PURPOSE: Chinese people are more frequent carriers of cytochrome P450 2C19 
(CYP2C19) loss-of-function alleles than Caucasians. The effect of the 
ATP-binding cassette, sub-family B, member 1 (ABCB1), and paraoxonase 1 (PON1) 
variants on platelet reactivity and clinical outcomes of clopidogrel treatment 
has not yet been reported in Chinese patients after percutaneous coronary 
intervention. The aim of this study was to investigate the effect of the 
CYP2C19, ABCB1, and PON1 variants on clopidogrel pharmacodynamics and clinical 
outcomes in these patients.
METHODS: Six hundred and seventy patients after percutaneous coronary 
intervention were enrolled in a single-center registry. The antiplatelet effect 
of clopidogrel was assessed by thromboelastography, and the CYP2C19, ABCB1, and 
PON1 genotypes were detected by the ligase detection reaction. Primary clinical 
endpoints included cardiovascular death, nonfatal myocardial infarction, target 
vessel revascularization, and stent thrombosis. The secondary clinical endpoints 
were thrombolysis in myocardial infarction bleeding. The follow-up period was 12 
months.
RESULTS: The frequency of the CYP2C19 loss-of-function alleles was relatively 
high (57.3 %). The risk of a low response to clopidogrel and composite ischemic 
events increased with the number of CYP2C19 loss-of-function alleles. However, 
there were not significant differences in clopidogrel pharmacodynamics and 
clinical outcomes across the ABCB1 and PON1 genotype groups; bleeding was not 
significantly different across the CYP2C19, ABCB1, and PON1 genotype groups.
CONCLUSIONS: The CYP2C19 loss-of-function alleles had a gene dose effect on the 
pharmacodynamics and composite ischemic events of clopidogrel in our study 
population. Neither the ABCB1 nor the PON1 genotype significantly influenced the 
antiplatelet effect and clinical outcomes of clopidogrel in these patients.