-6 or ω-3 PUFA intakes on BP change over time, but suggest a possible interaction of ω-3 PUFA with the CYP4F2 V433M. [ABSTRACT FROM AUTHOR]

Introduction Warfarin is characterized by a large inter-individual variability in dosage requirement. This study aimed to analyze the contribution of the CYP4F2 genetic polymorphism and plasma vitamin K concentration on the warfarin pharmacodynamics in patients and to clarify the plasma vitamin K concentration affecting warfarin sensitivity index in rats. Materials and Methods Genetic analyses of selected genes were performed and plasma concentrations of warfarin, vitamin K1 (VK1) and menaquinone-4 (MK-4) were measured in 217 Japanese patients. We also assessed the association of plasma VK1 and MK-4 concentrations with the warfarin sensitivity index (INR/Cp) in rats. Results Patients with the CYP4F2 (rs2108622) TT genotype had significantly higher plasma VK1 and MK-4 concentrations than those with CC and CT genotypes. The multiple linear regression model including VKORC1, CYP4F2, and CYP2C9 genetic variants, age, and weight could explain 42% of the variability in warfarin dosage. The contribution of CYP4F2 polymorphism was estimated to be 2.2%. In contrast, plasma VK1 and MK-4 concentrations were not significantly associated with warfarin dosage in patients. Nevertheless, we were able to demonstrate that the warfarin sensitivity index was attenuated and negatively correlated with plasma VK1 concentration by the oral administration of VK1 in rats, as it resulted in a higher VK1 concentration than that in patients. Conclusions The plasma VK1 and MK-4 concentrations are significantly influenced by CYP4F2 genetic polymorphism but not associated with warfarin therapy at the observed concentration in Japanese patients. The CYP4F2 polymorphism is poorly associated with inter-individual variability of warfarin dosage requirement. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to determine the influence of CYP2C9, VKORC1, CYP4F2, and GGCX genetic polymorphisms on mean daily dose of acenocoumarol in South Indian patients and to develop a new pharmacogenetic algorithm based on clinical and genetic factors. Methods: Patients receiving acenocoumarol maintenance therapy ( n = 230) were included in the study. Single nucleotide polymorphisms (SNP) of CYP2C9, VKORC1, CYP4F2, and GGCX were genotyped by real-time polymerase chain reaction (RT-PCR) method. Results: The mean daily acenocoumarol maintenance dose was found to be 3.7 ± 2.3 (SD) mg/day. The CYP2C9 *1*2, CYP2C9 *1*3, and CYP2C9 *2*3 variant genotypes significantly reduced the dose by 56.7 % (2.0 mg), 67.6 % (1.6 mg), and 70.3 % (1.5 mg) than wild-type carriers 4.1 mg, p < 0.0001. The genetic variants of CYP2C9 and GGCX (rs11676382) were found to be associated with lower acenocoumarol dose, whereas CYP4F2 (rs2108622) was associated with higher doses. Age, body mass index (BMI), variation of CYP2C9, VKORC1, CYP4F2, and GGCX were the major determinants of acenocoumarol maintenance dose, accounting for 61.8 % of its variability (adjusted r = 0.615, p < 0.0001). Among the VKORC1 variants, rs9923231 alone contributed up to 28.6 % of the acenocoumarol dose variation. Conclusion: VKORC1 rs9923231 polymorphism had the highest impact on acenocoumarol daily dose. A new pharmacogenetic algorithm was established to determine the acenocoumarol dose in South Indian population. [ABSTRACT FROM AUTHOR]

Objective Warfarin represents the most commonly prescribed oral anticoagulants, which functions as an antagonist of vitamin K, an essential factor of blood coagulation cascade. Warfarin has a narrow therapeutic index. An insufficient dose can cause failure of antithrombotic effect, and an overdose increases a risk of bleeding. It is known that variability in two genes ( CYP2C9 and VKORC1) has a significant effect on individual response to warfarin dose. These polymorphisms influence more than one-third of known warfarin dose effect. Pharmacogenetics of warfarin is less affected by polymorphisms in the other genes such as CYP4F2 , CYP2C19, and GGCX. Material and Methods The frequency of selected single nucleotide polymorphisms including CYP2 C9*2 (430 C>T), CYP2 C9*3 (1075 A> C), VKORC1*2 (−1639 G> A/1173 C> T), VKORC1*3 (3730 G> A), GGCX (12970 C> G, 8016 G> A), CYP2 C19*2 (681 G> A), and CYP4 F2*3 (1297 G> A) was tested in a control group consisting of 112 randomly selected individuals by allele-specific real-time PCR, restriction fragment length polymorphism, and bidirectional PCR allele-specific amplification. Results and Discussion The current results were statistically evaluated and compared with other populations. The presented results in Slovak population which is in Hardy- Weinberg equilibrium were compared with the prevalence in different countries. The incidence of selected polymorphisms in Slovak population correlates with Caucasians. [ABSTRACT FROM AUTHOR]

