Massive accumulation of glycosaminoglycans in the aortic valve of a patient with Hunter syndrome during enzyme replacement therapy.

This report describes the pathologic findings for a patient with Hunter syndrome who underwent aortic valve replacement at 10 years of age, 3 years after the initiation of enzyme replacement therapy. Aortic valve pathology showed mild thickening and fibrosis as well as massive glycosaminoglycan accumulation. This suggests that enzyme replacement therapy has limited efficacy for cardiac valve disease both clinically and pathologically.