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Ndadza A, Muyambo S, Mntla P, Wonkam A, Chimusa E, Kengne AP, Ntsekhe M, Dandara C. Profiling of warfarin pharmacokinetics-associated genetic variants: Black Africans portray unique genetic markers important for an African specific warfarin pharmacogenetics-dosing algorithm. J Thromb Haemost 2021; 19:2957-2973. [PMID: 34382722 PMCID: PMC9543705 DOI: 10.1111/jth.15494] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/28/2021] [Accepted: 08/09/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Warfarin dose variability observed in patients is attributed to variation in genes involved in the warfarin metabolic pathway. Genetic variation in CYP2C9 and VKORC1 has been the traditional focus in evaluating warfarin dose variability, with little focus on other genes. OBJECTIVE We set out to evaluate 27 single nucleotide polymorphisms (SNPs) in the CYP2C cluster loci and 8 genes (VKORC1, ABCB1, CYP2C9, CYP2C19, CYP2C8, CYP1A2, CYP3A4, and CYP3A5) involved in pharmacokinetics of warfarin. PATIENTS/METHODS 503 participants were recruited among black Africans and Mixed Ancestry population groups, from South Africa and Zimbabwe, and a blood sample taken for DNA. Clinical parameters were obtained from patient medical records, and these were correlated with genetic variation. RESULTS Among black Africans, the SNPs CYP2C rs12777823G>A, CYP2C9 c.449G>A (*8), CYP2C9 c.1003C>T (*11) and CYP2C8 c.805A>T (*2) were significantly associated with warfarin maintenance dose. Conversely, CYP2C9 c.430C>T (*2), CYP2C8 c.792C>G (*4) and VKORC1 g.-1639G>A were significantly associated with maintenance dose among the Mixed Ancestry. The presence of CYP2C8*2 and CYP3A5*6 alleles was associated with increased mean warfarin maintenance dose, whereas CYP2C9*8 allele was associated with reduced warfarin maintenance dose. CONCLUSION African populations present with a diversity of variants that are important in predicting pharmacogenetics-based warfarin dosing in addition to those reported in CYP2C9 and VKORC1. It is therefore important, to include African populations in pharmacogenomics studies to be able to identify all possible biomarkers that are potential predictors for drug response.
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Affiliation(s)
- Arinao Ndadza
- Pharmacogenomics and Drug Metabolism Research GroupDivision of Human GeneticsDepartment of Pathology & Institute of Infectious Disease and Molecular Medicine (IDM)Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
| | - Sarudzai Muyambo
- Department of Clinical PharmacologyCollege of Health ScienceUniversity of ZimbabweHarareZimbabwe
- Department of Biological SciencesFaculty of Science and EngineeringBindura University of Science and EducationBinduraZimbabwe
| | - Pindile Mntla
- Department of CardiologySefako Makgatho Health Sciences University and Dr. George Mukhari HospitalPretoriaSouth Africa
| | - Ambroise Wonkam
- Pharmacogenomics and Drug Metabolism Research GroupDivision of Human GeneticsDepartment of Pathology & Institute of Infectious Disease and Molecular Medicine (IDM)Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
| | - Emile Chimusa
- Pharmacogenomics and Drug Metabolism Research GroupDivision of Human GeneticsDepartment of Pathology & Institute of Infectious Disease and Molecular Medicine (IDM)Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
| | - Andre P. Kengne
- Non‐Communicable Diseases Research UnitSouth African Medical Research Council and University of Cape TownCape TownSouth Africa
| | - Mpiko Ntsekhe
- Division of CardiologyDepartment of MedicineFaculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
| | - Collet Dandara
- Pharmacogenomics and Drug Metabolism Research GroupDivision of Human GeneticsDepartment of Pathology & Institute of Infectious Disease and Molecular Medicine (IDM)Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
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Hirata TDC, Dagli-Hernandez C, Genvigir FDV, Lauschke VM, Zhou Y, Hirata MH, Hirata RDC. Cardiovascular Pharmacogenomics: An Update on Clinical Studies of Antithrombotic Drugs in Brazilian Patients. Mol Diagn Ther 2021; 25:735-755. [PMID: 34357562 DOI: 10.1007/s40291-021-00549-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2021] [Indexed: 10/20/2022]
Abstract
Anticoagulant and antiplatelet drugs effectively prevent thrombotic events in patients with cardiovascular diseases, ischemic stroke, peripheral vascular diseases, and other thromboembolic diseases. However, genetic and non-genetic factors affect the response to antithrombotic therapy and can increase the risk of adverse events. This narrative review discusses pharmacogenomic studies on antithrombotic drugs commonly prescribed in Brazil. Multiple Brazilian studies assessed the impact of pharmacokinetic (PK) and pharmacodynamic (PD) gene variants on warfarin response. The reduced function alleles CYP2C9*2 and CYP2C9*3, and VKORC1 rs9923231 (c.-1639G>A) are associated with increased sensitivity to warfarin and a low dose requirement to prevent bleeding episodes, whereas CYP4F2 rs2108622 (p.Val433Met) carriers have higher dose requirements (warfarin resistance). These deleterious variants and non-genetic factors (age, gender, body weight, co-administered drugs, food interactions, and others) account for up to 63% of the warfarin dose variability. Few pharmacogenomics studies have explored antiplatelet drugs in Brazilian cohorts, finding associations between CYP2C19*2, PON1 rs662 and ABCC3 rs757421 genotypes and platelet responsiveness or clopidogrel PK in subjects with coronary artery disease (CAD) or acute coronary syndrome (ACS), whereas ITGB3 contributes to aspirin PK but not platelet responsiveness in diabetic patients. Brazilian guidelines on anticoagulants and antiplatelets recommend the use of a platelet aggregation test or genotyping only in selected cases of ACS subjects without ST-segment elevation taking clopidogrel, and also suggest CYP2C9 and VKORC1 genotyping before starting warfarin therapy to assess the risk of bleeding episodes or warfarin resistance.
