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Marasanapalle VP, Masimirembwa C, Sivasubramanian R, Sayyed S, Weinzierl-Hinum A, Mehta D, Kapungu NN, Kanji C, Thelingwani R, Zack J. Investigation of the Differences in the Pharmacokinetics of CYP2D6 Substrates, Desipramine, and Dextromethorphan in Healthy African Subjects Carrying the Allelic Variants CYP2D6*17 and CYP2D6*29, When Compared with Normal Metabolizers. J Clin Pharmacol 2024; 64:578-589. [PMID: 37803948 DOI: 10.1002/jcph.2366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/04/2023] [Indexed: 10/08/2023]
Abstract
This study investigated the differences in the pharmacokinetics (PK) of dextromethorphan and desipramine in healthy African volunteers to understand the effect of allelic variants of the human cytochrome P450 2D6 (CYP2D6) enzyme, namely the diplotypes of CYP2D6*1/*2 (*1*1, *1*2, *2*2) and the genotypes of CYP2D6*17*17 and CYP2D6*29*29. Overall, 28 adults were included and split into 3 cohorts after genotype screening: CYP2D6*1/*2 (n = 12), CYP2D6*17*17 (n = 12), and CYP2D6*29*29 (n = 4). Each subject received a single oral dose of dextromethorphan 30 mg syrup on day 1 and desipramine 50 mg tablet on day 8. The PK parameters of area under the plasma concentration-time curve from time of dosing to time of last quantifiable concentration (AUClast), and extrapolated to infinity (AUCinf), and the maximum plasma concentration (Cmax) were determined. For both dextromethorphan and desipramine, AUCinf and Cmax were higher in subjects of the CYP2D6*29*29 and CYP2D6*17*17 cohorts, as compared with subjects in the CYP2D6*1/*2 diplotype cohort and with normal metabolizers from the literature. All PK parameters, including AUCinf, Cmax, and the elimination half-life, followed a similar trend: CYP2D6*17*17 > CYP2D6*29*29 > CYP2D6*1/*2. The plasma and urinary drug/metabolite exposure ratios of both drugs were higher in subjects of the CYP2D6*17*17 and CYP2D6*29*29 cohorts, when compared with subjects in the CYP2D6*1/*2 diplotype cohort. All adverse events were mild, except in 1 subject with CYP2D6*17*17 who had moderately severe headache with desipramine. These results indicate that subjects with CYP2D6*17*17 and CYP2D6*29*29 genotypes were 5-10 times slower metabolizers than those with CYP2D6*1/*2 diplotypes. These findings suggest that dose optimization may be required when administering CYP2D6 substrate drugs in African patients. Larger studies can further validate these findings.
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Affiliation(s)
| | - Collen Masimirembwa
- African Institute of Biomedical Science & Technology (AiBST), Harare, Zimbabwe
| | | | | | | | - Dheeraj Mehta
- Novartis Healthcare Private Limited, Hyderabad, India
| | | | - Comfort Kanji
- African Institute of Biomedical Science & Technology (AiBST), Harare, Zimbabwe
| | - Roslyn Thelingwani
- African Institute of Biomedical Science & Technology (AiBST), Harare, Zimbabwe
| | - Julia Zack
- Novartis Pharmaceutical Corporation, East Hanover, NJ, USA
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2
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Tan EY, Bharwani L, Chia YH, Soong RCT, Lee SSY, Chen JJC, Chan PMY. Impact of cytochrome P450 2D6 polymorphisms on decision-making and clinical outcomes in adjuvant hormonal therapy for breast cancer. World J Clin Oncol 2022; 13:712-724. [PMID: 36160461 PMCID: PMC9476606 DOI: 10.5306/wjco.v13.i8.712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/08/2021] [Accepted: 07/18/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND There are concerns that tamoxifen is less effective in Asian women because of the high prevalence of impaired function cytochrome P450 2D6 (CYP2D6) polymor-phisms.
AIM To evaluate how knowledge of CYP2D6 genotype impacted the choice of hormonal agent and how CYP2D6 genotype and agent were associated with clinical outcomes.
METHODS Eighty-two women were recruited. Seventy-eight completed CYP2D6 genotyping and were categorized into poor, intermediate (IM) and extensive or ultra metabolizer phenotypes. Women with poor metabolizer and IM phenotypes were recommended aromatase inhibitors as the preferred agent.
RESULTS More than 70% of the women had an IM phenotype, 32% an extensive or ultra metabolizer phenotype, and 0% had a poor metabolizer phenotype. Regardless of genotype, more women opted for aromatase inhibitors. Overall, 80% of women completed 5 years of hormonal therapy. Five women developed recurrence, 3 contralateral breast cancer, 5 died, and 1 was diagnosed with a second primary cancer. Five-year recurrence-free and overall survival were slightly better in women with the extensive or ultra metabolizer phenotype compared to those with the IM phenotype, though not statistically significant [P = 0.743, hazard ratio (HR): 1.441, 95% confidence interval (CI): 0.191 to 10.17 and P = 0.798, HR: 1.327, 95%CI: 0.172 to 9.915, respectively]. Women receiving aromatase inhibitors also appeared to have a better, but also nonsignificant, 5-year recurrence-free and overall survival (P = 0.253, HR: 0.368, 95%CI: 0.031 to 0.258 and P = 0.292, HR: 0.252, 95%CI: 0.005 to 4.951, respectively).
CONCLUSION The IM phenotype was highly prevalent but was not associated with clinical outcome.
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Affiliation(s)
- Ern-Yu Tan
- Department of General Surgery, Tan Tock Seng Hospital, Singapore 308433, Singapore
- Lee Kong Chian School of Medicine, Singapore 308232, Singapore
- Institute of Molecular and Cell Biology, A*STAR, Singapore 138673, Singapore
| | - Lavina Bharwani
- Department of Medical Oncology, Tan Tock Seng Hospital, Singapore 308433, Singapore
| | - Yee-Hong Chia
- Department of Medical Oncology, Tan Tock Seng Hospital, Singapore 308433, Singapore
| | - Richie C T Soong
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 119077, Singapore
| | - Sherylyn S Y Lee
- Department of General Surgery, Tan Tock Seng Hospital, Singapore 308433, Singapore
| | - Juliana J C Chen
- Department of General Surgery, Tan Tock Seng Hospital, Singapore 308433, Singapore
| | - Patrick M Y Chan
- Department of General Surgery, Tan Tock Seng Hospital, Singapore 308433, Singapore
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3
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Zhou Y, Lauschke VM. Population pharmacogenomics: an update on ethnogeographic differences and opportunities for precision public health. Hum Genet 2022; 141:1113-1136. [PMID: 34652573 PMCID: PMC9177500 DOI: 10.1007/s00439-021-02385-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/05/2021] [Indexed: 11/25/2022]
Abstract
Both safety and efficacy of medical treatment can vary depending on the ethnogeographic background of the patient. One of the reasons underlying this variability is differences in pharmacogenetic polymorphisms in genes involved in drug disposition, as well as in drug targets. Knowledge and appreciation of these differences is thus essential to optimize population-stratified care. Here, we provide an extensive updated analysis of population pharmacogenomics in ten pharmacokinetic genes (CYP2D6, CYP2C19, DPYD, TPMT, NUDT15 and SLC22A1), drug targets (CFTR) and genes involved in drug hypersensitivity (HLA-A, HLA-B) or drug-induced acute hemolytic anemia (G6PD). Combined, polymorphisms in the analyzed genes affect the pharmacology, efficacy or safety of 141 different drugs and therapeutic regimens. The data reveal pronounced differences in the genetic landscape, complexity and variant frequencies between ethnogeographic groups. Reduced function alleles of CYP2D6, SLC22A1 and CFTR were most prevalent in individuals of European descent, whereas DPYD and TPMT deficiencies were most common in Sub-Saharan Africa. Oceanian populations showed the highest frequencies of CYP2C19 loss-of-function alleles while their inferred CYP2D6 activity was among the highest worldwide. Frequencies of HLA-B*15:02 and HLA-B*58:01 were highest across Asia, which has important implications for the risk of severe cutaneous adverse reactions upon treatment with carbamazepine and allopurinol. G6PD deficiencies were most frequent in Africa, the Middle East and Southeast Asia with pronounced differences in variant composition. These variability data provide an important resource to inform cost-effectiveness modeling and guide population-specific genotyping strategies with the goal of optimizing the implementation of precision public health.
