The GUSB gene encodes beta-glucuronidase, a lysosomal hydrolase involved in the stepwise degradation of glucuronic acid-containing glycosaminoglycans. It is a tetrameric glycoprotein composed of identical subunits. GUSB plays an important role in the degradation of dermatan and keratan sulfates. GUSB has two isoforms with the molecular mass of 75 kDa and 69 kDa, and it always can be detected as 78 kDa, 60 kDa and 18 kDa.