COL4A4 and focal segmental glomerulosclerosis: Where kidney biopsies are performed in individuals with a monoallelic P/LP COL4A3 or COL4A4 variant, various light microscopic abnormalities have been reported, including normal appearances, minimal change disease, mesangioproliferative nephritis, membranous nephritis, focal segmental glomerulosclerosis, tubulointerstitial nephritis and atrophy, and even IgA deposits [19, 20].