Association of transforming growth factor-β1 gene +869T/C polymorphism with autoimmune thyroid disease

Abstract

Objective To clarify whether the +869T/C polymorphism in the transforming growth factor-β1 (TGF-β1) gene is associated with TGF-β1 expression,and involved in the severity of Graves disease(GD) and Hashimoto's thyroiditis(HT).Methods The TGF-β1+869T/C polymorphism was genotyped by using PCR-sequence specific primers(PCR-SSP) in genomic DNA samples in blood from 158 patients with HT who developed hypothyroidism before they were 45 years old (severe HT) and 125 untreated,euthyroid patients with HT who were older than 45(mild HT).Using the same method,129 euthyroid patients with GD who had been under treatment and were still positive for anti-thyrotropin receptor antibodies (intractable GD) and 130 euthyroid patients with GD in remission and 144 healthy controls were examined.Results It had no difference between GD,HT groups and control group (x2 =1.488,0.439; 0.626,0.005; all P ＞ 0.05 ).The frequency of the TT genotype and the T allele were higher in group with severe HT[34.81％(55/158),58.86％( 186/316)] than in those with mild HT[ 17.60％ (22/125),43.60％ (109/250); x2 =14.040,13.026,all P ＜ 0.05].In contrast,the frequency of the CC genotype was higher in group with intractable GD[ (21.03％(31/129),51.16％(132/258)] than in group with GD in remission[ 13.85％ (18/130),40.38％( 105/260); x2 =12.225,6.061,all P ＜ 0.05 ].TGF-β1 +869 T/C genotype had the correlation with severe groups of HT and GD.C allele would increase in severity of GD(OR =1.546,95％ CI =0.192 - 2.190),and T allele would increase in severity of HT(OR =1.851,95％ CI =1.323 - 2.589).Conclusion The +869T/C polymorphism in the TGF-β1 gene is associated with the severity and intractability of autoimmune thyroid disease. Key words: Thyroid disease; Transforming growth factor beta 1 ; Multifactorial inheritance; Alleles; Gene frequency