Aims  Clopidogrel is prescribed for the prevention of atherothrombotic events. While investigations have identified genetic determinants of inter-individual variability in on-treatment platelet inhibition (e.g. CYP2C19*2), evidence that these variants have clinical utility to predict major adverse cardiovascular events (CVEs) remains controversial. Methods and results  We assessed the impact of 31 candidate gene polymorphisms on adenosine diphosphate (ADP)-stimulated platelet reactivity in 3391 clopidogrel-treated coronary artery disease patients of the International Clopidogrel Pharmacogenomics Consortium (ICPC). The influence of these polymorphisms on CVEs was tested in 2134 ICPC patients (N = 129 events) in whom clinical event data were available. Several variants were associated with on-treatment ADP-stimulated platelet reactivity (CYP2C19*2, P = 8.8 × 10−54; CES1 G143E, P = 1.3 × 10−16; CYP2C19*17, P = 9.5 × 10−10; CYP2B6 1294 + 53 C > T, P = 3.0 × 10−4; CYP2B6 516 G > T, P = 1.0 × 10−3; CYP2C9*2, P = 1.2 × 10−3; and CYP2C9*3, P = 1.5 × 10−3). While no individual variant was associated with CVEs, generation of a pharmacogenomic polygenic response score (PgxRS) revealed that patients who carried a greater number of alleles that associated with increased on-treatment platelet reactivity were more likely to experience CVEs (β = 0.17, SE 0.06, P = 0.01) and cardiovascular-related death (β = 0.43, SE 0.16, P = 0.007). Patients who carried eight or more risk alleles were significantly more likely to experience CVEs [odds ratio (OR) = 1.78, 95% confidence interval (CI) 1.14–2.76, P = 0.01] and cardiovascular death (OR = 4.39, 95% CI 1.35–14.27, P = 0.01) compared to patients who carried six or fewer of these alleles. Conclusion  Several polymorphisms impact clopidogrel response and PgxRS is a predictor of cardiovascular outcomes. Additional investigations that identify novel determinants of clopidogrel response and validating polygenic models may facilitate future precision medicine strategies.

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ABSTRACT:Our objectives were to identify CYP2D6 genetic polymorphisms in a Korean population, to compare the allele frequencies with those of other ethnic groups, and to evaluate variant-induced functional variations in dextromethorphan (DM) metabolism in vitro and in vivo. Thirty-eight single nucleotide polymorphisms of CYP2D6 were identified by direct DNA sequencing in 51 Koreans. An extended set of 707 subjects were screened for the identified variants. A group of 202 healthy subjects was subjected to phenotypic analysis on DM metabolism. CYP2D6*10 was found to be the most frequent allele (45.6%), followed by CYP2D6*1 (32.3%), *2 (9.9%), *5 (5.6%), *41 (2.2%), *49 (1.4%), and some other rare alleles (<1%). The newly identified E418K and S183Stop were assigned as CYP2D6*52 and CYP2D6*60, respectively, by the Human P450 (CYP) Allele Nomenclature Committee. Individuals having the CYP2D6*10/*49 genotype (n ‫؍‬ 5) exhibited a significant decrease in CYP2D6 metabolic activity compared with those with the CYP2D6*1/*1 genotype (n ‫؍‬ 31) (P < 0.019). Variations in CYP2D6 protein levels in liver tissues (n ‫؍‬ 49) were observed with CYP2D6 genotypes, and correlation between the CYP2D6 protein content and the activity was significant (r 2 ‫؍‬ 0.7). Given the importance of CYP2D6 in drug metabolism, subjects with the CYP2D6*10/*49 genotype may benefit from genotype analysis to achieve optimal drug therapy.Polymorphisms of the gene for cytochrome P450 2D6 (CYP2D6) influence the rate of elimination of CYP2D6 substrates, which represent approximately 20% of commonly prescribed therapeutic drugs. CYP2D6 substrates include antipsychotic drugs (haloperidol and risperidone), antiarrhythmic agents (flecainide and perphenazine), tricyclic antidepressants (imipramine and amitriptyline), ␤-blockers (metoprolol and carvedilol), and opioids (codeine and tramadol) (Zanger et al., 2004;Ingelman-Sundberg, 2005). The CYP2D6 gene locus is highly polymorphic, and various point mutations, nucleotide deletions or insertions, gene rearrangements, and multiplication/deletion of the entire CYP2D6 gene, resulting in more than 106 different alleles

The heterozygous CYP2C9 and VKORC1 genotypes influence warfarin dosing in an early phase as well as steady state of warfarin therapy in Korean patients with mechanical heart valve replacement.

Antiplatelet response to clopidogrel shows wide variation, and poor response is correlated with adverse clinical outcomes. CYP2C19 loss-of-function alleles play an important role in this response, but account for only a small proportion of variability in response to clopidogrel. An aim of the International Clopidogrel Pharmacogenomics Consortium (ICPC) is to identify other genetic determinants of clopidogrel pharmacodynamics and clinical response. A genomewide association study (GWAS) was performed using DNA from 2,750 European ancestry individuals, using