ERAP1 and rheumatoid arthritis: Significant differences were also observed in the rs27044 C > G polymorphic site of the ERAP1 gene for the GG genotype, which was less frequent in the group of patients with RA compared to controls [3.73% vs. 8.86%, p = 0.017, OR = 0.398, 95% CI (0.188-0.844)].