Cytochrome P450 (CYP) 4A and 4F enzymes metabolize arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). Although CYP4A-derived 20-HETE is known to have prohypertensive and proangiogenic properties, the effects of CYP4F-derived metabolites are not well characterized. To investigate the role of CYP4F2 in vascular disease, we generated mice with endothelial expression of human CYP4F2 (Tie2-CYP4F2-Tr). LC/MS/MS analysis revealed 2-fold increases in 20-HETE levels in tissues and endothelial cells (ECs), relative to wild-type (WT) controls. Tie2-CYP4F2-Tr ECs demonstrated increases in growth (267.1±33.4 vs. 205.0±13% at 48 h) and tube formation (7.7±1.1 vs. 1.6±0.5 tubes/field) that were 20-HETE dependent and associated with up-regulation of prooxidant NADPH oxidase and proangiogenic VEGF. Increases in VEGF and NADPH oxidase levels were abrogated by inhibitors of NADPH oxidase and MAPK, respectively, suggesting the possibility of crosstalk between pathways. Interestingly, IL-6 levels in Tie2-CYP4F2-Tr mice (18.6±2.7 vs. 7.9±2.7 pg/ml) were up-regulated via NADPH oxidase- and 20-HETE-dependent mechanisms. Although Tie2-CYP4F2-Tr aortas displayed increased vasoconstriction, vasorelaxation and blood pressure were unchanged. Our findings indicate that human CYP4F2 significantly increases 20-HETE production, CYP4F2-derived 20-HETE mediates EC proliferation and angiogenesis via VEGF- and NADPH oxidase-dependent manners, and the Tie2-CYP4F2-Tr mouse is a novel model for examining the pathophysiological effects of CYP4F2-derived 20-HETE in the vasculature. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine how genetic variants contribute to warfarin dosing variability when non-genetic factors are controlled. Thirty healthy subjects were subjected to a warfarin dosing algorithm with daily international normalized ratio (INR) measurements to INR ≥ 2.0, then off warfarin to INR ≤ 1.2. The primary outcome was the cumulative dose required to achieve INR ≥ 2.0 for 2 consecutive days. CYP2C9 (p=0.004) and VKORC1 (p=0.02) variant carriers required lower cumulative doses, and CYP4F2 carriers required higher doses (p=0.04). Subjects with variants in both CYP2C9 and VKORC1 required fewer days to reach INR ≥ 2.0 than wild-type subjects or those with variants in CYP2C9 or VKORC1 (p=0.01). Genetic contribution to dose variability (~62%) was greater than previously reported, suggesting that uncontrolled clinical variables influence the effect of these variants. In conclusion, genotype-guided warfarin-dosing algorithms may rely more on genetic variables in healthier individuals than in patients with clinical confounders. ClinicalTrials.gov Identifier: NCT01520402 [ABSTRACT FROM AUTHOR]

Abstract: Purpose: The aim of the present study was to investigate the genetic variability of VKORC1, CYP2C9 and CYP4F2 genes in patients who required a very low and high warfarin dose, in order to identify novel variants that could help to explain the particular extreme dose requirements. Methods: Among patients followed and treated with warfarin at the Center of Haemostasis and Thrombosis of the PTV, we selected twelve patients showing a high divergence from warfarin standard doses required to achieve the therapeutic effect. All VKORC1, CYP2C9 and CYP4F2 coding regions, 3’ and 5’ UTR and exon/intron boundaries were analyzed by direct sequencing. Results: The 1173T and -1639A allele variants in VKORC1 gene, associated with warfarin sensitivity, were present, as expected, mostly in low dose patients while 3730A allele, linked to warfarin resistance, has been found only in high dose patients. Interestingly, we found that three out of six low dose subjects presented CYP2C9*3/*3 homozygous genotype, very rare in Caucasians. Besides these common polymorphisms, we identified 5 SNPs in CYP2C9 gene and 19 SNPs in CYP4F2 gene. Among these, all polymorphisms identified in CYP2C9 gene were present only in low dose patients and three of them resulted in linkage with CYP2C9*2 and CYP2C9*3. Regarding CYP4F2 SNPs, we did not observe differences between the high and low dose patients. At the end, the whole sequencing did not reveal any novel polymorphism/mutation. Conclusion: Further studies are required to identify other genetic factors contributing to extreme warfarin requirement. [Copyright &y& Elsevier]

