Functional annotation of biological processes revealed that proteins highly expressed in the mild BD group were enriched in immune response (C1QA, ECM1, IGHV1‐3, TUBB, APOA2, IGHV2‐26, IGKV1D‐33, IGHV1‐18, C3, IGLL5, IGLV1‐51, ADAMTS13, IGKV1‐27, IGLV6‐57, CFHR4, C1RL, LCP1, A2M, PF4, LTF), protein activation cascade (C3, C1QA, CFHR4, FGG, C1RL, FBLN1, A2M), and immune effector response (C3, C1QA, IGLL5, IGHV1‐3, CFHR4, TUBB, C1RL, APOA2, LCP1, IGHV2‐26, A2M, IGHV1‐18). This evidence concerns the gene C3 and Behcet disease.