PTPN22 and rheumatoid arthritis: Although not consistently higher in ACPA+ RA, notable associations such as SNPs in PTPN22 (OR = 1.74 ACPA+, 1.23 ACPA-) and TRAF1-C5 (OR = 1.32 ACPA+, 1.08 ACPA-) have increased effects in ACPA+ RA, and the authors consider this heterogeneity to denote a separate disease subtype.