Purpose: The aim of this study was to assess the pharmacokinetics and pharmacodynamics of warfarin associated with genetic polymorphisms in VKORC1, CYP2C9, CYP2C19, and CYP4F2 in Indonesian patients treated with low-dose warfarin. Methods: Genotyping of VKORC1, CYP2C9, CYP2C19, and CYP4F2 was carried out in 103 patients treated with a daily dose of 1-2 mg warfarin, 89 of whom were treated with a fixed daily dose of warfarin (1 mg). The plasma concentrations of S- and R-warfarin and S- and R-7-hydroxywarfarin were used as pharmacokinetic indices, while prothrombin time expressed as the international normalized ratio (PT-INR) was used as a pharmacodynamic index. Results: In patients treated with a fixed daily dose of warfarin (1 mg), a higher PT-INR was associated with VKORC1-1639 AA [median 1.35; interquartile range (IQR) 1.21-1.50] than with the GA (1.18; IQR 1.12-1.32; p < 0.01) and GG (1.02; IQR = 1.02-1.06; p < 0.01) polymorphisms, and with CYP2C9*1/*3 (1.63; IQR 1.45-1.85) compared to *1/*1 (1.23; IQR 1.13-1.43; p < 0.05). The S-warfarin concentration was significantly higher in patients with CYP2C9*1/*3 than in those with *1/*1 ( p < 0.05). With low-dose warfarin administration, there was no significant difference in the concentrations of warfarin metabolites among any of the genotype variants. The genotype variations of CYP2C19 and CYP4F2 were not significantly associated with the PT-INR. Conclusion: For low-dose warfarin treatment, the VKORC1-1639 G > A and CYP2C9 genotype variations affected the pharmacokinetics and pharmacodynamics of warfarin, while we could not find significant effects of CYP4F2 or CYP2C19 genotype variations on warfarin (metabolite) concentrations or PT-INR. [ABSTRACT FROM AUTHOR]

What is known and Objective: Coumarin derivatives such as acenocoumarol represent the therapy of choice for the long-term treatment and prevention of thromboembolic diseases. Many genetic, clinical and demographic factors have been shown to influence the anticoagulant dosage. Our aim was to investigate the contribution of genetic and non-genetic factors to variability in response to acenocoumarol in Moroccan patients. Methods: Our study included 114 adult Moroccan patients, receiving long-term acenocoumarol therapy for various indications. Tests for VKORC1 -1639G>A promoter polymorphism (rs9923231), CYP2C9*2 rs1799853, CYP2C9*3 rs1057910, and CYP4F2 rs2108622 alleles were undertaken using Taq Man® Pre-Developed Assay Reagents for allelic discrimination. The statistical analysis was performed using the SAS V9 statistical package. Results and Discussion: Genotyping showed that the allele frequencies for the SNPs studied were no different to those found in Caucasians population. A significant association was observed between the weekly maintenance dose and the VKORC1 ( P = 0·0027) and CYP2C9 variant genotypes ( P = 0·0082). A final multivariate regression model that included the target International Normalized Ratio, VKORC1 and CYP2C9 genotypes explained 36·2% of the overall interindividual variability in acenocoumarol dose requirement. What is new and Conclusion: Our study shows large interindividual variability in acenocoumarol maintenance dose requirement in our population. VKORC1 and CYP2C9 variants significantly affected acenocoumarol dose, in-line with results in other populations. For the Moroccan population, the SNPs that have the largest effect on acecoumarol dose are CYP2C9 rs1799853, CYP2C9 rs1057910 and VKORC1 rs9923231. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Multiple warfarin pharmacogenetic algorithms have been confirmed to predict warfarin dose more accurately than clinical algorithm or the fixed-dose approach. However, their performance has never been objectively evaluated in patients under low intensity warfarin anticoagulation, which is optimal for prevention of thromboembolism in Asian patients. Material and methods: We sought to compare the performances of 8 eligible pharmacogenetic algorithms in a cohort of Chinese patients (n=282) under low intensity warfarin anticoagulation with target international normalized ratio (INR) ranged from 1.6 to 2.5. The performance of each algorithm was evaluated by calculating the percentage of patients whose predicted dose fell within 20% of their actual therapeutic dose (percentage within 20%), and the mean absolute error (MAE) between each predicted dose and actual stable dose. Results: In the entire cohort, the pharmacogenetic algorithms could predict warfarin dose with the average MAE of 0.87±0.17mg/day (0.73-1.17mg/day), and the average percentage within 20% of 43.8%±8.1% (29.1% - 52.1%). By pairwise comparison, warfarin dose prediction was significantly more accurate with the algorithms derived from Asian patients (48.6% – 50.0%) than those from Caucasian patients (29.1% - 39.7%; odds ratio [OR]: 1.61-3.36, p ≤0.02). Algorithms with additional covariates of INR values or CYP4F2*3 performed better than those without the covariates (adding INR: OR: 1.71 (1.08-2.72), p =0.029; adding CYP4F2*3: OR: 2.67(1.41-5.05), p =0.004). When the patients were stratified according to the dose range, the algorithms from Caucasian and racially mixed populations tended to perform better in higher dose group (≥4.5mg/day), and algorithms from Asian populations performed better in intermediate dose group (1.5-4.5mg/day). None of the algorithms performed well in lower dose group (≤1.5mg/day). Conclusions: No eligible pharmacogenetic algorithm could perform the best for all dosing range in the Chinese patients under low intensity warfarin anticoagulation. Construction of a refinement pharmacogenetic algorithm integrating 3 genotypes (CYP2C9, VKORC1 and CYP4F2) and INR data should be warranted to improve the warfarin dose prediction in such patients. [Copyright &y& Elsevier]

