Enzyme replacement therapy in mucopolysaccharidosis type II (Hunter syndrome): a preliminary report. Acta Paediatr 2002; Suppl 439: 98-99. Stockholm. ISSN 0803-5326Mucopolysaccharidosis type II (MPS II; Hunter syndrome) is an X-linked disease caused by a de ciency of the enzyme iduronate-2-sulphatas e (IDS), which results in the lysosomal accumulation of glycosaminoglycans (GAG). This paper describes a knockout mouse model of MPS II which has been used to assess the effect of enzyme replacement therapy. Therapy with IDS results in a marked decrease in urinary GAGs, as well as reduced GAG accumulation in several tissues. These studies have been used to support the rst clinical trial of recombinant IDS in patients with Hunter syndrome.