Mismatches in gene deletions and kidney-related proteins are novel histocompatibility factors in kidney transplantation

BackgroundThe genomic mismatch level between donor and recipient is associated with the risk of acute rejection and long-term graft survival. In the present study, we determined the association of genome-level matching with acute rejection in a single-center kidney transplantation cohort. MethodsAltogether, 1025 pairs of deceased donors and kidney transplant recipients transplanted in 2007-2017 were genotyped. The associations between the sums of whole genome missense variant mismatches and missense mismatches in transmembrane, secretory, and kidney-related proteins, with acute rejection were estimated using Cox proportional hazards model. Additionally, we analyzed 40 common deletion-tagging variants using Cox model. ResultsThe increasing mismatch sum in kidney-related proteins associated with acute rejection with an unadjusted HR of 1.15 (95% CI, 1.01-1.30; P=0.029) when dividing the sum into quartiles. The sums of other mismatches were not associated with acute rejection. In deletion analysis, a mismatch in rs7542235 (NC_000001.11:g.196854483A>G), genotype GG tagging a homozygous deletion at the complement Factor H-related (CFHR) proteins locus, predisposed to acute rejection with adjusted HR of 2.97 (95% CI, 1.46-6.05; P=0.003). ConclusionsThe present study supports that mismatches in gene deletions and kidney-related proteins are novel histocompatibility factors in kidney transplantation. The relative importance of different gene deletions varies between populations, as we found evidence for CFH-related gene deletion but not for the previously reported LIMS1 deletion. SIGNIFICANCE STATEMENTThe first genome-wide association studies have not identified strong candidate genes for complication risks of kidney transplantation whereas matching of non-HLA genes may be promising. The current study determined the association of genome-level matching with acute rejection among 1025 kidney transplant pairs. The increasing mismatch sum in kidney-related proteins was associated with acute allograft rejection. Also, an association between acute allograft rejection and rs7542235 genotype GG, tagging a homozygous deletion at the complement factor H-related (CFHR) loci on chr 1 was found. The present study suggests that mismatches in gene deletions and kidney-related proteins are important novel histocompatibility factors in kidney transplantation.