C3 glomerulonephritis is recognized by the presence of glomerulonephritis under light microscopy, immunofluorescent staining with C3, but not with immunoglobulins, C4 or C1q, and the presence of mesangial or subendothelial deposition, which can be observed using electron microscopy [5–7]. The gene discussed is C4A; the disease is glomerulonephritis.