Feasibility of a Microarray-Based Point-of-Care CYP2C19 Genotyping Test for Predicting Clopidogrel On-Treatment Platelet Reactivity

Clopidogrel is a prodrug which is converted into active metabolite by cytochrome P450 isoenzyme, CYP2C19. Numerous polymorphisms of CYP2C19 are reported, and a strong link exists between loss-of-function (LOF) or gain-of-function polymorphisms, clopidogrel metabolism, and clinical outcome. Hence, a fully automated point-of-care CYP2C19 genotyping assay is more likely to bring personalized antiplatelet therapy into real practice. We assessed the feasibility of the Verigene 2C19/CBS Nucleic Acid Test, a fully automated microarray-based assay, compared to bidirectional sequencing, and performed VerifyNow P2Y12 assay to evaluate the effect of CYP2C19 polymorphisms on on-treatment platelet reactivity in 57 Korean patients treated with clopidogrel after percutaneous coronary intervention. The Verigene 2C19/CBS assay identified *2, *3, and *17 polymorphisms with 100% concordance to bidirectional sequencing in 180 minutes with little hands-on time. Patients were classified into 4 groups: extensive (*1/*1; n = 12, 21.1%), intermediate (*1/*2, *1/*3; n = 33, 57.9%), poor (*2/*2, *2/*3, and *3/*3; n = 11, 19.3%), and ultrarapidmetabolizers (*1/*17; n = 1, 1.8%). The prevalence of the CYP2C19 *2, *3, and *17 alleles was 36.0%, 12.3%, and 0.9%. Platelet reactivity showed gene dose response according to the number of CYP2C19 LOF allele. In conclusion, the Verigene 2C19/CBS assay gave accurate CYP2C19 genotype results which were in well match with the differing on-treatment platelet reactivity.