C3 and primary membranoproliferative glomerulonephritis: This pattern may be seen in the setting of various secondary conditions [1, 2] as well as in primary forms that are distinguished into C3 glomerulopathy (C3G) and immunoglobulin-associated MPGN (Ig-MPGN), on the basis of immunofluorescence showing predominant or exclusive C3 deposits in C3G and combined C3 and Ig deposits in Ig-MPGN (Box 1) [1, 3].