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Kawai VK, Cunningham A, Vear SI, Van Driest SL, Oginni A, Xu H, Jiang M, Li C, Denny JC, Shaffer C, Bowton E, Gage BF, Ray WA, Roden DM, Stein CM. Genotype and risk of major bleeding during warfarin treatment. Pharmacogenomics 2015; 15:1973-83. [PMID: 25521356 DOI: 10.2217/pgs.14.153] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
AIM To determine whether genetic variants associated with warfarin dose variability were associated with increased risk of major bleeding during warfarin therapy. MATERIALS & METHODS Using Vanderbilt's DNA biobank we compared the prevalence of CYP2C9, VKORC1 and CYP4F2 variants in 250 cases with major bleeding and 259 controls during warfarin therapy. RESULTS CYP2C9*3 was the only allele that differed significantly among cases (14.2%) and controls (7.8%; p = 0.022). In the 214 (85.6%) cases with a major bleed 30 or more days after warfarin initiation, CYP2C9*3 was the only variant associated with bleeding (adjusted odds ratio: 2.05; 95% CI: 1.04, 4.04). CONCLUSION The CYP2C9*3 allele may double the risk of major bleeding among patients taking warfarin for 30 or more days.
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Structural Modeling Insights into Human VKORC1 Phenotypes. Nutrients 2015; 7:6837-51. [PMID: 26287237 PMCID: PMC4555152 DOI: 10.3390/nu7085313] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/03/2015] [Accepted: 08/06/2015] [Indexed: 11/17/2022] Open
Abstract
Vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) catalyses the reduction of vitamin K and its 2,3-epoxide essential to sustain γ-carboxylation of vitamin K-dependent proteins. Two different phenotypes are associated with mutations in human VKORC1. The majority of mutations cause resistance to 4-hydroxycoumarin- and indandione-based vitamin K antagonists (VKA) used in the prevention and therapy of thromboembolism. Patients with these mutations require greater doses of VKA for stable anticoagulation than patients without mutations. The second phenotype, a very rare autosomal-recessive bleeding disorder caused by combined deficiency of vitamin K dependent clotting factors type 2 (VKCFD2) arises from a homozygous Arg98Trp mutation. The bleeding phenotype can be corrected by vitamin K administration. Here, we summarize published experimental data and in silico modeling results in order to rationalize the mechanisms of VKA resistance and VKCFD2.
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Parra EJ, Botton MR, Perini JA, Krithika S, Bourgeois S, Johnson TA, Tsunoda T, Pirmohamed M, Wadelius M, Limdi NA, Cavallari LH, Burmester JK, Rettie AE, Klein TE, Johnson JA, Hutz MH, Suarez-Kurtz G. Genome-wide association study of warfarin maintenance dose in a Brazilian sample. Pharmacogenomics 2015; 16:1253-63. [PMID: 26265036 DOI: 10.2217/pgs.15.73] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
AIM Extreme discordant phenotype and genome-wide association (GWA) approaches were combined to explore the role of genetic variants on warfarin dose requirement in Brazilians. METHODS Patients receiving low (≤ 20 mg/week; n = 180) or high stable warfarin doses (≥ 42.5 mg/week; n = 187) were genotyped with Affymetrix Axiom(®) Biobank arrays. Imputation was carried out using data from the combined 1000 Genomes project. RESULTS Genome-wide signals (p ≤ 5 × 10(-8)) were identified in the well-known VKORC1 (lead SNP, rs749671; OR: 20.4; p = 1.08 × 10(-33)) and CYP2C9 (lead SNP, rs9332238, OR: 6.8 and p = 4.4 × 10(-13)) regions. The rs9332238 polymorphism is in virtually perfect LD with CYP2C9*2 (rs1799853) and CYP2C9*3 (rs1057910). No other genome-wide significant regions were identified in the study. CONCLUSION We confirmed the important role of VKORC1 and CYP2C9 polymorphisms in warfarin dose. Original submitted 14 January 2015; Revision submitted 26 May 2015.
