OBJECTIVE: To investigate the association of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) gene A/G polymorphism with susceptibility to diabetes mellitus in Han Chinese. METHODS: An A/G transition at position 49 of exon 1 was analyzed in 31 patients with type 1 diabetes, 31 patients with type 2 diabetes, and 36 controls were analyzed by polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS: A highly significant increase in the frequency of the G allele was seen in patients with type 1 diabetes compared with controls (66.1 % vs. 34.7%, respectively; P
