Association of Cytokine Gene Polymorphisms (IL6, IL10, TNF-α, TGF-β and IFN-γ) and Graves’ Disease in Turkish Population

Introduction: Cytokines play a crucial role in the pathogenesis of autoimmune thyroid disease, and recent studies have demonstrated an association between cytokine gene polymorphisms and Graves' Disease (GD) in different ethnic groups. The aim of the present study was to investigate the relationship of interleukin-6 (IL-6), IL-10, tumor necrosis factor-alpha (TNF-α), transforming growth factor-beta (TGF-β), and interferon-gamma (INF-γ) gene polymorphisms in the development of GD in Turkish population. Material and Methods: A total of 224 subjects were included in the study comprising of 100 patients with GD (70 female, 30 male; mean age, 43.9 ±13.8 years) and 124 healthy subjects (81 female, 43 male); mean age, 37.8 ±10.2 years) without antithyroid autoantibodies or family history of autoimmune disorders. Genotyping was conducted by using PCR and sequence-specific primers. Results: Statistical analysis showed a significant association between high TNF-α -308GA and IL-6 -174CC gene polymorphisms in patients with GD compared to control subjects (p=0.016, p=0.044, respectively). However, no significant differences were observed between GD and control subjects for IL-10, TGF-β, and INF-γ gene polymorphisms. Conclusion: TNF-α-308GA and IL-6 -174CC gene polymorphisms are involved in susceptibility to GD in Turkish population. The polymorphism hypothesis in pro-inflammatory cytokines might be involved in predisposition to GD. Keywords: Cytokine, graves' disease, interferon, interleukin, polymorphism, transforming growth factor, tumour necrosis factor.