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Effects of NAD(P)H quinone oxidoreductase 1 polymorphisms on stable warfarin doses in Korean patients with mechanical cardiac valves. Eur J Clin Pharmacol 2015; 71:1229-36. [PMID: 26257249 DOI: 10.1007/s00228-015-1915-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 07/23/2015] [Indexed: 01/21/2023]
Abstract
PURPOSE NAD(P)H dehydrogenase, encoded by NAD(P)H quinone oxidoreductase 1 (NQO1), is an enzyme that catalyzes the reduction of quinones, including vitamin K. Given its potential role in vitamin K metabolism, this study aimed to investigate the effects of NQO1 polymorphisms on stable warfarin doses. METHODS We tested a possible effect of gene polymorphisms on variability in warfarin response using 206 Korean patients with mechanical cardiac valves. Single nucleotide polymorphisms (SNPs) of NQO1 with a minor allele frequency of at least 15% were included. Also, genotypes of vitamin K epoxide reductase complex subunit 1 (VKORC1), cytochrome P450 (CYP) 2C9, CYP4F2, gamma-glutamyl carboxylase (GGCX), and GATA4 were determined. RESULTS NQO1 rs1800566 (C>T) and rs10517 (C>T) were significantly associated with stable warfarin doses. Variant homozygote carriers required lower stable warfarin doses than those with wild-type C allele in rs1800566 (4.85 ± 1.61 vs. 5.61 ± 1.94 mg; p = 0.033), whereas patients with wild homozygote required lower doses than those with T allele in rs10517 (5.11 ± 1.73 vs. 5.75 ± 1.98 mg; p = 0.017). Similar results were obtained from stratified analysis using VKORC1 variant homozygote carriers in both SNPs. Multivariate analysis showed that rs10517 (C>T) increased contribution of gene variations to the overall warfarin dose variability from 42.5 to 43.8%. CONCLUSION Our results demonstrate that NQO1 gene polymorphisms influence stable warfarin doses in Korean patients.
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Lee KE, Chang BC, Park S, Gwak HS. Effects of single nucleotide polymorphisms in c-Myc on stable warfarin doses in patients with cardiac valve replacements. Pharmacogenomics 2015; 16:1101-8. [PMID: 26249541 DOI: 10.2217/pgs.15.37] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIM This study aimed to investigate an association between c-Myc SNPs and stable warfarin doses. MATERIALS & METHODS The influences of genetic polymorphisms on dose requirements were investigated by genotyping ten SNPs in 201 patients with stable warfarin doses; VKORC1 (rs9923231), CYP2C9 (rs1057910), CYP4F2 (rs2108622), GATA4 (rs10090884), c-Myc (rs4645962, rs4645943, rs4645948 and rs4645974) and 8q24 (rs1447295 and rs16901979). RESULTS Around 44.3% of the overall interindividual variability in warfarin dose requirements was explained by the multivariate regression model; VKORC1 genotype accounted for 26.4%, CYP2C9 genotype for 4.9%, age for 3.4%, c-Myc genotypes for 5.2% (rs4645974 for 2.4% and rs4645943 for 2.8%), CYP4F2 genotype for 2.9% and diuretic use for 1.5%. CONCLUSION Our results revealed that c-Myc could be a determinant of stable warfarin doses.
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You JHS. Universal versus genotype-guided use of direct oral anticoagulants in atrial fibrillation patients: a decision analysis. Pharmacogenomics 2015; 16:1089-100. [PMID: 26230572 DOI: 10.2217/pgs.15.64] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIM This study aims to compare clinical and economic outcomes of CYP2C9 and VKORC1 genotype-guided (PG-DOAC) versus universal use of direct oral anticoagulant (DOAC) for stroke prevention in patients with atrial fibrillation (AF). METHODS Outcomes of oral anticoagulation therapy were simulated using life-long Markov modeling. In PG-DOAC, patients with genotype of high or low warfarin sensitivity were treated with DOAC, and patients with normal warfarin sensitivity genotype received warfarin. RESULTS Expected quality-adjusted life-years (QALYs) and cost of DOAC were higher than PG-DOAC. Incremental cost per QALY (ICER) of DOAC versus PG-DOAC was 314,129 USD/QALY, exceeding willingness-to-pay threshold (50,000 USD/QALY). CONCLUSION Using individual genotype to guide the use of DOAC versus warfarin appears to be the preferred strategy.
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Oldenburg J, Watzka M, Bevans CG. VKORC1 and VKORC1L1: Why do Vertebrates Have Two Vitamin K 2,3-Epoxide Reductases? Nutrients 2015; 7:6250-80. [PMID: 26264021 PMCID: PMC4555119 DOI: 10.3390/nu7085280] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/08/2015] [Accepted: 07/15/2015] [Indexed: 01/01/2023] Open
Abstract
Among all cellular life on earth, with the exception of yeasts, fungi, and some prokaryotes, VKOR family homologs are ubiquitously encoded in nuclear genomes, suggesting ancient and important biological roles for these enzymes. Despite single gene and whole genome duplications on the largest evolutionary timescales, and the fact that most gene duplications eventually result in loss of one copy, it is surprising that all jawed vertebrates (gnathostomes) have retained two paralogous VKOR genes. Both VKOR paralogs function as entry points for nutritionally acquired and recycled K vitamers in the vitamin K cycle. Here we present phylogenetic evidence that the human paralogs likely arose earlier than gnathostomes, possibly in the ancestor of crown chordates. We ask why gnathostomes have maintained these paralogs throughout evolution and present a current summary of what we know. In particular, we look to published studies about tissue- and developmental stage-specific expression, enzymatic function, phylogeny, biological roles and associated pathways that together suggest subfunctionalization as a major influence in evolutionary fixation of both paralogs. Additionally, we investigate on what evolutionary timescale the paralogs arose and under what circumstances in order to gain insight into the biological raison d’être for both VKOR paralogs in gnathostomes.
