Correlation between CTLA-4 and CD40 gene polymorphisms and their interaction in graves' disease in a Chinese Han population

Abstract

Background: Single-nucleotide polymorphism (SNP) haplotype and SNP-SNP interactions of CTLA-4 and CD40 genes, with susceptibility to Graves' disease (GD), were explored in a Chinese Han population. Methods: SNP were genotyped by high resolution melting (HRM). Use the method of Pearson χ2 test and Logistic regression for the association between single SNP and Graves' disease. Using the method of χ2 test and Multifactor Dimensionality Reduction (MDR) to analysis the haplotype frequency distribution, the interaction of SNPs respectively. Results: Genotypic and allelic frequencies of SNP rs231775, rs3087243 and rs1883832 were statistically different between controls and GD (p < 0.05). Mutant allelic frequency of G rs231775 was higher, and A and T allelic frequencies of rs3087243 and rs1883832 were lower in GD than in controls (P < 0.05). In CTLA-4 rs1024161, rs5742909, rs231775, rs231777, rs231779, rs3087243 and rs11571319 showed D' < 50% and r 2 < 0.3 among each SNP. We identified six commonly found haplotypes; TCGCTGC was associated with the highest GD risk (OR = 2.565) and TCACTAC the lowest (OR = 0.096). MDR analysis indicated interactions among the rs231775 GG, rs231779 TT and rs3087243 GG genotypes in CTLA-4 might increase GD risk by 2.53-fold (OR = 2.53). Conclusion: CTLA-4 and CD40 were associated with GD incidence in a Chinese Han population. The TCGCTGC and TCACTAC haplotypes in the CTLA-4 gene, were risk and protective factors for Graves'disease respectively. Interactions among the SNPs of rs231775, rs231779 and rs3087243 significantly increase the susceptibility to GD.