C3 and primary membranoproliferative glomerulonephritis: Membranoproliferative or mesangiocapillary glomerulonephritis (MPGN) has been traditionally classified based on the light and electron microscopy (EM) findings; here, there are three categories: type I, characterized by the presence of immune deposits in the subendothelial space and mesangium of glomeruli; type II, characterized by C3 deposits within the mesangium and in the basement membranes highly osmiophilic on electron microscopy (dense deposits disease; DDD); and type III, which is a variant of type I [1].