primary membranoproliferative glomerulonephritis (MONDO_0018904) is a rare glomerular disease characterized by a pattern of glomerular injury on kidney biopsy with characteristic light microscopic changes: mesangial hypercellularity, endocapillary proliferation, and thickening of the glomerular basement membrane (GBM). On the basis of immunofluorescence (IF) the disorder is divided into C3 glomerulopathy (C3G) or immunoglobulin-mediated membranoproliferative glomerulonephritis. Through electron microscopy C3G is further divided into Dense deposit disease, with highly electrondense deposits in the glomerular basement membrane, and C3 glomerulonephritis, with mesangial, intramembranous, subendothelial and subepithelial deposits. Secondary causes (autoimmune, infectious, malignancies) are excluded. Also known as: MPGN, Mesangiocapillary glomerulonephritis.