C3 and membranoproliferative glomerulonephritis: Both diseases are characterized by a distinct pattern of glomerular C3 deposition in the absence of immunoglobulins, frequently producing a membranoproliferative glomerulonephritis pattern of injury.1, 2, 3 Patients commonly present with a nephrotic or nephritic syndrome and often with low serum C3 levels, and the diagnosis is confirmed with a kidney biopsy.