Background: Cyclosporine is used as an immunosuppressive agent in kidney transplantation. It has a
narrow therapeutic window. Cyclosporine is predominantly metabolized by CYP3A4 and CYP3A5. The most common
Single Nucleotide Polymorphisms (SNPs) affecting cyclosporine metabolism (CYP3A4*1B, CYP3A4*1G,
CYP3A4*22 and CYP3A5*3) were investigated among Jordanian kidney transplanted patients to find out the genotypes
and allele frequencies of these SNPs. Additionally, this study investigated whether genotypes of CYP3A4 and
CYP3A5 affect C2 blood levels, dosing of cyclosporine and the prevalence of acute rejection.
Methods: Blood samples of 109 adult patients taking cyclosporine as their primary immunosuppressant for kidney
transplantation were collected from the Prince Hamzah Hospital, Amman, Jordan. Patients’ first C2 blood levels and
their first two given doses were collected. Patients were genotyped for the four SNPs using Polymerase Chain Reaction-
restriction Fragment Length Polymorphism (PCR-RFLP) assay method.
Results: Allele frequencies among Jordanian patients for CYP3A4*1B, CYP3A4*1G, CYP3A4*22 and CYP3A5*3
were 0.037, 0.399, 0.037 and 0.271, respectively. There was a significant association between CYP3A4*22 and mean
difference in the second and first given doses (P=0.034). There was a big difference between CYP3A4*22 and the
mean of the first C2 blood levels (P=0.063).
Conclusion: There was a strong association between CYP3A4*22 and the mean difference between the second and
first given doses. There was a trend of significant difference between the mean of the first C2 blood levels among
heterozygous CYP3A4*22 patients. Pharmacogenomics may hold promise in assisting the prediction of the best
cyclosporine dose and C2 blood level among Jordanian kidney transplant patients.