Because the structural renal cystic burden indices (e.g. KL) reflect a cumulative effect of the disease activity that is exerted over years, the weaker and insignificant association between the cumulative cystic burden index and CD206+ indices further support the potential utility of the urinary CD206+ resident macrophage-like cells as a marker of the disease activity in ADPKD. The gene discussed is MRC1; the disease is autosomal dominant polycystic kidney disease.