ERAP1 and rheumatoid arthritis: RA patients also differed in the rs26618 ERAP1 TT polymorphism [53.22% vs. 43.88%, p = 0.036, OR = 1.455, 95% CI (1.032-2.052)] and CT [38.31% vs. 47.68%, p = 0.034, OR = 0.681, 95% CI (0.482-0.964)].