Dataset Information

The CYP2C19*17 variant is not independently associated with clopidogrel response.

ABSTRACT: Cytochrome P450 2C19 (CYP2C19) is the principal enzyme responsible for converting clopidogrel into its active metabolite, and common genetic variants have been identified, most notably CYP2C19*2 and CYP2C19*17, that are believed to alter its activity and expression, respectively.We evaluated whether the consequences of the CYP2C19*2 and CYP2C19*17 variants on clopidogrel response were independent of each other or genetically linked through linkage disequilibrium (LD).We genotyped the CYP2C19*2 and CYP2C19*17 variants in 621 members of the Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study and evaluated the effects of these polymorphisms singly and then jointly, taking into account LD, on clopidogrel prodrug level, clopidogrel active metabolite level, and adenosine 5'-diphosphate (ADP)-stimulated platelet aggregation before and after clopidogrel exposure.The CYP2C19*2 and CYP2C19*17 variants were in LD (|D'| = 1.0; r(2) = 0.07). In association analyses that did and did not account for the effects of CYP2C19*17, CYP2C19*2 was strongly associated with levels of clopidogrel active metabolite (? = -5.24, P = 3.0 × 10(-9) and ? = -5.36, P = 3.3 × 10(-14) , respectively) and posttreatment ADP-stimulated platelet aggregation (? = 7.55, P = 2.9 × 10(-16) and ? = 7.51, P = 7.0 × 10(-15) , respectively). In contrast, CYP2C19*17 was marginally associated with clopidogrel active metabolite levels and ADP-stimulated platelet aggregation before (? = 1.57, P = 0.04 and ? = -1.98, P = 0.01, respectively) but not after (? = 0.40, P = 0.59 and ? = -0.13, P = 0.69, respectively) adjustment for the CYP2C19*2 variant. Stratified analyses of CYP2C19*2/CYP2C19*17 genotype combinations revealed that CYP2C19*2, and not CYP2C19*17, was the primary determinant in altering clopidogrel response.Our results suggest that CYP2C19*17 has a small (if any) effect on clopidogrel-related traits and that the observed effect of this variant is due to LD with the CYP2C19*2 loss-of-function variant.

SUBMITTER: Lewis JP

PROVIDER: S-EPMC3773276 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature

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The CYP2C19*17 variant is not independently associated with clopidogrel response.

Lewis J P JP Stephens S H SH Horenstein R B RB O'Connell J R JR Ryan K K Peer C J CJ Figg W D WD Spencer S D SD Pacanowski M A MA Mitchell B D BD Shuldiner A R AR

Journal of thrombosis and haemostasis : JTH 20130901 9

<h4>Background</h4>Cytochrome P450 2C19 (CYP2C19) is the principal enzyme responsible for converting clopidogrel into its active metabolite, and common genetic variants have been identified, most notably CYP2C19*2 and CYP2C19*17, that are believed to alter its activity and expression, respectively.<h4>Objective</h4>We evaluated whether the consequences of the CYP2C19*2 and CYP2C19*17 variants on clopidogrel response were independent of each other or genetically linked through linkage disequilibr ...[more]