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Affiliation(s)
- Yitian Zhou
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Volker M Lauschke
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden.
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany.
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4
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Mehlotra RK, Gaedigk A, Howes RE, Rakotomanga TA, Ratsimbasoa AC, Zimmerman PA. CYP2D6 Genetic Variation and Its Implication for Vivax Malaria Treatment in Madagascar. Front Pharmacol 2021; 12:654054. [PMID: 33959023 PMCID: PMC8093859 DOI: 10.3389/fphar.2021.654054] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 03/01/2021] [Indexed: 12/19/2022] Open
Abstract
Plasmodium vivax is one of the five human malaria parasite species, which has a wide geographical distribution and can cause severe disease and fatal outcomes. It has the ability to relapse from dormant liver stages (hypnozoites), weeks to months after clearance of the acute blood-stage infection. An 8-aminoquinoline drug primaquine (PQ) can clear the hypnozoites, and thus can be used as an anti-relapse therapeutic agent. Recently, a number of studies have found that its efficacy is compromised by polymorphisms in the cytochrome P450 2D6 (CYP2D6) gene; decreased or absence of CYP2D6 activity contributes to PQ therapeutic failure. The present study sought to characterize CYP2D6 genetic variation in Madagascar, where populations originated from admixture between Asian and African populations, vivax malaria is endemic, and PQ can be deployed soon to achieve national malaria elimination. In a total of 211 samples collected from two health districts, CYP2D6 decreased function alleles CYP2D6*10, *17, *29, *36+*10, and *41 were observed at frequencies of 3.55-17.06%. In addition, nonfunctional alleles were observed, the most common of which were CYP2D6*4 (2.13%), *5 (1.66%), and the *4x2 gene duplication (1.42%). Given these frequencies, 34.6% of the individuals were predicted to be intermediate metabolizers (IM) with an enzyme activity score (AS) ≤ 1.0; both the IM phenotype and AS ≤ 1.0 have been found to be associated with PQ therapeutic failure. Furthermore, the allele and genotype frequency distributions add to the archaeological and genomic evidence of Malagasy populations constituting a unique, Asian-African admixed origin. The results from this exploratory study provide fresh insights about genomic characteristics that could affect the metabolism of PQ into its active state, and may enable optimization of PQ treatment across human genetic diversity, which is critical for achieving P. vivax elimination.
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Affiliation(s)
- Rajeev K Mehlotra
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Andrea Gaedigk
- Division of Clinical Pharmacology, Toxicology & Therapeutic Innovation, Children's Mercy Kansas City, Kanas City, MO, United States
| | - Rosalind E Howes
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom.,Foundation for Innovative New Diagnostics, Geneva, Switzerland
| | - Tovonahary A Rakotomanga
- The National Malaria Control Program, Ministry of Health, Antananarivo, Madagascar.,University of Fianarantsoa, Fianarantsoa, Madagascar
| | - Arsene C Ratsimbasoa
- The National Malaria Control Program, Ministry of Health, Antananarivo, Madagascar.,University of Fianarantsoa, Fianarantsoa, Madagascar
| | - Peter A Zimmerman
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, OH, United States
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5
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Bakar NS. Pharmacogenetics of common SNP affecting drug metabolizing enzymes: comparison of allele frequencies between European and Malaysian/Singaporean. Drug Metab Pers Ther 2021; 36:173-181. [PMID: 34412170 DOI: 10.1515/dmpt-2020-0153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 01/03/2021] [Indexed: 11/15/2022]
Abstract
Compared to Europe, data on genetic variation in genes transcribing drug metabolizing enzymes among Asian is limited due to ethnic diversity. Here we compare frequencies for clinically relevant single nucleotide polymorphism (SNP) commonly observed in drug metabolizing enzymes between European and Malaysian/Singaporean. Minor allele frequencies (MAF) for the indicated SNPs for European, South Asian and East Asian populations were obtained from the NCBI website (https://www.ncbi.nlm.nih.gov/snp). The SNP prevalence among Malaysian/Singaporean was characterized from gene association studies. Generally, some SNPs in CYP2D6 and CYP2C19 do not show good agreement between the two populations as to the MAF value obtained. CYP2D6*4 tends to be more common among European, whereas CYP2D6*10 is more common in Malays and Chinese among Singaporean. Regardless of different phenotype, MAF of CYP2D6*4 for Indians is similar to that seen by the European. Singaporeans show smaller MAF for CYP2C19*17 but higher CYP2C19*2 frequencies as opposed to European ones. Following growing attention to the contribution of CYP3A4/5, N-acetyltransferases (NAT2), thiopurine methyltransferase (TPMT) and uridine diphosphate glucuronosyltransferases (UGT)2B7 in predicting drug response across Europe, there are limited pharmacogenetics (PGx) studies examining the gene-drug interaction among Malaysian/Singaporean. To better understand the heterogeneity of the drug response, PGx studies for the abovementioned enzymes between ethnics in Malaysian/Singaporean should be identified.
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Affiliation(s)
- Nur Salwani Bakar
- School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
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6
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Bakar NS. Pharmacogenetics of common SNP affecting drug metabolizing enzymes: comparison of allele frequencies between European and Malaysian/Singaporean. Drug Metab Pers Ther 2021; 0:dmdi-2020-0153. [PMID: 33735954 DOI: 10.1515/dmdi-2020-0153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 01/03/2021] [Indexed: 11/15/2022]
Abstract
Compared to Europe, data on genetic variation in genes transcribing drug metabolizing enzymes among Asian is limited due to ethnic diversity. Here we compare frequencies for clinically relevant single nucleotide polymorphism (SNP) commonly observed in drug metabolizing enzymes between European and Malaysian/Singaporean. Minor allele frequencies (MAF) for the indicated SNPs for European, South Asian and East Asian populations were obtained from the NCBI website (https://www.ncbi.nlm.nih.gov/snp). The SNP prevalence among Malaysian/Singaporean was characterized from gene association studies. Generally, some SNPs in CYP2D6 and CYP2C19 do not show good agreement between the two populations as to the MAF value obtained. CYP2D6*4 tends to be more common among European, whereas CYP2D6*10 is more common in Malays and Chinese among Singaporean. Regardless of different phenotype, MAF of CYP2D6*4 for Indians is similar to that seen by the European. Singaporeans show smaller MAF for CYP2C19*17 but higher CYP2C19*2 frequencies as opposed to European ones. Following growing attention to the contribution of CYP3A4/5, N-acetyltransferases (NAT2), thiopurine methyltransferase (TPMT) and uridine diphosphate glucuronosyltransferases (UGT)2B7 in predicting drug response across Europe, there are limited pharmacogenetics (PGx) studies examining the gene-drug interaction among Malaysian/Singaporean. To better understand the heterogeneity of the drug response, PGx studies for the abovementioned enzymes between ethnics in Malaysian/Singaporean should be identified.
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Affiliation(s)
- Nur Salwani Bakar
- School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
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7
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Wang T, Zhou Y, Cao G. Pharmacogenetics of tamoxifen therapy in Asian populations: from genetic polymorphism to clinical outcomes. Eur J Clin Pharmacol 2021; 77:1095-1111. [PMID: 33515076 DOI: 10.1007/s00228-021-03088-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/11/2021] [Indexed: 12/15/2022]
Abstract
BACKGROUND Compared with western countries, Asian breast cancer patients have unique pathological and biological characteristics. Most of them are premenopausal women with HR positive. Tamoxifen as the first-line drug for premenopausal women with HR+ is involved in multiple enzymes and transporters during metabolizing and transporting process. Variants that cause decreased or inactive gene products leading to abnormal responses in tamoxifen therapy have well been studied in western countries, whereas such information is much less reported in Asian populations. OBJECTIVE In order to elucidate the relationship between genetic variants and tamoxifen-induced individual drug reactions in different Asian populations and further identify genotypes/phenotypes with potential therapeutic significance. METHODS We reviewed the frequencies of genetic variants in major enzymes and transporter genes involved in the metabolism and transport of tamoxifen across Asian populations as well as significant correlations between genotypes/metabolic phenotypes and metabolites concentrations or BC clinical outcomes. RESULTS Significant inter-ethnic differences in allele frequencies was found among Asian populations, such as CYP2D6*4, *10, *41, CYP2C9*2, ABCB1 C3435T and SLCO1B1*5, and CYP2D6*10/*10 is the most common genotype correlated with adverse clinical outcomes. Moreover, we summarized the barriers and controversies of implementing pharmacogenetics in tamoxifen therapy and concluded that more population-specific pharmacogenetic studies are needed in the future. CONCLUSION This review revealed more systematic pharmacogenomics of genes involved in the metabolism and transport besides CYP2D6, are required to optimize the genotyping strategies and guide the personalized tamoxifen therapy in Asian populations.
