Aim: To evaluate the association of PTPN22 gene polymorphism with autoimmune thyroid disease (AITD) in Chinese people and to analyze the relationship between SNP of CTLA-4 gene and SNP of PTPN22 gene.
Methods: 149 patients with Graves' disease (GD) and 82 patients with Hashimoto's thyroiditis (HT) as well as 131 healthy people as controls were investigated. PTPN22 gene polymorphism +1858 C>T and CTLA-4 gene polymorphism 49A>G were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). PTPN22 gene polymorphism -1123G>C at promoter was genotyped by single allele-specific primer polymerase chain reaction (SASP-PCR).
Results: (1) +1858C>T for PTPN22 gene was not polymorphic enough in patients and controls. (2) Statistic differences in alleles and genotype frequency of -1123G>C were observed between GD patients and controls (P=0.040, 0.013; OR=1.44, 2.33, respectively). (3) Differences in alleles and genotype frequency of 49A>G for CTLA-4 gene were observed in patients and controls. (4) Individuals with PTPN22 CC genotype and CTILA-4 G alleles had an increased risk of developing GD (OR=3.31, 95%CI: 2.69-8.89) compared with those with PTPN22 G alleles and CTLA-4 AA genotype.
Conclusion: -1123 G>C SNP of PTPN22 gene is associated with GD. There is coordination between PTPN22 CC genotype and CTLA-4 G alleles in the development of GD.