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Affiliation(s)
- Thiago Dominguez Crespo Hirata
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes 580, Sao Paulo, 05508-000, Brazil
| | - Carolina Dagli-Hernandez
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes 580, Sao Paulo, 05508-000, Brazil
| | - Fabiana Dalla Vecchia Genvigir
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes 580, Sao Paulo, 05508-000, Brazil
| | - Volker Martin Lauschke
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Solna, Sweden.,Dr Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, 70376, Germany
| | - Yitian Zhou
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Solna, Sweden
| | - Mario Hiroyuki Hirata
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes 580, Sao Paulo, 05508-000, Brazil
| | - Rosario Dominguez Crespo Hirata
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes 580, Sao Paulo, 05508-000, Brazil.
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Pratt VM, Cavallari LH, Del Tredici AL, Hachad H, Ji Y, Kalman LV, Ly RC, Moyer AM, Scott SA, Whirl-Carrillo M, Weck KE. Recommendations for Clinical Warfarin Genotyping Allele Selection: A Report of the Association for Molecular Pathology and the College of American Pathologists. J Mol Diagn 2020; 22:847-859. [PMID: 32380173 DOI: 10.1016/j.jmoldx.2020.04.204] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 03/18/2020] [Accepted: 04/01/2020] [Indexed: 11/19/2022] Open
Abstract
The goal of the Association for Molecular Pathology (AMP) Clinical Practice Committee's AMP Pharmacogenomics (PGx) Working Group is to define the key attributes of PGx alleles recommended for clinical testing and a minimum set of variants that should be included in clinical PGx genotyping assays. This document series provides recommendations for a minimum panel of variant alleles (tier 1) and an extended panel of variant alleles (tier 2) that will aid clinical laboratories when designing assays for PGx testing. The AMP PGx Working Group considered functional impact of the variants, allele frequencies in multiethnic populations, the availability of reference materials, as well as other technical considerations for PGx testing when developing these recommendations. The ultimate goal is to promote standardization of PGx gene/allele testing across clinical laboratories. These recommendations are not to be interpreted as prescriptive but to provide a reference guide. Of note, a separate article with recommendations for CYP2C9 allele selection was previously developed by the PGx Working Group that can be applied broadly to CYP2C9-related medications. The warfarin allele recommendations in this report incorporate the previous CYP2C9 allele recommendations and additional genes and alleles that are specific to warfarin testing.
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Affiliation(s)
- Victoria M Pratt
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana.
