Assessment of renal biopsy specimens at second admission demonstrated membranoproliferative glomerulonephritis via light microscopy and positive stains for IgG, IgM, IgA, C3, and C1q in immunofluorescence studies, compatible with class IV + V lupus nephritis (Figs. 5, 6, 7). The gene discussed is C3; the disease is membranoproliferative glomerulonephritis.