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Bevans CG, Krettler C, Reinhart C, Watzka M, Oldenburg J. Phylogeny of the Vitamin K 2,3-Epoxide Reductase (VKOR) Family and Evolutionary Relationship to the Disulfide Bond Formation Protein B (DsbB) Family. Nutrients 2015; 7:6224-49. [PMID: 26230708 PMCID: PMC4555120 DOI: 10.3390/nu7085281] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 06/25/2015] [Accepted: 07/09/2015] [Indexed: 12/04/2022] Open
Abstract
In humans and other vertebrate animals, vitamin K 2,3-epoxide reductase (VKOR) family enzymes are the gatekeepers between nutritionally acquired K vitamins and the vitamin K cycle responsible for posttranslational modifications that confer biological activity upon vitamin K-dependent proteins with crucial roles in hemostasis, bone development and homeostasis, hormonal carbohydrate regulation and fertility. We report a phylogenetic analysis of the VKOR family that identifies five major clades. Combined phylogenetic and site-specific conservation analyses point to clade-specific similarities and differences in structure and function. We discovered a single-site determinant uniquely identifying VKOR homologs belonging to human pathogenic, obligate intracellular prokaryotes and protists. Building on previous work by Sevier et al. (Protein Science 14:1630), we analyzed structural data from both VKOR and prokaryotic disulfide bond formation protein B (DsbB) families and hypothesize an ancient evolutionary relationship between the two families where one family arose from the other through a gene duplication/deletion event. This has resulted in circular permutation of primary sequence threading through the four-helical bundle protein folds of both families. This is the first report of circular permutation relating distant α-helical membrane protein sequences and folds. In conclusion, we suggest a chronology for the evolution of the five extant VKOR clades.
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Jiménez-Varo E, Cañadas-Garre M, Garcés-Robles V, Gutiérrez-Pimentel MJ, Calleja-Hernández MÁ. Extrapolation of acenocoumarol pharmacogenetic algorithms. Vascul Pharmacol 2015; 74:151-157. [PMID: 26122664 DOI: 10.1016/j.vph.2015.06.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 06/01/2015] [Accepted: 06/23/2015] [Indexed: 01/29/2023]
Abstract
INTRODUCTION Acenocoumarol (ACN) has a narrow therapeutic range that is especially difficult to control at the start of its administration. Various dosing pharmacogenetic-guided dosing algorithms have been developed, but further work on their external validation is required. The aim of this study was to evaluate the extrapolation of pharmacogenetic algorithms for ACN as an alternative to the development of a specific algorithm for a given population. MATERIAL AND METHODS The predictive performance, deviation, accuracy, and clinical significance of five pharmacogenetic algorithms (EU-PACT, Borobia, Rathore, Markatos, Krishna Kumar) were compared in 189 stable ACN patients representing all indications for anticoagulant treatment. RESULTS The correlation between the dose predictions of the five pharmacogenetic models ranged from 7.7 to 70.6% and the percentage of patients with a correct prediction (deviation ≤20% from actual ACN dose) ranged from 5.9 to 40.7%. EU-PACT and Borobia pharmacogenetic dosing algorithms were the most accurate in our setting and evidenced the best clinical performance. CONCLUSIONS Among the five models studied, the EU-PACT and Borobia pharmacogenetic dosing algorithms demonstrated the best potential for extrapolation.
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Tzveova R, Dimitrova-Karamfilova A, Saraeva R, Solarova T, Naydenova G, Petrova I, Hristova N, Popov I, Nachev G, Mitev V, Kaneva R. Estimation and validation of acenocoumarol dosing algorithms in Bulgarian patients with cardiovascular diseases. Per Med 2015; 12:209-220. [PMID: 29771648 DOI: 10.2217/pme.14.80] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aim & Methods: A total of 169 Bulgarian patients were genotyped for CYP2C9*2,*3, VKORC1-1639G>A and VKORC11173C>T. The effect of genetic and nongenetic factors on acenocoumarol dose variability was tested in a derivation cohort of patients and the obtained algorithm was validated in a test cohort. RESULTS & DISCUSSION It was found that VKORC-1639G>A (25.5%), CYP2C9*2 (7.8%), CYP2C9*3 (6.1%), age (13.6%) and diagnosis (6.0%) significantly affected acenocoumarol dose variability in the derivation cohort. These factors with additional factors, such as sex (0.1%, p = 0.76), weight (2.6%, p = 0.14) and amiodarone use (3.0%, p = 0.059) accounted for 46.5% and 23.0% of the dose variability for genetic and clinical models, respectively. CONCLUSION Based on the results of this investigation, validated clinical and pharmacogenetic algorithms for the prediction of a stable anticoagulant dose were developed, specifically designed for the Bulgarian population.
