What is C3G?
C3 Glomerulopathy (C3G) describes a group of diseases in which uncontrolled complement activation leads to complement deposition within the glomerulus. It is an ultra-rare condition, with an incidence of ~ 1 per million per year. It typically presents in childhood and young adulthood but can present throughout adulthood. C3G is classified into dense deposit disease (DDD) and C3 glomerulonephritis (C3GN) and overlaps with the term membranoproliferative glomerulonephritis (MPGN).
Clinical Features of C3G
Clinical Features include proteinuria (including nephrotic syndrome), haematuria, hypertension and progressive renal failure.
Complement consumption, usually at the level of the C3 convertase results in low C3 levels (secondary complement deficiency that could result in increased risk of infections).
Drusen, age-related macular degeneration and acquired partial lipodystrophy have been reported in association with C3G.
Familial history has been reported in cases of C3G. In particular, large pedigrees of C3G have been identified with Cypriot ancestry with CFHR5 nephropathy. These patients often have synpharyngic haematuria. Prognosis is often worse in males with CFHR5 nephropathy.
Prognosis of C3G
Patients with C3G have a heterogenous clinical course. However, there are no approved treatments. Approximately 50% of patients progress to end-stage renal failure within 10 years. Rates of disease recurrence following renal transplantation are high.