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Zhao L, Zhai Z, Li P. One Rare Warfarin Resistance Case and Possible Mechanism Exploration. Pharmgenomics Pers Med 2023; 16:609-615. [PMID: 37359384 PMCID: PMC10290475 DOI: 10.2147/pgpm.s404474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 05/26/2023] [Indexed: 06/28/2023] Open
Abstract
One 59-year-old female patient with deep venous thrombosis (DVT) and pulmonary embolism (PE) was treated with 6 mg warfarin once daily as an anticoagulant. Before taking warfarin, her international normalized ratio (INR) was 0.98. Two days after warfarin treatment, her INR did not change from baseline. Due to the high severity of the PE, the patient needed to reach her target range (INR goal = 2.5, range = 2~3) rapidly, so the dose of warfarin was increased from 6 mg daily to 27 mg daily. However, the patient's INR did not improve with the dose escalation, still maintaining an INR of 0.97-0.98. We drew a blood sample half an hour before administering 27 mg warfarin and detected single nucleotide polymorphism for the following genes, which were identified to be relevant with warfarin resistance: CYP2C9 rs1799853, rs1057910, VKORC1 rs9923231, rs61742245, rs7200749, rs55894764, CYP4F2 rs2108622, and GGCX rs2592551. The trough plasma concentration of warfarin was 196.2 ng/mL after 2 days of warfarin administration with 27 mg QD, which was much lower than the therapeutic drug concentration ranges of warfarin (500-3,000 ng/mL). The genotype results demonstrate that the CYP4F2gene has rs2108622 mutation which can explain some aspect of warfarin resistance. Further investigations are necessary to fully characterize other pharmacogenomics or pharmacodynamics determinants of warfarin dose-response in Chinese.
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Affiliation(s)
- Li Zhao
- Pharmacy Department, China-Japan Friendship Hospital, Beijing, People’s Republic of China
| | - Zhenguo Zhai
- Department of Respiratory and Critical Care Medicine, China-Japan Friendship Hospital, Beijing, People’s Republic of China
| | - Pengmei Li
- Pharmacy Department, China-Japan Friendship Hospital, Beijing, People’s Republic of China
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2
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Jallul M, Alhudiri I, Al-Eitan L, Elzagheid A. Warfarin pharmacogenomics in African populations: the importance of ethnicity-based algorithms. Pharmacogenomics 2022; 23:753-757. [PMID: 36004679 DOI: 10.2217/pgs-2022-0067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Tweetable abstract It is well accepted that pharmacogenomics (PGx) information from Asia and Europe should not be applied to Africa. More work is needed on different ethnic groups to generate population-specific algorithms that can be used effectively and safely.
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Affiliation(s)
- Mwada Jallul
- Genetic Engineering Department, Libyan Biotechnology Research Centre, Tripoli, P.O. Box. 30313, Libya
| | - Inas Alhudiri
- Genetic Engineering Department, Libyan Biotechnology Research Centre, Tripoli, P.O. Box. 30313, Libya
| | - Laith Al-Eitan
- Department of Biotechnology & Genetic Engineering, Jordan University of Science & Technology, Irbid, 22110, Jordan
| | - Adam Elzagheid
- Genetic Engineering Department, Libyan Biotechnology Research Centre, Tripoli, P.O. Box. 30313, Libya
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Wanounou M, Shaul C, Abu Ghosh Z, Alamia S, Caraco Y. The Impact of CYP2C9*11 Allelic Variant on the Pharmacokinetics of Phenytoin and (S)-Warfarin. Clin Pharmacol Ther 2022; 112:156-163. [PMID: 35426132 PMCID: PMC9322346 DOI: 10.1002/cpt.2613] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/07/2022] [Indexed: 12/21/2022]
Abstract
Cytochrome P450 2C9 (CYP2C9) is responsible for the oxidative metabolism of about 15% of commonly used drugs, some of which are characterized by a narrow therapeutic window. CYP2C9 is highly polymorphic, and over 60 alleles have been described. CYP2C9*2 and CYP2C9*3 are the most common polymorphisms among White patients and both are associated with decreased activity. The evidence concerning the functional importance of less frequent variant alleles is scarce. The objective of the current study was to characterize the in vivo activity of CYP2C9 among carriers of CYP2C9*11, one of the "African" alleles and the fourth most common CYP2C9 variant allele among White patients by using two prototype substrates, phenytoin and (S)-warfarin. Single 300-mg phenytoin and 20-mg warfarin doses were given to 150 healthy Ethiopian Jewish participants who were nonsmokers, at least one week apart. (S)-warfarin oral clearance and phenytoin metabolic ratio (PMR) derived from the ratio of 5-(4-hydroxyphenyl)-5-phenylhydantoin in 24-hour urine collection to plasma phenytoin 12 hours (PMR 24/12) or 24 hours (PMR 24/24) post dosing, were used as markers of CYP2C9 activity. PMR 24/12 and PMR 24/24 were reduced by 50% and 62.2%, respectively, among carriers of CYP2C9*1/*11 (n = 13) as compared with carriers of CYP2C9*1/*1 (n = 127) (false discovery rate (FDR) q < 0.001). The respective decrease in (S)-warfarin oral clearance was 52.6% (FDR q < 0.001). In conclusion, the enzyme encoded by CYP2C9*11 is characterized by a more than 50% decrease in the enzymatic activity, resembling the extent of decrease associated with CYP2C9*3 ("no-function allele"). Among patients of African ancestry, CYP2C9*11 genetic analysis should be considered prior to prescribing of narrow therapeutic window drugs such as phenytoin, warfarin, nonsteroidal anti-inflammatory drugs, or siponimod.
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Affiliation(s)
- Maor Wanounou
- Clinical Pharmacology Unit, Division of Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.,Faculty of Medicine, Institute of Drug Research, School of Pharmacy, Hebrew University, Jerusalem, Israel
| | - Chanan Shaul
- Clinical Pharmacology Unit, Division of Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.,Faculty of Medicine, Institute of Drug Research, School of Pharmacy, Hebrew University, Jerusalem, Israel
| | - Zahi Abu Ghosh
- Clinical Pharmacology Unit, Division of Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Shoshana Alamia
- Clinical Pharmacology Unit, Division of Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Yoseph Caraco
- Clinical Pharmacology Unit, Division of Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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Nthontho KC, Ndlovu AK, Sharma K, Kasvosve I, Hertz DL, Paganotti GM. Pharmacogenetics of Breast Cancer Treatments: A Sub-Saharan Africa Perspective. Pharmgenomics Pers Med 2022; 15:613-652. [PMID: 35761855 PMCID: PMC9233488 DOI: 10.2147/pgpm.s308531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 05/31/2022] [Indexed: 11/30/2022] Open
Abstract
Breast cancer is the most frequent cause of cancer death in low- and middle-income countries, in particular among sub-Saharan African women, where response to available anticancer treatment therapy is often limited by the recurrent breast tumours and metastasis, ultimately resulting in decreased overall survival rate. This can also be attributed to African genomes that contain more variation than those from other parts of the world. The purpose of this review is to summarize published evidence on pharmacogenetic and pharmacokinetic aspects related to specific available treatments and the known genetic variabilities associated with metabolism and/or transport of breast cancer drugs, and treatment outcomes when possible. The emphasis is on the African genetic variation and focuses on the genes with the highest strength of evidence, with a close look on CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4/5, CYP19A1, UGT1A4, UGT2B7, UGT2B15, SLC22A16, SLC38A7, FcγR, DPYD, ABCB1, and SULT1A1, which are the genes known to play major roles in the metabolism and/or elimination of the respective anti-breast cancer drugs given to the patients. The genetic variability of their metabolism could be associated with different metabolic phenotypes that may cause reduced patients’ adherence because of toxicity or sub-therapeutic doses. Finally, this knowledge enhances possible personalized treatment approaches, with the possibility of improving survival outcomes in patients with breast cancer.
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Affiliation(s)
- Keneuoe Cecilia Nthontho
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Gaborone, Botswana
- Botswana-University of Pennsylvania Partnership, Gaborone, Botswana
| | - Andrew Khulekani Ndlovu
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Gaborone, Botswana
| | | | - Ishmael Kasvosve
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Gaborone, Botswana
| | - Daniel Louis Hertz
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI, USA
| | - Giacomo Maria Paganotti
- Botswana-University of Pennsylvania Partnership, Gaborone, Botswana
- Division of Infectious Diseases, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Biomedical Sciences, Faculty of Medicine, University of Botswana, Gaborone, Botswana
- Correspondence: Giacomo Maria Paganotti, Botswana-University of Pennsylvania Partnership, PO Box 45498, Riverwalk Gaborone, Botswana, Tel +267 3555375, Email
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Lopes JL, Harris K, Karow MB, Peterson SE, Kluge ML, Kotzer KE, Lopes GS, Larson NB, Bielinski SJ, Scherer SE, Wang L, Weinshilboum RM, Black JL, Moyer AM. Targeted Genotyping in Clinical Pharmacogenomics: What Is Missing? J Mol Diagn 2022; 24:253-261. [PMID: 35041929 PMCID: PMC8961466 DOI: 10.1016/j.jmoldx.2021.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/09/2021] [Accepted: 11/29/2021] [Indexed: 01/01/2023] Open
Abstract
Clinical pharmacogenomic testing typically uses targeted genotyping, which only detects variants included in the test design and may vary among laboratories. To evaluate the potential patient impact of genotyping compared with sequencing, which can detect common and rare variants, an in silico targeted genotyping panel was developed based on the variants most commonly included in clinical tests and applied to a cohort of 10,030 participants who underwent sequencing for CYP1A2, CYP2C19, CYP2C9, CYP2D6, CYP3A4, CYP3A5, DPYD, SLCO1B1, TPMT, UGT1A1, and VKORC1. The results of in silico targeted genotyping were compared with the clinically reported sequencing results. Of the 10,030 participants, 2780 (28%) had at least one potentially clinically relevant variant/allele identified by sequencing that would not have been detected in a standard targeted genotyping panel. The genes with the largest number of participants with variants only detected by sequencing were SLCO1B1, DPYD, and CYP2D6, which affected 13%, 6.3%, and 3.5% of participants, respectively. DPYD (112 variants) and CYP2D6 (103 variants) had the largest number of unique variants detected only by sequencing. Although targeted genotyping detects most clinically significant pharmacogenomic variants, sequencing-based approaches are necessary to detect rare variants that collectively affect many patients. However, efforts to establish pharmacogenomic variant classification systems and nomenclature to accommodate rare variants will be required to adopt sequencing-based pharmacogenomics.