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Roth JA, Bradley K, Thummel KE, Veenstra DL, Boudreau D. Alcohol misuse, genetics, and major bleeding among warfarin therapy patients in a community setting. Pharmacoepidemiol Drug Saf 2015; 24:619-27. [PMID: 25858232 PMCID: PMC4478047 DOI: 10.1002/pds.3769] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 01/25/2015] [Accepted: 02/16/2015] [Indexed: 12/30/2022]
Abstract
PURPOSE Little is known about the impact of alcohol consumption on warfarin safety, or whether demographic, clinical, or genetic factors modify risk of adverse events. We conducted a case-control study to assess the association between screening positive for moderate/severe alcohol misuse and the risk of major bleeding in a community sample of patients using warfarin. METHODS The study sample consisted of 570 adult patients continuously enrolled in Group Heath for at least 2 years and receiving warfarin. The main outcome was major bleeding validated through medical record review. Cases experienced major bleeding, and controls did not experience major bleeding. Exposures were Alcohol Use Disorders Identification Test Consumption Questionnaire (AUDIT-C) scores and report of heavy episodic drinking (≥5 drinks on an occasion). The odds of major bleeding were estimated with multivariate logistic regression models. The overall sample was 55% male, 94% Caucasian, and had a mean age of 70 years. RESULTS Among 265 cases and 305 controls, AUDIT-C scores indicative of moderate/severe alcohol misuse and heavy episodic drinking were associated with increased risk of major bleeding (OR = 2.10, 95% CI = 1.08-4.07; and OR = 2.36, 95% CI = 1.24-4.50, respectively). Stratified analyses demonstrated increased alcohol-related major bleeding risk in patients on warfarin for ≥1 year and in those with a low-dose genotype (CYP2C9*2/*3, VKORC1(1173G>A), CYP4F2*1), but not in other sub-groups evaluated. CONCLUSIONS Alcohol screening questionnaires, potentially coupled with genetic testing, could have clinical utility in selecting patients for warfarin therapy, as well as refining dosing and monitoring practices.
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Park YK, Lee MJ, Kim JH, Kim SJ, Kim JS, Lee SY, Bang OY. Lack of Association of Clinical Factors (SAMe-TT2R2) with CYP2C9/ VKORC1 Genotype and Anticoagulation Control Quality. J Stroke 2015; 17:192-8. [PMID: 26060806 PMCID: PMC4460338 DOI: 10.5853/jos.2015.17.2.192] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 02/27/2015] [Accepted: 02/27/2015] [Indexed: 12/28/2022] Open
Abstract
Background and Purpose Advantages of new oral anticoagulations may be greater in atrial fibrillation (AF) patients of poor anticoagulation control with warfarin. The SAMe-TT2R2 scoring system, based on clinical variables, was recently developed to aid in identifying these patients. In this study, we investigated the association of this clinical composite score with genetic factors related warfarin dosing and the quality of anticoagulation control. Methods Clinical and genetic data were collected from 380 consecutive Korean patients with AF (CHA2DS2-VASc score, 3.5±1.8) who were followed for an average of 4 years. We evaluated factors associated with time in therapeutic range (TTR, INR 2-3), including the CYP2C9 and VKORC1 genotypes and the SAMe-TT2R2 score (Sex female, Age <60 years, Medical history [>two co-morbidities], Treatment [interacting drugs, e.g., amiodarone], Tobacco use within 2 years [doubled], and Race non-white [doubled]). Results The average SAMe-TT2R2 score was 3.4±0.9, range 2-7; and 153 patients (40.2%) had SAMe-TT2R2 scores ≥4. Time in specific INR ranges varied depending on the VKORC1 genotype but not with the CYP2C9 genotype or the SAMe-TT2R2 score. TTR was higher in patients with the VKORC1 1173C>T than in VKORC1 TT (61.7±16% vs. 56.7±17.4%, P=0.031). Multivariate testing showed that VKORC1 genotype but not the SAMe-TT2R2 score was significantly associated with labile INRs. There was no correlation between the SAMe-TT2R2 scores and pharmacogenetic data. Conclusions A genetic factor, but none of the common clinical and demographic factors, as combined in the SAMe-TT2R2 score, was associated with the quality of anticoagulation control in Korean patients with AF.
