Membranoproliferative Glomerulonephritis Recent advances in understanding the biology and pathology of Membranoproliferative Glomerulonephritis (MPGN) have led healthcare professionals to change how they classify and talk about these diagnoses — these disease states are now known and diagnosed as Complement 3 Glomerulopathy, or C3G. The problem with the old paradigm of MPGN is that it was purely descriptive based on biopsy and did not include specific mechanistic properties of the disease. Learn more about C3G here.