| | - Larisa H Cavallari
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Pharmacotherapy and Translational Research and Center for Pharmacogenomics and Precision Medicine, University of Florida, Gainesville, Florida
| | - Andria L Del Tredici
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Millennium Health, LLC, San Diego, California
| | - Houda Hachad
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Translational Software, Bellevue, Washington
| | - Yuan Ji
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Pathology and ARUP Laboratories, University of Utah School of Medicine, Salt Lake City, Utah
| | - Lisa V Kalman
- Division of Laboratory Systems, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Reynold C Ly
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ann M Moyer
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Stuart A Scott
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York; Sema4, a Mount Sinai venture, Stamford, Connecticut
| | - Michelle Whirl-Carrillo
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Biomedical Data Science, Stanford University, Stanford, California
| | - Karen E Weck
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Departments of Pathology and Laboratory Medicine and Genetics, University of North Carolina, Chapel Hill, North Carolina
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Ndadza A, Thomford NE, Mukanganyama S, Wonkam A, Ntsekhe M, Dandara C. The Genetics of Warfarin Dose-Response Variability in Africans: An Expert Perspective on Past, Present, and Future. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2020; 23:152-166. [PMID: 30883300 DOI: 10.1089/omi.2019.0018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Coumarins such as warfarin are prescribed for prevention and treatment of thromboembolic disorders. Warfarin remains the most widely prescribed and an anticoagulant of choice in Africa. Warfarin use is, however, limited by interindividual variability in pharmacokinetics and a narrow therapeutic index. The difference in patients' pharmacodynamic responses to warfarin has been attributed to genetic variation in warfarin metabolism and molecular targets (e.g., CYP2C9 and VKORC1) and host-environment interactions. This expert review offers a synthesis of human genetics studies in Africans with respect to pharmacogenetics-informed warfarin dosing. We identify areas that need future research attention or could benefit from harnessing existing pharmacogenetics knowledge toward rational and optimal therapeutics with warfarin in African patients. A literature search was conducted until January 2019. A total of 343 articles were retrieved from nine African countries: Botswana, Ethiopia, Egypt, Ghana, Kenya, South Africa, Sudan, Tanzania, and Mozambique. We found 19 studies on genetics of warfarin treatment specifically among Africans. Genes examined included CYP2C9, VKORC1, CYP4F2, APOE, CALU, GGCX, and EPHX1. CYP2C9*2 and *3 alleles were highly frequent among Egyptians, while rare in other African populations. CYP2C9*5, *8, *9, and *11, and VKORC1 Asp36Tyr genetic variants explained warfarin variability in Africans better, compared to CYP2C9*2 and *3. In Africa, there is limited pharmacogenetics data on warfarin. Therefore, future research and funding commitments should be prioritized to ensure safe and effective use of warfarin in Africa. Lessons learned in Africa from the science of pharmacogenetics would inform rational therapeutics in hematology, cardiology, and surgical specialties worldwide.
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Affiliation(s)
- Arinao Ndadza
- 1 Pharmacogenomics and Drug Metabolism Research Group, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Nicholas Ekow Thomford
- 1 Pharmacogenomics and Drug Metabolism Research Group, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | | | - Ambroise Wonkam
- 1 Pharmacogenomics and Drug Metabolism Research Group, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Mpiko Ntsekhe
- 3 Division of Cardiology, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Collet Dandara
- 1 Pharmacogenomics and Drug Metabolism Research Group, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Genetic causes of resistance to vitamin K antagonists in Polish patients: a novel p.Ile123Met mutation in VKORC1 gene. Blood Coagul Fibrinolysis 2018; 29:429-434. [PMID: 29794812 DOI: 10.1097/mbc.0000000000000737] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
: Mutations in the genes encoding vitamin K epoxide reductase complex subunit 1 (VKORC1) and cytochrome P450 2C9 (CYP2C9) largely contribute to the inter-individual variations in vitamin K antagonists (VKAs) dose requirements. Up to 50% of the dosage variability can be explained by genetic polymorphisms in these genes. We sought to identify the mutations responsible for VKA resistance in a series of Polish patients. Of the 607 patients treated with VKA, 35 (6%) individuals with the VKA resistance defined as a daily dose of acenocoumarol more than 8 mg (n = 15, 43%) or warfarin more than 10 mg (n = 20, 57%) were selected for further mutational analysis using Sanger sequencing (VKORC1) or real-time PCR genotyping (CYP2C9). The indications for anticoagulant treatment were venous thromboembolism (n = 28, 80%), atrial fibrillation (n = 6, 17%), or artificial heart valve (n = 1, 3%). Patients taking medication interfering with VKA were ineligible. Almost all of VKA-resistant patients (n = 34, 97%) possessed at least one VKORC1*3 (n = 29, 83%) or VKORC1*4 (n = 15, 43%) haplotypes. In a 70-year-old man atrial fibrillation patient on the daily acenocoumarol dose of 16 mg, a novel p.Ile123Met (c.369C>G) VKORC1 mutation was found. In-silico analysis showed that the p.Ile123Met can functionally underlie the acenocoumarol resistance, presumably by altering VKA binding. To our knowledge this is the first cohort of Polish patients resistant to VKA evaluated for the causal genetic background. We found one new detrimental mutation underlying VKA resistance. Our study highlights a key role of unidentified environmental factors in VKA resistance in daily clinical practice.
