Influence of ABCB1 gene polymorphism on concentration to dose ratio and adverse effects of tacrolimus in Pakistani liver transplant recipients

OBJECTIVE: To evaluate the possible association of ABCB1 single nucleotide polymorphism (SNPs) of the ABCB1 gene with tacrolimus dosages, concentration-to-dose ratios (CDR) and adverse effects in Pakistani liver transplant recipients. METHODS: This observational study was conducted at Shifa International Hospital, Shifa Tameer-e-Millat University, Islamabad and Basic Medical Sciences Institute, Karachi from September 2016 to July 2020. Eighty-one liver transplant recipients were included. Demographics, clinical data, tacrolimus trough levels and doses were monitored. Electrochemiluminescence immunoassay (ECLIA) was used to measure tacrolimus trough levels. Transplant recipients were genotyped for three ABCB1 SNPs (rs1045642, rs2032582 and rs1128503). Acute cellular rejection (ACR), sepsis and other adverse events were monitored. RESULTS: ABCB1 rs1045642 CC genotype showed lower tacrolimus CDR as compared to CT and TT genotype in the first week of the post-transplantation period (p=0.02). There was a significant association of polymorphisms in rs1045642, rs2032582 and rs1128503 with psychosis, sepsis and ACR respectively. CONCLUSION: Identification of ABCB1 rs1045642 polymorphism may shorten the time to achieve optimum levels of tacrolimus during dose titration. ABCB1 polymorphism rs1045642, rs2032582 and rs1128503 may predict adverse effects in liver transplant recipients receiving tacrolimus.