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Šupe S, Poljaković Z, Božina T, Ljevak J, Macolić Šarinić V, Božina N. Clinical Application of Genotype-guided Dosing of Warfarin in Patients with Acute Stroke. Arch Med Res 2015; 46:265-73. [PMID: 25989350 DOI: 10.1016/j.arcmed.2015.05.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 05/12/2015] [Indexed: 01/27/2023]
Abstract
BACKGROUND Patients with certain types of stroke need urgent anticoagulation and it is extremely important for them to achieve fast and stable anticoagulant effect and receive individualized treatment during the initiation of warfarin therapy. METHODS We conducted a prospective study among 210 acute stroke patients who had an indication for anticoagulation and compared the impact of CYP2C9 and VKORC1 genotype-guided warfarin dosing (PhG) with fixed dosing (NPhG) on anticoagulation control and clinical outcome between groups. RESULTS PhG achieved target INR values earlier, i.e., on average in 4.2 (4.1-4.7, 95% CI) days compared to NPhG (5.2 days [4.7-6.4, 95% CI]) (p = 0.0009), spent a higher percentage of time in the therapeutic INR range (76.3% [74.7-78.5, 95% CI] vs. 67.1% [64.5-69.6, 95% CI] in NPhG), and spent less time overdosed (INR > 3.1) (PhG 0.4 [0.1-0.7, 95% CI], NPhG 1.7 [1.1-2.3, 95% CI] days; p >0.000). PhG reached stable maintenance dose faster (10 [9.9-10.7, 95% CI] vs. 13.9 [13.3-14.7, 95% CI] days in controls; p = 0.0049) and had a better clinical outcome in relation to neurological deficit on admission as compared to NPhG. CONCLUSION We confirmed that warfarin therapy with genotype-guided dosing instead of fixed dosing reduces the time required for stabilization and improves anticoagulant control with better clinical outcome in early stages of warfarin therapy introduction among acute stroke patients, which is essential for clinical practice.
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O' Sullivan KE, Meany B, Hurley JP. Warfarin resistance due to VKORC1 gene mutation in a patient following mechanical aortic valve replacement with an ON-X valve. Int J Cardiol 2015; 188:63-4. [PMID: 25885753 DOI: 10.1016/j.ijcard.2015.04.045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 04/03/2015] [Indexed: 10/23/2022]
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Lee YM, Eggen J, Soni V, Drozda K, Nutescu EA, Cavallari LH. Warfarin dose requirements in a patient with the CYP2C9*14 allele. Pharmacogenomics 2015; 15:909-14. [PMID: 24956244 DOI: 10.2217/pgs.14.47] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We describe a 64-year-old male of Indian descent with a history of atrial fibrillation who was started on warfarin after hospital admission for acute stroke. He received genotype-guided warfarin dosing as per the standard-of-care at our hospital, with daily dose recommendations provided by the pharmacogenetics service. Genotyping revealed the rare CYP2C9*1/*14 genotype and warfarin insensitive VKORC1 -1639GG and CYP4F2 433Met/Met genotypes. The patient received an initial warfarin loading dose of 4 mg for 2 days, followed by 2-3 mg/day for the following 11 days. He reached a therapeutic international normalized ratio on day 5, which was maintained over the following week. This report adds to the limited data of the effects of the CYP2C9*14 allele on warfarin dose requirements.
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Scott SA, Lubitz SA. Warfarin pharmacogenetic trials: is there a future for pharmacogenetic-guided dosing? Pharmacogenomics 2015; 15:719-22. [PMID: 24897277 DOI: 10.2217/pgs.14.18] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Cavallari LH, Duarte JD. Genes affecting warfarin response-interactive or additive? J Clin Pharmacol 2014; 55:258-60. [PMID: 25385663 DOI: 10.1002/jcph.425] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 11/04/2014] [Indexed: 01/11/2023]
Abstract
Genotypes for cytochrome P450 (CYP) 2C9 and vitamin K epoxide reductase complex 1 (VKORC1) contribute significantly to the inter-patient variability in warfarin dose requirements. These genotypes in addition to clinical factors explain approximately 50% of the dose variability in Europeans, but less in other populations. Thus, a large portion of the variability remains unexplained and has been the focus of on-going research. Trials evaluating the clinical utility of genotype-guided warfarin dosing have shown a benefit in Europeans, but not in an ethnically diverse cohort. Identifying and accounting for variants important in non-European populations will likely be necessary before a benefit with genotype-guided dosing will be realized in these populations.