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Affiliation(s)
- Tingyu Wang
- College of Pharmacy, Hubei University of Chinese Medicine, Wuhan, 430065, China
| | - Yitian Zhou
- Department of Physiology and Pharmacology, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Guosheng Cao
- College of Pharmacy, Hubei University of Chinese Medicine, Wuhan, 430065, China.
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8
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Dorji PW, Tshering G, Na‐Bangchang K. CYP2C9, CYP2C19, CYP2D6 and CYP3A5 polymorphisms in South‐East and East Asian populations: A systematic review. J Clin Pharm Ther 2019; 44:508-524. [DOI: 10.1111/jcpt.12835] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 02/15/2019] [Accepted: 03/10/2019] [Indexed: 12/22/2022]
Affiliation(s)
- Palden Wangyel Dorji
- Chulabhorn International College of Medicine, Rangsit Center Thammasat University Klong Luang Pathum Thani Thailand
| | - Gyem Tshering
- Chulabhorn International College of Medicine, Rangsit Center Thammasat University Klong Luang Pathum Thani Thailand
| | - Kesara Na‐Bangchang
- Chulabhorn International College of Medicine, Rangsit Center Thammasat University Klong Luang Pathum Thani Thailand
- Center of Excellence in Pharmacology and Molecular Biology of Malaria and Cholangiocarcinoma, Chulabhorn International College of Medicine, Rangsit Center Thammasat University Klong Luang Pathum Thani Thailand
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9
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Saghafi F, Salehifar E, Janbabai G, Zaboli E, Hedayatizadeh-Omran A, Amjadi O, Moradi S. CYP2D6*3 (A2549del), *4 (G1846A), *10 (C100T) and *17 (C1023T) genetic polymorphisms in Iranian breast cancer patients treated with adjuvant tamoxifen. Biomed Rep 2018; 9:446-452. [PMID: 30345040 DOI: 10.3892/br.2018.1145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 09/06/2018] [Indexed: 01/04/2023] Open
Abstract
There is controversy regarding the efficacy of tamoxifen in breast cancer patients who are carriers of cytochrome P450 2D6 (CYP2D6) gene polymorphisms. Poor metabolizer genotypes may not fully convert tamoxifen to its active metabolite endoxifen and thus have less exposure to anti-estrogen therapy. The present study was conducted to identify the prevalence of CYP2D6 genotypes among Iranian breast cancer patients. A total of 84 estrogen receptor-positive breast cancer patients treated at a referral center in the north of Iran were examined. A peripheral blood sample was obtained from each patient to determine the presence of *3, *4, *10 and *17 single nucleotide polymorphisms of the CYP2D6 gene by polymerase chain reaction-based restriction fragment-length polymorphism analysis. Of the four genotypes assessed, CYP2D6*4 was the most common variant and was identified in 41 (48.8%) patients as heterozygous (G/A) and 3 (3.6%) as homozygous (A/A) alleles. CYP2D6*10 heterozygous mutated alleles (C/T) were also a common genotype that presented in 22 (26.2%) of the study subjects. Variant *17 was less common and was detected only as heterozygous (C/T) in 3 patients (3.6%). No CYP2D6*3 heterozygous or homozygous mutated alleles were observed. In conclusion, the frequency of the CYP2D6 nonfunctional alleles *4 and *10 appeared relatively high in Iranian patients with hormone-sensitive breast cancer. This finding may affect the selection of an optimal hormone therapy, as patients with low CYP2D6 pathway activity may not sufficiently convert tamoxifen to its active metabolite endoxifen.
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Affiliation(s)
- Fatemeh Saghafi
- Pharmaceutical Research Center, Mazandaran University of Medical Sciences, Sari 48471-16548, Iran
| | - Ebrahim Salehifar
- Department of Clinical Pharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari 48471-16548, Iran
| | - Ghasem Janbabai
- Department of Internal Medicine, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari 48471-16548, Iran
| | - Ehsan Zaboli
- Department of Internal Medicine, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari 48471-16548, Iran
| | - Akbar Hedayatizadeh-Omran
- Gastrointestinal Cancer Research Center, Mazandaran University of Medical Sciences, Sari 48166-33131, Iran
| | - Omolbanin Amjadi
- Gastrointestinal Cancer Research Center, Mazandaran University of Medical Sciences, Sari 48166-33131, Iran
| | - Siavash Moradi
- Gastrointestinal Cancer Research Center, Mazandaran University of Medical Sciences, Sari 48166-33131, Iran
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10
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Yu CY, Ang GY, Subramaniam V, Johari James R, Ahmad A, Abdul Rahman T, Mohd Nor F, Shaari SA, Teh LK, Salleh MZ. Inference of the Genetic Polymorphisms of CYP2D6 in Six Subtribes of the Malaysian Orang Asli from Whole-Genome Sequencing Data. Genet Test Mol Biomarkers 2017; 21:409-415. [PMID: 28525288 DOI: 10.1089/gtmb.2016.0235] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS CYP2D6 is one of the major enzymes in the cytochrome P450 monooxygenase system. It metabolizes ∼25% of prescribed drugs and hence, the genetic diversity of a CYP2D6 gene has continued to be of great interest to the medical and pharmaceutical industries. This study was designed to perform a systematic analysis of the CYP2D6 gene in six subtribes of the Malaysian Orang Asli. METHODS Genomic DNAs were extracted from the blood samples followed by whole-genome sequencing. The reads were aligned to the reference human genome hg19 and variants in the CYP2D6 gene were analyzed. CYP2D6*5 and duplication of CYP2D6 were analyzed using previously established methods. RESULTS A total of 72 single nucleotide polymorphisms were identified. CYP2D6*1, *2, *4, *5, *10,*41, and duplication of the gene were found in the Orang Asli, whereby CYP2D6*2 and *41 alleles are reported for the first time in the Malaysian population. CONCLUSION The findings in this study provide insights into the genetic polymorphisms of CYP2D6 in the Orang Asli of Peninsular Malaysia.
