Development of a multiplex and cost-effective genotype test toward more personalized medicine for the antiplatelet drug clopidogrel

Association of ABCB1 Gene Polymorphisms and Clopidogrel Responsiveness in Iranian Patients undergoing Percutaneous Coronary Intervention

Clopidogrel is an antiplatelet agent currently used for preventing stent thrombosis. Despite certain clinical benefits of clopidogrel in patients undergoing percutaneous coronary intervention (PCI), adequate antiplatelet effect has not been obtained in some patients. The present study was designed to investigate the potential association of ABCB1 (ATP-Binding Cassette, Subfamily B, member1) gene polymorphism, and clopidogrel responsiveness in Iranian patients after PCI. Sixty-seven patients were included in the study. Blood samples were taken from patients at baseline, 2 h after administration of 600-mg loading dose of clopidogrel, 24 h and 30 days after PCI. Platelet aggregation was measured by light transmittance aggregometry (LTA) with two levels of adenosine diphosphate (ADP) concentrations (5 and 20 µM). ABCB1 genotyping was performed by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR). The allelic frequencies of wild type, heterozygote, and homozygote genotypes of ABCB1 were 20.9%, 74.6%, and 4.5%, respectively. There was no significant association between polymorphism of ABCB1 and clopidogrel non-responsiveness (P > 0.05) in various situations. No significant difference was observed for demographic characteristics. Genetic and demographic factors had no significant effect on the platelet activity of clopidogrel in an Iranian population.

Development of a Polymerase Chain Reaction/Ligase Detection Reaction Assay for Detection of CYP2C19 Polymorphisms

AIMS

Cytochrome P450 2C19 (CYP2C19) genotypes are associated with differential drug metabolism. The aim of this study was to establish a reliable assay for CYP2C19 genotyping based on a polymerase chain reaction/ligase detection reaction (PCR-LDR).

MATERIALS AND METHODS

Specific primers and probes were designed to detect CYP2C19*1, *2, *3, and *17. A control for each allele was prepared and used for performance evaluation. A total of 200 clinical samples were analyzed using the PCR-LDR assay and Sanger sequencing.

RESULTS

The detection limit of the PCR-LDR assay was 2 ng/μL of genomic DNA. Common interfering substances in the blood did not affect the results of the detection. For the clinical samples, the results of the PCR-LDR and the Sanger sequencing were identical. Among the 200 patients, 104 (52%) were wild type (*1/*1), 64 (32%) were *1/*2, 16 (8%) were *1/*3, 8 (4%) were *2/*2, 7 (3.5%) were *2/*3, and 1 (0.5%) was *1/*7. No *3/*3 genotype was detected in these patients.

CONCLUSION

This PCR-LDR assay is reliable for the detection of CYP2C19 genotypes in a clinical setting. It will be a useful tool to screen for CYP2C19 loss-of-function alleles in patients before clopidogrel and proton pump inhibitor treatment.