FKBP-CaN-NFAT pathway polymorphisms selected by in silico biological function prediction are associated with tacrolimus efficacy in renal transplant patients.

Abstract Aim : The aim of the present study was to investigate the potential effects of genetic variations in the FKBP-CaN-NFAT pathway on clinical events associated with tacrolimus efficacy in Chinese renal transplant patients. Methods : One hundred and forty Chinese renal transplant patients of Han ethnicity with over five years of follow-up were enrolled in our study. A pool of single nucleotide polymorphisms (SNPs) (1284 SNPs) was extracted from the Ensembl database according to chromosomal regions of the candidate genes. Next, 109 SNPs were screened out from this pool using multiple bioinformatics tools for subsequent genotyping using the MALDI-TOF-MS method. The associations of these candidate SNPs with acute rejection, nephrotoxicity, pneumonia and post-transplant estimated glomerular filtration rate (eGFR) were explored. Results : Fourty-four SNPs were found to be associated with tacrolimus-related clinical drug response. Specifically, eight SNPs were associated with the incidence of biopsy-proven acute rejection, four SNPs were associated with the rate of nephrotoxicity, 16 SNPs were correlated with the onset of pneumonia, and 26 SNPs were found to significantly influence post-transplant eGFR trend. An elaborate scoring system was implemented to prioritise the validation of these potentially causal SNPs. In particular, NFATC2 rs150348438 (G>T) performed well during integrative scoring (Ptotal=23.8) and was significantly associated with the occurrence of pneumonia (P=0.0035, HR=0.91, 95% CI=0.85-0.97) and post-transplant eGFR levels (P=0.000003). Conclusions : NFATC2 rs150348438, rs6013219, rs1052653, and NFATC1 rs754093, ranking high in scoring, significantly affected the post-transplant eGFR and the incidence of pneumonia, acute rejection, and nephrotoxicity in renal transplant patients taking tacrolimus. Those SNPs may alter the expression and regulation of FKBP-CaN-NFAT pathway by influencing transcription regulation, mature mRNA degradation and RNA splicing, or protein coding. Critical SNPs of high ranking may serve as PD-associated pharmacogenetic biomarkers indicating individual response variability of TAC, and thus aid the clinical management of renal transplant patients.