The Effect Of CYP3A4, CYP3A5, And MDR-1 Gene Polymorphism On Tacrolimus Plasma Concentration Taken By Renal Transplant Recipients In Sichuan

Objective:To investigate the genotype and the allelic frequency of CYP3 A4* 18B(rs2242480), CYP3 A56989A/G(rs776746), and MDR1 C1236T (rs1128503), G2677T/A(rs2032582), C3435T(rs1045642) in Sichuan Han population by an accurate, fast and simple gene chip method. To explore the relevance between the polymorphisms of CYP3A4*18B, CYP3A56989A/G, MDR1C1236T, MDR1G2677T/A, MDR1C3435T and boood concentration/dosage ratio of kidney transplanted patients taking tacrolimus (FK506). To provide valuable information and data for personalized FK506 taking by kidney transplanted patients in Si Chuan area by genetic technology. Methods:101 healthy volunteers and 56 patients receiving parental kidney transplant longer than 6 months were recruited in this study, and gene chips was used to detect the genotype of CYP3A4*18B, CYP3A56989A/G, MDR1C1236T, G2677T/A, C3435T. A total of 100 sites were randomly chosen, and the genotype detected by gene chips was validated by sequencing. FK506 was taken in an empty stomach every 12 hours, and 4ml periphery venous blood were collected in tubes containing EDTA. FK506 trough concentration of 56 patients was detected by enzyme multiplies immunoassay technique (EMIT) after 7 days,14 days,30 days,3 months and 6 months of surgery. The relevance between trough concentration/dosage ratio and polymorphism was analyzed.Results:The frequencies of homozygote of CYP3A4*18B SNP wild type CC was 61.4%, and heterozygots of CYP3A4*18B SNP mutant type CT was 29.7%, homozygote of CYP3A4*18B SNP mutant type TT was 8.9%. The frequencies of homozygote of CYP3A5 A6989G SNP wild type AA was 5.9%, and heterozygots of A6989G SNP mutant type AG was 40.6%, homozygote of A6989G SNP mutant type GG was 53.5%. The frequencies of homozygote of MDR1:C1236T SNP wild type CC was 12.9%, and heterozygots of C1236T SNP mutant type CT was 44.6%, homozygote of C1236T SNP mutant type TT was 42.6%. The frequencies of homozygote of G2677T/A SNP wild type GG was 23.8%,and homozygote of G2677T/A SNP mutant type, including TT, AT, and AA was 23.8%,13.9%,2.0%,respectively; heterozygots of G2677T/A SNP mutant type, including GT and GA was 24.8%,11.9%, respectively. The frequencies of homozygote of MDR1:C3435T SNP wild type CC was 40.6%, and heterozygots of C3435T SNP mutant type CT was 38.6%, homozygote of C3435T SNP mutant type TT was 20.8%.In 101 Sichuan Han population, the allelic frequency distribution of the CYP3A4*18B, CYP3A5 6989A/G, MDR1C1236T, G2677T/A, C3435T genetic variants in our samples was 23.75%、73.8%、64.8%、43.05%、14.90% and 40.10%, respectively. The effect of genetic polymorphism to FK506 boood concentration/dosage ratio in kidney transplanted patients The single nucleotide polymorphisms (SNP) of CYP3A5 was relevant to the boood concentration/dosage ratio in kidney transplanted patients. After 6 months of surgery, the trough concentration/dosage of homozygous mutant GG (*3/*3) has shown significant difference compared to homozygous wild type AA(*1/*1) and heterozygous mutant AG (P<0.05), and there was no significant difference between CYP3A5AA and CYP3A5AG. The SNP of CYP3A4*18B was relevant to FK506 boood concentration/dosage ratio in patients receiving kidney transplant, the trough concentration/dosage of homozygous wild type CC has shown significant difference compared to homozygous mutant TT and heterozygous mutant CT (P<0.05), and there was no significant difference between CT and TT. The SNP of MDR1C3435T, G2677T/A, C1236T had no relevance to FK506 boood concentration in patients receiving kidney transplant. Conlusion:This study has shown that the gene frequency of CYP3A4*18B, CYP3A5 6989A/G, MDR1 C1236T, G2677T/A, C3435T of 56 Sichuan Han population kidney transplanted patients was consistent with the results from 101 healthy Sichuan Han population. The distribution of the alleles is fit for Hardy-Weinberg equilibrium, that means the population in this study can represent Sichuan Han population. The gene chip method was first used in investigating CYP3A4* 18B、CYP3A5A6989G、 MDR1C1236T、G2677T/A、C3435T.This study has found that the FK506 boood concentration/dosage ratio was relevant to the SNP of CYP3A4 and CYP3A5, but not to that of MDR1C3435、G2677T/A、C1236T.Whether MDR1 had significant contribution to tacrolimus boood concentration/dosage ratio remains unclear, thus further research is required.