Due to disease-specific changes of glomerular permeability [47], different patterns of plasma proteins including transferrin, α1 antitrypsin (A1AT), and antithrombin III would be lost in urine of patients with nephrotic syndrome and might not be specific for FSGS as they could be detected in nephrotic range proteinuria secondary to any etiology [54]. Here, SERPINC1 is linked to focal segmental glomerulosclerosis.