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Affiliation(s)
- Jaime L. Lopes
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Kimberley Harris
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Mary Beth Karow
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Sandra E. Peterson
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Michelle L. Kluge
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Katrina E. Kotzer
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Guilherme S. Lopes
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | - Nicholas B. Larson
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota
| | | | - Steven E. Scherer
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Liewei Wang
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - Richard M. Weinshilboum
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - John L. Black
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Ann M. Moyer
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota,Address correspondence to Ann M. Moyer, M.D., Ph.D., Mayo Clinic, 200 First St SW, Rochester, MN 55905.
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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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Holcomb D, Alexaki A, Hernandez N, Hunt R, Laurie K, Kames J, Hamasaki-Katagiri N, Komar AA, DiCuccio M, Kimchi-Sarfaty C. Gene variants of coagulation related proteins that interact with SARS-CoV-2. PLoS Comput Biol 2021; 17:e1008805. [PMID: 33730015 PMCID: PMC8007013 DOI: 10.1371/journal.pcbi.1008805] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 03/29/2021] [Accepted: 02/15/2021] [Indexed: 12/30/2022] Open
Abstract
Thrombosis is a recognized complication of Coronavirus disease of 2019 (COVID-19) and is often associated with poor prognosis. There is a well-recognized link between coagulation and inflammation, however, the extent of thrombotic events associated with COVID-19 warrants further investigation. Poly(A) Binding Protein Cytoplasmic 4 (PABPC4), Serine/Cysteine Proteinase Inhibitor Clade G Member 1 (SERPING1) and Vitamin K epOxide Reductase Complex subunit 1 (VKORC1), which are all proteins linked to coagulation, have been shown to interact with SARS proteins. We computationally examined the interaction of these with SARS-CoV-2 proteins and, in the case of VKORC1, we describe its binding to ORF7a in detail. We examined the occurrence of variants of each of these proteins across populations and interrogated their potential contribution to COVID-19 severity. Potential mechanisms, by which some of these variants may contribute to disease, are proposed. Some of these variants are prevalent in minority groups that are disproportionally affected by severe COVID-19. Therefore, we are proposing that further investigation around these variants may lead to better understanding of disease pathogenesis in minority groups and more informed therapeutic approaches.
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Affiliation(s)
- David Holcomb
- Center for Biologics Evaluation and Research, Office of Tissues and Advanced Therapies, Division of Plasma Protein Therapeutics, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Aikaterini Alexaki
- Center for Biologics Evaluation and Research, Office of Tissues and Advanced Therapies, Division of Plasma Protein Therapeutics, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Nancy Hernandez
- Center for Biologics Evaluation and Research, Office of Tissues and Advanced Therapies, Division of Plasma Protein Therapeutics, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Ryan Hunt
- Center for Biologics Evaluation and Research, Office of Tissues and Advanced Therapies, Division of Plasma Protein Therapeutics, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Kyle Laurie
- Center for Biologics Evaluation and Research, Office of Tissues and Advanced Therapies, Division of Plasma Protein Therapeutics, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Jacob Kames
- Center for Biologics Evaluation and Research, Office of Tissues and Advanced Therapies, Division of Plasma Protein Therapeutics, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Nobuko Hamasaki-Katagiri
- Center for Biologics Evaluation and Research, Office of Tissues and Advanced Therapies, Division of Plasma Protein Therapeutics, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Anton A. Komar
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio, United States of America
| | - Michael DiCuccio
- National Center of Biotechnology Information, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Chava Kimchi-Sarfaty
- Center for Biologics Evaluation and Research, Office of Tissues and Advanced Therapies, Division of Plasma Protein Therapeutics, Food and Drug Administration, Silver Spring, Maryland, United States of America
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8
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B. Tata E, A. Ambele M, S. Pepper M. Barriers to Implementing Clinical Pharmacogenetics Testing in Sub-Saharan Africa. A Critical Review. Pharmaceutics 2020; 12:pharmaceutics12090809. [PMID: 32858798 PMCID: PMC7560181 DOI: 10.3390/pharmaceutics12090809] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/19/2020] [Accepted: 08/22/2020] [Indexed: 12/14/2022] Open
Abstract
Clinical research in high-income countries is increasingly demonstrating the cost- effectiveness of clinical pharmacogenetic (PGx) testing in reducing the incidence of adverse drug reactions and improving overall patient care. Medications are prescribed based on an individual’s genotype (pharmacogenes), which underlies a specific phenotypic drug response. The advent of cost-effective high-throughput genotyping techniques coupled with the existence of Clinical Pharmacogenetics Implementation Consortium (CPIC) dosing guidelines for pharmacogenetic “actionable variants” have increased the clinical applicability of PGx testing. The implementation of clinical PGx testing in sub-Saharan African (SSA) countries can significantly improve health care delivery, considering the high incidence of communicable diseases, the increasing incidence of non-communicable diseases, and the high degree of genetic diversity in these populations. However, the implementation of PGx testing has been sluggish in SSA, prompting this review, the aim of which is to document the existing barriers. These include under-resourced clinical care logistics, a paucity of pharmacogenetics clinical trials, scientific and technical barriers to genotyping pharmacogene variants, and socio-cultural as well as ethical issues regarding health-care stakeholders, among other barriers. Investing in large-scale SSA PGx research and governance, establishing biobanks/bio-databases coupled with clinical electronic health systems, and encouraging the uptake of PGx knowledge by health-care stakeholders, will ensure the successful implementation of pharmacogenetically guided treatment in SSA.
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Affiliation(s)
- Emiliene B. Tata
- Institute for Cellular and Molecular Medicine, Department of Immunology, and South African Medical Research Council Extramural Unit for Stem Cell Research & Therapy, Faculty of Health Sciences, University of Pretoria, Pretoria 0084, South Africa; (E.B.T.); (M.A.A.)
| | - Melvin A. Ambele
- Institute for Cellular and Molecular Medicine, Department of Immunology, and South African Medical Research Council Extramural Unit for Stem Cell Research & Therapy, Faculty of Health Sciences, University of Pretoria, Pretoria 0084, South Africa; (E.B.T.); (M.A.A.)
- Department of Oral Pathology and Oral Biology, Faculty of Health Sciences, School of Dentistry, University of Pretoria, PO BOX 1266, Pretoria 0001, South Africa
| | - Michael S. Pepper
- Institute for Cellular and Molecular Medicine, Department of Immunology, and South African Medical Research Council Extramural Unit for Stem Cell Research & Therapy, Faculty of Health Sciences, University of Pretoria, Pretoria 0084, South Africa; (E.B.T.); (M.A.A.)
- Correspondence: ; Tel.: +27-12-319-2190
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9
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Asiimwe IG, Zhang EJ, Osanlou R, Krause A, Dillon C, Suarez-Kurtz G, Zhang H, Perini JA, Renta JY, Duconge J, Cavallari LH, Marcatto LR, Beasly MT, Perera MA, Limdi NA, Santos PCJL, Kimmel SE, Lubitz SA, Scott SA, Kawai VK, Jorgensen AL, Pirmohamed M. Genetic Factors Influencing Warfarin Dose in Black-African Patients: A Systematic Review and Meta-Analysis. Clin Pharmacol Ther 2020; 107:1420-1433. [PMID: 31869433 PMCID: PMC7217737 DOI: 10.1002/cpt.1755] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 12/05/2019] [Indexed: 12/20/2022]
Abstract
Warfarin is the most commonly used oral anticoagulant in sub-Saharan Africa. Dosing is challenging due to a narrow therapeutic index and high interindividual variability in dose requirements. To evaluate the genetic factors affecting warfarin dosing in black-Africans, we performed a meta-analysis of 48 studies (2,336 patients). Significant predictors for CYP2C9 and stable dose included rs1799853 (CYP2C9*2), rs1057910 (CYP2C9*3), rs28371686 (CYP2C9*5), rs9332131 (CYP2C9*6), and rs28371685 (CYP2C9*11) reducing dose by 6.8, 12.5, 13.4, 8.1, and 5.3 mg/week, respectively. VKORC1 variants rs9923231 (-1639G>A), rs9934438 (1173C>T), rs2359612 (2255C>T), rs8050894 (1542G>C), and rs2884737 (497T>G) decreased dose by 18.1, 21.6, 17.3, 11.7, and 19.6 mg/week, respectively, whereas rs7294 (3730G>A) increased dose by 6.9 mg/week. Finally, rs12777823 (CYP2C gene cluster) was associated with a dose reduction of 12.7 mg/week. Few studies were conducted in Africa, and patient numbers were small, highlighting the need for further work in black-Africans to evaluate genetic factors determining warfarin response.
