Although we have purified urinary exosomes to avoid the interferences of abundant urinary proteins, possible bias would exist in patients with renal disease such as nephrotic syndrome, glomerular disease, and chronic kidney disease which would have highly expressed levels of alpha-1antitrypsin and H2B1K in urine23, 24 Biomarker potentials of alpha 1-antitrypsin and H2B1K warrant further large-scale studies for validation. Here, SERPINA1 is linked to nephrotic syndrome.