Membranoproliferative glomerulonephritis (MPGN)

Overview

• also known as mesangiocapillary glomerulonephritis (MCGN)
• may present as nephrotic syndrome, haematuria or proteinuria
• Dense deposit disease is unique among glomerulopathies, because it is caused by IgG antibodies (termed C3 nephritic factor) directed against C3 convertase of the alternative complement pathway
• These antibodies reacting with C3 convertase lead to persistent complement activation and kidney damage
• poor prognosis

Type 1

• accounts for 90% of cases
• subendothelial immune deposits of electron dense material resulting in a 'tram-track' appearance
• cause: cryoglobulinaemia, hepatitis C

Type 2 - 'dense deposit disease (DDD)'

• causes: partial lipodystrophy, familial, factor H deficiency
  • Partial lipodystrophy (aka Barraquer-Simons syndrome) result from dysregulation of the alternative complement pathway, particularly involving C3 nephritic factor (C3NeF) autoantibodies. Approximately 20-30% of DDD patients develop acquired partial lipodystrophy, characterised by progressive loss of subcutaneous fat from the face and upper body.
• reduced serum complement
• C3b nephritic factor (an antibody against C3bBb) found in 70%

Type 3

• causes: hepatitis B and C

Management

• steroids may be effective

Px