What is known and Objective: Polymorphisms in the gene encoding CYP4F2 may partly explain the variability in warfarin maintenance dose by altering the metabolism of vitamin K. To determine the genetic factors that cause large inter-patient variability in warfarin efficacy, we investigated the relationship between serum warfarin concentration and CYP4F2 V433M (1347C>T, rs2108622) polymorphism in Japanese subjects. Methods: Gene variations in VKORC1, CYP2C9 and CYP4F2 were analysed in 126 Japanese patients treated with warfarin. The daily dosage of warfarin, concentration of S- and R-warfarin in plasma, and prothrombin time international normalized ratio (PT-INR) was used as the pharmacokinetic and pharmacodynamic indices. Results and Discussion: The maintenance dose of warfarin was larger in the CYP4F2 1347 CT genotype group (3·59 ± 1·80 mg/day, P = 0·027) than in the CYP4F2 CC genotype group (2·88 ± 1·00 mg/day). CYP4F2 1347C>T polymorphism significantly affected serum R-warfarin concentration when the VKORC1-1639 genotypes are AG and GG. What is new and Conclusion: Although a significant inter-patient difference in warfarin maintenance dose was observed between the CYP4F2 CC and CT genotypes, serum S-warfarin concentration was not significantly different between them. An effect of CYP4F2 V433M polymorphism on warfarin maintenance dose was observed but was relatively small when compared to the effects of CYP2C9 and VKOR polymorphism. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Warfarin is a commonly used oral anticoagulant and the dosage is individually adjusted on the basis of the international normalized ratio (INR) monitoring. It is well known that gene polymorphisms of CytochromeP450 (CYP) 2C9 gene and the vitamin K epoxide reductase complex 1 (VKORC1) were significantly associated with warfarin dose. However, the association between Cytochrome P450 4F2 (CYP4F2) polymorphism and warfarin dose requirement is still controversial. This study was to investigate the influence of the CYP4F2 polymorphism, V433M (rs2108622) on warfarin dose for patients by meta-analysis. Methods: Strict inclusion and exclusion criteria were set, and the studies prior to December 19, 2010 were searched in PubMed, EMBASE and CNKI. References were examined and experts of primary studies were consulted for additional information. Revman 5.0.2 software was used to analyze the relationship between warfarin maintenance dose and CYP4F2 polymorphism Results: Thirteen studies were included in the meta-analysis which consisted of Caucasian, Asian and African populations. Compared to individuals with the homozygous CYP4F2 genotype (CC), carriers of CT, TT genotypes required 10.0% (95% confidence interval(CI) 4.0-15.0) and 21.0% (95% CI 9.0-33.0) higher warfarin doses respectively (P value <0.05). In addition, T carriers required 11.0% (95% CI 6.0-17.0) higher warfarin dose than CC genotype. Conclusions: Our study showed that polymorphism of CYP4F2 had a moderate but statistically significant association with the variation of interindividual warfarin dose. However, whether CYP4F2 can improve the prediction of warfarin dose warrants need further investigation when combined with environmental factors. [Copyright &y& Elsevier]

Abstract: Background and aim: The genetic basis of Metabolic syndrome (MetS) is largely unknown but a link with salt sensitivity is recognized. The cytochrome P450 isoform 4F2 (CYP4F2) is involved in renal production of 20-hydroxyeicosatethraenoic acid (20-HETE), a natriuretic substance associated with salt sensitivity. The same enzyme is implicated in ω-hydroxylation of very long and medium chain fatty acids in the liver suggesting its possible influence on gluco-metabolic components of MetS. The aim of the present study was to evaluate the effect of CYP4F2 V433M, a functional polymorphism previously associated with hypertension via renal salt reabsorption, on the individual components of MetS and MetS itself. Methods: The polymorphism was genotyped in the cardiovascular cohort of the Malmö Diet and Cancer (MDC-CVA) study and successively in the Malmö Preventive Project (MPP) cohort. Different definitions of the MetS were applied. Results: In the MDC-CVA, male, but not female, CYP4F2 M433 carriers had significantly higher levels of waist, triglycerides, BP and a composite sum of MetS phenotypes (MetS score) beside lower HDL-cholesterol respect to V-homozygotes. MetS, as defined in the ATPIII and the AHA/NHLBI definitions, was more prevalent in M-carriers with respect to V-homozygotes. In the MPP cohort, significant association was detectable only for triglycerides at baseline and for Diastolic BP at reinvestigation in male M-carriers. Conclusion: The initial positive association of the CYP4F2 V433M polymorphism with components of MetS and MetS itself, found in MDC-CVA, was partially denied in another large cohort. The first association either could be due to a false positive result or alternatively, different genetic background or population stratification could have hidden the effect of the polymorphism in the replication cohort. [Copyright &y& Elsevier]