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Verhoef TI, Redekop WK, Daly AK, van Schie RMF, de Boer A, Maitland-van der Zee AH. Pharmacogenetic-guided dosing of coumarin anticoagulants: algorithms for warfarin, acenocoumarol and phenprocoumon. Br J Clin Pharmacol 2014; 77:626-41. [PMID: 23919835 DOI: 10.1111/bcp.12220] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 07/17/2013] [Indexed: 12/13/2022] Open
Abstract
Coumarin derivatives, such as warfarin, acenocoumarol and phenprocoumon are frequently prescribed oral anticoagulants to treat and prevent thromboembolism. Because there is a large inter-individual and intra-individual variability in dose-response and a small therapeutic window, treatment with coumarin derivatives is challenging. Certain polymorphisms in CYP2C9 and VKORC1 are associated with lower dose requirements and a higher risk of bleeding. In this review we describe the use of different coumarin derivatives, pharmacokinetic characteristics of these drugs and differences amongst the coumarins. We also describe the current clinical challenges and the role of pharmacogenetic factors. These genetic factors are used to develop dosing algorithms and can be used to predict the right coumarin dose. The effectiveness of this new dosing strategy is currently being investigated in clinical trials.
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Suarez-Kurtz G, Botton MR. Pharmacogenetics of coumarin anticoagulants in Brazilians. Expert Opin Drug Metab Toxicol 2014; 11:67-79. [PMID: 25345887 DOI: 10.1517/17425255.2015.976201] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Coumarin vitamin K antagonists are the mainstay of anticoagulant therapy in atrial fibrillation, prosthetic heart valves and thromboembolic conditions. Concerns with these drugs include large inter-individual variability in dose requirements, narrow therapeutic index and need to monitor prothrombin time repeatedly. AREAS COVERED Pharmacogenetic studies and dosing algorithms for warfarin and phenprocoumon. EXPERT OPINION Gene candidate studies in Brazilian patients verified consistently the association of warfarin and pheprocoumon stable dose requirements with CYP2C9 and VKORC1 polymorphisms, and minor or no influence of other pharmacogenes (e.g., CYP4F2 and F7). The predictive power of warfarin and phenprocoumon dosing algorithms developed for Brazilians compares favorably with those reported for other populations. A warfarin dosing algorithm derived for an admixed cohort performed equally well in self-reported White and Black patients, in marked contrast with the considerably poorer performance of other warfarin algorithms in patients of African descent compared to those of European ancestry. This discrepancy is ascribed to the extensive European/African admixture among Brazilians. Prospective studies of clinical utility of coumarin dosing algorithms, in the context of the Brazilian Public Health System, would represent an important counterpart to recently published trials in European and North American cohorts with predominant or exclusive European ancestry.
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Yildirim E, Erol K, Birdane A. Warfarin dose requirement in Turkish patients: the influences of patient characteristics and polymorphisms in CYP2C9, VKORC1 and factor VII. Hippokratia 2014; 18:319-327. [PMID: 26052198 PMCID: PMC4453805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
BACKGROUND To determine the contribution of cytochrome P4502C9 (CYP2C9), vitamin K epoxide reductase (VKORC1) and factor VII genotypes, age, body mass index (BMI), international normalized ratio (INR) and other individual patient characteristics on warfarin dose requirements in an adult Turkish population. METHODS Blood samples were collected from 101 Turkish patients. Genetic analyses for CYP2C9*2 and *3, VKORC1 -1639 G>A and factor VII -401 G>T polymorphisms were performed. Age, INR, BMI values and other individual patient characteristics were also recorded. RESULTS The mean daily warfarin dosage was significantly higher in patients with the CYP2C9*1/*1 genotype than in the CYP2C9*2/*2 and CYP2C9*1/*3 groups (p ≤ 0.05). With respect to the VKORC1 -1639 G>A polymorphism, the mean warfarin daily dose requirement was higher in the wild type group compared to the heterozygous group (p≤0.001). The mean daily dose requirement for patients with the GG form of factor VII was significantly higher than that of patients with the TT genotype (p ≤ 0.05). Age, gender, BMI, INR had no statistically significant correlation with warfarin dose (p ≥ 0.05). CONCLUSIONS Polymorphisms in CYP2C9, VKORC1 and factor VII did partially affect daily warfarin dose requirements, while age, gender, BMI and INR do not. However, further case-control studies with a larger study size and different genetic loci are needed to confirm our study.