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Warfarin resistance associated with genetic polymorphism of VKORC1: linking clinical response to molecular mechanism using computational modeling. Pharmacogenet Genomics 2016; 26:44-50. [PMID: 26513304 DOI: 10.1097/fpc.0000000000000184] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The variable response to warfarin treatment often has a genetic basis. A protein homology model of human vitamin K epoxide reductase, subunit 1 (VKORC1), was generated to elucidate the mechanism of warfarin resistance observed in a patient with the Val66Met mutation. The VKORC1 homology model comprises four transmembrane (TM) helical domains and a half helical lid domain. Cys132 and Cys135, located in the N-terminal end of TM-4, are linked through a disulfide bond. Two distinct binding sites for warfarin were identified. Site-1, which binds vitamin K epoxide (KO) in a catalytically favorable orientation, shows higher affinity for S-warfarin compared with R-warfarin. Site-2, positioned in the domain occupied by the hydrophobic tail of KO, binds both warfarin enantiomers with similar affinity. Displacement of Arg37 occurs in the Val66Met mutant, blocking access of warfarin (but not KO) to Site-1, consistent with clinical observation of warfarin resistance.
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Mboup MC, Dia K, Ba DM, Fall PD. [Resistance to acenocoumarol revealing a missense mutation of the vitamin K epoxyde reductase VKORC1: a case report]. Ann Cardiol Angeiol (Paris) 2015; 64:59-61. [PMID: 24095214 DOI: 10.1016/j.ancard.2013.08.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 08/12/2013] [Indexed: 06/02/2023]
Abstract
A significant proportion of the interindividual variability of the response to vitamin K antagonist (VKA) treatment has been associated with genetic factors. Genetic variations affecting the vitamin K epoxide reductase complex subunit 1 (VKORC1) are associated with hypersensitivity or rarely with resistance to VKA. We report the case of a black women patient who presents a resistance to acenocoumarol. Despite the use of high doses of acenocoumarol (114 mg/week) for the treatment of recurrent pulmonary embolism, the International Normalized Ratio was below the therapeutic target. This resistance to acenocoumarol was confirmed by the identification of a missense mutation Val66Met of the vitamin K epoxide reductase.
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Affiliation(s)
- M C Mboup
- Service de cardiologie, hôpital principal de Dakar, 1, avenue Nelson Mandéla, BP 3006, Dakar, Sénégal.
| | - K Dia
- Service de cardiologie, hôpital principal de Dakar, 1, avenue Nelson Mandéla, BP 3006, Dakar, Sénégal
| | - D M Ba
- Service de cardiologie, hôpital principal de Dakar, 1, avenue Nelson Mandéla, BP 3006, Dakar, Sénégal
| | - P D Fall
- Service de cardiologie, hôpital principal de Dakar, 1, avenue Nelson Mandéla, BP 3006, Dakar, Sénégal
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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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Affiliation(s)
- Guilherme Suarez-Kurtz
- Instituto Nacional de Câncer, Pharmacology Division , Rua André Cavalcanti 37, Rio de Janeiro, CEP 20231-050, RJ , Brazil +5521 3207 6502 ;
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Suarez-Kurtz G, Botton MR. Pharmacogenomics of warfarin in populations of African descent. Br J Clin Pharmacol 2013; 75:334-46. [PMID: 22676711 PMCID: PMC3579249 DOI: 10.1111/j.1365-2125.2012.04354.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 05/30/2012] [Indexed: 12/21/2022] Open
Abstract
Warfarin is the most commonly prescribed oral anticoagulant worldwide despite its narrow therapeutic index and the notorious inter- and intra-individual variability in dose required for the target clinical effect. Pharmacogenetic polymorphisms are major determinants of warfarin pharmacokinetic and dynamics and included in several warfarin dosing algorithms. This review focuses on warfarin pharmacogenomics in sub-Saharan peoples, African Americans and admixed Brazilians. These 'Black' populations differ in several aspects, notably their extent of recent admixture with Europeans, a factor which impacts on the frequency distribution of pharmacogenomic polymorphisms relevant to warfarin dose requirement for the target clinical effect. Whereas a small number of polymorphisms in VKORC1 (3673G > A, rs9923231), CYP2C9 (alleles *2 and *3, rs1799853 and rs1057910, respectively) and arguably CYP4F2 (rs2108622), may capture most of the pharmacogenomic influence on warfarin dose variance in White populations, additional polymorphisms in these, and in other, genes (e.g. CALU rs339097) increase the predictive power of pharmacogenetic warfarin dosing algorithms in the Black populations examined. A personalized strategy for initiation of warfarin therapy, allowing for improved safety and cost-effectiveness for populations of African descent must take into account their pharmacogenomic diversity, as well as socio-economical, cultural and medical factors. Accounting for this heterogeneity in algorithms that are 'friendly' enough to be adopted by warfarin prescribers worldwide requires gathering information from trials at different population levels, but demands also a critical appraisal of racial/ethnic labels that are commonly used in the clinical pharmacology literature but do not accurately reflect genetic ancestry and population diversity.
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Affiliation(s)
- Guilherme Suarez-Kurtz
- Divisão de Farmacologia, Coordenação de Pesquisa, Instituto Nacional de Câncer, Rio de Janeiro, Brazil.
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