Progression of organ manifestations upon enzyme replacement therapy in a patient with mucopolysaccharidosis type I/Hurler.

BACKGROUND Enzyme replacement therapy (ERT) has been increasingly used as an interim treatment in severe mucopolysaccharidosis type I (MPSI)/Hurler patients prior to hematopoietic stem cell transplantation (HSCT). METHODS We present the outcome of a patient with MPSI/Hurler after 14 months of ERT prior to HSCT. RESULTS Urinary glucosaminoglycan excretion decreased by 70% after one month of ERT. Liver volume decreased by 14% of baseline after 12 months of ERT. Pre-existing thoracolumbar kyphosis progressed to thoracolumbar dislocation with complete displacement of facets after 12 months of ERT. New development of mitral valve thickening was found by echocardiography and mild hearing loss progressed to severe sensorineural hearing loss after 13 months of ERT. CONCLUSIONS ERT over a period of 14 months did not prevent progression of organ manifestations in our patient. Patients should be monitored every 6 months for cardiac, skeletal and audiological involvement on ERT.