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Affiliation(s)
- Innocent G. Asiimwe
- The Wolfson Centre for Personalized Medicine, MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool
| | - Eunice J. Zhang
- The Wolfson Centre for Personalized Medicine, MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool
| | - Rostam Osanlou
- The Wolfson Centre for Personalized Medicine, MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool
| | - Amanda Krause
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, The University of the Witwatersrand, Johannesburg, South Africa
| | - Chrisly Dillon
- Department of Neurology & Epidemiology, Hugh Kaul Precision Medicine Institute, The University of Alabama at Birmingham
| | | | - Honghong Zhang
- Department of Pharmacology, Center for Pharmacogenomics, Northwestern University, Chicago IL
| | - Jamila A Perini
- Research Laboratory of Pharmaceutical Sciences, West Zone State University-UEZO, Rio de Janeiro, Brazil
| | - Jessicca Y. Renta
- University of Puerto Rico School of Pharmacy, Medical Sciences Campus, PO Box 365067, San Juan, PR 00936-5067
| | - Jorge Duconge
- University of Puerto Rico School of Pharmacy, Medical Sciences Campus, PO Box 365067, San Juan, PR 00936-5067
| | - Larisa H Cavallari
- Center for Pharmacogenomics, Department of Pharmacotherapy and Translational Research, University of Florida College of Pharmacy, Gainesville, FL, USA
| | - Leiliane R. Marcatto
- Laboratory of Genetics and Molecular Cardiology, Faculdade de Medicina FMUSP, Heart Institute (InCor), Universidade de São Paulo, São Paulo, Brazil
| | - Mark T. Beasly
- Department of Neurology & Epidemiology, Hugh Kaul Precision Medicine Institute, The University of Alabama at Birmingham
| | - Minoli A Perera
- Department of Pharmacology, Center for Pharmacogenomics, Northwestern University, Chicago IL
| | - Nita A. Limdi
- Department of Neurology & Epidemiology, Hugh Kaul Precision Medicine Institute, The University of Alabama at Birmingham
| | - Paulo C. J. L. Santos
- Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo, EPM-Unifesp, São Paulo, Brazil
| | - Stephen E. Kimmel
- Perelman School of Medicine at the University of Pennsylvania, Department of Biostatistics, Epidemiology, and Informatics
| | - Steven A. Lubitz
- Cardiac Arrhythmia Service and Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA
| | - Stuart A. Scott
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Sema4, a Mount Sinai venture, Stamford, CT 06902, USA
| | - Vivian K. Kawai
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Andrea L. Jorgensen
- Department of Biostatistics, Institute of Translational Medicine, University of Liverpool
- These authors contributed equally: Andrea Jorgensen and Munir Pirmohamed
| | - Munir Pirmohamed
- The Wolfson Centre for Personalized Medicine, MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool
- These authors contributed equally: Andrea Jorgensen and Munir Pirmohamed
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Zhang H, De T, Zhong Y, Perera MA. The Advantages and Challenges of Diversity in Pharmacogenomics: Can Minority Populations Bring Us Closer to Implementation? Clin Pharmacol Ther 2020; 106:338-349. [PMID: 31038731 DOI: 10.1002/cpt.1491] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 04/18/2019] [Indexed: 01/01/2023]
Abstract
Health disparities exist among minorities in the United States, with differences seen in disease prevalence, mortality, and responses to medications. These differences are multifactorial with genetic variation explaining a portion of this variability. Pharmacogenomics aims to find the effect of genetic variations on drug response, with the goal of optimizing drug therapy and development. Although genome-wide association studies have been useful in unbiasedly surveying the genome for genetic drivers of clinically relevant phenotypes, most of these studies have been conducted in mainly participants of European and Asian descent, contributing to a growing health disparity in precision medicine. Diversity is important to pharmacogenomic studies, and there may be real advantages to the use of these complex genomes in pharmacogenomics. In this review we will outline some of the advantages and confounders of pharmacogenomics in minorities, describe the role of genetic variation in pharmacologic pathways, and highlight a number of population-specific findings.
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Affiliation(s)
- Honghong Zhang
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Tanima De
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Yizhen Zhong
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Minoli A Perera
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
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11
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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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12
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Radouani F, Zass L, Hamdi Y, Rocha JD, Sallam R, Abdelhak S, Ahmed S, Azzouzi M, Benamri I, Benkahla A, Bouhaouala-Zahar B, Chaouch M, Jmel H, Kefi R, Ksouri A, Kumuthini J, Masilela P, Masimirembwa C, Othman H, Panji S, Romdhane L, Samtal C, Sibira R, Ghedira K, Fadlelmola F, Kassim SK, Mulder N. A review of clinical pharmacogenetics Studies in African populations. Per Med 2020; 17:155-170. [PMID: 32125935 PMCID: PMC8093600 DOI: 10.2217/pme-2019-0110] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Effective interventions and treatments for complex diseases have been implemented globally, however, coverage in Africa has been comparatively lower due to lack of capacity, clinical applicability and knowledge on the genetic contribution to disease and treatment. Currently, there is a scarcity of genetic data on African populations, which have enormous genetic diversity. Pharmacogenomics studies have the potential to revolutionise treatment of diseases, therefore, African populations are likely to benefit from these approaches to identify likely responders, reduce adverse side effects and optimise drug dosing. This review discusses clinical pharmacogenetics studies conducted in African populations, focusing on studies that examined drug response in complex diseases relevant to healthcare. Several pharmacogenetics associations have emerged from African studies, as have gaps in knowledge.
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Affiliation(s)
- Fouzia Radouani
- Research Department, Chlamydiae & Mycoplasmas Laboratory, Institut Pasteur du Maroc, Casablanca 20360, Morocco
| | - Lyndon Zass
- Computational Biology Division, Department of Integrative Biomedical Sciences, IDM, CIDRI Africa Wellcome Trust Centre, University of Cape Town, South Africa
| | - Yosr Hamdi
- Laboratory of Biomedical Genomics & Oncogenetics, Institut Pasteur de Tunis, Université Tunis El Manar, 13, Place Pasteur BP 74, 1002 Tunis, Belvédère, Tunisie
| | - Jorge da Rocha
- Sydney Brenner Institute for Molecular Bioscience, University of The Witwatersrand, Johannesburg, South Africa
| | - Reem Sallam
- Medical Biochemistry & Molecular Biology Department, Faculty of Medicine, Ain Shams University, Abbaseya, Cairo 11381, Egypt
| | - Sonia Abdelhak
- Laboratory of Biomedical Genomics & Oncogenetics, Institut Pasteur de Tunis, Université Tunis El Manar, 13, Place Pasteur BP 74, 1002 Tunis, Belvédère, Tunisie
| | - Samah Ahmed
- Centre for Bioinformatics & Systems Biology, Faculty of Science, University of Khartoum, 321 Khartoum, Sudan.,Faculty of Clinical & Industrial Pharmacy, National University, Khartoum, Sudan
| | - Maryame Azzouzi
- Research Department, Chlamydiae & Mycoplasmas Laboratory, Institut Pasteur du Maroc, Casablanca 20360, Morocco
| | - Ichrak Benamri
- Research Department, Chlamydiae & Mycoplasmas Laboratory, Institut Pasteur du Maroc, Casablanca 20360, Morocco.,Systems & Data Engineering Team, National School of Applied Sciences of Tangier, Morocco
| | - Alia Benkahla
- Laboratory of Bioinformatics, Biomathematics & Biostatistics LR 16 IPT 09, Institute Pasteur de Tunis, Tunisia
| | - Balkiss Bouhaouala-Zahar
- Laboratory of Venoms & Therapeutic Molecules, Pasteur Institute of Tunis, 13 Place Pasteur, BP74, Tunis Belvedere- University of Tunis El Manar, Tunisia
| | - Melek Chaouch
- Laboratory of Bioinformatics, Biomathematics & Biostatistics LR 16 IPT 09, Institute Pasteur de Tunis, Tunisia
| | - Haifa Jmel
- Laboratory of Biomedical Genomics & Oncogenetics, Institut Pasteur de Tunis, Université Tunis El Manar, 13, Place Pasteur BP 74, 1002 Tunis, Belvédère, Tunisie
| | - Rym Kefi
- Laboratory of Biomedical Genomics & Oncogenetics, Institut Pasteur de Tunis, Université Tunis El Manar, 13, Place Pasteur BP 74, 1002 Tunis, Belvédère, Tunisie
| | - Ayoub Ksouri
- Laboratory of Bioinformatics, Biomathematics & Biostatistics LR 16 IPT 09, Institute Pasteur de Tunis, Tunisia.,Laboratory of Venoms & Therapeutic Molecules, Pasteur Institute of Tunis, 13 Place Pasteur, BP74, Tunis Belvedere- University of Tunis El Manar, Tunisia
| | - Judit Kumuthini
- H3ABioNet, Bioinformatics Department, Centre for Proteomic & Genomic Research, Cape Town, South Africa
| | - Phumlani Masilela
- Computational Biology Division, Department of Integrative Biomedical Sciences, IDM, CIDRI Africa Wellcome Trust Centre, University of Cape Town, South Africa
| | - Collen Masimirembwa
- Sydney Brenner Institute for Molecular Bioscience, University of The Witwatersrand, Johannesburg, South Africa.,DMPK Department, African Institute of Biomedical Science & Technology, Harare, Zimbabwe
| | - Houcemeddine Othman
- Sydney Brenner Institute for Molecular Bioscience, University of The Witwatersrand, Johannesburg, South Africa
| | - Sumir Panji
- Computational Biology Division, Department of Integrative Biomedical Sciences, IDM, CIDRI Africa Wellcome Trust Centre, University of Cape Town, South Africa
| | - Lilia Romdhane
- Laboratory of Biomedical Genomics & Oncogenetics, Institut Pasteur de Tunis, Université Tunis El Manar, 13, Place Pasteur BP 74, 1002 Tunis, Belvédère, Tunisie.,Département des Sciences de la Vie, Faculté des Sciences de Bizerte, Université Carthage, 7021 Jarzouna, BP 21, Tunisie
| | - Chaimae Samtal
- Biotechnology Laboratory, Faculty of Sciences Dhar El Mahraz, Sidi Mohammed Ben Abdellah University, Fez 30000, Morocco.,Department of Biology, University of Mohammed Premier, Oujda, Morocco.,Department of Biology Faculty of Sciences, University of Sidi Mohamed Ben Abdellah, Fez, Morocco
| | - Rania Sibira
- Centre for Bioinformatics & Systems Biology, Faculty of Science, University of Khartoum, 321 Khartoum, Sudan.,Department of Neurosurgery, National Center For Neurological Sciences, Khartoum, Sudan
| | - Kais Ghedira
- Laboratory of Bioinformatics, Biomathematics & Biostatistics LR 16 IPT 09, Institute Pasteur de Tunis, Tunisia
| | - Faisal Fadlelmola
- Centre for Bioinformatics & Systems Biology, Faculty of Science, University of Khartoum, 321 Khartoum, Sudan
| | - Samar Kamal Kassim
- Medical Biochemistry & Molecular Biology Department, Faculty of Medicine, Ain Shams University, Abbaseya, Cairo 11381, Egypt
| | - Nicola Mulder
- Computational Biology Division, Department of Integrative Biomedical Sciences, IDM, CIDRI Africa Wellcome Trust Centre, University of Cape Town, South Africa
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13
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Koshy L, Harikrishnan S, Sudhakaran PR. Prioritizing rs7294 as a mirSNP contributing to warfarin dosing variability. Pharmacogenomics 2020; 21:257-267. [PMID: 31973625 DOI: 10.2217/pgs-2019-0137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Aim: The role of mirSNPs in the 3'UTR of VKORC1, CYP2C9 and CYP4F2 genes that could influence warfarin dose variability via a discrete miRNA-mediated mechanism remains unexplained. Methods: Genotypic data in the 1000 Genomes dataset were analyzed for pair-wise linkage disequilibrium and allelic enrichment. Results: MirSNP rs7294 in the 3'UTR of VKORC1 gene displayed varying strengths of linkage disequilibrium with rs9923231 and rs9934438 across populations, albeit consistently associated with higher warfarin dose requirements based on genome-wide association studies, meta-analysis and population-based association studies. In silico analysis predicted altered hybrid stability for the hsa-miR-133a-3p conserved binding site, providing evidence for miRNA-mediated gene regulation. Conclusion: The results support the inclusion of rs7294 as a functional variable for population-specific dosing algorithms to improve dosing accuracy.
