Arg25Pro (c.915G>C) polymorphism of transforming growth factor β1 gene suggests an association with increased risk for Hashimoto's thyroiditis

Abstract

BackgroundThe etiopathogenesis of Hashimoto's thyroiditis (HT) — has not been clearly elucidated although the role of chronic inflammation, endothelial dysfunction, and imbalance between pro- and anti-inflammatory cytokines has been established. Transforming growth factor β1 (TGFβ1) is required to maintain immune homeostasis, and is implicated in lymphocyte infiltration, production of autoantibodies and thyrocyte destruction seen in patients with HT. AimThe aim of the present study was to investigate the possible association of Leu10Pro (c.869T>C) and Arg25Pro (c.915G>C) single nucleotide polymorphisms (SNPs) of TGFβ1 gene with the occurrence of HT. MethodsWe analyzed the genotype and allele frequencies of polymorphisms at codon 10 and 25 in 178 patients who had been diagnosed as having HT and 197 healthy controls using PCR-restriction fragment length polymorphism (RFLP). ResultsThere was no notable risk for HT afflicted by Leu10Pro (c.869T>C) polymorphism of TGFβ1 gene. However, there was a significant increase of Arg25Pro (c.915G>C) C allele frequency in patients with HT compared with healthy controls (p=0.003, OR=1.87, 95% CI=1.23–2.84). Moreover, heterozygous (CG) subjects had a 2.53-fold increased risk for developing HT with respect to wild (GG) homozygotes (p<0.001, 95% CI=1.57–4.05). TSH levels in CG heterozygous patients were increased in comparison with wild homozygotes (p=0.006). ConclusionThis study indicates that the Arg25Pro (c.915G>C) polymorphism of TGFβ1 gene may be related to increased risk for HT.