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Affiliation(s)
- Choo Yee Yu
- 1 Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM) , Puncak Alam, Malaysia
| | - Geik Yong Ang
- 1 Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM) , Puncak Alam, Malaysia
| | - Vinothini Subramaniam
- 1 Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM) , Puncak Alam, Malaysia
| | - Richard Johari James
- 1 Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM) , Puncak Alam, Malaysia .,2 Faculty of Pharmacy, Universiti Teknologi MARA (UiTM) , Sungai Buloh, Malaysia
| | - Aminuddin Ahmad
- 3 Faculty of Medicine, Universiti Teknologi MARA (UiTM) , Sungai Buloh, Malaysia
| | | | - Fadzilah Mohd Nor
- 3 Faculty of Medicine, Universiti Teknologi MARA (UiTM) , Sungai Buloh, Malaysia
| | - Syahrul Azlin Shaari
- 3 Faculty of Medicine, Universiti Teknologi MARA (UiTM) , Sungai Buloh, Malaysia
| | - Lay Kek Teh
- 1 Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM) , Puncak Alam, Malaysia .,2 Faculty of Pharmacy, Universiti Teknologi MARA (UiTM) , Sungai Buloh, Malaysia
| | - Mohd Zaki Salleh
- 1 Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM) , Puncak Alam, Malaysia .,2 Faculty of Pharmacy, Universiti Teknologi MARA (UiTM) , Sungai Buloh, Malaysia
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11
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Sivadas A, Salleh MZ, Teh LK, Scaria V. Genetic epidemiology of pharmacogenetic variants in South East Asian Malays using whole-genome sequences. THE PHARMACOGENOMICS JOURNAL 2016; 17:461-470. [PMID: 27241059 DOI: 10.1038/tpj.2016.39] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 03/16/2016] [Accepted: 05/02/2016] [Indexed: 12/28/2022]
Abstract
Expanding the scope of pharmacogenomic research by including multiple global populations is integral to building robust evidence for its clinical translation. Deep whole-genome sequencing of diverse ethnic populations provides a unique opportunity to study rare and common pharmacogenomic markers that often vary in frequency across populations. In this study, we aim to build a diverse map of pharmacogenetic variants in South East Asian (SEA) Malay population using deep whole-genome sequences of 100 healthy SEA Malay individuals. We investigated the allelic diversity of potentially deleterious pharmacogenomic variants in SEA Malay population. Our analysis revealed 227 common and 466 rare potentially functional single nucleotide variants (SNVs) in 437 pharmacogenomic genes involved in drug metabolism, transport and target genes, including 74 novel variants. This study has created one of the most comprehensive maps of pharmacogenetic markers in any population from whole genomes and will hugely benefit pharmacogenomic investigations and drug dosage recommendations in SEA Malays.
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Affiliation(s)
- A Sivadas
- GN Ramachandran Knowledge Center for Genome Informatics, CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), New Delhi, India
| | - M Z Salleh
- Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM) Malaysia, Puncak Alam, Selangor, Malaysia.,Faculty of Pharmacy, Universiti Teknologi MARA (UiTM) Malaysia, Puncak Alam, Selangor, Malaysia
| | - L K Teh
- Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM) Malaysia, Puncak Alam, Selangor, Malaysia.,Faculty of Pharmacy, Universiti Teknologi MARA (UiTM) Malaysia, Puncak Alam, Selangor, Malaysia
| | - V Scaria
- GN Ramachandran Knowledge Center for Genome Informatics, CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), New Delhi, India
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12
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Chin FW, Chan SC, Abdul Rahman S, Noor Akmal S, Rosli R. CYP2D6 Genetic Polymorphisms and Phenotypes in Different Ethnicities of Malaysian Breast Cancer Patients. Breast J 2015; 22:54-62. [DOI: 10.1111/tbj.12518] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fee Wai Chin
- Genetic Medicine Research Centre; Faculty of Medicine and Health Sciences; Universiti Putra Malaysia; Serdang Selangor Malaysia
| | - Soon Choy Chan
- Perdana University Graduate School of Medicine (PUGSOM); Serdang Selangor Malaysia
| | - Sabariah Abdul Rahman
- Medical Education Unit; Faculty of Medicine; Universiti Teknologi MARA; Batu Caves Selangor Malaysia
- Laboratory of Medical Sciences; Faculty of Medicine; Universiti Teknologi MARA; Sungai Buloh Selangor Malaysia
| | - Sharifah Noor Akmal
- Department of Pathology; Faculty of Medicine; Universiti Kebangsaan Malaysia Medical Centre; Cheras Kuala Lumpur Malaysia
| | - Rozita Rosli
- Genetic Medicine Research Centre; Faculty of Medicine and Health Sciences; Universiti Putra Malaysia; Serdang Selangor Malaysia
- UPM-MAKNA Cancer Research Laboratory; Institute of Bioscience; Universiti Putra Malaysia; Serdang Selangor Malaysia
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Bagheri A, Kamalidehghan B, Haghshenas M, Azadfar P, Akbari L, Sangtarash MH, Vejdandoust F, Ahmadipour F, Meng GY, Houshmand M. Prevalence of the CYP2D6*10 (C100T), *4 (G1846A), and *14 (G1758A) alleles among Iranians of different ethnicities. Drug Des Devel Ther 2015; 9:2627-34. [PMID: 25999696 PMCID: PMC4435087 DOI: 10.2147/dddt.s79709] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The presence of polymorphisms in the CYP2D6 gene may modulate enzyme level and activity, thereby affecting individual responses to pharmacological treatment. Here, we compared the prevalence of the CYP2D6*10, *4, and 14* alleles in an Iranian population of different ethnicities with those of other populations. Allele and genotype frequency distributions of CYP2D6*10 variants and predicted phenotypes including extensive metabolizers, intermediate metabolizers, and poor metabolizers were analysed in blood samples of 300 unrelated healthy individuals in an Iranian population using polymerase chain reaction (PCR)-restriction fragment length polymorphism, PCR-single-strand conformation polymorphism, and direct genomic DNA sequencing. The CYP2D6*4 (G1846A) and *14 (G1758A) allelic frequencies were not detected in different ethnicities, demonstrating the absence of a significant contribution of these alleles in Iranian populations. However, the T/T, C/T, and C/C genotype frequencies of the CYP2D6*10 allele were significantly different (P<0.01) in all Iranian ethnic groups. Additionally, the frequency of the homozygous T/T variant of the CYP2D6*10 allele was significantly high in the Lure (P<0.017) and low in the Kurd (P<0.002) ethnicities. The frequency of the T/T variant of the CYP2D6*10 allele in central Iran was the highest (P<0.001), while the south of Iran had the lowest frequency (P<0.001). The frequency of the C/T variant of the CYP2D6*10 allele was significantly a bit high (P<0.001) in females compare to males, while the frequencies of the T/T variant in females is similar to males, which are 24.4% and 24.3%, respectively. In contrast to absence of the CYP2D6*4 (G1846A) and *14 (G1758A) alleles in Iranian populations of different ethnicities, the prediction of the CYP2D6*10 allele is required in drug research and routine treatment, where the information would be helpful for clinicians to optimize therapy or identify persons at risk of adverse drug reactions before clinical trials. Approximately 39.3% of subjects (24.3% homozygous T/T CYP2D6*10 as poor metabolizers and 15% heterozygous C/T CYP2D6*10 as intermediate metabolizers) had this allele; therefore, the harmful effects of drugs are relatively common among Iranians.
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Affiliation(s)
- Ali Bagheri
- Department of Biology, University of Sistan and Baluchestan, Zahedan, Iran
| | - Behnam Kamalidehghan
- Department of Pharmacy, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Maryam Haghshenas
- Department of Biology, Pardis International Unit, University of Guilan, Rasht, Iran
| | - Parisa Azadfar
- Department of Biology, Science and Research Branch, Azad University, Tehran, Iran
| | - Leila Akbari
- Department of Biology, Science and Research Branch, Azad University, Tehran, Iran
| | | | | | - Fatemeh Ahmadipour
- Department of Pharmacy, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Goh Yong Meng
- Department of Animal Science, Faculty of Veterinary Medicine, Universiti Putra Malaysia, Serdang, Malaysia
| | - Massoud Houshmand
- Medical Genetics Department, Special Medical Center, National Institute for Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran ; Medical Genetics Department, National Institute for Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
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LLerena A, Naranjo MEG, Rodrigues-Soares F, Penas-LLedó EM, Fariñas H, Tarazona-Santos E. Interethnic variability ofCYP2D6alleles and of predicted and measured metabolic phenotypes across world populations. Expert Opin Drug Metab Toxicol 2014; 10:1569-83. [PMID: 25316321 DOI: 10.1517/17425255.2014.964204] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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15
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Zahari Z, Ismail R. Influence of Cytochrome P450, Family 2, Subfamily D, Polypeptide 6 (CYP2D6) Polymorphisms on Pain Sensitivity and Clinical Response to Weak Opioid Analgesics. Drug Metab Pharmacokinet 2014; 29:29-43. [DOI: 10.2133/dmpk.dmpk-13-rv-032] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Hamzah S, Teh LK, Siew JSK, Ahmad G, Wong HS, Zakaria ZA, Salleh MZ. Pharmacogenotyping of CYP3A5 in predicting dose-adjusted trough levels of tacrolimus among Malaysian kidney-transplant patients. Can J Physiol Pharmacol 2014; 92:50-7. [DOI: 10.1139/cjpp-2013-0128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tacrolimus (FK506) is a calcineurin inhibitor with a narrow therapeutic index that exhibits large interindividual variation. Seventy-eight kidney transplant patients treated with tacrolimus were recruited to study the correlation of dose adjusted trough level (level/dose; L/D) of tacrolimus with CYP3A5 and ABCB1 genotypes, as well as the mRNA copy number of ABCB1 in blood. Patients were genotyped for ABCB1 (C1236T, G2677T/A, and C3435T) and CYP3A5 (G6986A), while ABCB1 mRNA transcript copy number was determined by absolute quantification (real-time PCR) in 46 patients. CYP3A5*3 genotypes were found to be a good predictor of tacrolimus L/D in kidney-transplant patients. Significantly higher L/D was observed among non-expressors (2.85, 95%: 2.05–3.70 (ng·mL–1)/(mg·kg–1)) as compared with the expressors (1.15, 95%: 0.95–1.80 (ng·mL–1)/(mg·kg–1)) of CYP3A5 (Mann–Whitney U test; P < 0.001). No correlation was observed between L/D and the ABCB1 genotypes. A significant inverse correlation of blood ABCB1 mRNA level with L/D was demonstrated (Spearman’s Rank Order correlation; P = 0.016, rs = –0.348). However, in multiple regression analysis, only CYP3A5*3 genotype groups were found to be significantly correlated with tacrolimus L/D (P < 0.001). These findings highlight the importance of CYP3A5*3 pharmacogenotyping among kidney-transplant patients treated with tacrolimus, and confirm the role of blood cell P-glycoprotein in influencing the L/D for tacrolimus.
