Objective: To examine whether CTLA-4 gene confers susceptibility to rheumatoid arthritis (RA) in Japanese.
Methods: We investigated the distribution of a CTLA-4 gene polymorphism in 85 Japanese patients with RA and 200 controls. An A/G transition at position 49 of exon 1 was analyzed by the polymerase chain reaction (PCR)-restriction fragment length polymorphism method. The patients were also analyzed with respect to HLA-DR status. HLA-DR typing was performed by PCR sequence-specific oligonucleotide typing.
Results: The distribution of genotype frequencies differed between RA and controls (chi-squared 8.63, 2 df, p = 0.013). The CTLA-4 AG genotype occurred more frequently in patients with RA (59 vs 44%), and the presence of at least one G allele (GG or AG) conferred an odds ratio of 2.53 (95% CI 1.74-3.32). When the patients were analyzed with respect to HLA-DR status, this association was restricted to patients carrying the susceptible HLA allele (HLA-DRB1*0405).
Conclusion: The CTLA-4 gene is associated with Japanese patients with RA carrying the susceptible HLA allele.