Co-Existence of CYP2C19 *1/*2 and ABCB1c .3435 CT Genotype has a Potential Impact on Clinical Outcome in CAD Patients Treated with Clopidogrel.

Clopidogrel, is a standard treatment in the prevention of major adverse cardiovascular events (MACE) in patients with coronary artery disease (CAD). Clopidogrel response is highly variable, mainly due to the presence of polymorphisms in the genes involved in drug metabolism. The aim of this study was to evaluate the association between the presence of the ABCB1 C3435T and CYP2C19* 2 polymorphism and the clinical outcome in patients with CAD treated with clopidogrel. A total of 96 patients with CAD were included in the study. Genomic DNA from peripheral blood was extracted from all patients with standard phenol/chloroform protocol. The genotyping was performed by Real-Time PCR using TagMan assays. The frequency of the reduced-function allele, in both genes, was higher in patients with negative outcome (36.36% vs 21.15%). A negative clinical outcome and an increased risk for MACE was observed in patients with concomitant inheritance of the CYP2C19 *1/*2 and ABCB1 CT genotype vs patients with other genotypes (22.73% vs 9.62%; OR 3.455; 95% CI= [0.936-12.743], p=0.05722. A trend towards higher risk of MACE was also noted in carriers of the CYP2C19*1/*1 and ABCB1 CC/CT genotype. Our results support the data on the association of the CYP2C19 *2 alone, or in combination with the ABCB1 C polymorphism with the increased risk of MACE. The results also indicate that the presence of ABCB1 C343T polymorphism might be potentially considered as independent predictor of MACE in patients on clopidogrel. However, these results are preliminary and should be confirmed on a larger number of patients.