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Affiliation(s)
- Sharina Hamzah
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA (UiTM), 42300 Puncak Alam, Selangor DE, Malaysia
| | - Lay Kek Teh
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA (UiTM), 42300 Puncak Alam, Selangor DE, Malaysia
| | - John Shia Kwong Siew
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA (UiTM), 42300 Puncak Alam, Selangor DE, Malaysia
| | - Ghazali Ahmad
- Department of Nephrology, Hospital Kuala Lumpur, Kuala Lumpur, Malaysia
| | - Hin Seng Wong
- Department of Nephrology, Hospital Selayang, Selangor, Malaysia
| | - Zainul Amiruddin Zakaria
- Department of Biomedical Sciences, Faculty of Medicine and Health Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
- Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA (UiTM), 42300 Puncak Alam, Selangor DE, Malaysia
| | - Mohd Zaki Salleh
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA (UiTM), 42300 Puncak Alam, Selangor DE, Malaysia
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Polymorphisms and phenotypic analysis of cytochrome P450 2D6 in the Tibetan population. Gene 2013; 527:360-5. [DOI: 10.1016/j.gene.2013.03.110] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 03/20/2013] [Accepted: 03/25/2013] [Indexed: 11/22/2022]
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18
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Teh LK, Bertilsson L. Pharmacogenomics of CYP2D6: molecular genetics, interethnic differences and clinical importance. Drug Metab Pharmacokinet 2011; 27:55-67. [PMID: 22185816 DOI: 10.2133/dmpk.dmpk-11-rv-121] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CYP2D6 has received intense attention since the beginning of the pharmacogenetic era in the 1970s. This is because of its involvement in the metabolism of more than 25% of the marketed drugs, the large geographical and inter-ethnic differences in the genetic polymorphism and possible drug-induced toxicity. Many interesting reviews have been published on CYP2D6 and this review aims to reinstate the importance of the genetic polymorphism of CYP2D6 in different populations as well as some clinical implications and important drug interactions.
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Affiliation(s)
- Lay Kek Teh
- Pharmacogenomics Centre PROMISE, Faculty of Pharmacy, Universiti Teknologi MARA, Selangor DE, Malaysia.
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Teh LK, Mohamed NI, Salleh MZ, Rohaizak M, Shahrun NS, Saladina JJ, Shia JKS, Roslan H, Sood S, Rajoo TS, Muniandy SP, Henry G, Ngow HA, Hla U KT, Din J. The risk of recurrence in breast cancer patients treated with tamoxifen: polymorphisms of CYP2D6 and ABCB1. AAPS JOURNAL 2011; 14:52-9. [PMID: 22183189 DOI: 10.1208/s12248-011-9313-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Accepted: 11/28/2011] [Indexed: 01/26/2023]
Abstract
CYP2D6 plays a major role in the metabolism of tamoxifen, and polymorphism of P-glycoprotein has been associated with resistance of many drug therapies. This study investigates the clinical impact of genetic variants of CYP2D6 and ABCB1 in breast cancer patients treated with tamoxifen. Blood samples from 95 breast cancer patients treated with tamoxifen were collected and genotyped for CYP2D6 and ABCB1 variants using allele-specific PCR method. Recurrence risks were calculated using Kaplan-Meier analysis and compared using the log-rank test. Patients carrying CYP2D6*10/*10 and heterozygous null allele (IM) showed higher risks of developing recurrence and metastasis (OR 13.14; 95% CI 1.57-109.94; P = 0.004) than patients with CYP2D6*1/*1 and *1/*10 genotypes. Patients with homozygous CC genotypes of ABCB1 C3435T showed a shorter time to recurrence. Patients who were CYP2D6 IM and homozygous CC genotype of C3435T have statistically significant higher risks of recurrence (P = 0.002). Similarly, median time to recurrence in these patients was only 12 months (95% CI = 0.79-23.2) compared to those without this combination which was 48 months (95% CI = 14.7-81.2). Patients with CYP2D6 IM and homozygous CC genotype of ABCB1 C3435T have shorter times to recurrence. The results confirmed the findings of previous studies and support FDA recommendation to perform pre-genotyping in patients before the choice of therapy is determined in breast cancer patients.
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Affiliation(s)
- L K Teh
- Pharmacogenomics Centre, Faculty of Pharmacy, Universiti Teknologi MARA, Campus Puncak Alam, Selangor Darul Ehsan, Malaysia.
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Suwannasri P, Thongnoppakhun W, Pramyothin P, Assawamakin A, Limwongse C. Combination of multiplex PCR and DHPLC-based strategy for CYP2D6 genotyping scheme in Thais. Clin Biochem 2011; 44:1144-1152. [DOI: 10.1016/j.clinbiochem.2011.06.985] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 06/01/2011] [Accepted: 06/26/2011] [Indexed: 10/18/2022]
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21
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Perwitasari DA, Wessels JAM, van der Straaten RJHM, Baak-Pablo RF, Mustofa M, Hakimi M, Nortier JWR, Gelderblom H, Guchelaar HJ. Association of ABCB1, 5-HT3B receptor and CYP2D6 genetic polymorphisms with ondansetron and metoclopramide antiemetic response in Indonesian cancer patients treated with highly emetogenic chemotherapy. Jpn J Clin Oncol 2011; 41:1168-76. [PMID: 21840870 DOI: 10.1093/jjco/hyr117] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE Suboptimal treatment of chemotherapy-induced nausea and vomiting and unsatisfactory response to antiemetic drugs cause impairment of cancer patient's daily functioning. This study was aimed to investigate the association of selected germline polymorphisms with ondansetron and metoclopramide response in Indonesian cancer patients treated with highly emetogenic chemotherapy. METHODS We enrolled 202 chemotherapy naïve patients treated with cisplatin at a dosage of ≥50 mg/m(2) as monotherapy or as combined chemotherapy. Ondansetron 8 mg and dexamethasone 8 mg intravenously were the standard antiemetic therapy for prevention of acute chemotherapy-induced nausea and vomiting. Metoclopramide 10 mg orally, three times per day as fixed prescription, was given until 5 days after chemotherapy to prevent delayed chemotherapy-induced nausea and vomiting. Primary and secondary outcomes were the occurrence of chemotherapy-induced nausea and vomiting in the acute and delayed phase. The following single-nucleotide polymorphisms were determined in ABCB1: rs1045642, rs2032582 and rs1128503; in 5-HT3B-R: rs45460698, rs4938058 and rs7943062; and in CYP2D6: rs16947 (CYP2D6 2), rs3892097 (CYP2D6 4) and rs1065852 (CYP2D6 10) using Taqman assays. RESULTS During the acute phase, 21.8 and 30.2% patients experienced Grade 3 and 4 nausea and vomiting, respectively, whereas 38.6% patients experienced nausea and/or vomiting in the delayed phase. Carriers of the CTG haplotype of the ABCB1 gene experienced Grade 3 and 4 chemotherapy-induced nausea and vomiting more often than other haplotypes in the delayed phase (P< 0.05). No associations were found with the 5-HT3B receptor haplotypes and CYP2D6-predicted phenotypes. CONCLUSIONS Our study shows that in Indonesian cancer patients treated with highly cytostatic emetogenic, carriership of the CTG haplotype of the ABCB1 gene is related to an increased risk of delayed chemotherapy-induced nausea and vomiting.