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Affiliation(s)
- Linda Koshy
- Inter-University Centre for Genomics & Gene Technology, Department of Biotechnology, University of Kerala, Trivandrum-695 581, Kerala, India
| | - S Harikrishnan
- Department of Cardiology, Sree Chitra Tirunal Institute for Medical Sciences & Technology, Trivandrum-695 011, Kerala, India
| | - P R Sudhakaran
- Inter-University Centre for Genomics & Gene Technology, Department of Biotechnology, University of Kerala, Trivandrum-695 581, Kerala, India.,Department of Computational Biology & Bioinformatics, University of Kerala, Trivandrum-695 581, Kerala, India
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14
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Tshabalala S, Choudhury A, Beeton-Kempen N, Martinson N, Ramsay M, Mancama D. Targeted ultra-deep sequencing of a South African Bantu-speaking cohort to comprehensively map and characterize common and novel variants in 65 pharmacologically-related genes. Pharmacogenet Genomics 2019; 29:167-178. [PMID: 31162291 PMCID: PMC6675649 DOI: 10.1097/fpc.0000000000000380] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/16/2019] [Indexed: 01/11/2023]
Abstract
BACKGROUND African populations are characterised by high genetic diversity, which provides opportunities for discovering and elucidating novel variants of clinical importance, especially those affecting therapeutic outcome. Significantly more knowledge is however needed before such populations can take full advantage of the advances in precision medicine. Coupled with the need to concisely map and better understand the pharmacological implications of genetic diversity in populations of sub-Sharan African ancestry, the aim of this study was to identify and characterize known and novel variants present within 65 important absorption, distribution, metabolism and excretion genes. PATIENTS AND METHODS Targeted ultra-deep next-generation sequencing was used to screen a cohort of 40 South African individuals of Bantu ancestry. RESULTS We identified a total of 1662 variants of which 129 are novel. Moreover, out of the 1662 variants 22 represent potential loss-of-function variants. A high level of allele frequency differentiation was observed for variants identified in this study when compared with other populations. Notably, on the basis of prior studies, many appear to be pharmacologically important in the pharmacokinetics of a broad range of drugs, including antiretrovirals, chemotherapeutic drugs, antiepileptics, antidepressants, and anticoagulants. An in-depth analysis was undertaken to interrogate the pharmacogenetic implications of this genetic diversity. CONCLUSION Despite the new insights gained from this study, the work illustrates that a more comprehensive understanding of population-specific differences is needed to facilitate the development of pharmacogenetic-based interventions for optimal drug therapy in patients of African ancestry.
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Affiliation(s)
- Sibongile Tshabalala
- Division of Human Genetics, National Health Laboratory Service, School of Pathology, Faculty of Health Sciences
- Sydney Brenner Institute for Molecular Bioscience (SBIMB), Faculty of Health Sciences
- CSIR Biosciences Unit, Pretoria, South Africa
| | - Ananyo Choudhury
- Sydney Brenner Institute for Molecular Bioscience (SBIMB), Faculty of Health Sciences
| | | | - Neil Martinson
- Perinatal HIV Research Unit, Baragwanath Hospital and Faculty of Health Sciences
- Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg
| | - Michèle Ramsay
- Division of Human Genetics, National Health Laboratory Service, School of Pathology, Faculty of Health Sciences
- Sydney Brenner Institute for Molecular Bioscience (SBIMB), Faculty of Health Sciences
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15
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Tan-Koi WC, Limenta M, Mohamed EHM, Lee EJD. The Importance of Ethnicity Definitions and Pharmacogenomics in Ethnobridging and Pharmacovigilance. Pharmacogenomics 2019. [DOI: 10.1016/b978-0-12-812626-4.00011-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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16
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Ndadza A, Cindi Z, Makambwa E, Chimusa E, Wonkam A, Kengne AP, Ntsekhe M, Dandara C. Warfarin Dose and CYP2C Gene Cluster: An African Ancestral-Specific Variant Is a Strong Predictor of Dose in Black South African Patients. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2018; 23:36-44. [PMID: 30566377 DOI: 10.1089/omi.2018.0174] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Warfarin is a widely prescribed anticoagulant with a narrow therapeutic index. The rs12777823G>A single-nucleotide polymorphism (SNP) in the CYP2C gene cluster has been shown to influence optimal warfarin doses in African Americans. We report here effects of rs12777823G>A SNP on warfarin dose requirements in two South African population groups, black Africans (BA) and mixed ancestry (MA). A total of 425 participants on warfarin treatment were enrolled in the study. The age group of the studied population ranged between 44 and 66 years, with 69% females enrolled. Genetic characterization of the rs12777823G>A was done using the TaqMan SNP genotyping assay. To further compare effects of rs12777823G>A to those of other SNPs, VKORC1 g.-1639G>A and 4 SNPs in CYP2C9 gene (i.e., CYP2C9 c.430C>T, c.1075A>C, c.449G>A, and c.1003C>T) were analyzed. The rs12777823A variant allele frequencies were 0.28 and 0.25 in the BA and MA, respectively. The rs12777823A/A genotype was associated with significantly (p = 0.002) reduced mean warfarin dosage (27 ± 5.3 mg/week) compared with the G/G genotype (45 ± 16.1 mg/week) among BA, but not among the MA. The rs12777823G>A is located in a nongenomic region, suggesting that this SNP might be in linkage disequilibrium with another, likely causal SNP that is present in BA only. Given ongoing worldwide efforts to identify clinically relevant human genetic variation impacting on optimal warfarin dose selection, the African ancestry-specific genetic variant in the CYP2C cluster and others warrant further research and consideration in development of future warfarin dosing algorithms for precision medicine guidelines.
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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
| | - Zinhle Cindi
- 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
| | - Edson Makambwa
- 2 Division of Cardiology, Department of Medicine, Faculty of Health Sciences, University of Cape Town , Cape Town, South Africa
| | - Emile Chimusa
- 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
| | - Andre P Kengne
- 3 Non-Communicable Diseases Research Unit, South African Medical Research Council and University of Cape Town , Cape Town, South Africa
| | - Mpiko Ntsekhe
- 2 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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17
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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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18
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De T, Park CS, Perera MA. Cardiovascular Pharmacogenomics: Does It Matter If You're Black or White? Annu Rev Pharmacol Toxicol 2018; 59:577-603. [PMID: 30296897 DOI: 10.1146/annurev-pharmtox-010818-021154] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Race and ancestry have long been associated with differential risk and outcomes to disease as well as responses to medications. These differences in drug response are multifactorial with some portion associated with genomic variation. The field of pharmacogenomics aims to predict drug response in patients prior to medication administration and to uncover the biological underpinnings of drug response. The field of human genetics has long recognized that genetic variation differs in frequency between ancestral populations, with some single nucleotide polymorphisms found solely in one population. Thus far, most pharmacogenomic studies have focused on individuals of European and East Asian ancestry, resulting in a substantial disparity in the clinical utility of genetic prediction for drug response in US minority populations. In this review, we discuss the genetic factors that underlie variability to drug response and known pharmacogenomic associations and how these differ between populations, with an emphasis on the current knowledge in cardiovascular pharmacogenomics.
