Association of polymorphisms G1193/C exon 8 and C2145/T exon 12 with Anti-TPO titer in Iranian population

Autoimmune thyroid diseases (AITD) are common and it is important to identify the genetic determinants. 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.

We selected 184 individuals from Tehran Lipid and Glucose Study, categorized as the Anti-TPO- (n=72) and Anti-TPO+ (n=112) groups. Inclusion criteria for cases was Anti-TPO and Anti-Tg>100U/L with a history of hypothyroidism. Anti-TPO levels in subjects were 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 in 28.8% of normal individuals. This allele was significantly associated with increased levels of Anti-TPO [(T 140±330 pmol/L; vs. C 436±380 pmol/L; P<0.001), (OR: 9.2)]. The G1193/C was not associated with the level of serum Anti-TPO in this study.

We demonstrated that the C allele polymorphism in C2145/T exon 12 is associated with high levels of serum Anti-TPO and that carriers of this allele are predisposed to disease 9.2 times more than those who do not have A allele.