Lysosomal glycosaminoglycans containing beta-D-glucuronic acid residues (GlcA-GAGs)

Lysosomal glycosaminoglycans containing beta-D-glucuronic acid residues are complex, long-chain polysaccharides that accumulate pathologically in individuals with Mucopolysaccharidosis type VII (MPS VII), also known as Sly syndrome (NORD, 2023). These molecules, which include dermatan sulfate, heparan sulfate, and chondroitin sulfate, are normally degraded in a stepwise fashion within the lysosome. The enzyme beta-glucuronidase is specifically responsible for cleaving the terminal beta-D-glucuronic acid residues from the non-reducing ends of these chains (UniProt P08236). In the absence of functional beta-glucuronidase, these partially degraded chains remain trapped within lysosomes, leading to progressive cellular damage, organomegaly, and skeletal abnormalities. Therapeutic intervention typically involves enzyme replacement therapy, such as vestronidase alfa, which provides the exogenous enzyme necessary to resume the breakdown of these accumulated residues (FDA Mepsevii Label, 2017). Monitoring the reduction of these glycosaminoglycans in the urine is a primary method for assessing treatment efficacy and disease progression.

Other names

Glucuronic acid-containing glycosaminoglycansBeta-D-glucuronic acid-terminated GAGsMucopolysaccharidesLysosomal GAGs

Vestronidase alfa, a recombinant human beta-glucuronidase, provides the exogenous enzyme required to catalyze the hydrolysis of terminal beta-D-glucuronic acid residues from the non-reducing ends of accumulated glycosaminoglycans within the lysosome (FDA Mepsevii Label, 2017).