Of the thirteen proteins upregulated specifically in PR3-AAV compared to population controls, ten overlapped with those in RA versus population controls, and two with those in SLE; three proteins (AZU1, MMP-9, PGLYRP1) were exclusive to PR3-AAV (Table 2; Supplementary Table 13). This evidence concerns the gene MMP9 and systemic lupus erythematosus.