Objective: To investigate the correlations between polymorphisms at position 49 in exon 1 and position 318 in the promoter of the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) gene and autoimmune thyroid diseases in a Han Chinese population.
Methods: Polymerase chain reaction-restriction fragment length polymorphism was utilized. The MseI and BbvI restriction endonucleases were used to detect and analyse position 49 in exon 1 and position 318 in the promoter as well as the T/C alleles of the CTLA-4 gene in peripheral blood samples from 112 patients with Graves’ disease (GD), 101 with Hashimoto’s thyroiditis (HT) and 100 healthy individuals.
Results: At position 49 of exon 1, the frequencies of the GG genotype and the G allele in the GD group (χ2 = 12.147; p = 0.002) were statistically significantly higher than those in the control group (χ2 = 9.925; p = 0.002), while no statistically significant differences were found between the frequencies of the GG genotype and the G allele in the HT group (χ2 = 1.195; p = 0.550) and those in the control group (χ2 = 0.984; p = 0.321). No statistically significant differences in the promoter (-318) or the T/C alleles were observed among the three groups. Position 49 in the 17th codon of exon 1 of the CTLA-4 gene may be a candidate susceptibility marker in patients of Han ethnicity with GD.
Conclusion: This finding helps us to better understand the genetic risks for GD and provides a direction for targeted gene therapy.