Abstract: Background: The cytochrome P450 (CYP) 4F2 isozyme has been reported to metabolize vitamin K1 in vitro, and the V433M polymorphism in the CYP4F2 gene has been associated with reduced vitamin K1 metabolism and the need for a higher maintenance dosage in patients receiving warfarin. Objective: The purpose of the present study was to evaluate the effects of V433M polymorphism on warfarin response during the induction phase. Methods: Warfarin-naive white patients in whom warfarin was scheduled to be initiated with a target INR of 2 to 3 were enrolled into the study. On enrollment, a single blood sample for the genotyping of CYP4F2, CYP2C9, and VKORC1 was drawn. The international normalized ratio (INR) was followed daily during induction and twice weekly until stable anticoagulation was reached. The relationships between several markers of warfarin response during induction and CYP4F2 polymorphism were determined. Results: The cohort consisted of 241 patients (115 men; mean [SD] age, 55.2 [19.4] years; weight, 79.5 [18.3] kg). Most of the patients were carriers of the CYP4F2 CC genotype (112 patients) or the CT genotype (104 patients). In carriers of the TT genotype (25 patients), INR >3 was >4-fold lower compared with that in carriers of the CC or CT genotype, suggesting that patients with the TT genotype were less sensitive to warfarin during induction. Also in TT carriers, the extent of excessive anticoagulation was >10-fold lower than in the other carriers. Both of these findings had a nominal P value of <0.05. After adjustment for false discovery rate, none of the findings remained significant at a threshold q value of <0.05. Among CC carriers, the concurrent use of a statin was associated with a 1-mg/d reduction in warfarin maintenance dosage. No similar effect was noted in the CT or TT carriers, suggesting a possible genetic influence on warfarin-statin interaction. Conclusions: These preliminary findings suggest that among white patients treated with warfarin, CYP4F2 polymorphism had a measurable effect on warfarin responsiveness during induction; however, the observed differences failed to reach the level of statistical significance. The possibility that the effect of statins on warfarin anticoagulation varies among carriers of different CYP4F2 genotypes could not be excluded and should be evaluated further in a larger patient sample. [Copyright &y& Elsevier]

This is the first study to evaluate the spectrum and prevalence of dose-predictive genetic polymorphisms of the CYP2C9, CYP4F2 and VKORC1 loci together, in a geographically defined, ethnically admixed healthy adult Omani population sharing common lifestyle/environmental factors. Since the present-day Omani population is the result of an admixture of Caucasian, African and Asian ancestries, we compared the pharmacogenetic profile of these three loci in this population. Interestingly, the Omani pharmacogenetic profile, in terms of allele and genotype distribution, has values that are intermediate between Caucasians and African Americans, the African admixture further substantiated by the presence of the CYP2C9*8 allele. However, limitations and usefulness of such comparisons warrant caution, as the data from pharmacogenetic literature do not always represent bona fide population categories. Furthermore, definition of study population based on microgeographical scale would be more appropriate in pharmacogenetic research rather than the flawed racial, ethnic, or social categorizations since pharmacogenetic variation is clinal, and genetic influences will be further altered by lifestyle and environmental factors. [ABSTRACT FROM AUTHOR]

Background: Individuals with implanted mechanical valve prostheses require lifelong anticoagulation therapy with warfarin. The narrow therapeutic index of warfarin makes it difficult to dose and maintain proper anticoagulation. A number of single nucleotide polymorphisms (SNPs) affecting vitamin K or warfarin metabolism have been shown to affect warfar in dosing. Our aim was to study the effect of the CYP4F2 rs2108622-1347 (C > T) variant on warfarin dosing in Chinese patients. Methods: We studied 352 patients after heart valve replacement surgery. Warfarin dosing for patients was adjusted to achieve 1.8 ? INR ? 2.5. We determined the presence of SNPs in CYP4F2 in these patients and investigated their association with warfarin dosing. Results: We found the frequency of the CYP4F2 rs2108622 C allele was 79.5% and T-allele frequency was 20.5%. The warfarin dose requirement for CC individuals was significantly lower than that for CT or TT individuals (P < 0.05). TT-homozygous individuals required a 0.56 mg/day higher dose of warfarin than their CC counterparts. Conclusions: This study demonstrates that CYP4F2 rs2108622 significantly affects the warfarin dose requirement to achieve adequate anticoagulant activity in Chinese individuals. Genotyping of this SNP may allow clinicians to determine the initiation dose for patients following valve-replacement surgery in China. [ABSTRACT FROM AUTHOR]

Objective: Warfarin is an FDA-approved oral anticoagulant for long-term prevention of thromboembolism. Substantial inter-individual variation in dosing requirements and the narrow therapeutic index of this widely-prescribed drug make safe initiation and dose stabilization challenging. Single nucleotide polymorphisms (SNPs) occurring in CYP2C9, VKORC1, and CYP4F2 genes are known to impact dose, and VKORC1 and CYP4F2 polymorphisms are associated with higher therapeutic dose requirements in our cohort. However, the most advanced regression models using personal, clinical, and genetic factors to predict individual stable dose account for only 50% to 60% of the observed variability in stable theapeutic dose in Caucasians. Design and Methods: In this study, we used DNA sequence analysis to determine whether additional variants in CYP4F2 and VKORC1 gene coding regions contribute to variable dosing requirements among individuals for whom the actual dose was the highest relative to regression model-predicted dose. Results and Conclusions: No novel DNA variants in the coding regions of these genes were identified among subjects requiring high warfarin doses, suggesting that other factors yet to be defined contribute to variability in warfarin dose requirements in this subset of our cohort. [ABSTRACT FROM AUTHOR]

