In the urine and plasma of patients with FSGS, activated fragments of the complement cascade, such as C3a, C3b, Ba, Bb, C4a, and sC5b-9, are increased compared to patients with other renal diseases such as antineutrophilic cytoplasmic antibody (ANCA) vasculitis and lupus nephritis or in healthy controls (48). The gene discussed is C3; the disease is vasculitis.