PDCD1 and rheumatoid arthritis: We observed significant correlation between rs11568821 (PD-1.3 G/A) and RA risk in addictive model and dominant model (A vs G: OR = 1.20, 95% CI = 1.03–1.41; AG + AA vs GG: OR = 1.19, 95% CI = 1.01–1.41) in Caucasian.