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Warfarin is an oral anticoagulant widely used for thromboembolic disease prophylaxis. The pharmacokinetics and pharmacodynamics of this drug vary with environmental and genetic factors. Several algorithms including genetic and non-genetic factors have been developed for different populations. These investigations have shown that polymorphisms in CYP2C9 and VKORC1 genes are related to warfarin dose variation. WHAT THIS STUDY ADDS • This study confirms that CYP2C9 and VKORC1 genes are the main predictors of warfarin dose, but there are other genes with smaller effects that can improve the algorithm for better dose prediction. • This study observed for the first time an effect of the F2 gene on warfarin dose prediction. • The inclusion for the first time of co-medication with amlodipine, carbamazepine, β-adrenoceptor blockers and diuretics refined the construction of an algorithm for dose prediction. AIMS To investigate the influence of polymorphisms in CYP2C9, VKORC1, CYP4F2 and F2 genes on warfarin dose-response and develop a model including genetic and non-genetic factors for warfarin dose prediction needed for each patient. METHODS A total of 279 patients of European ancestry on warfarin medication were investigated. Genotypes for −1639G>A, 1173C>T, and 3730G>A SNPs in the VKORC1 gene, CYP2C9*2 and CYP2C9*3, 1347C>T in the CYP4F2 gene and 494C>T in the F2 gene were determined by allelic discrimination with Taqman 5'-nuclease assays. RESULTS The CYP2C9*2 and CYP2C9*3 polymorphisms in the CYP2C9 gene, −1639G>A and 1173C>T in the VKORC1 gene and 494C>T in the F2 gene are responsible for lower anticoagulant doses. In contrast, 1347C>T in the CYP4F2 gene and 3730G>A in the VKORC1 gene are responsible for higher doses of warfarin. An algorithm including genetic, biological and pharmacological factors that explains 63.3% of warfarin dose variation was developed. CONCLUSION The model suggested has one of the highest coefficients of determination among those described in the literature. [ABSTRACT FROM AUTHOR]

Warfarin is a commonly used oral anticoagulant with a narrow therapeutic index and various genetic and clinical factors that influence interpatient variability in dose requirements. This study investigated the impact of genetic and nongenetic factors on warfarin dose requirements in Egyptians.DNA was extracted from 207 patients taking warfarin for more than 2 months and genotyped for VKORC1 (3673 G>A), CYP2C9 ∗2∗3∗4∗5∗8, CYP4F2 (V33M; rs2108622), APOE (rs429358, rs7412), and CALU(rs339097) gene polymorphisms. Linear regression modeling was conducted to identify the genetic and nongenetic factors that independently influence warfarin dose requirements.VKORC1 3673 AA or GA genotype (P<0.0001), one or two variant alleles of CYP2C9 gene (P=0.0004), APOE ε2 haplotype (P=0.01), and increasing age (P<0.0001) were all associated with lower warfarin dose, whereas smoking (P=0.025) and pulmonary embolism (P=0.0059) showed association with higher warfarin doses. These factors explained 31% of the warfarin dose variability. This is the first independent confirmation of the association of the CALU rs339097 variant with higher warfarin dose requirement, although inclusion of thissinglenucleotide polymorphism in the multiple regressionmodel failed to achieve significance (P=0.066). CYP4F2 (V33M) polymorphism was not significant (P=0.314), despite itshigh frequency in the studied population (42%).The study shows that VKORC1, CYP2C9 polymorphisms, APOE ε2 variant, and several clinical/demographic variables are important determinants of warfarin dose requirements in Egyptian patients. The percentage of variability explained by these factors is lowerthan in those of European ancestry, but similar tothevariability explained in Asians and African ancestry. [ABSTRACT FROM AUTHOR]

