To study whether C3, FB and FD are aberrantly filtered, activated and excreted in the urine, we induced experimental nephrotic syndrome in Nphs2Δipod*Cfb−/−, Nphs2Δipod*Cfd−/− and Nphs2Δipod*C3−/− mice and their Nphs2Δipod littermates. The gene discussed is CFD; the disease is nephrotic syndrome.