Population-Specific Exploration of MIR146A Gene Polymorphism in Acute Renal Rejection: A Cross-Sectional, Case–Control Study

Acute renal allograft rejection (AR) is immune-mediated. Recent evidence highlights some microRNAs as immune modulators. Few and conflicting studies have studied the impact of the MIR146A gene single-nucleotide polymorphism rs2910164 (C>G) on AR. We explored the association of rs2910164 with AR in a single-center cohort of 533 kidney transplant recipients (KTRs) by genotyping cases with biopsy-proven late AR (AR group, n = 35) and matched control KTRs without AR (non-AR group, n = 60). Genotyping was performed with real-time PCR. Multivariable logistic regression and Firth penalized logistic regression, as a sensitivity analysis, were used to adjust for confounding factors. Donor–recipient age difference was significantly higher in the AR group than in the non-AR group (23.37 ± 11.29 vs. 14.83 ± 10.54, p < 0.001). Recipient mean age in the AR group is lower than in the non-AR group (27.51 ± 10.34 vs. 32.83 ± 9.76 years, p = 0.014), while the opposite is observed with the donor mean age (49.57 ± 10.37 vs. 43.27 ± 10.27 years, p = 0.005). AR was associated with preformed donor-specific antibodies (DSAs) (45.7% vs. 8.3%, p = 0.000, OR = 9.263, 95% CI (2.988–28.720)), and with two HLA/A* mismatches (17.1% vs. 3.3%, p = 0.048, OR = 6.000, 95% CI (1.139–31.595)). Moreover, post-transplant viral infections, particularly with CMV and SARS-CoV-2, were associated with AR (p < 0.05). However, rs2910164 was not associated with AR across all the tested genetic models (p > 0.05). Our study provides population-specific negative association data on rs2910164 and AR. Larger multicentric studies and future meta-analyses are needed to clarify whether any effect is modest or context-dependent.