Background Clopidogrel antiplatelet effects differ according to genotypes ABCB1 and CYP2C19, establishing normal, intermediate and slow metabolizers. The intermediate and slow metabolizers and poor transporters are responsible for the poor response to the antiplatelet drug.

Purpose To determine the prevalence of CYP2C19 and ABCB1 genetic polymorphism in the normal Andalusian population (control) and compare it with other populations as a step to implement this determination in clinical practise.

Materials and Methods We genotyped 100 controls from the Andalusian DNA bank for CYP2C19 * 2 (rs4244285), CYP2C19 * 3 (rs4986893) and ABCB1 (rs1045642) using TaqMan probes and allelic discrimination technique. Statistical analysis for allelic and genotypic distributions was calculated by chi-squared test or Fisher’s exact test, when necessary, using the Statcalc software packages.

Results Genotype frequencies CYP2C19 (*2) in the Andalusian population: *1/*1: 73%, *1/*2: 25%, *2/*2: 2%, and CYP2C19 * 3: none; the same results as in HapMap (NW European ancestry) population. ABCB1: Andalusian population: CC 36%, CT 44%, TT 20%; HapMap population CC 27%, CT 50%, TT 23%. Allelic frequencies: NW European ancestry HapMap CYP2C19 * 2: G is 85% and A is 15%, the same as our Andalusian control results. ABCB1: HapMap C allele frequency is 45% and the T is 55%, and our frequencies are 57% C and 43% T. Having made the genotype study, 59% of the controls were sensitive to clopidogrel and 41% resistant to it.

Conclusions

• Frequencies for CYP2C19 * 2 and * 3 were similar to those reported in other studies. The frequencies for ABCB1 differed slightly

• It is necessary to perform this type of study in patients with acute coronary syndrome undergoing a percutaneous coronary intervention, to ensure effective treatment as it is documented that clopidogrel is not an effective drug in polymorphisms with allele CYP2C19 * 2 (*1/*2 and *2/*2) and/or ABCB1 TT.

No conflict of interest.