Association between serum level of anti-TPO titer and polymorphisms G1193/C Exon 8 and C2145/T Exon 12 of thyroid peroxidase gene in an Iranian population

Autoimmune thyroid diseases (AITD) are common, with important epidemiological data, including family and twin studies, supporting a strong genetic background on the etiology of AITD. The aim of this study was to assess the relationship between two polymorphisms of Thyroid Peroxidase gene (TPO) and serum level of Anti-TPO titer in an Iranian population.Patients and A sample of 184 participants from the Tehran Lipid and Glucose Study was selected as the case (No.=112) and control (No.=72) groups. Inclusion criteria for cases were Anti-TPO and Anti-Tg>100U/L with a history of hypothyroidism. Anti-TPO level in subjects was measured by the ELISA kit. Genomic DNA was extracted using Salting-out/Proteinase K method. Polymorphism detection of Exon 8 and 12 was done using the PCR-RFLP method. The PCR products were incubated with restriction enzymes SacII and BsrI, respectively. The C allele frequency of C2145/T polymorphism Exon 12 (rs732608) was observed in 71.2% of patients and 28.8% of normal individuals. This allele was significantly associated with increased levels of anti-TPO [(TT, 140±330 pmol/L; vs. CC, 436±380 pmol/L; P < 0.001), (OR: 9.2)]. The G1193/C was not polymorphic and no association between this SNP and the level of serum anti-TPO was found in this study. We found that the C allele polymorphism in C2145/T exon 12 is associated with the high level of serum anti-TPO and that carriers of this allele are predisposed to disease 9.2 times more than those, who have no C allele. The selected polymorphism of exon 8 has no effect on increased levels of anti-TPO.