The Design and Implementation of a Novel Pharmacogenomic Assay to Genotype the CYP3A53 (rs776746) and CYP3A51E (rs4646453) Genetic Variants

Abstract Background The cytochrome P450 3A5 CYP3A5 enzymes are important for metabolizing the drug tacrilomus, an immunosuppressive agent used in solid organ transplantation. Genetic variants in the CYP3A5 gene are significant determinants of tacrolimus efficacy. The present study was undertaken to design a novel pharmacogenetic assay (Single step-Tetra Arms Polymerase Chain Reaction) to study the distribution of the CYP3A5*3 (rs776746) and CYP3A5*1E (rs4646453) variants by genotyping a cohort of healthy individuals. Results The CYP3A5*3 variant was the most frequent allele detected at 82% and the CYP3A5*1E C allele was found in 66.5% of the samples. The allele frequencies of CYP3A5*3 (rs776746) and CYP3A5*1E (rs4646453) were statistically significant (p < 0.05) when compared with the Asian ethnic group. The observed CYP3A5 genotype frequency distributions for the CYP3A5*3 (rs776746) and CYP3A5*1E (rs4646453) variants in the study population were consistent with the Hardy–Weinberg equilibrium (P > 0.05). For the CYP3A5*3 variant the frequency of the T/T [extensive metabolizer], C/T [intermediate metabolizer] and C/C [poor metabolizer] variants were 4%, 28% and 68% respectively. Furthermore, a significant linkage disequilibrium among rs4646453 and rs776746 was identified (p < 0.05). Conclusions A novel tetra-primer ARMS PCR assay was successfully designed and implemented for genotyping of the CYP3A5 variants CYP3A5*3 (rs776746) and CYP3A5*1E (rs4646453). These pharmacogenomic assays could be offered to patients to predict their response to tacrolimus.