Single-Nucleotide Polymorphisms in the Thioredoxin Antioxidant System and Their Association with Diabetic Nephropathy in Slovenian Patients with Type 2 Diabetes-A Preliminary Study

Diabetic nephropathy (DN) is a microvascular complication of type 2 diabetes mellitus (T2DM) that develops after years of T2DM and affects approximately one in four diabetic patients. Thioredoxin (TXN), thioredoxin reductase (TXNRD), and thioredoxin-interacting protein (TXNIP) are part of the thioredoxin antioxidant system, which is involved in DN. We included 897 Slovenian patients with T2DM lasting more than 10 years in our preliminary study. In total, 344 patients with DN were included in our case group, while 553 without DN comprised our control group. The genotypes of TXN2 rs8140110, TXNRD2 rs1548357, and TXNIP rs7212 were determined for all participants using real-time PCR. We found a statistically significant association between the T allele of the TXN2 rs8140110 polymorphism and DN (p < 0.001; OR: 0.52; 95% CI: 0.36-0.74). The TT and TC genotypes were also significantly less likely to develop DN in comparison to the CC genotype according to the dominant model of inheritance (p < 0.001; OR: 0.51; 95 CI: 0.34-0.75). We did not find a statistically significant association between rs1548357 or rs7212 and DN. To conclude, the rs8140110 polymorphism in the TXN2 gene is associated with DN in Slovenian patients with T2DM.