SPP1 and rheumatoid arthritis: By contrast, CLYBL [48], SMIM21 [48], SPP1 [63], CLEC16A [64], IRF5 [65], DCIR [66, 67], LEMD2, CSMD1, FCRL3 [57], IL-33 [68], PRL [59], and NFIA [59] have been reported to be associated with ACPA− RA (although not at genome-wide significance thresholds), and many of these markers are not associated with ACPA+ RA.