Nine patients (the 4 with C3GN, 1 with DDD and 4 with IC-MPGN) fell into cluster 1 and were characterized by low serum C3 and very high plasma sC5b-9 at onset, and subendothelial and frequently subepithelial and mesangial deposits (Tables 1, 4). The gene discussed is C3; the disease is primary membranoproliferative glomerulonephritis.