PRTN3 and rheumatoid arthritis: There were no significant differences in all three salivary markers of inflammation between patients with RA who were positive for ACPA in their saliva (median [interquartile range, IQR]: total protein 1,380 μg/mL [1,057–1,747], total IgA 343 μg/mL [253–562], MMP‐8 123 ng/mL [33–150]) and those who were not (median [IQR]: total protein 1,411 μg/mL [1,040–1,621], total IgA 259 μg/mL [169–386], MMP‐8 83 ng/mL [26–138]) (Supplementary Figure 2A–C).