The evaluation of endothelin 1 (EDN1) and endothelin receptor type A (EDNRA) gene polymorphisms in Hashimoto's thyroiditis

PURPOSE

Endothelin1 (EDN1) is well established marker of inflammation. The functions of EDN1 are mediated mainly by endothelin receptors type A (EDNRA). The etiopathogenesis of Hashimoto's thyroiditis (HT) remains still elusive although the role of chronic inflammation and subsequent endothelial dysfunction has been established. This study examined firstly the possible association of EDN1 (G5665Tand T-1370G) and EDNRA (C+70G and G-231A) single nucleotide polymorphisms (SNPs) with the occurrence of HT, and evaluates the relationship between genotypes and clinical/laboratory manifestation of HT.

MATERIALS AND METHODS

We analyzed genotype and allele distributions of above mentioned polymorphisms in 163 patients with HT and 181 healthy controls by real-time PCR combined with melting curve analysis.

RESULTS

No significant associations between HT and variant alleles of EDN1 5665 and -1370, as well as EDNRA +70 and -231 SNPs were found. Haplotype analysis demonstrated that there was a strong (D'=0.76, r(2)=0.487) and weak (D'=0.403, r(2)=0.086) linkage disequilibrium (LD) between EDN1 -1370 and 5665, and between EDNRA -231 and +70 SNPs, respectively. However, haplotype frequencies in patients were similar to those in controls. In addition, it was observed that the EDNRA +70 G allele had protective effect against early (at age before 40 years) disease onset of HT (OR: 0.51, 95% CI=0.32-0.79, p=0.003).

CONCLUSION

Although no significant associations between susceptibility to HT with EDN1 5665 and -1370, as well as with EDNRA+70 and -231 SNPs were found, EDNRA +70 polymorphism was related with decreased risk for early onset HT.

Polymorphisms of endothelin 1 (G5665T and T-1370G) and endothelin receptor type A (C+70G and G-231A) in Graves' disease

PURPOSE

Endothelin 1 (EDN1) is a strong angiogenic and mitogenic factor, playing a key role in hypervascularization, thyroid follicle cell hyperplasia, and lymphocyte infiltration in the thyroid gland of patients with Graves' disease (GD). EDN1 induces angiogenesis and mitogenesis via endothelin receptor type A (EDNRA). This study examined the possible association of EDN1 (G5665T and T-1370G) and EDNRA (C+70G and G-231A) single nucleotide polymorphisms (SNPs) with the occurrence of GD, and evaluates the relationship between genotypes and clinical/laboratory manifestations of GD.

MATERIALS AND METHODS

We analyzed genotype and allele distributions of EDN1 and EDNRA polymorphisms in 165 patients with GD and 181 healthy controls by real-time PCR combined with melting curve analysis.

RESULTS

No significant associations between GD and variant alleles of the studied polymorphisms were observed. However, the anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) levels in EDN1 G5665T GG genotype were higher than those in T allele carriers (GT+TT) (p=0.001 and p=0.026, respectively). In addition, anti-TPO levels in EDN1 T-1370G wild-type homozygous patients were found to be higher than in mutant gene carrying patients (GT+GG) (p=0.006). The presence of EDNRA+70G allele was associated with 3.37-fold increased risk for development of ophthalmopathy in GD patients (p=0.009).

CONCLUSION

Although there were no associations between EDN1 (G5665T and T-1370G) and EDNRA (C+70G and G-231A) SNPs and susceptibility to GD, EDN1 G5665T and T-1370G polymorphisms were related to alterations of autoantibody production and EDNRA C+70G polymorphism is related with increased risk for ophthalmopathy in GD patients.