Glycosaminoglycan excretion in connective tissue diseases

Abnormal glycosaminoglycan metabolism has been widely studied in cases of mucopolysaccharidoses (MPSD) with increased acid glycosaminoglycan (aGAG) excretion. A disorder in aGAG metabolism can be confirmed in several diseases with known etiology. We have carried out a comparative study on the urinary aGAG output in systemic connective tissue diseases and in childhood cases of MPSD. In children suffering from rheumatoid arthritis or scleroderma, the urinary aGAG output did not surpass 80% of the value excreted in MPSD; furthermore, 20 to 30% was uronic acid. In the case of osteogenesis imperfecta the remarkably high amount of excreted aGAG contained over 60% uronic acid.