Editor—Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by deficiency of the enzymes catalysing the stepwise degradation of glycosaminoglycans (GAG). Bone marrow transplantation can slow down or reverse some of the features of these diseases. Enzyme replacement (ERT) studies in several animal models of MPS disorders have shown promising results1-3; human clinical trials of ERT in MPS type I have only recently become possible.4 The clinical symptoms of MPS usually become evident only between the second and third years of life. This therefore argues for early therapeutic intervention before the development of irreversible changes.

Quantitative measurement of urinary GAG (glycosaminoglycans) can be used to …