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Teh LK, Zahri MK, Zakaria ZA, Ismail R, Salleh MZ. Mutational analysis of CYP2C8 in hypertensive patients using denaturing high performance liquid chromatography. J Clin Pharm Ther 2010; 35:723-8. [DOI: 10.1111/j.1365-2710.2009.01146.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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23
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Genetic polymorphism, linkage disequilibrium, haplotype structure and novel allele analysis of CYP2C19 and CYP2D6 in Han Chinese. THE PHARMACOGENOMICS JOURNAL 2009; 9:380-94. [DOI: 10.1038/tpj.2009.31] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Nurfadhlina M, Foong K, Teh LK, Tan SC, Mohd Zaki S, Ismail R. CYP2A6 polymorphisms in Malays, Chinese and Indians. Xenobiotica 2008; 36:684-92. [PMID: 16891249 DOI: 10.1080/00498250600715932] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The genetically polymorphic cytochrome P450 (CYP) 2A6 is the major nicotine-oxidase in humans that may contribute to nicotine dependence and cancer susceptibility. The authors investigated the types and frequencies of CYP2A6 alleles in the three major ethnic groups in Malaysia and CYP2A6*1A, CYP2A6*1B, CYP2A6*1x2, CYP2A6*2, CYP2A6*3, CYP2A6*4, CYP2A6*5, CYP2A6*7, CYP2A6*8 and CYP2A6*10 were determined by allele-specific polymerase chain reaction (PCR) in 270 Malays, 172 Chinese and 174 Indians. Except for CYP2A6*2 and *3 that were not detected in the Malays and Chinese, all the other alleles were detected. Frequencies for the CYP2A6*4 allele were 7, 5 and 2%, respectively, in Malays, Chinese and Indians. A statistically significant high frequency of the duplicated CYP2A6*1x2 allele occurred among Chinese. Among Malays and Chinese, the most common allele was CYP2A6*1B, but it was CYP2A6*1A among Indians. These ethnic difference in frequencies suggested that further studies are required to investigate the implications on diseases such as cancer and smoking behaviour among these major ethnic groups in Malaysia.
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Affiliation(s)
- M Nurfadhlina
- Pharmacogenetics Research Group, INFORMM, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
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Ngow H, Teh LK, Langmia IM, Lee WL, Harun R, Ismail R, Salleh MZ. Role of pharmacodiagnostic of CYP2C9 variants in the optimization of warfarin therapy in Malaysia: a 6-month follow-up study. Xenobiotica 2008; 38:641-51. [PMID: 18570163 DOI: 10.1080/00498250801999087] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
1. A retrospective study was conducted to explore the importance of CYP2C9 genotyping for the initiation and maintenance therapy of warfarin in clinical practice. A total of 191 patients on warfarin therapy in a local hospital were recruited after written informed consent. Their medical records were reviewed and no intervention of warfarin dose was performed. 2. A total of 5 ml of blood were taken from each subject for DNA extraction and identification of 1, 2, 3 and 4 CYP2C9 alleles, using a nested-allele-specific-multiplex-polymerase chain reaction (PCR). Half the patients were Malays and the remaining were Chinese. 3. Two genotypes were detected; 93.2% had CYP2C9 1/1 and 6.8% were CYP2C9 1/3. Warfarin doses were higher in patients with CYP2C91/1. Patients with the 1/3 genotype experienced a higher rate of serious and life-threatening bleeding; 15.4 versus 6.2 per 100 patients per 6 months. 4. The observation clearly highlights the inadequacy of the current dosing regimens and the need to move toward a more individualized approach to warfarin therapy. Prospective clinical studies are now being conducted to assess dosing algorithms that incorporate the contribution of the genotype to allow the individualization of warfarin dose.
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Affiliation(s)
- H Ngow
- Department of Internal Medicine, International Islamic University Malaysia, Pahang, Malaysia
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Gan SH, Ismail R, Wan Adnan WA, Zulmi W. Impact of CYP2D6 genetic polymorphism on tramadol pharmacokinetics and pharmacodynamics. Mol Diagn Ther 2007; 11:171-81. [PMID: 17570739 DOI: 10.1007/bf03256239] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND AND OBJECTIVE Tramadol is metabolized by the highly polymorphic enzyme cytochrome P450 (CYP)2D6. Patients with different CYP2D6 genotypes may respond differently to tramadol in terms of pain relief and adverse events. In this study, we compare the pharmacokinetics and effects of tramadol in Malaysian patients with different genotypes to establish the pharmacokinetic-pharmacodynamic relationship of tramadol. STUDY DESIGN AND SETTING All patients received an intravenous dose of tramadol 100mg as their first postoperative analgesic. Blood was sampled at 0 minutes and subsequently at 15 and 30 minutes, 1, 2, 4, 8, 16, 20, and 24 hours for serum tramadol and analyzed by high-performance liquid chromatography (HPLC). Patients were genotyped for CYP2D6*1, *3, *4, *5, *9, *10, and *17 alleles and duplication of the gene by means of an allele-specific PCR. Pain was measured using the Visual Analog Scales, and adverse effects were recorded. RESULTS About half of the patients had the wild-type allele (CYP2D6*1), with the 'Asian'CYP2D6*10 allele accounting for most of the rest (40%). None of the genotypes predicted poor metabolism. Twenty-seven percent of the patients were intermediate metabolizers (IM) and 2.9% were ultra-rapid (UM) metabolizers; the remaining 70% were extensive metabolizers (EM). The mean total clearance (CL) predicted by the model was lower (19 L/h) and the half-life longer (5.9 hours) than those reported in Western populations. This may due to the high frequency of the CYP2D6*10 allele amongst Malaysian patients. The UM and EM groups had 2.6- and 1.3-times faster CL, respectively, than the IM. CL was 16, 18, 23, and 42 L/h while mean half-lives were 7.1, 6.8, 5.6, and 3.8 hours among the IM, EM1, EM2, and UM groups, respectively. However, the analgesic effects of tramadol were not measured adequately among the postoperative patients to establish its full therapeutic effects. There were significant differences in the adverse-effect profiles amongst the various genotype groups, with the IM group experiencing more adverse effects than the EM, and the EM having more adverse effects than the UM. CONCLUSION CYP2D6 activity may play an important role in determining the pharmacokinetics of tramadol and in predicting its adverse effects. If these results can be confirmed in a larger population, genotyping may be an important tool in determining the dose of tramadol.
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Affiliation(s)
- Siew Hua Gan
- Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia.
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Teh LK, Lee WL, Amir J, Salleh MZ, Ismail R. Single step PCR for detection of allelic variation of MDR1 gene (P-glycoprotein) among three ethnic groups in Malaysia. J Clin Pharm Ther 2007; 32:313-9. [PMID: 17489883 DOI: 10.1111/j.1365-2710.2007.00822.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND P-glycoprotein (PgP) is the most extensively studied ATP-binding cassette (ABC) coded by MDR1 gene. To date, 29 single nucleotide polymorphisms (SNPs) have been identified; but only SNP C3435T has been correlated with intestinal PgP expression levels and shown to influence the absorption of orally taken drugs that are PgP substrates. Individuals homozygous for the T allele have more than fourfold lower PgP expression compared with C/C individuals. We developed a one step primer based allele specific PCR method to detect SNP at C3435T to investigate the distribution of this genotype in the local population. METHOD DNA was extracted from 5 mL of whole blood using standard salting-out method. Primers were designed specific to 3' end which amplify the variants of C3435T. The method was validated by direct DNA sequencing. Seven hundred and sixty-three healthy blood donors comprising of three major ethnic groups in Malaysia were recruited and DNA subjected to genotyping of C3435T using this method. RESULT The method was found to be robust and reproducible in detecting SNP of C3435T. Interethnic variations in genotype and allele frequency were observed in PgP among the ethnic groups. In comparison to both the Caucasians and the other Asian countries, the Malay and Chinese showed a higher frequency of allele C (50-60%); while the Indian exhibits a lower frequency (40%), similar to other Indian populations. DISCUSSION AND CONCLUSION Using a new simple method to investigate the distribution of C3435T, we found that the allele frequency of MDR1 showed variablity between the different ethnic groups within the Malaysian population.
