The kidneys of aged Grn-/- mice showed significantly higher numbers of F4/80+ macrophages within the interstitium and perivascular regions (Fig. 3A; renal cortex P 0.039; renal medulla P = 0.0031), but H&E and PAS stainings (Fig. 3B) did not reveal signs of glomerulonephritis, tubulonephritis or tubulosclerosis. This evidence concerns the gene GRN and glomerulonephritis.