Medical Condition:
Complement 3 Nephritic Factor
A magnesium-dependent IMMUNOGLOBULIN G autoantibody found in serum of patients with chronic mesangioproliferative hypocomplementemic glomerulonephritis. It causes inactivation of C3 in the alternate pathway by cleaving C3 into two inactive fragments, C3c and C3d, instead of the normal C3b.