Abstract: Objective To learn the relationship between CTLA-4 exon 1 49A/G and APS Ⅲ. Methods 52 normal control, 39 T1DMA cases and 16 APS Ⅲ cases. Results The frequency of allele G, 0.788 was higher than A, 0.212. GG genotype and G allele was higher in NC group. But it was no significant difference(χ²=2.856, P=0.24; χ²=0.003, P=0.352). G and A alleles in 3 groups was no significant difference too. Conclusion The main allele is G in the research groups. The CTLA-4 polymorphism has race difference. There is a increased trend of A allele in NC, T1DM and APS Ⅲ. So there may be a relation between A allele and susceptibility of autoimmune disease.

Key words: APS Ⅲ, T1DM, autoimmune disease