Effects of Genetic Polymorphism in CYP3A4 and CYP3A5 Genes on Tacrolimus Dose Among Kidney Transplant Recipients.

INTRODUCTION: This study aimed to evaluate the effects of single nucleotide polymorphisms CYP3A4*1B and CYP3A5*3 on tacrolimus dose requirement among kidney transplant recipients.

MATERIALS AND METHODS: Blood levels of tacrolimus were measured using microparticle enzyme immunoassay. Genotyping analysis utilized specific polymerase chain reaction-restriction fragment length polymorphism methods for 137 kidney transplant recipients.

RESULTS: The median tacrolimus dose was significantly lower in the CYP3A4*1/*1 carriers (0.06 mg/kg/d; range, 0.007 mg/kg/d to 0.17 mg/kg/d) as compared to the CYP3A4*1B/*1B carriers (0.1 mg/kg/d; range, 0.03 mg/kg/d to 0.22 mg/kg/d; P = .001). Patients with at least 1 CYP3A5*1 wild-type allele required higher median doses of tacrolimus (median, 0.08 mg/kg/d; range, 0.03 mg/kg/d to 0.22 mg/kg/d) as compared to the CYP3A5*3 carriers (median, 0.05 mg/kg/d; range, 0.007 mg/kg/d  to 0.17 mg/kg/d; P = .002).

CONCLUSIONS: This study showed that tacrolimus dose requirement is lower in Jordanian kidney transplant recipients compared to other populations. Moreover, we found a correlation between genetic variations in CYP3A4 and CYP3A5 enzymes and tacrolimus blood levels among our kidney transplant recipients.