The Study Of The Relationship Between A/G Polymorphism At Position 49 In Exon 1 Of Cytotoxic T Lymphocyte-Assosiated Antigen-4 Gene And Relapse Of Graves' Hyperthyroidism After Antithyroid Withdrawal

Objective To explore the relationship between A/G polymorphism at position 49 in exon 1 of cytotoxic T lymphocyte-assosiated antigen-4 gene and relapse of Graves'hyperthyroidism after antithyroid withdrawal.Methods We stadyed A/G polymorphism at position 49 in exon 1 of cytotoxic T lymphocyte-assosiated antigen-4 (CTLA-4) gene in 120 recurrent Graves'disease ( GD) patients , 66 initial GD patients and 100 healthy controls. Recurrent GD patients were divided into two groups according to the time of relapse after antithyroid withdrawal: group A, early relapse within 3 years ; group B, relapse 3 or more years after antithyroid withdrawal .The SNP was determined by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) method , useing restriction enzyme Bbvl , which acts on the G variation , but not on the A variation . The difference of frequencies of genotypes and alleles among each group was analyzed by Chi-square test. We studied the frequencies of AA, AG and GG genotypes and A and G alleles of the A/G polymorphism at position 49 in exon 1 of CTLA-4 and analyzed whether the gene polymorphism was associated with GD and its relapes after antithyroid withdrawal.Results (1) The frequencies of GG+AG genotype and G allele in initial GD group were significantly higher than those in controls(P=0.007,P=0.017). (2)The frequencies of GG+AG genotype and G allele in recurrent GD group were significantly higher than those in controls(P<0.001, P<0.001) . ( 3 ) The frequencies of GG+AG genotype and G allele in recurrent GD group were higher than those in initial GD patients,but there were no significant differences(P=0.069, P=0.163). (4 )The frequencies of GG +AG genotype and G allele in group A were significantly higher than those in group B (P=0.003, P=0.003) and initial GD group(P=0.002, P=0.016). There were no significant differences between group B and initial GD group.Conclusions (1 )The A/G polymorphism at position 49 in exon 1 of CTLA-4 was associated...