Association of glutathione peroxidase 1 gene polymorphism (rs1050450) with Hashimoto's thyroiditis in Northwest Iran

Hashimoto's thyroiditis (HT) is an inflammatory and autoimmune thyroid disorder. The oxidative stress and inflammation crosstalk play pivotal role in the pathogenesis of HT. The activity of glutathione peroxidase-1 (GPx-1) enzyme is affected by single nucleotide polymorphism in the rs1050450 position, which influence the risk of several diseases. The aim of this study is to determine the association of rs1050450 genotype variant and the HT risk. A hundred and five patients HT patients were enrolled and DNA and serum were isolated from the whole blood, and used for genotyping and serum total antioxidant capacity (sTAC), determination of antibody titer and thyroid stimulating hormone (TSH) level assessment. The glutathione peroxidase-1 genotyping performed using polymerase chain reaction and restriction fragment length polymorphism with ApaI enzyme. The sTAC were measured by FRAP method. Anti-thyroid peroxidase antibody (anti-TPO) and TSH levels were measured via ELISA assay. The results indicated the sTAC in HT patients (30.32 +/- 16.84 mu mol/L) is significantly lower than healthy controls (44.39 +/- 19.94 mu mol/L). There is a significant association between the rs1050450 genotype and the HT risk. T allele frequency is higher in HT patients than healthy control groups while there is no significant difference in sTAC between three rs1050450 genotype (CC, CT and TT). The T allele is associated with higher anti-TPO levels (TT = 136.33 +/- 82.27, CT = 308.40 +/- 259.39, CC = 294.57 +/- 309.54 IU/mL). We found a significant negative correlation between TSH and age of patients. The T allele in rs1050450 position of glutathione peroxidase-1 gene associated with higher HT risk independent from serum antioxidant power and may mediated by local antioxidant activity in thyroid gland microenvironment.