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Affiliation(s)
- L K Teh
- Faculty of Pharmacy, Universiti Teknologi MARA, 41050 Shah Alam, Malaysia.
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Ismail R, Teh LK. The relevance of CYP2D6 genetic polymorphism on chronic metoprolol therapy in cardiovascular patients. J Clin Pharm Ther 2006; 31:99-109. [PMID: 16476126 DOI: 10.1111/j.1365-2710.2006.00699.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND OBJECTIVE CYP2D6 polymorphisms are well described in normal populations but there are few data on its clinical significance. We therefore investigated the influence of CYP2D6 polymorphism on steady-state plasma concentrations and apparent oral clearance of metoprolol in patients with cardiovascular diseases. METHODS Ninety-one patients on metoprolol were recruited. Plasma concentrations of metoprolol and alpha-hydroxy metoprolol were measured at 4-h post-dose. CYP2D6 genotyping (*1, *3, *4, *5, *9, *8, *10, *17 and duplication) were performed on the DNA extracted. Ratio of plasma concentrations of metoprolol and alpha-hydroxy metoprolol and the apparent oral clearance of metoprolol were calculated. The influences of CYP2D6 genotypes were investigated. RESULTS A 100-fold variation was noted for both plasma concentrations of metoprolol and alpha-hydroxy metoprolol. There was a weak correlation between the total daily doses and plasma concentrations of both. Plasma concentrations were found to be higher in patients with genotypes that predicted lower enzyme activity. One patient homozygous for CYP2D6*4 had the highest metoprolol concentration per unit dose. With an antimode of 10. Two patients were identified as poor metabolizers (PMs) (2.1%; 95% CI: 2.9). The PMs who had a plasma metabolic ratio (pMR) of 37.8 was homozygous CYP2D6*4 whereas the other with pMR 14.5 was genotyped CYP2D6 *4/*10. There was a 36-fold difference between the highest and lowest clearance values. Large overlaps in the clearance values were noted between most of the genotypes. CONCLUSIONS Our data suggest that pharmacogenetic measures could be used to design a more individualized metoprolol dosage regimen for patients.
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Affiliation(s)
- R Ismail
- Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Malaysia.
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Yu AM, Idle JR, Gonzalez FJ. Polymorphic cytochrome P450 2D6: humanized mouse model and endogenous substrates. Drug Metab Rev 2004; 36:243-77. [PMID: 15237854 DOI: 10.1081/dmr-120034000] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cytochrome P450 2D6 (CYP2D6) is the first well-characterized polymorphic phase I drug-metabolizing enzyme, and more than 80 allelic variants have been identified for the CYP2D6 gene, located on human chromosome 22q13.1. Human debrisoquine and sparteine metabolism is subdivided into two principal phenotypes--extensive metabolizer and poor metabolizer--that arise from variant CYP2D6 genotypes. It has been estimated that CYP2D6 is involved in the metabolism and disposition of more than 20% of prescribed drugs, and most of them act in the central nervous system or on the heart. These drug substrates are characterized as organic bases containing one nitrogen atom with a distance about 5, 7, or 10 A from the oxidation site. Aspartic acid 301 and glutamic acid 216 were determined as the key acidic residues for substrate-enzyme binding through electrostatic interactions. CYP2D6 transgenic mice, generated using a lambda phage clone containing the complete wild-type CYP2D6 gene, exhibits enhanced metabolism and disposition of debrisoquine. This transgenic mouse line and its wild-type control are models for human extensive metabolizers and poor metabolizers, respectively, and would have broad application in the study of CYP2D6 polymorphism in drug discovery and development, and in clinical practice toward individualized drug therapy. Endogenous 5-methoxyindole- thylamines derived from 5-hydroxytryptamine were identified as high-affinity substrates of CYP2D6 that catalyzes their O-demethylations with high enzymatic capacity and specificity. Thus, polymorphic CYP2D6 may play an important role in the interconversions of these psychoactive tryptamines, including a crucial step in a serotonin-melatonin cycle.
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Affiliation(s)
- Ai-Ming Yu
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Gan SH, Ismail R, Wan Adnan WA, Zulmi W, Kumaraswamy N, Larmie ET. Relationship between Type A and B personality and debrisoquine hydroxylation capacity. Br J Clin Pharmacol 2004; 57:785-9. [PMID: 15151524 PMCID: PMC1884512 DOI: 10.1111/j.1365-2125.2004.02076.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
AIM A person with Type A personality is an 'aggressor' compared with the rarely harried Type B. Although debrisoquine hydroxylase (CYP2D6) capacity has been associated with personality, no study has specifically investigated its association with personality Type A and B. Therefore the aim of this research was to study the impact of CYP2D6 on Type A and B personality. METHODS Type A and B personality questionnaires were administered to 48 healthy patients undergoing elective orthopaedic surgery. After obtaining informed consent, patients were genotyped for the various CYP2D6 alleles by allele-specific polymerase chain reaction. Based on the genotypes, patients were grouped as extensive metabolizer (EM)1 (normal) (CYP2D6*1/*1), EM2 (intermediate) (CYP2D6*1/*4, CYP2D6*1/*5, CYP2D6*1/*9 and CYP2D6*1/*10) and EM3 (slow) (CYP2D6*4/*10, CYP2D6*5/*10, CYP2D6*10/*10 and CYP2D6*10/*17). Chi(2) was used to determine the relationship between the groups and personality types. RESULTS The percentages of patients who were of the EM1, EM2 and EM3 groups were 20.8%, 52.1% and 27.1%, respectively. There was a significant difference (P = 0.032) between the three groups in terms of personality type, in which EM1 showed a tendency to be of personality Type A while EM2 and EM3 tended to be of personality Type B. CONCLUSION The study suggests that there is a relationship between CYP2D6 activity and Type A and B personality.
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Affiliation(s)
- S H Gan
- Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.
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Ismail R, Teh LK, Amir J, Alwi Z, Lopez CG. Genetic polymorphism of CYP2D6 in Chinese subjects in Malaysia. J Clin Pharm Ther 2003; 28:279-84. [PMID: 12911679 DOI: 10.1046/j.1365-2710.2003.00490.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Although Malaysian Chinese share an origin with the mainland Chinese, their evolution has been influenced by intermarriages. With a gene such as CYP2D6, which is highly polymorphic, it is expected that the Malaysian Chinese would exhibit a polymorphism profile different from those of the Chinese populations in other geographical locations. OBJECTIVE To study the genotype distribution of CYP2D6 among the Chinese people in Malaysia. METHOD We obtained DNA from 236 Chinese individuals in Malaysia and used PCR-based methods to identify any common CYP2D6 alleles. RESULTS A total of 236 subjects were enrolled and were successfully genotyped. Malaysian Chinese were relatively heterogeneous in terms of their CYP2D6 genotypes with nine genotypes recorded. CYP2D6*4, *5, *9, *10 and *17 were detected with the most common genotype being *1/*10. No subject had genotypes that predicted poor metabolic activity. However, 40% showed genotypes (e.g. CYP2D6*10/*10, *17, *4 and *9 and *9/*9) that predicted an intermediate metabolizer phenotype. Another subject carried the defective CYP2D6*17 allele and six carried the defective CYP2D6*9 allele. Both these alleles have not been reported in other earlier Chinese studies. CONCLUSION This study revealed that, in terms of CYP2D6 polymorphism, Malaysian Chinese were a heterogeneous group of people. Although sharing some similarities with other Orientals, they also seemed to have some notable differences. The alleles CYP2D6*4, *5, *9, *10 and *17 were all detected. CYP2D6*3 was however absent.