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Affiliation(s)
- Tanima De
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA;
| | - C Sehwan Park
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA;
| | - Minoli A Perera
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA;
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19
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Mili FD, Allen T, Wadell PW, Hooper WC, Staercke CD, Bean CJ, Lally C, Austin H, Wenger NK. VKORC1-1639A allele influences warfarin maintenance dosage among Blacks receiving warfarin anticoagulation: a retrospective cohort study. Future Cardiol 2017; 14:15-26. [PMID: 29218998 DOI: 10.2217/fca-2017-0025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
AIM The study objectives were to investigate the association between selected CYP2C9 and VKORC1 single nucleotide polymorphisms with serious bleeding or thrombotic risk, and to estimate mean daily maintenance dose of warfarin and international normalized ratio measurements among Blacks receiving warfarin anticoagulation. METHODS We conducted a retrospective cohort study among 230 Black adults receiving warfarin for a minimum of three consecutive months with a confirmed date of first dosage. RESULTS A lower mean daily maintenance dosage of warfarin was required to maintain an international normalized ratio measurement within the therapeutic range among Blacks with the VKORC1-1639G>A variant alleles ([G/A vs G/G, p = 0.02], [A/A vs G/A, p = 0.008] and [A/A vs G/G, p = 0.001]). CONCLUSION Data indicated that VKORC1-1639A variant allele influenced warfarin daily maintenance dosage among our small, likely admixed Black patient population.
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Affiliation(s)
- Fatima Donia Mili
- Hemostasis Laboratory Branch, Division of Blood Disorders, Centers for Disease Control & Prevention, Atlanta, GA 30329, USA
| | - Tenecia Allen
- Emory Heart & Vascular Center, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Paula Weinstein Wadell
- Hemostasis Laboratory Branch, Division of Blood Disorders, Centers for Disease Control & Prevention, Atlanta, GA 30329, USA
| | - W Craig Hooper
- Hemostasis Laboratory Branch, Division of Blood Disorders, Centers for Disease Control & Prevention, Atlanta, GA 30329, USA
| | - Christine De Staercke
- Hemostasis Laboratory Branch, Division of Blood Disorders, Centers for Disease Control & Prevention, Atlanta, GA 30329, USA
| | - Christopher J Bean
- Hemostasis Laboratory Branch, Division of Blood Disorders, Centers for Disease Control & Prevention, Atlanta, GA 30329, USA
| | - Cathy Lally
- Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA 30322, USA
| | - Harland Austin
- Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA 30322, USA
| | - Nanette K Wenger
- Emory Heart & Vascular Center, Emory University School of Medicine, Atlanta, GA 30322, USA
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20
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Disease burden and the role of pharmacogenomics in African populations. GLOBAL HEALTH EPIDEMIOLOGY AND GENOMICS 2017; 2:e1. [PMID: 29868213 PMCID: PMC5870420 DOI: 10.1017/gheg.2016.21] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 11/22/2016] [Accepted: 11/24/2016] [Indexed: 12/15/2022]
Abstract
Background The burden of communicable and non-communicable diseases in Sub-Saharan Africa poses a challenge in achieving quality healthcare. Although therapeutic drugs have generally improved health, their efficacy differs from individual to individual. Variability in treatment response is mainly because of genetic variants that affect the pharmacokinetics and pharmacodynamics of drugs. Method The intersection of disease burden and therapeutic intervention is reviewed, and the status of pharmacogenomics knowledge in African populations is explored. Results The most commonly studied variants with pharmacogenomics relevance are discussed, especially in genes coding for enzymes that affect the response to drugs used for HIV, malaria, sickle cell disease and cardiovascular diseases. Conclusions The genetically diverse African population is likely to benefit from a pharmacogenomics-based healthcare approach, especially with respect to reduction of drug side effects, and separation of responders and non-responders leading to optimized drug choices and doses for each patient.
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21
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Poor warfarin dose prediction with pharmacogenetic algorithms that exclude genotypes important for African Americans. Pharmacogenet Genomics 2015; 25:73-81. [PMID: 25461246 DOI: 10.1097/fpc.0000000000000108] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
OBJECTIVES Recent clinical trial data cast doubt on the utility of genotype-guided warfarin dosing, specifically showing worse dosing with a pharmacogenetic versus clinical dosing algorithm in African Americans. However, many genotypes important in African Americans were not accounted for. We aimed to determine whether omission of the CYP2C9*5, CYP2C9*6, CYP2C9*8, CYP2C9*11 alleles and rs12777823 G > A genotype affects performance of dosing algorithms in African Americans. METHODS In a cohort of 274 warfarin-treated African Americans, we examined the association between the CYP2C9*5, CYP2C9*6, CYP2C9*8, CYP2C9*11 alleles and rs12777823 G > A genotype and warfarin dose prediction error with pharmacogenetic algorithms used in clinical trials. RESULTS The http://www.warfarindosing.org algorithm overestimated doses by a median (interquartile range) of 1.2 (0.02-2.6) mg/day in rs12777823 heterozygotes (P<0.001 for predicted vs. observed dose), 2.0 (0.6-2.8) mg/day in rs12777823 variant homozygotes (P = 0.004), and 2.2 (0.5-2.9) mg/day in carriers of a CYP2C9 variant (P < 0.001). The International Warfarin Pharmacogenetics Consortium (IWPC) algorithm underdosed warfarin by 0.8 (-2.3 to 0.4) mg/day for patients with the rs12777823 GG genotype (P < 0.001) and overdosed warfarin by 0.7 (-0.4 to 1.9) mg/day in carriers of a variant CYP2C9 allele (P = 0.04). Modifying the http://www.warfarindosing.org algorithm to adjust for variants important in African Americans led to better dose prediction than either the original http://www.warfarindosing.org (P < 0.01) or IWPC (P < 0.01) algorithm. CONCLUSION These data suggest that, when providing genotype-guided warfarin dosing, failure to account for variants important in African Americans leads to significant dosing error in this population.
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Patel SR, Langaee TY, Wong SS, Cavallari LH. Pyrosequencing of the CYP2C9 -1766T>C polymorphism as a means of detecting the CYP2C9*8 allele. Pharmacogenomics 2015; 15:1717-22. [PMID: 25410896 DOI: 10.2217/pgs.14.130] [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: 12/14/2022] Open
Abstract
The CYP2C9 c.449G>A (p.R150H, rs7900194) polymorphism, which confers the CYP2C9*8 allele, is common in persons of African descent and results in reduced clearance of the narrow therapeutic index drugs, warfarin and phenytoin. Because of significant homology in DNA sequence at the 449G>A locus among CYP2C genes, the 449G>A variant cannot be reliably detected via PCR-based genotyping assays that require a short PCR product, such as pyrosequencing. Herein, we propose genotyping for the CYP2C9 c.-1766T>C polymorphism via pyrosequencing as an alternative and accurate means of identifying the CYP2C9*8 allele.
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Affiliation(s)
- Shitalben R Patel
- Department of Pharmacy Practice, University of Illinois at Chicago, Chicago, IL, USA
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Daneshjou R, Gamazon ER, Burkley B, Cavallari LH, Johnson JA, Klein TE, Limdi N, Hillenmeyer S, Percha B, Karczewski KJ, Langaee T, Patel SR, Bustamante CD, Altman RB, Perera MA. Genetic variant in folate homeostasis is associated with lower warfarin dose in African Americans. Blood 2014; 124:2298-305. [PMID: 25079360 PMCID: PMC4183989 DOI: 10.1182/blood-2014-04-568436] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/14/2014] [Indexed: 01/20/2023] Open
Abstract
The anticoagulant warfarin has >30 million prescriptions per year in the United States. Doses can vary 20-fold between patients, and incorrect dosing can result in serious adverse events. Variation in warfarin pharmacokinetic and pharmacodynamic genes, such as CYP2C9 and VKORC1, do not fully explain the dose variability in African Americans. To identify additional genetic contributors to warfarin dose, we exome sequenced 103 African Americans on stable doses of warfarin at extremes (≤ 35 and ≥ 49 mg/week). We found an association between lower warfarin dose and a population-specific regulatory variant, rs7856096 (P = 1.82 × 10(-8), minor allele frequency = 20.4%), in the folate homeostasis gene folylpolyglutamate synthase (FPGS). We replicated this association in an independent cohort of 372 African American subjects whose stable warfarin doses represented the full dosing spectrum (P = .046). In a combined cohort, adding rs7856096 to the International Warfarin Pharmacogenetic Consortium pharmacogenetic dosing algorithm resulted in a 5.8 mg/week (P = 3.93 × 10(-5)) decrease in warfarin dose for each allele carried. The variant overlaps functional elements and was associated (P = .01) with FPGS gene expression in lymphoblastoid cell lines derived from combined HapMap African populations (N = 326). Our results provide the first evidence linking genetic variation in folate homeostasis to warfarin response.
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Affiliation(s)
- Roxana Daneshjou
- Department of Genetics, Stanford University School of Medicine, Stanford, CA
| | - Eric R Gamazon
- Department of Medicine, University of Chicago, Chicago, IL
| | - Ben Burkley
- Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, FL
| | - Larisa H Cavallari
- Department of Pharmacy Practice, University of Illinois at Chicago, Chicago, IL
| | - Julie A Johnson
- Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, FL
| | - Teri E Klein
- Department of Genetics, Stanford University School of Medicine, Stanford, CA
| | - Nita Limdi
- Department of Neurology and Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL; and
| | - Sara Hillenmeyer
- Biomedical Informatics Training Program, Stanford University School of Medicine, Stanford, CA
| | - Bethany Percha
- Biomedical Informatics Training Program, Stanford University School of Medicine, Stanford, CA
| | - Konrad J Karczewski
- Biomedical Informatics Training Program, Stanford University School of Medicine, Stanford, CA
| | - Taimour Langaee
- Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, FL
| | - Shitalben R Patel
- Department of Pharmacy Practice, University of Illinois at Chicago, Chicago, IL
| | - Carlos D Bustamante
- Department of Genetics, Stanford University School of Medicine, Stanford, CA
| | - Russ B Altman
- Department of Genetics, Stanford University School of Medicine, Stanford, CA
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The VKORC1 Asp36Tyr variant and VKORC1 haplotype diversity in Ashkenazi and Ethiopian populations. J Appl Genet 2014; 55:163-71. [PMID: 24425227 DOI: 10.1007/s13353-013-0189-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 12/16/2013] [Accepted: 12/26/2013] [Indexed: 12/30/2022]
Abstract
The vitamin K epoxide reductase (VKORC1) is a key enzyme in the vitamin K cycle impacting various biological processes. VKORC1 genetic variability has been extensively studied in the context of warfarin pharmacogenetics revealing different distributions of VKORC1 haplotypes in various populations. We previously identified the VKORC1 Asp36Tyr mutation that was associated with warfarin resistance and with distinctive ethnic distribution. In this study, we performed haplotype analysis using Asp36Tyr and seven other VKORC1 markers in Ashkenazi and Ethiopian-Jewish and non-Jewish individuals. The VKORC1 variability was represented by nine haplotypes (V1-V9) that could be grouped into two distinct clusters (V1-V3 and V4-V9) with intra-cluster difference limited to two nucleotide changes. Phylogeny analysis suggested that these haplotypes could have developed from an ancestral variant, the common V8 haplotype (40 % in all population samples), after ten single mutation events. Asp36Tyr was exclusive to the V5 haplotype of the second cluster. Two haplotypes V5 and V4, distinguished only by Asp36Tyr, were prevalent in both Ethiopian population samples. The V2 haplotype, belonging to the first cluster, was the second most prevalent haplotype in the Ashkenazi population sample (15.8 %) but relatively uncommon in the Ethiopian origin (4.5-4.7 %). We discuss the genetic diversity among studied populations and its potential impact on warfarin-dose management in certain populations of African and European origin.