Genome-wide association studies (GWAS) on warfarin and acenocoumarol showed that interindividual dosage variation is mainly associated with single nucleotide polymorphisms (SNPs) in VKORC1 and to a lesser extent in CYP2C9 and CYP4F2. For phenprocoumon dosage, the genes encoding CYP3A4 and ApoE might play a role.To assess the association between common genetic variants within VKORC1, CYP2C9, CYP4F2, CYP3A4, and ApoE and phenprocoumon maintenance dosage, and to identify novel signals using GWAS.We selected all participants from the Rotterdam study who were treated with phenprocoumon. For each SNP, we tested the association between the above-mentioned genotypes and age, sex, body mass index, and target INR adjusted-phenprocoumon maintenance dosage.Within our study population (N=244), VKORC1, CYP2C9, CYP4F2 genotypes together explained 46% of phenprocoumon maintenance dosage variation. Each additional VKORC1 variant allele reduced phenprocoumon maintenance dosage by 4.8 mg/week (P<0.0001) and each additional CYP2C9 variant allele by 2.2 mg/week (P=0.002). Each additional variant allele of CYP4F2 increased phenprocoumon dosage by 1.5 mg/week (P=0.022). Variant alleles of CYP3A41∗B and ApoE showed no association with phenprocoumon dosage. Genome-wide significant SNPs were all related to VKORC1 activity. Best associated were two SNPs in complete linkage disequilibrium with each other and with SNPs within VKORC1: rs10871454 [Syntaxin 4A (STX4A)] and rs11150604 (ZNF646), each with a P value of 2.1×10-22. Each reduced phenprocoumon maintenance dosage weekly by 4.9 mg per variant allele.Similar to earlier findings with warfarin and acenocoumarol, phenprocoumon maintenance dosage depended on polymorphisms in the VKORC1 gene. CYP2C9 and CYP4F2 were of modest relevance. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Several factors responsible for inter-individual differences in response to warfarin have been confirmed; however, unidentified factors appear to remain. The purpose of this study was to examine a simple method to evaluate whether optional variables are appropriate as factors to improve dosing algorithms. Materials and Methods: All patients were Japanese. Genotyping of selected genes was conducted, and other information was obtained from medical record. Dosing algorithms were constructed by multivariate linear regression analyses and were evaluated by the Akaike Information Criterion (AIC). Results and Conclusions: Multivariate analysis showed that white blood-cell count (WBC), concomitant use of allopurinol, and CYP4F2 genotype are apparently involved in warfarin dose variation, in addition to well-known factors, such as age and VKORC1 genotype. We evaluated the adequacy of these variables as factors to improve the dosing algorithm using the AIC. Addition of WBC, allopurinol administration and CYP4F2 genotype to the basal algorithm resulted in decreased AIC, suggesting that these factor candidates may contribute to improving the prediction of warfarin maintenance dose. This study is the first to evaluate the warfarin dosing algorithm by AIC. To further improve the dosing algorithm, AIC may be a simple and useful tool to evaluate both the model itself and factors to be incorporated into the algorithm. [ABSTRACT FROM AUTHOR]

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Genetic polymorphisms of VKORC1 and CYP2C9 are known to influence warfarin dosage. • Recent studies among Caucasians showed that polymorphisms of CYP4F2 also play a role in warfarin pharmacogenetics. • The contribution of CYP4F2 variants to the variability inwarfarin dose requirement in Chinese subjects remains to be investigated. WHAT THIS STUDY ADDS • This research was to study the effect of CYP4F2 variants on warfarin requirements in the Han Chinese population. • This study developed a multiple regression model including CYP2C9, VKORC1 3673G>A, CYP4F2 genotypes and age, weight, combination use of amiodarone which could explain 56.1% of the individual variability in warfarin dose CYP4F2 could explain 4% of the variance in warfarin dose. • We found that one novel genotypic polymorphism 5417G>T for Asp36Tyr, which was identified as an important marker of warfarin resistance, was absent in the Han Chinese population in our study. AIMS The objective of this study was to assess the effect of the CYP4F2 on the daily stable warfarin dose requirement in Han Chinese patients with mechanical heart valve replacement (MHVR). METHODS From March 2007 to November 2008, 222 Han Chinese MHVR patients were recruited in our study. VKORC1 3673G>A, 5417G>T, CYP2C9*3 and CYP4F2 rs2108622 were genotyped by using the polymerase chain reaction restriction fragment length polymorphism method (PCR-RFLP). Polymorphisms of VKORC1 9041G>A were detected by direct sequencing. Multiple linear regression analysis was used to investigate the contribution of CYP4F2. RESULTS The CYP4F2 rs2108622 CT/TT group took a significantly higher stable warfarin dose (3.2 mg day−1) than the CC group (2.9 mg day−1, 95% CI 0.2, 1.0, P= 0.033). The multiple linear regression model included VKORC1 3673G>A, CYP2C9, CYP4F2 genotypes and clinical characteristics. The model could explain 56.1% of the variance in stable warfarin dose in Han Chinese patients with MHVR. CYP4F2 contributed about 4% to the variance in the warfarin dose. There was no variation in the SNPs of VKORC1 5417G>T. CONCLUSION CYP4F2 is a minor significant factor of individual variability in the stable warfarin dose in Han Chinese patients with MHVR. The effect of CYP2C9 and VKORC1 genotypes on variability in the stable warfarin dose had also been confirmed. [ABSTRACT FROM AUTHOR]

Warfarin dosing remains challenging because of its narrow therapeutic window and large variability in dose response. We sought to analyze new factors involved in its dosing and to evaluate eight dosing algorithms, including two developed by the International Warfarin Pharmacogenetics Consortium (IWPC).we enrolled 108 patients on chronic warfarin therapy and obtained complete clinical and pharmacy records; we genotyped single nucleotide polymorphisms relevant to the VKORC1, CYP2C9, and CYP4F2 genes using integrated fluidic circuits made by Fluidigm.When applying the IWPC pharmacogenetic algorithm to our cohort of patients, the percentage of patients within 1 mg/d of the therapeutic warfarin dose increases from 54% to 63% using clinical factors only, or from 38% using a fixed-dose approach. CYP4F2 adds 4% to the fraction of the variability in dose (R2) explained by the IWPC pharmacogenetic algorithm (P<0.05). Importantly, we show that pooling rare variants substantially increases the R2 for CYP2C9 (rare variants: P=0.0065, R2=6%; common variants: P=0.0034, R2=7%; rare and common variants: P=0.00018; R2=12%), indicating that relatively rare variants not genotyped in genome-wide association studies may be important. In addition, the IWPC pharmacogenetic algorithm and the Gage (2008) algorithm perform best (IWPC: R2=50%; Gage: R2=49%), and all pharmacogenetic algorithms outperform the IWPC clinical equation (R2=22%). VKORC1 and CYP2C9 genotypes did not affect long-term variability in dose. Finally, the Fluidigm platform, a novel warfarin genotyping method, showed 99.65% concordance between different operators and instruments.CYP4F2 and pooled rare variants of CYP2C9 significantly improve the ability to estimate warfarin dose. [ABSTRACT FROM AUTHOR]

