title: CTLA-4 gene A/G polymorphism associated with diabetes mellitus in Han Chinese.
abstract: 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 < 0.0005; OR = 3.670) . This reflected an increase in the GG genotype in patients (48.4% vs. 22.2%, respectively; P =0.025; OR =3.281) and a significant decrease in the AA genotype (16.1 % vs. 52.8%, respectively; P = 0.002). The allele frequencies of A and G in patients with type 2 diabetes were not significantly different from controls(A/G, 50.0/50.0% vs. 65.3/34.7%; P = not significant) . The distribution of genotype, however, differed significantly. This difference reflected an increase in the AG genotype in patients (54.8% vs.25.0%, respectively; P=0.012; OR=3.643) and a decrease in the AA genotype (22.6% vs. 52.8%, respectively; P=0.011).
  
  
  CONCLUSIONS
  CTLA-4 49 AA is protective from diabetes mellitus, whereas, CTLA-4 49 G allele (both as homozygotes and as heterozygotes ) confers an increased risk of diabetes mellitus.
authors.affiliation: Department of Endocrinology, The First Affiliated Hospital, Lanzhou Medical College, Lanzhou, China. mahl@public.lz.gs.cn
authors.forename: Yun
authors.initials: Y
authors.lastname: Ma
authors.forename: Xulei
authors.initials: X
authors.lastname: Tang
authors.forename: Wei
authors.initials: W
authors.lastname: Chang
authors.forename: Lin
authors.initials: L
authors.lastname: Gao
authors.forename: Maoxin
authors.initials: M
authors.lastname: Li
authors.forename: Wenwei
authors.initials: W
authors.lastname: Yan
mesh_terms: D000069594:Abatacept; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000235:genetics*; D060908:CTLA-4 Antigen; D002681:China / Q000208:ethnology; D003920:Diabetes Mellitus / Q000235:genetics*; D006801:Humans; D018796:Immunoconjugates; D011110:Polymorphism, Genetic
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D018796:Immunoconjugates; D000069594:Abatacept