(FSGS) a condition in which there is scarring in some (focal) glomeruli that affects only part (segmental) of the glomerular capillary tuft. Primary FSGS overlaps with *minimal change nephropathy and typically presents with the *nephrotic syndrome. Secondary FSGS has a wide range of causes, from viral infections, including HIV, to haemodynamic changes associated with reduced renal mass, hypertension, and obesity, and is usually associated with less severe proteinuria.