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Oldenburg J, Müller CR, Rost S, Watzka M, Bevans CG. Comparative genetics of warfarin resistance. Hamostaseologie 2013; 34:143-59. [PMID: 24287886 DOI: 10.5482/hamo-13-09-0047] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 09/25/2013] [Indexed: 11/05/2022] Open
Abstract
Warfarin and other 4-hydroxycoumarin-based oral anticoagulants targeting vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) are administered to humans, mice and rats with different purposes in mind - to act as pesticides in high-dosage baits for killing rodents, but also to save lives when administered in low dosages as antithrombotic drugs in humans. However, high-dosage warfarin used to control rodent populations has resulted in numerous mutations causing warfarin resistance. Currently, six single missense mutations in mice, 12 distinct missense mutations in rats, as well as compound heterozygous or homozygous mutations with up to six distinct missense mutations per Vkorc1 allele have been described. Warfarin resistance missense mutations for human VKORC1 have also been found world-wide, but differ characteristically from those in rodents. In humans, 26 distinct mutations have been characterized, but occur only rarely either in heterozygous or, even rarer, in homozygous form. In this review, we summarize the known VKORC1 missense mutations causing warfarin and other 4-hydroxycoumarin drug resistance, identify genomics databases as new sources of data, explore possible underlying genetic mechanisms, and summarize similarities and differences between warfarin resistant VKORC1 variants in humans and rodents.
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Affiliation(s)
- J Oldenburg
- Prof. Dr. Johannes Oldenburg, Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund Freud Str. 25, 53105 Bonn, Germany, E-mail: , Tel. +49/(0)228/287 51 75, Fax +49/(0)228/287 51 76
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Anton AI, Cerezo-Manchado JJ, Padilla J, Perez-Andreu V, Corral J, Vicente V, Roldan V, Gonzalez-Conejero R. Novel associations of VKORC1 variants with higher acenocoumarol requirements. PLoS One 2013; 8:e64469. [PMID: 23691226 PMCID: PMC3656883 DOI: 10.1371/journal.pone.0064469] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 04/16/2013] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Algorithms combining both clinical and genetic data have been developed to improve oral anticoagulant therapy. Three polymorphisms in two genes, VKORC1 and CYP2C9, are the main coumarin dose determinants and no additional polymorphisms of any relevant pharmacogenetic importance have been identified. OBJECTIVES To identify new genetic variations in VKORC1 with relevance for oral anticoagulant therapy. METHODS AND RESULTS 3949 consecutive patients taking acenocoumarol were genotyped for the VKORC1 rs9923231 and CY2C9* polymorphisms. Of these, 145 patients with a dose outside the expected range for the genetic profile determined by these polymorphisms were selected. Clinical factors explained the phenotype in 88 patients. In the remaining 57 patients, all with higher doses than expected, we sequenced the VKORC1 gene and genetic changes were identified in 14 patients. Four patients carried VKORC1 variants previously related to high coumarin doses (L128R, N = 1 and D36Y, N = 3).Three polymorphisms were also detected: rs17878544 (N = 5), rs55894764 (N = 4) and rs7200749 (N = 2) which was in linkage disequilibrium with rs17878544. Finally, 2 patients had lost the rs9923231/rs9934438 linkage. The prevalence of these variations was higher in these patients than in the whole sample. Multivariate linear regression analysis revealed that only D36Y and rs55894764 variants significantly affect the dose, although the improvement in the prediction model is small (from 39% to 40%). CONCLUSION Our strategy identified novel associations of VKORC1 variants with higher acenocoumarol doses albeit with a low effect size. Further studies are necessary to test their influence on the VKORC1 function and the cost/benefit of their inclusion in pharmacogenetic algorithms.
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Affiliation(s)
- Ana Isabel Anton
- Centro Regional de Hemodonación and Morales Meseguer Hospital, University of Murcia, Murcia, Spain
| | - Juan J. Cerezo-Manchado
- Centro Regional de Hemodonación and Morales Meseguer Hospital, University of Murcia, Murcia, Spain
| | - Jose Padilla
- Centro Regional de Hemodonación and Morales Meseguer Hospital, University of Murcia, Murcia, Spain
| | - Virginia Perez-Andreu
- Centro Regional de Hemodonación and Morales Meseguer Hospital, University of Murcia, Murcia, Spain
| | - Javier Corral
- Centro Regional de Hemodonación and Morales Meseguer Hospital, University of Murcia, Murcia, Spain
| | - Vicente Vicente
- Centro Regional de Hemodonación and Morales Meseguer Hospital, University of Murcia, Murcia, Spain
| | - Vanessa Roldan
- Centro Regional de Hemodonación and Morales Meseguer Hospital, University of Murcia, Murcia, Spain
| | - Rocio Gonzalez-Conejero
- Centro Regional de Hemodonación and Morales Meseguer Hospital, University of Murcia, Murcia, Spain
- * E-mail:
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Alessandrini M, Asfaha S, Dodgen TM, Warnich L, Pepper MS. Cytochrome P450 pharmacogenetics in African populations. Drug Metab Rev 2013; 45:253-75. [PMID: 23590174 DOI: 10.3109/03602532.2013.783062] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The Cytochrome P450 (CYP450) family of enzymes is involved in the oxidative metabolism of many therapeutic drugs, carcinogens and various endogenous substrates. These enzymes are highly polymorphic at an inter-individual and inter-ethnic level. Polymorphisms or genetic variations account for up to 30% of inter-individual differences seen in a variety of drug responses. The frequencies of the different metabolizer categories (slow, intermediate, extensive and ultra-rapid), the distribution of genetic variants, genotype-phenotype correlations and the clinical importance of the CYP450 enzymes have been extensively documented in Caucasian and Oriental populations. Limited data exists for African populations, despite the fact that this knowledge is critically important for these populations who experience a heavy burden of communicable and non-communicable diseases. In addition, the costs incurred through adverse drug reactions and non-responsiveness to therapy could be reduced through the wide-scale application of pharmacogenetics. This review provides an overview and investigation of CYP450 genotypic and phenotypic reports published from 1980 to present in African populations. Our findings confirm the high degree of variability that is expected when comparing individuals of African origin to other ethnic groups and also highlight the distribution of clinically relevant CYP450 alleles amongst the various African populations. The notable discordance in genotypic and phenotypic data amongst African populations exemplifies the need for in-depth and well-orchestrated molecular and pharmacological investigations of these populations in the future, for which whole genome sequencing and association studies will be critical.
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Affiliation(s)
- Marco Alessandrini
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
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28
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Shahin MHA, Cavallari LH, Perera MA, Khalifa SI, Misher A, Langaee T, Patel S, Perry K, Meltzer DO, McLeod HL, Johnson JA. VKORC1 Asp36Tyr geographic distribution and its impact on warfarin dose requirements in Egyptians. Thromb Haemost 2013; 109:1045-50. [PMID: 23571513 DOI: 10.1160/th12-10-0789] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 03/03/2013] [Indexed: 02/04/2023]
Abstract
The VKORC1 Asp36Tyr single nucleotide polymorphism (SNP) is one of the most promising predictors of high warfarin dose, but data on its population prevalence is incomplete. We determined the frequency of this SNP in participants from seven countries on four continents and investigated its effect on warfarin dose requirement. One thousand samples were analysed to define the population prevalence of this SNP. Those samples included individuals from Egypt, Ghana, Sudan, Kenya, Saudi Arabia, Peru and African Americans from the United States. A total of 206 Egyptian samples were then used to investigate the effect of this SNP on warfarin dose requirements. This SNP was most frequent among Kenyans and Sudanese, with a minor allele frequency (MAF) of 6% followed by Saudi Arabians and Egyptians with a MAF of 3% and 2.5%, respectively. It was not detected in West Africans, based on our data from Ghana, and a large cohort of African Americans. Egyptian carriers of the VKORC1 Tyr36 showed higher warfarin dose requirement (57.1 ± 29.4 mg/week) than those with the Asp36Asp genotype (35.8 ± 16.6 mg/week; p=0.03). In linear regression analysis, this SNP had the greatest effect size among the genetic factors (16.6 mg/week increase in dose per allele), and improved the warfarin dose variability explained in Egyptians (model R2 from 31% to 36.5%). The warfarin resistant VKORC1 Asp36Tyr appears to be confined to north-eastern Africa and nearby Middle-Eastern populations, but in those populations where it is present, it has a significant influence on warfarin dose requirement and the percent of warfarin dose variability that can be explained.
