SDC4 and Balkan nephropathy: We have recently reported that knock-out (KO) of the HSPG receptor syndecan-4 (Sdc4) ameliorates fibrosis in the murine unilateral ureteric obstruction (UUO) and aristolochic acid nephrotoxicity (AAN) models, and that this is connected with a lower level of extracellular TG2 protein and activity27.