PRTN3 and rheumatoid arthritis: The effects on RA risk of this SNP were further tested according to the characteristics of RF, ACPA, CRP, ESR, DAS28, and function class; significant associations were detected among the RF-positive and RF-negative groups, which suggested that the TT genotype of rs16840252 polymorphisms might be associated with the expression of RF (Supplementary Table 1).