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Affiliation(s)
- Mohamed Hossam A Shahin
- Center for Pharmacogenomics, University of Florida, Health Science Center, PO Box 100486, Gainesville, FL 32610, USA
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Daly AK. Optimal dosing of warfarin and other coumarin anticoagulants: the role of genetic polymorphisms. Arch Toxicol 2013; 87:407-20. [PMID: 23376975 DOI: 10.1007/s00204-013-1013-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 01/17/2013] [Indexed: 12/14/2022]
Abstract
Coumarin anticoagulants, which include warfarin, acenocoumarol and phenprocoumon, are among the most widely prescribed drugs worldwide. There is now a large body of published data showing that genotype for certain common polymorphisms in the genes encoding the target vitamin K epoxide reductase (G-1639A/C1173T) and the main metabolizing enzyme CYP2C9 (CYP2C9*2 and *3 alleles) are important determinants of the individual coumarin anticoagulant dose requirement. Additional less common polymorphisms in these genes together with polymorphisms in other genes relevant to blood coagulation such as the cytochrome P450 CYP4F2, gamma-glutamyl carboxylase, calumenin and cytochrome P450 oxidoreductase may also be significant predictors of dose, especially in ethnic groups such as Africans where there have been fewer genetic studies compared with European populations. Using relevant genotypes to calculate starting dose may improve safety during the initiation period. Various algorithms for dose calculation, which also take patient age and other characteristics into consideration, have been developed for all three widely used coumarin anticoagulants and are now being tested in ongoing large randomised clinical trials. One recently completed study has provided encouraging results suggesting that calculation of warfarin dose on the basis of individual patient genotype leads to few adverse events and a higher proportion of time within the therapeutic coagulation rate window, but these findings still need confirmation.
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Affiliation(s)
- Ann K Daly
- Institute of Cellular Medicine, Newcastle University Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
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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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Cavallari LH, Perera MA. The future of warfarin pharmacogenetics in under-represented minority groups. Future Cardiol 2012; 8:563-76. [PMID: 22871196 DOI: 10.2217/fca.12.31] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Genotype-based dosing recommendations are provided in the US FDA-approved warfarin labeling. However, data that informed these recommendations were from predominately Caucasian populations. Studies show that variants contributing to warfarin dose requirements in Caucasians provide similar contributions to dose requirements in US Hispanics, but significantly lesser contributions in African-Americans. Further data demonstrate that variants occurring commonly in individuals of African ancestry, but rarely in other racial groups, significantly influence dose requirements in African-Americans. These data suggest that it is important to consider variants specific for African-Americans when implementing genotype-guided warfarin dosing in this population.
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Affiliation(s)
- Larisa H Cavallari
- Department of Pharmacy Practice, University of Illinois at Chicago, College of Pharmacy, 833 South Wood Street, Chicago, IL 60612-7230, USA.
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The prevalence of VKORC1 1639 G>A and CYP2C9*2*3 genotypes in patients that requiring anticoagulant therapy in Turkish population. Mol Biol Rep 2012; 39:11017-22. [PMID: 23065265 DOI: 10.1007/s11033-012-2004-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 10/01/2012] [Indexed: 12/28/2022]
Abstract
The aim was to investigate the prevalence of VKORC1 and CYP2C9 genotypes in patients requiring anticoagulant therapy in two different region's populations of Turkey. The recent cohort included 292 patients that needed anticoagulant therapy, and who had a history of deep vein thrombosis and/or pulmonary artery thromboembolism. Genomic DNA was isolated from peripheral blood samples and the StripAssay reverse hybridization or Real Time PCR technique was used for genotype analysis. Genotypes for CYP2C9 were detected as follows: 165 (56.5 %) for CYP2C9*1/*1, 67 (23.0 %) for CYP2C9*1/*2, 25 (8.6 %) for CYP2C9*1/*3, 9 (3.0 %) for CYP2C9*2/*2, 21 (7.2 %) for CYP2C9*2/*3, 5(1.7 %) for CYP2C9*3/*3 for CYP2C9 and the allele frequencies were: 0.723 for allele*1, 0.182 for allele*2 and 0.095 for allele*3 respectively. Genotypes for VKORC1 were detected as follows: 64 (21.9 %) for GG, 220 (75.4 %) for GA and 8 (2.7 %) for AA alleles. The G allele frequency was detected as 0.596, and the A allele frequency was 0.404. The VKORC1 1639 G>A and CYP2C9 mutation prevalence and allele frequency of the current results from two different populations (Sivas and Canakkale) showed similarly very variable profiles when compared to the other results from the Turkish population.
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Fung E, Patsopoulos NA, Belknap SM, O'Rourke DJ, Robb JF, Anderson JL, Shworak NW, Moore JH. Effect of genetic variants, especially CYP2C9 and VKORC1, on the pharmacology of warfarin. Semin Thromb Hemost 2012; 38:893-904. [PMID: 23041981 DOI: 10.1055/s-0032-1328891] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The genes encoding the cytochrome P450 2C9 enzyme (CYP2C9) and vitamin K-epoxide reductase complex unit 1 (VKORC1) are major determinants of anticoagulant response to warfarin. Together with patient demographics and clinical information, they account for approximately one-half of the warfarin dose variance in individuals of European descent. Recent prospective and randomized controlled trial data support pharmacogenetic guidance with their use in warfarin dose initiation and titration. Benefits from pharmacogenetics-guided warfarin dosing have been reported to extend beyond the period of initial dosing, with supportive data indicating benefits to at least 3 months. The genetic effects of VKORC1 and CYP2C9 in African and Asian populations are concordant with those in individuals of European ancestry; however, frequency distribution of allelic variants can vary considerably between major populations. Future randomized controlled trials in multiethnic settings using population-specific dosing algorithms will allow us to further ascertain the generalizability and cost-effectiveness of pharmacogenetics-guided warfarin therapy. Additional genome-wide association studies may help us to improve and refine dosing algorithms and potentially identify novel biological pathways.
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Affiliation(s)
- Erik Fung
- Section of Cardiology, Heart & Vascular Center, Lebanon, New Hampshire 03756, USA.
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35
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Kurnik D, Qasim H, Sominsky S, Lubetsky A, Markovits N, Li C, Stein CM, Halkin H, Gak E, Loebstein R. Effect of the VKORC1 D36Y variant on warfarin dose requirement and pharmacogenetic dose prediction. Thromb Haemost 2012; 108:781-8. [PMID: 22871975 DOI: 10.1160/th12-03-0151] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 07/12/2012] [Indexed: 02/06/2023]
Abstract
Pharmacogenetic dosing algorithms help predict warfarin maintenance doses, but their predictive performance differs in different populations, possibly due to unsuspected population-specific genetic variants. The objectives of this study were to quantify the effect of the VKORC1 D36Y variant (a marker of warfarin resistance previously described in 4% of Ashkenazi Jews) on warfarin maintenance doses and to examine how this variant affects the performance of the International Warfarin Pharmacogenetic Consortium (IWPC) dose prediction model. In 210 Israeli patients on chronic warfarin therapy recruited at a tertiary care centre, we applied the IWPC model and then added D36Y genotype as covariate to the model (IWPC+D36Y) and compared predicted with actual doses. Median weekly warfarin dose was 35 mg (interquartile range [IQR], 24.5 to 52.5 mg). Among 16 heterozygous D36Y carriers (minor allele frequency = 3.8%), warfarin weekly dose was increased by a median of 43.7 mg (IQR, 40.5 to 47.2 mg) compared to non-carriers after adjustment for all IWPC parameters, a greater than two-fold dose increase. The IWPC model performed suboptimally (coefficient of determination R²=27.0%; mean absolute error (MAE), 14.4 ± 16.2 mg/week). Accounting for D36Y genotype using the IWPC+D36Y model resulted in a significantly better model performance (R²=47.2%, MAE=12.6 ± 12.4 mg/week). In conclusion, even at low frequencies, variants with a strong impact on warfarin dose may greatly decrease the performance of a commonly used dose prediction model. Unexpected discrepancies of the performance of universal prediction models in subpopulations should prompt searching for unsuspected confounders, including rare genetic variants.
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Affiliation(s)
- Daniel Kurnik
- Institute of Clinical Pharmacology and Toxicology, Sheba Medical Center, Tel Hashomer, Israel.
