HLA, CTLA-4 and TNF- $\beta$ Gene Polymorphisms and Disease Susceptibility in Korean Children with Graves' Disease

Background: Graves' disease(GD) is an organ-specific autoimmune disorder that is inherited as a complex trait. At Present three loci, namely the human leukocyte antigen(HLA), the cytotoxic T lymphocyte antigen-4 (CTLA-4) and a thyroid stimulating hormone receptor (TSHR) are the only well-known genetic determinants for GD. To understand the mechanisms underlying the development of GD, we investigated the relationship of HLA alleles, polymorphisms of CTLA-4 gene and the tumor necrosis factor(TNF)- gene, with the disease susceptibility. Methods: Fifty-two Korean children with GD (45 girls an 7 boys), and 119 healthy children, were investigated in this study. The HLA alleles were determined by a standard lymphocyte microtoxicity technique, ARMS-PCR(Amplification Refractory Mutation System-Polymerase Chain Reaction), PCR-SSP(Sequence Specific Primer) and PCR-SSOP(Sequence Specific Oliogonucleotide Probe) method. The CTLA-4 gene polymorphism was analyzed by PCR-SSCP(Single Strand Conformation Polymorphism), and the TNF- gene polymorphism by PCR-RFLP(Restriction Fragment Length Polymorphism). Results: (1) The frequencies of HLA-A2, B46, DRB1 *08 and DPB1 *0202 were significantly increased, and those of HLA-A24, DQA1 *01 and DQB1 *05 were significantly decreased, in the GD patients compared to the control subjects. (2) A significant difference in the distributions of the AA, AG, and GG genotypes of the CTLA-4 exon 1 were observed between the GD patients and the control subjects, and a significant increase in the frequency of the G (alanine) allele was seen in the GD patients compared with the control subjects (84.6% vs 63.4%; RR=3.2; p was observed between the GD patients and the control subjects. No significant difference in the distributions of the 1/1, 1/2, and 2/2 genotypes and the 1 and 2 alleles of TNF- were observed between the GD patients with or without exophthalmos but a significant increase in the frequency of the 2/2 allele was seen in the GD patients having TSHRAb 45% compared with GD patients having TSHRAb gene polymorphism was associated with the TSHRAb activity.