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Mycophenolate mofetil (MMF), a widely used immunosuppressant, is characterized by highly variable pharmacokinetics. UGT1A8, UGT1A9, UGT2B7 and ABCC2 have been proved to be critical genes associated with inter-individual variation of MMF pharmacokinetics. In this study, we investigated the genetic polymorphisms of UGT1A8*2, UGT1A8*3, UGT1A9 C-2152T, UGT1A9 T-275A, UGT1A9 T98C, UGT2B7*2, ABCC2 C-24T and ABCC2 C3972T in 200 Chinese renal transplant recipients and compared them with those in other ethnic groups reported in the literature, to start the exploration of a better use of MMF in Chinese. A much higher frequency of UGT1A8*2 variant allele was found in Chinese than in Caucasians and Africans, while the UGT2B7*2 variant allele was significantly rarer in Chinese than in Caucasians and Africans. For ABCC2, -24T allele was more common and 3972T allele was less common in Chinese than in Caucasians and Africans. However, none of the SNPs in UGT1A9 were present in our study population. The findings of this study suggest that Chinese renal transplant recipients may exhibit a response profile to MMF that is different from those of other ethnic groups.

The pregnane X receptor (PXR/NR1I2) gene is a master regulator for a number of cytochrome P450s (CYPs) and drug transporters. This study aimed to detect the single nucleotide polymorphisms (SNPs) of the PXR gene in Han Chinese (n = 186) and to compare the frequencies of polymorphisms of the PXR gene with those in Caucasian and African Americans reported in the literature. The SNPs of the PXR gene were analyzed using the polymerase chain reaction (PCR) and direct sequencing analysis. The mutant frequencies of A11156C and T11193C in Han Chinese were 55% (95% confidence interval (CI): 0.49-0.61) and 59% (95% CI: 0.52-0.64), respectively, higher than those of Caucasian Americans (16 and 16%, respectively) and African Americans (33 and 30%, respectively). However, the reported SNPs in exons 2 and 4 (PXR*2,*3,*4,*6,*9,*10,and *11) were not detected in Han Chinese. These results indicate that there are marked differences in the mutant frequencies of A11156C and T11193C of PXR between Han Chinese and other ethnic groups. The mutant frequency in the coding region (exons 2 and 4) of PXR was very low in Han Chinese. Further studies are needed to determine the impact of common SNPs of PXR in Han Chinese and other ethnic populations on the phenotypic activity of cytochrome P450s and drug transporters transactivated by PXR., ((c) 2008 S. Karger AG, Basel)