PMID: 23809542

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Project description:ObjectivesThis study sought to evaluate the influence of the genetic polymorphisms on platelet reactivity and clinical outcomes in acute ischemic stroke patients taking clopidogrel.BackgroundLittle research has been published on relationships between genetic polymorphisms, platelet reactivity, and clinical outcomes in stroke patients treated with clopidogrel.MethodsPatients hospitalized in Changhai Hospital with acute ischemic stroke were randomly enrolled into treatment with a 75-mg daily maintenance dose of clopidogrel. Genotyping was detected by the MassARRAY iPLEX genotyping system (Sequenom Inc, San Diego, CA), and platelet reactivity was evaluated by the VerifyNow P2Y12 test (Accumetrics Inc., San Diego, CA). Sixteen single nucleotide polymorphisms (SNPs) within 9 genes were selected and high on-clopidogrel platelet reactivity (HPR) was defined as P2Y12 reaction units (PRU) value ≥230. The primary endpoint was ischemic events, including major adverse cardiac events (MACE), recurrence of stroke, transient ischemic attack (TIA), and the composite of vascular death, and the secondary endpoint was bleeding.ResultsOf the 345 patients recruited, 275 (79.7%) patients were followed up for 1 year and 122 (35.4%) patients were categorized as HPR. Among the SNPs selected, only the CYP2C19*2 allele and the CYP2C19*3 allele were statistically significantly associated with PRU (P < 0.001 and P = 0.003, respectively). Similarly, the prevalence of HPR was associated with CYP2C19*2 and CYP2C19*3 (P < 0.001 and P = 0.001, respectively). During the 1 year of follow-up, a total of 64 (23.3%) cases of clinical events occurred, including 60 ischemic events and 4 bleeding events. There were no correlation between CYP2C19 variant alleles and clinical outcomes (P > 0.05), but a statistically significant relevance was found between the HPR and the ischemic events in 1 year of follow-up (P = 0.001).ConclusionsCYP2C19*2 and CYP2C19*3 had a significant impact on clopidogrel response, but was not associated with ischemic events during 1 year of follow-up in patients with acute ischemic stroke. HPR was an independent risk factor for ischemic events, and the VerifyNow P2Y12 test may be available to guide individualized antiplatelet therapies in stroke patients in China.

Project description:ObjectiveTo evaluate the accumulated information from genetic association studies investigating the impact of variants of the cytochrome P450 (CYP) 2C19 genotype on the clinical efficacy of clopidogrel.DesignSystematic review and meta-analysis with a structured search algorithm and prespecified eligibility criteria for retrieval of relevant studies; dominant genetic model assumptions and quantitative methods for calculating summary effect estimates from study level odds ratios; systematic assessment of bias within and between studies; and grading of the cumulative evidence by consensus criteria.Data sourcesMedline, Embase, the Cochrane Library, online databases, contents pages and bibliographies of general medical, cardiovascular, pharmacological, and genetic journals. Eligibility criteria for selecting studies Original full length reports assessing the cumulative incidence of major adverse cardiovascular events or stent thrombosis over a follow-up period of at least a month in association with carrier status for the loss of function or gain of function CYP2C19 allele in adult patients with coronary artery disease and a clinical presentation of acute coronary syndrome or stable angina pectoris who were taking clopidogrel.Results15 studies met the inclusion criteria. The random effects summary odds ratio for stent thrombosis in carriers of at least one CYP2C19 loss of function allele versus non-carriers combining nine studies was 1.77 (95% confidence interval 1.31 to 2.40; P < 0.001). This nominally significant odds ratio was subject to considerable bias across the studies (small study effect bias and replication diversity). The adjustment for these quality modifiers tended to abolish the association. The corresponding random effects summary odds ratio of major adverse cardiovascular events for 12 studies combined was 1.11 (0.89 to 1.39; P = 0.36). The random effects summary odds ratio of stent thrombosis in carriers versus non-carriers of at least one CYP2C19*17 gain of function allele for three studies combined was 0.99 (0.60 to 1.62; P = 0.96), and the corresponding odds ratio of major adverse cardiovascular events in five studies was 0.93 (0.75 to 1.14; P = 0.48). The overall quality of epidemiological evidence was graded as low, which excludes reliable clinical assessments.ConclusionsAccumulated information from genetic association studies does not indicate a substantial or consistent influence of CYP2C19 gene polymorphisms on the clinical efficacy of clopidogrel. The current evidence does not support the use of individualised antiplatelet regimens guided by CYP2C19 genotype.

Dataset Information

The CYP2C19*17 variant is not independently associated with clopidogrel response.

Publications

The CYP2C19*17 variant is not independently associated with clopidogrel response.

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