Association of Cyp2c19 Genotype with Variability in Clopidogrel Response in Coronary Patients

The variability of clopidogrel response is due to many factors including polymorphisms affecting CYP2C19. This study aims to assess the impact of the CYP2C19*2(681G > A), CYP2C19*3(636G > A) and CYP2C19*17(-806 C > T) polymorphisms on platelet response to clopidogrel in patients with coronary artery disease. This is a cross-sectional study led on patients treated with clopidogrel (75 mg/day for at least seven days). Platelet reactivity was assessed by the VerifyNow^® P2Y12 test and high on treatment platelet reactivity was defined by a PRU ≥ 208. The genotyping of CYP2C19 polymorphisms was performed by PCR- RFLP. The study involved 115 coronary patients with a mean age of 58 ± 10 years. The VerifyNow^®P2Y12 test showed that 27.8% were resistant to clopidogrel. The genetic study showed that CYP2C19*2(681G > A) is significantly associated with biological resistance to clopidogrel (G vs. A, OR = 4.713 [95% CI: 1.738-12.780]; p = 0.002), while CYP2C19*17(-806 C > T) is a protective factor against clopidogrel non-responsiveness (C vs. T, OR = 0.413 [95% CI: 0.174-0.981]; p = 0.02). By classifying patients into extensive (*1/*1: 52%), intermediate (*1/*2: 16%) and ultra-rapid metabolizers (*1/*17;*17/*17: 32%), we found that the type of metabolizer had a significant impact on clopidogrel response (p = 0.001). CYP2C19*2 (681G > A) is significantly associated with biological resistance to clopidogrel while CYP2C19*17(-806 C > T) is a protective factor against clopidogrel non-responsiveness.