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Affiliation(s)
- R Ismail
- Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia.
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Preskorn SH. Polypharmacy in a case of refractory major depression: part II: implications for clinical management. J Psychiatr Pract 2003; 9:71-8. [PMID: 15985916 DOI: 10.1097/00131746-200301000-00007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Sheldon H Preskorn
- Department of Psychiatry, University of Kansas School of Medicine-Wichita, USA
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Shimizu T, Ochiai H, Asell F, Shimizu H, Saitoh R, Hama Y, Katada J, Hashimoto M, Matsui H, Taki K, Kaminuma T, Yamamoto M, Aida Y, Ohashi A, Ozawa N. Bioinformatics Research on Inter-racial Difference in Drug Metabolism I. Analysis on Frequencies of Mutant Alleles and Poor Metabolizers on CYP2D6 and CYP2C19. Drug Metab Pharmacokinet 2003; 18:48-70. [PMID: 15618719 DOI: 10.2133/dmpk.18.48] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The enzyme activities of CYP2D6 and CYP2C19 show a genetic polymorphism, and the frequency of poor metabolizers (PMs) on these enzymes depends on races. In the present study, the frequencies of mutant alleles and PMs in each race were analyzed based on information from published studies, considering the genetic polymorphisms of CYP2D6 and CYP2C19 as the causal factors of racial and inter-individual differences in pharmacokinetics. As a result, it was shown that there were racial differences in the frequencies of each mutant allele and PMs. The frequencies of PMs on CYP2D6 are 1.9% of Asians and 7.7% of Caucasians, and those of PMs on CYP2C19 are 15.8% of Asians and 2.2% of Caucasians. Based on the results, it was suggested that there would be racial differences in the frequencies of PM subjects whose blood concentrations might be higher for drugs metabolized by these enzymes. Additionally, it was suggested that enzyme activities would vary according to the number of functional alleles even in subjects judged to be extensive metabolizers (EMs). In the bridging study, genetic information regarding CYP2D6 and CYP2C19 of the subjects will help extrapolate foreign clinical data to a domestic population.
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Yu A, Kneller BM, Rettie AE, Haining RL. Expression, purification, biochemical characterization, and comparative function of human cytochrome P450 2D6.1, 2D6.2, 2D6.10, and 2D6.17 allelic isoforms. J Pharmacol Exp Ther 2002; 303:1291-300. [PMID: 12438554 DOI: 10.1124/jpet.102.039891] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Polymorphism at the cytochrome P450 2D6 (CYP2D6) locus is one of the most widely known causes of pharmacogenetic variability in humans. Our goal is to investigate the intrinsic enzymatic differences that exist among active CYP2D6 isoforms to test the hypothesis that these enzymatic differences are substrate-dependent. Active CYP2D6.1, 2, 10, and 17 holo-enzymes were expressed in vitro and purified to a high degree of homogeneity as confirmed with SDS-polyacrylamide gel electrophoresis, CO-difference spectroscopy, and mass spectral analysis. Purified enzyme was reconstituted with lipid and cytochrome P450 reductase in a 2:1 ratio before kinetic analysis. The reaction rate for dextromethorphan (DXM) O-demethylation, DXM N-demethylation, codeine O-demethylation, and fluoxetine N-demethylation catalyzed by each of the variants was determined. The CYP2D6.10 enzyme was the most impaired, exhibiting an estimated enzyme efficiency (as V(max)/K(m)) 50-fold lower for DXM O-demethylation and 100-fold lower for fluoxetine N-demethylation when compared with CYP2D6.1, whereas no measurable catalytic activity was observed for this variant toward codeine. The atypical DXM N-demethylation pathway catalyzed by this variant decreased only 2-fold in comparison. In the case of CYPD6.17, estimated clearances for each metabolite were decreased 6 to 33%. Likewise, the intrinsic clearance of CYP2D6.2 enzyme was consistently decreased for each reaction examined, indicating that the ultra-rapid metabolizer phenotype sometimes associated with this genotype is not a function of the underlying amino acid substitutions. Overall enzyme efficiencies for the metabolism of each substrate therefore decreased in the order of 2D6.1 > 2D6.2 > 2D6.17 > 2D6.10.
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Affiliation(s)
- Aiming Yu
- Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia 26506-9530, USA
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Gan SH, Ismail R, Wan Adnan WA, Wan Z. Correlation of tramadol pharmacokinetics and CYP2D6*10 genotype in Malaysian subjects. J Pharm Biomed Anal 2002; 30:189-195. [PMID: 12191703 DOI: 10.1016/s0731-7085(02)00214-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aim of the present study is to investigate the influence of the CYP2D6*10 allele on the disposition of tramadol hydrochloride in Malaysian subjects. A single dose of 100 mg tramadol was given intravenously to 30 healthy orthopaedic patients undergoing various elective surgeries. After having obtained written informed consents, patients were genotyped for CYP2D6*10: the most common CYP2D6 allele among Asians by means of allele-specific polymerase chain reaction. The presence of other mutations (CYP2D6*1, *3, *4, *5, *9 and *17) was also investigated. Tramadol was extracted from 1 ml serum with an n-hexane: ethylacetate combination (4:1) after alkalinisation with ammonia (pH 10.6). Serum concentrations were measured by means of high-performance liquid chromatography. The pharmacokinetics of tramadol was studied during the 24 h after the dose. As among other Asians, the allele frequency for CYP2D6*10 among Malaysians was high (0.43). Subjects who were homozygous for CYP2D6*10 had significantly (P=0.046) longer mean serum half-life of tramadol than subjects of the normal or the heterozygous group (Kruskal-Wallis test). When patients were screened for the presence of other alleles, the pharmacokinetic parameter values were better explained. CYP2D6 activity may play a main role in determining tramadol pharmacokinetics. The CYP2D6*10 allele particularly was associated with higher serum levels of tramadol compared with the CYP2D6*1 allele. However, genotyping for CYP2D6*10 alone is not sufficient to explain tramadol disposition.
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Affiliation(s)
- S H Gan
- Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.
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Bradford LD. CYP2D6 allele frequency in European Caucasians, Asians, Africans and their descendants. Pharmacogenomics 2002; 3:229-43. [PMID: 11972444 DOI: 10.1517/14622416.3.2.229] [Citation(s) in RCA: 535] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Over 40 cytochrome P450 (CYP) 2D6 allelic variants have been discovered thus far. The alleles may be classified on the basis of the level of activity for which they encode CYP2D6 enzymes, into functional, non-functional and reduced function groups. CYP2D6 allele frequency is known to vary amongst racial/ethnic groups. Generally, for European Caucasians and their descendants, the functional group of alleles are predominant, with a frequency of 71%. Non-functional alleles represent 26% of the variability, mainly CYP2D6*4. In Asians and their close descendants, functional alleles represent only ~ 50% of the frequency of CYP2D6 alleles. Asians and Pacific Islanders have a high frequency (median = 41%) of a reduced function allele, CYP2D6*10, contributing to the population shift to the right of metabolic rates indicating slower metabolism. Information concerning Amerindians from North (Canada), Central and South America indicate comparatively low frequencies of CYP2D6*10, perhaps a "founders" effect. The frequency of functional alleles in Africans and African Americans is also about 50%. Both Africans and African Americans have reduced function alleles representing 35% of allele variation, mainly CYP2D6*17. African Americans, however, have more than twice the median frequency of nonfunctional alleles compared with Africans (14.5% vs 6.3%). Non-functional and reduced function alleles represent about 50% of allele frequency in Black populations but a much greater variety than carried in Asians. Since alleles which encode for no or reduced functioning clearly affect metabolic activity of drugs mediated by CYP2D6, studies are needed in populations in which these alleles play a major role in order to assure optimal dosing recommendations are based on empirical pharmacogenetics.
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Affiliation(s)
- L DiAnne Bradford
- Department of Psychiatry and Medicine, Morehouse School of Medicine, 720 Westview Dr. S.W., Atlanta, GA, 30310-1495, USA.
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