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Jin B, Hong Y, Zhu J, Li Y, Shi HM. The impact of VKORC1-1639G > A genetic polymorphism upon warfarin dose requirement in different ethnic populations. Curr Med Res Opin 2014; 30:1505-11. [PMID: 24708259 DOI: 10.1185/03007995.2014.912982] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Published data on the association between vitamin K epoxide reductase complex 1 (VKORC1)-1639G > A polymorphism and warfarin dose requirement are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. METHODS AND RESULTS Studies were identified in English-language articles by search of PubMed and Embase database (inception to July 2013). A total of 32 prospective clinical trials involving 5005 patients were identified and included for analysis. Overall, the weighted mean maintenance dosage of warfarin in patients with the -1639AA genotype decreased 2.62 mg/d compared with that in the -1639GG genotype patients (95% CI -3.10 to -2.14; P < 0.00001) when 24 eligible studies were pooled into the meta-analysis. Furthermore, significantly lower warfarin dose requirement was found in patients with GA genotype versus GG genotype (WMD, -1.32; 95% CI -1.67 to -0.96; P < 0.00001). In the subgroup analysis by ethnicity, statistically significant lower maintenance dosage of warfarin in patients with the AA genotype versus GG genotype were found in both Caucasians (WMD, -2.47; 95% CI -2.92 to -2.03; P < 0.00001) and Asians (WMD, -2.84; 95% CI -4.57 to -1.11; P = 0.001). CONCLUSIONS This meta-analysis indicated that the VKORC1-1639G > A genetic polymorphism is associated with the variation of interindividual warfarin dose requirement in different ethnic populations.
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Jiménez-Varo E, Cañadas-Garre M, Henriques CI, Pinheiro AM, Gutiérrez-Pimentel MJ, Calleja-Hernández MÁ. Pharmacogenetics role in the safety of acenocoumarol therapy. Thromb Haemost 2014; 112:522-36. [PMID: 24919870 DOI: 10.1160/th13-11-0941] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 04/23/2014] [Indexed: 11/05/2022]
Abstract
Vitamin K antagonists (VKAs) remain as the most prescribed drug for treatment and prevention of thrombotic disorders in many countries, despite the recent approval of the new oral anticoagulants (NOACs). Although effectiveness and safety of VKAs are tightly associated to maintaining the patient within the international normalised ratio (INR) therapeutic range (TWR), they have been likened to NOACs when patients are in good INR control (≥66% of TWR). Therefore, assessing the safety of patients should be a priority in the selection of the anticoagulation therapy. The aim of this study was to evaluate the association between CYP2C9*2, CYP2C9*3, VKORC1, CYP4F2*3, ABCB1 C3435T, APOE, CYP2C19*2 and CYP2C19*17 gene polymorphisms and treatment safety in 128 patients diagnosed with atrial fibrillation or venous thromboembolism during the initial first seven months of acenocoumarol therapy. After the first month, VKORC1-T-allele and APOE-E3/E3 genotype were independently associated to higher time above therapeutic range (TAR) and lower time below the therapeutic range (TBR). After seven months, VKORC1 T-allele predicted higher TAR, and was also associated to increased INR>4, particularly the TT-genotype (odds ratio [OR]: 32; 95% confidence interval [CI95%]: 6-175; p=810⁻⁵). C-alleles for CYP2C9*3 (OR: 5.5; CI95%: 1.8-17; p=0.003) and ABCB1 (OR: 8.9;CI95%: 1.1-70; p=0.039) independently influenced on INR>6 . Patients VKORC1-TT/ABCB1-C remained 26.8% [19.7-38.9] TAR, with associated relative risk (RR) for INR>4 1.8 higher (CI95%: 1.2-2.5; p=0.015). Patients VKORC1-TT also presented the highest risk of bleeding events (RR: 3.5;CI95%: 1.4-8.4; p=0,010). In conclusion, VKORC1, CYP2C9*3, APOE and ABCB1 genotypes should be considered in prevention of overanticoagulation and bleeding events in the initiation of acenocoumarol therapy.
