Some SNPs within the CTLA-4 gene have already been analyzed for susceptibility to rheumatoid arthritis (RA) in the Mexican population; among them, rs5742909, rs231775 and rs3087243, suggesting that the −319C/+49G/CT60G haplotype of the CTLA-4 gene is a risk factor for RA, whereas that the rs3087243 SNP could be a protective factor against this type of autoimmune disease.20 Here, CTLA4 is linked to rheumatoid arthritis.