A variant in the CYP4F2 gene, rs2108622, has been recently shown to determine stable warfarin dose requirements. CYP4F2 has also been shown recently to metabolize vitamin K.Three hundred and eleven patients were recruited prospectively from two UK hospitals and followed-up for 6 months. Fine mapping of the whole CYP4F2 region was performed to try and define the haplotype structure of CYP4F2. Genotyping was performed on the Sequenom platform. Univariate and multiple regression analyses were undertaken to assess the effect of CYP4F2 on predefined clinical outcomes of warfarin response.Fifty-nine single nucleotide polymorphisms in the CYP4F2 gene were analyzed. There was a high degree of linkage disequilibrium in the gene with two haplotype blocks. No association was found with warfarin stable dose and rs2108622 in our prospective cohort of patients even after adjustments to reduce patient heterogeneity. Interestingly, a single nucleotide polymorphism (rs2189784), which is in strong linkage disequilibrium with rs2108622, showed an association with time-to-therapeutic international normalized ratio which remained significant after the correction for multiple testing (Pc = 0.03). No association was shown with the haplotypes after false discovery rate correction.Although we were unable to demonstrate an association between rs2108622 and stable warfarin dose, our finding of an association between rs2189784 and time-to-therapeutic international normalized ratio is consistent with the recent finding that CYP4F2 plays a role in vitamin K metabolism. However, the effect of CYP4F2 is relatively small in all studies undertaken so far, and thus seems unlikely to be of clinical relevance. [ABSTRACT FROM AUTHOR]

Aiming to elucidate the system-wide effects of the alcohol-induced increase in the content of cytochrome P450 2E1 (CYP2E1) on drug metabolism, we explored the array of its protein-protein interactions (interactome) in human liver microsomes (HLM) with chemical crosslinking mass spectrometry (CXMS). Our strategy employs membrane incorporation of purified CYP2E1 modified with photoreactive crosslinkers benzophenone-4-maleimide and 4-(N-succinimidylcarboxy)benzophenone. Exposure of bait-incorporated HLM samples to light was followed by isolating the His-tagged bait protein and its crosslinked aggregates on Ni-NTA agarose. Analyzing the individual bands of SDS-PAGE slabs of thereby isolated protein with the toolset of untargeted proteomics, we detected the crosslinked dimeric and trimeric complexes of CYP2E1 with other drug-metabolizing enzymes. Among the most extensively crosslinked partners of CYP2E1 are the cytochromes P450 2A6, 2C8, 3A4, 4A11, and 4F2, UDP-glucuronosyltransferases (UGTs) 1A and 2B, fatty aldehyde dehydrogenase (ALDH3A2), epoxide hydrolase 1 (EPHX1), disulfide oxidase 1α (ERO1L), and ribophorin II (RPN2). These results demonstrate the exploratory power of the proposed CXMS strategy and corroborate the concept of tight functional integration in the human drug-metabolizing ensemble through protein-protein interactions of the constituting enzymes. [ABSTRACT FROM AUTHOR]

The sphingosine-1-phosphate receptor modulator fingolimod is predominantly hydroxylated by cytochrome CYP4F2. In vitro experiments showed that ketoconazole significantly inhibited the oxidative metabolism of fingolimod by human liver microsomes and by recombinant CYP4F2. The authors used ketoconazole as a putative CYP4F2 inhibitor to quantify its influence on fingolimod pharmacokinetics in healthy subjects. In a 2-period, singlesequence, crossover study, 22 healthy subjects received a single 5-mg dose of fingolimod in period 1. In period 2, subjects received ketoconazole 200 mg twice daily for 9 days and a single 5-mg dose of fingolimod coadministered on the 4th day of ketoconazole treatment. Ketoconazole did not affect fingolimod t[submax] or half-life, but there was a weak average increase in C[submax] of 1.22-fold (90% confidence interval, 1.15-1.30). The AUC over the 5 days of ketoconazole coadministration increased 1.40-fold (1.31-1.50), and the full AUC to infinity increased 1.71-fold (1.53-1.91). The AUC of the active metabolite fingolimod-phosphate was increased to a similar extent by 1.67-fold (1.50-1.85). Ketoconazole predose plasma levels were not altered by fingolimod. The magnitude of this interaction suggests that a proactive dose reduction of fingolimod is not necessary when adding ketoconazole to a fingolimod regimen. The clinician, however, should be aware of this interaction and bear in mind the possibility of a fingolimod dose reduction based on clinical monitoring. [ABSTRACT FROM AUTHOR]