Association of UDP-glucuronosyltransferase 1A9 (UGT1A9) gene polymorphism with kidney allograft function.

Background: UDP-glucuronosyltransferases (UGTs) are a group of enzymes involved in the detoxification and excretion of xeno- and endobiotics. Polymorphic variants of the UGT1A9 gene were shown to influence exposition to mycophenolate mophetil (MMF), a common immunosuppressive drug used in kidney allograft recipients. Therefore, the aim of this study was to evaluate an association between key clinical features of kidney post-transplant course in patients receiving MMF therapy and UGT1A9-2152C>T and -275 T>A SNPs, known to induce UGT1A9 gene expression and UGT1A9 98T>C, resulting in reduced enzyme activity.

Material/methods: DNA was isolated from peripheral blood of kidney allograft recipients (n=103) and a control group representing the background population of Poland (n=450). Presence of the analyzed SNP was detected using the PCR restriction fragment length polymorphism (RFLP) method. Accuracy of the applied method was confirmed by DNA sequencing.

Results: In patients carrying the UGT1A9-2152T and -275A minor alleles we observed a trend of increased risk of acute allograft rejection within 3 months after transplantation, but this difference was at the border of significance. However, the UGT1A9 98C allele was found to be associated with diminished estimated glomerular filtration rate (eGFR) during the first year after engraftment and transient proteinuria in the first and second month post-transplantation. This association was not observed for UGT1A9-2152C>T and -275 T>A. Our data show that transplanted kidney function may be affected in patients carrying UGT1A9 98C allele and receiving MMF.

Conclusions: Genotyping of the functional UGT1A9 SNP may be of practical use in kidney transplant recipients.