From genotype to protein: how the 308 G/A polymorphism of the TNF-α gene is associated with TNF-α protein levels in patients with Hashimoto’s thyroiditis

Aim. To study the 308 G/A polymorphism of the TNF-a gene and its influence on serum levels of TNF-a protein in patients with Hashimoto’s thyroiditis (HT) among the Azerbaijan population. Materials and methods. The study was conducted at the Department of Biochemistry, Azerbaijan Medical University, between 2021 and 2023. The study enrolled 170 patients diagnosed with HT, and a comparison group consisting of 65 individuals without thyroid pathology or other diseases affecting the immune system. The presence of the TNF-α-308 G/A polymorphism (SNP rs1800629) was determined by the PCR-PDRF method and TNF-α protein serum levels were measured according to the standard ELISA protocol in both groups. Results. The study on the 308 G/A polymorphism of the TNF-α gene has revealed 49.2 % of patients exhibited the G allele and 55.1 % – the A allele. The AG genotype has been found to be most prevalent in HT patients (57.9 %) being significantly higher than in the comparison group (21.7 % of individuals; p = 0.0006, χ2 = 11.87, OR = 2.85, 95 % CI = 1.55–5.23). Furthermore, serum TNF-α levels have been shown to be significantly higher in HT patients (3.48 ± 1.32 pg/ml) as compared to the control group (2.31 ± 0.74 pg/ml) with statistical significance (p < 0.01). Conclusions. The most prevalent AG genotype of the TNF-α gene 308 G/A polymorphism has been identified in patients diagnosed with Hashimoto’s thyroiditis. This polymorphism may serve as a genetic marker, indicating a predisposition to autoimmune thyroiditis among the Azerbaijan population. Furthermore, serum TNF-α protein levels have been found to be significantly elevated in patients with Hashimoto’s thyroiditis, which may be associated with the AG genotype of the 308 G/A TNF-α polymorphism.