The Effects of CES1A2 A(-816)C and CYP2C19 Loss-of-function Polymorphisms on Clopidogrel Response Variability Among Chinese Patients with Coronary Heart Disease

Objective: Carboxylesterase 1 hydrolyzes the majority of clopidogrel to the inactive metabolite. The aim of this study was to assess the effects of the CES1A2 A(-816)C polymorphism and other genetic and clinical factors on clopidogrel response variability. An additional aim was to investigate the relationship between genetic variations and development of stent thrombosis (ST).

Methods: We recruited 162 coronary heart disease patients treated with aspirin and clopidogrel, and we genotyped them for the CES1A2 A(-816)C, CYP2C19 *2/*3, PON1 Q192R, and ABCB1 C3435T polymorphisms. Platelet reactivity was analyzed using the VASP-PRI assay. We also carried out a case-control study in which 22 patients undergoing stent implantation who had ST were matched with 86 ST-free controls.

Results: The VASP-PRI values were significantly higher in the carriers of the CES1A2 -816C allele (P=0.014) and CYP2C19 loss of function (LOF) alleles (P=0.004). Furthermore, the patients with CYP2C19 LOF alleles showed an increased risk of ST (ORadj=4.28, P=0.033). However, there was no significant association between the CES1A2 -816C allele and the development of ST. The CYP2C19 and CES1A2 genotypes alone could explain 6.1 and 3.7% of the interindividual variability in the VASP-PRI results, respectively. The value increased to 12.5% when clinical factors (e.g. BMI and triglycerides) were also considered. The PON1 Q192R and ABCB1 C3435T genetic variations produced no significant impact.

Conclusion: The CES1A2 -816C and the CYP2C19 LOF alleles were associated with attenuated platelet reactivity to clopidogrel. CYP2C19 LOF was also predictive of ST; however, the association between the CES1A2 -816C allele and development of ST requires further study.