C3 and focal segmental glomerulosclerosis: Compared to patients with nephrotic syndrome who were diagnosed with focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD) on renal biopsy, patients with primary MN had several fold higher levels of serum C3a and C5a, illustrating that complement activation is a defining feature of MN that distinguishes it from other immune-mediated glomerulonephritides (40).