In the severe BD group, enriched proteins were predominantly associated with defense response (SERPINA3, ITIH4, COLEC10, FCN3, SERPINA1, TFRC, C1R, CFP, C8B, ORM2, CDH5, C5, PRDX5, C7, TIMP1, MBL2, ANXA1, F12, ADIPOQ, SERPINF2, RNASE4, AGT, ATRN, TF, PROC, MASP1) and protein activation cascade with complement activation (FCN3, C5, COLEC10, C7, C1R, F12, MASP1, C8B, CFP, MBL2) (Figure 3B). The gene discussed is C1R; the disease is Behcet disease.