Urinary glycosaminoglycans in aspartylglycosaminuria: evidence for disturbed proteoglycan metabolism.

An abnormal excretion pattern of urinary glycosaminoglycans was found in patients with aspartylglycosaminuria, a lysosomal storage disorder of glycoprotein metabolism. The mean daily GAG excretion, measured as uronic acids, was within the reference range, though higher than that of matched controls. However, in AGU patients fractionation of isolated urinary glycosaminoglycans revealed markedly increased proportions of heparan sulfate which were nearly 50% of the total glycosaminoglycans. The changes observed in glycosaminoglycan excretion reflect abnormalities of proteoglycan metabolism. They offer further evidence for the presence of a generalized connective tissue disorder in aspartylglycosaminuria. Increase of heparan sulfate may also refer to abnormalities of glycosaminoglycan metabolism in the central nervous system with a possible role in the neurological manifestations of the disorder.