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Shaw K, Amstutz U, Hildebrand C, Rassekh SR, Hosking M, Neville K, Leeder JS, Hayden MR, Ross CJ, Carleton BC. VKORC1 and CYP2C9 genotypes are predictors of warfarin-related outcomes in children. Pediatr Blood Cancer 2014; 61:1055-62. [PMID: 24474498 DOI: 10.1002/pbc.24932] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 12/16/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND Despite substantial evidence supporting a pharmacogenetic approach to warfarin therapy in adults, evidence on the importance of genetics in warfarin therapy in children is limited, particularly for clinical outcomes. We assessed the contribution of CYP2C9/VKORC1/CYP4F2 genotypes and variation in other genes involved in vitamin K and coagulation pathways to warfarin dose and related clinical outcomes in children. PROCEDURE Clinical and genetic data for 93 children (age ≤ 18 years) who received warfarin therapy were obtained. DNA was genotyped for 93 selected single nucleotide polymorphisms using a custom assay. RESULTS With a median age of 4.8 years, our cohort included more young children than most previous studies. Overall, 76.3% of dose variability was explained by weight, indication, VKORC1-1639G/A and CYP2C9 *2/*3, with genotypes accounting for 21.1% of variability. There was a strong correlation (R(2) = 0.68; P < 0.001) between actual and predicted warfarin dose using a pediatric genotype-based dosing model. VKORC1 genotype had a significant impact on time to therapeutic international normalized ratio (INR) (P = 0.047) and time to over-anticoagulation (INR > 4; P = 0.024) during the initiation of therapy. CYP2C9*3 carriers were also at increased risk of major bleeding while receiving warfarin (adjusted OR = 11.28). An additional variant in CYP2C9 (rs7089580) was significantly associated with warfarin dose (P = 0.020) in a multivariate clinical and genetic model. CONCLUSIONS This study confirms the importance of VKORC1/CYP2C9 genotypes for warfarin dosing in a young pediatric cohort and demonstrates an impact of genetic factors on clinical outcomes in children. Furthermore, we identified an additional variant in CYP2C9 of potential relevance for warfarin dosing in children.
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Moreau C, Pautas E, Duverlie C, Berndt C, Andro M, Mahé I, Emmerich J, Lacut K, Le Gal G, Peyron I, Gouin-Thibault I, Golmard JL, Loriot MA, Siguret V. A model predicting fluindione dose requirement in elderly inpatients including genotypes, body weight, and amiodarone. Thromb Haemost 2014; 111:705-12. [PMID: 24337438 DOI: 10.1160/th13-07-0555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 11/16/2013] [Indexed: 01/11/2023]
Abstract
Indandione VKAs have been widely used for decades, especially in Eastern Europe and France. Contrary to coumarin VKAs, the relative contribution of individual factors to the indandione-VKA response is poorly known. In the present multicentre study, we sought to develop and validate a model including genetic and non-genetic factors to predict the daily fluindione dose requirement in elderly patients in whom VKA dosing is challenging. We prospectively recorded clinical and therapeutic data in 230 Caucasian inpatients mean aged 85 ± 6 years, who had reached international normalized ratio stabilisation (range 2.0-3.0) on fluindione. In the derivation cohort (n=156), we analysed 13 polymorphisms in seven genes potentially involved in the pharmacological effect or vitamin-K cycle (VKORC1, CYP4F2, EPHX1) and fluindione metabolism/transport (CYP2C9, CYP2C19, CYP3A5, ABCB1). We built a regression model incorporating non-genetic and genetic data and evaluated the model performances in a separate cohort (n=74).Body-weight, amiodarone intake, VKORC1, CYP4F2, ABCB1 genotypes were retained in the final model, accounting for 31.5% of dose variability. None influence of CYP2C9 was observed. Our final model showed good performances: in 83.3% of the validation cohort patients, the dose was accurately predicted within 5 mg, i.e.the usual step used for adjusting fluindione dosage. In conclusion, in addition to body-weight and amiodarone-intake, pharmacogenetic factors (VKORC1, CYP4F2, ABCB1) related to the pharmacodynamic effect and transport of fluindione significantly influenced the dose requirement in elderly patients while CYP2C9 did not. Studies are required to know whether fluindione could be an alternative VKA in carriers of polymorphic CYP2C9 alleles, hypersensitive to coumarins.
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Drögemöller BI, Wright GEB, Warnich L. Considerations for rare variants in drug metabolism genes and the clinical implications. Expert Opin Drug Metab Toxicol 2014; 10:873-84. [PMID: 24673405 DOI: 10.1517/17425255.2014.903239] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Large-scale whole genome and exome resequencing studies have revealed that humans have a high level of deleterious rare variation, which has important implications for the design of future pharmacogenetics studies. AREAS COVERED Current pharmacogenetic guidelines focus on the implementation of common variation into dosing guidelines. However, it is becoming apparent that rare variation may also play an important role in differential drug response. Current sequencing technologies offer the opportunity to examine rare variation, but there are many challenges associated with such analyses. Nonetheless, if a comprehensive picture of the role that genetic variants play in treatment outcomes is to be obtained, it will be necessary to include the entire spectrum of variation, including rare variants, into pharmacogenetic research. EXPERT OPINION In order to implement pharmacogenetics in the clinic, patients should be genotyped for clinically actionable pharmacogenetic variants and patients responding unfavourably to treatment after pharmacogenetics-based dosing should be identified and resequenced to identify additional functionally relevant variants, including rare variants. All derived information should be added to a central database to allow for the updating of existing dosing guidelines. By routinely implementing such strategies, pharmacogenetics-based treatment guidelines will continue to improve.
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