In the lectin-induced complement pathway, complement proteins including C3, C3a, C3b, C4, C4a, C4b, C5, C5a, C5b, complement C3d receptor 2 (CD21), ficolin 3, and iC3b were downregulated by > 8-fold among RA patients. The gene discussed is C5; the disease is rheumatoid arthritis.