Kidney pathology in COL4A-associated FSGS often demonstrate glomerular basement membrane abnormalities. Female patient (6062) with COL4A3-associated disease showing (A) segmental scarring (periodic acid–Schiff staining, ×20 magnification), and on (B) ultrastructural examination, diffusely thin glomerular basement membranes, and extensive podocyte foot process effacement, at approximately 80% (×10,000 magnification). Female patient (6251) with NPHS2-associated disease showing (C) enlarged glomeruli (periodic acid–Schiff staining, ×10 magnification) and one glomerulus with a segmental scar (not shown). (D) Ultrastructural examination shows normal thickness glomerular basement membranes and diffuse podocyte foot process effacement, at approximately 90% (×6000 magnification).