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Pavani A, Naushad SM, Mishra RC, Malempati AR, Pinjala R, Kumar TR, Kutala VK. Retrospective evidence for clinical validity of expanded genetic model in warfarin dose optimization in a South Indian population. Pharmacogenomics 2012; 13:869-78. [DOI: 10.2217/pgs.12.62] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: To optimize warfarin dose in patients at risk for thrombotic events, we have recently developed a pharmacogenomic algorithm, which explained 44.9% of the variability in warfarin dose requirements using age, gender, BMI, vitamin K intake, CYP2C9 (*2 and *3) and VKORC1 (*3, *4 and -1639 G>A) as predictors. The aim of the current study is to develop an expanded genetic model that can explain greater percentage of warfarin variability and that has clinical validity. Patients & methods: CYP2C9*8, CYP4F2 V433M, GGCX G8016A and thyroid status were added to an expanded genetic model (n = 243). Results: The expanded genetic model explained 61% of the variability in warfarin dose requirements, has a prediction accuracy of ±11 mg/week and can differentiate warfarin sensitive and warfarin resistant groups efficiently (areas under receiver operating characteristic curves: 0.93 and 0.998, respectively; p < 0.0001). Higher percentage of International Normalized Ratios in therapeutic range (52.68 ± 4.21 vs 43.80 ± 2.27; p = 0.04) and prolonged time in therapeutic range (61.74 ± 3.18 vs 47.75 ± 5.77; p = 0.03) were observed in subjects with a prediction accuracy of <1 mg/day compared with subjects with prediction accuracy >1 mg/day. In the warfarin-resistant group, primary hypothyroidism was found to induce more resistance while in the warfarin-sensitive group, hyperthyroidism was found to increase sensitivity. Conclusion: The expanded genetic model explains greater variability in warfarin dose requirements and it prolongs time in therapeutic range and minimizes out-of-range International Normalized Ratios. Thyroid status also influences warfarin dose adjustments. Original submitted 21 March 2012; Revision submitted 16 April 2012
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Affiliation(s)
- Addepalli Pavani
- Departments of Clinical Pharmacology & Therapeutics, Nizam’s Institute of Medical Sciences, Hyderabad, India
| | - Shaik Mohammad Naushad
- Departments of Clinical Pharmacology & Therapeutics, Nizam’s Institute of Medical Sciences, Hyderabad, India
| | - Ramesh C Mishra
- Cardiothoracic Surgery, Nizam’s Institute of Medical Sciences, Hyderabad, India
| | | | | | - Takallapally Ramesh Kumar
- Departments of Clinical Pharmacology & Therapeutics, Nizam’s Institute of Medical Sciences, Hyderabad, India
| | - Vijay Kumar Kutala
- Departments of Clinical Pharmacology & Therapeutics, Nizam’s Institute of Medical Sciences, Hyderabad, India
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Drögemöller BI, Wright GEB, Niehaus DJH, Emsley RA, Warnich L. Whole-genome resequencing in pharmacogenomics: moving away from past disparities to globally representative applications. Pharmacogenomics 2012; 12:1717-28. [PMID: 22118054 DOI: 10.2217/pgs.11.119] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Africa suffers from a high burden of disease; nonetheless, it has been one of the most under-represented continents with regard to genomic research. It can be argued that this disproportionate research is related to the fact that the genome architecture of African individuals is poorly suited to SNP-based genome-wide association studies, given existing genotyping platforms. However, this argument is no longer plausible with the arrival of next-generation sequencing technologies, which allow for the analysis of entire genomes. Using pharmacogenes to critically examine the merit of next-generation sequencing technologies in pharmacogenomics, we found a substantial amount of novel/uncharacterized variation, which was predicted to alter protein function. This variation was predominantly observed in African individuals, emphasizing the benefit of next-generation sequencing technologies specifically for these individuals. We also observed an improvement in the reliability of sequencing technologies in a relatively short time. Therefore, as sequencing technologies develop and decrease in cost, the ability to reliably detect variation will improve and these technologies will begin to replace other less comprehensive genotyping assays.
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Affiliation(s)
- Britt I Drögemöller
- Department of Genetics, Stellenbosch University, Private Bag XI, Matieland 7602, South Africa
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Dandara C, Lombard Z, Du Plooy I, McLellan T, Norris SA, Ramsay M. Genetic variants in CYP (-1A2, -2C9, -2C19, -3A4 and -3A5), VKORC1 and ABCB1 genes in a black South African population: a window into diversity. Pharmacogenomics 2012; 12:1663-70. [PMID: 22118051 DOI: 10.2217/pgs.11.106] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
AIM The frequencies of variants of pharmacogenetic importance differ across populations. African populations exhibit the greatest genetic heterogeneity, cautioning against extrapolating results among African groups. The aim of this study was to genotype pharmacogenetically relevant variants in black South Africans, to expand the limited data set available for indigenous African populations. SUBJECTS & METHODS A total of 14 SNPs associated with seven genes known to influence drug metabolism or transport (CYP1A2, CYP2C19, CYP2C9, CYP3A4, CYP3A5, VKORC1 and ABCB1) were investigated in a South African black (SAB) population (n = 993) and allele frequencies were compared with populations of African, Asian and European origin. RESULTS The majority of SNPs in the SAB demonstrated significant allele frequency differences when compared with both Europeans and Asians. There was greater similarity between the SAB and the Luhya (Kenya) and the Yoruba (Nigeria), than with Maasai (Kenya) individuals. The CYP2C9 SNP (rs1799853) was not polymorphic in the SAB and two VKORC1 SNPs (rs17708472 and rs9934438) had low variant allele frequencies, limiting their relevance to warfarin dose in this population. Population differences are emphasized by the significant differences in ABCB1 and the CYP3A gene family allele frequencies, with implications for drug metabolism and transport. CONCLUSION This study highlights the importance of investigating and documenting genetic variation at loci of pharmacogenetic relevance among different populations since this information could be used to inform drug efficacy, safety and recommended dosage.
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Affiliation(s)
- Collet Dandara
- School of Molecular & Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
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Decreased warfarin clearance associated with the CYP2C9 R150H (*8) polymorphism. Clin Pharmacol Ther 2012; 91:660-5. [PMID: 22378156 DOI: 10.1038/clpt.2011.269] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The cytochrome P450 (CYP) 2C9 R150H (*8) allele occurs commonly in African Americans and is associated with lower warfarin dose requirements. We conducted a pharmacokinetic study to examine whether the CYP2C9*8 allele impacts warfarin clearance in African-American patients. We also conducted an in vitro kinetic study of S-warfarin 7-hydroxylation using complementary DNA (cDNA)-expressed CYP2C9 enzymes. We observed a 30% reduction in the unbound oral clearance of S-warfarin and a 25% lower R- to S-warfarin plasma concentration ratio in patients with the CYP2C9*8 allele (n = 12) as compared to CYP2C9*1 homozygotes (n = 26). Consistent with these findings, the in vitro intrinsic clearance of S-warfarin was 30% lower with the cDNA-expressed R150H protein as compared to the wild-type protein. These data show that the R150H variant protein expressed by the CYP2C9*8 allele is associated with lower S-warfarin clearance. This finding provides clinical and experimental evidence to explain the lower warfarin dose requirements in patients with the CYP2C9*8 allele.
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Zhang W, Zhang WJ, Zhu J, Kong FC, Li YY, Wang HY, Yang YH, Wang C. Genetic polymorphisms are associated with variations in warfarin maintenance dose in Han Chinese patients with venous thromboembolism. Pharmacogenomics 2012; 13:309-21. [PMID: 22248286 DOI: 10.2217/pgs.11.147] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
AIM Warfarin is a clinical anticoagulant that requires periodic monitoring because it is associated with adverse outcomes. Personalized medicine, which is based on pharmacogenetics, holds great promise in solving these types of problems. It aims to provide the tools and knowledge to tailor drug therapy to an individual patient, with the potential of increasing safety and efficacy of medications. MATERIALS & METHODS In the present study we analyzed genotypes of 14 SNPs for seven genes using DNA from 297 Han Chinese venous thromboembolism patients treated with warfarin. RESULTS Multiple regression analyses revealed that CYP2C9 genotype (p = 0.001), VKORC1 genotype (p < 0.001), age (p < 0.01) and weight (p < 0.001) were all associated with warfarin dose requirements, which can explain 37.4% of the variability of warfarin dose among Han Chinese patients. Meanwhile, in the validation cohort, the predicted warfarin daily dose was calculated using the best model with a 64.5% predicted dose being acceptable (-1 mg/day ≤Δwarfarin dose ≤1 mg/day). CONCLUSION We developed a pharmacogenetic dose algorithm for warfarin treatment that uses genotypes from two genes (VKORC1 and CYP2C9) and clinical variables to predict therapeutic maintenance doses in Chinese patients with venous thromboembolism. The validity of the dosing algorithm was confirmed in a cohort of venous thromboembolism patients on warfarin therapy.
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Affiliation(s)
- Wei Zhang
- Beijing Xiaotangshan Hospital, Xiaotangshan Town, Changping District, Beijing 102211, China
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Warnich L, Drögemöller BI, Pepper MS, Dandara C, Wright GEB. Pharmacogenomic Research in South Africa: Lessons Learned and Future Opportunities in the Rainbow Nation. ACTA ACUST UNITED AC 2011; 9:191-207. [PMID: 22563365 PMCID: PMC3228231 DOI: 10.2174/187569211796957575] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/25/2011] [Accepted: 05/28/2011] [Indexed: 12/11/2022]
Abstract
South Africa, like many other developing countries, stands to benefit from novel diagnostics and drugs developed by pharmacogenomics guidance due to high prevalence of disease burden in the region. This includes both communicable (e.g., HIV/AIDS and tuberculosis) and non-communicable (e.g., diabetes and cardiovascular) diseases. For example, although only 0.7% of the world's population lives in South Africa, the country carries 17% of the global HIV/AIDS burden and 5% of the global tuberculosis burden. Nobel Peace Prize Laureate Archbishop Emeritus Desmond Tutu has coined the term Rainbow Nation, referring to a land of wealth in its many diverse peoples and cultures. It is now timely and necessary to reflect on how best to approach new genomics biotechnologies in a manner that carefully considers the public health needs and extant disease burden in the region. The aim of this paper is to document and review the advances in pharmacogenomics in South Africa and importantly, to evaluate the direction that future research should take. Previous research has shown that the populations in South Africa exhibit unique allele frequencies and novel genetic variation in pharmacogenetically relevant genes, often differing from other African and global populations. The high level of genetic diversity, low linkage disequilibrium and the presence of rare variants in these populations question the feasibility of the use of current commercially available genotyping platforms, and may partially account for genotype-phenotype discordance observed in past studies. However, the employment of high throughput technologies for genomic research, within the context of large clinical trials, combined with interdisciplinary studies and appropriate regulatory guidelines, should aid in acceleration of pharmacogenomic discoveries in high priority therapeutic areas in South Africa. Finally, we suggest that projects such as the H3Africa Initiative, the SAHGP and PGENI should play an integral role in the coordination of genomic research in South Africa, but also other African countries, by providing infrastructure and capital to local researchers, as well as providing aid in addressing the computational and statistical bottlenecks encountered at present.
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Affiliation(s)
- Louise Warnich
- Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
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