The objectives of this program are: to further characterize the natural progression of MPS VI disease; to generate and disseminate information on the care and management of MPS VI patients to clinical and medical professionals; to provide a resource to physicians and patients by providing information for optimizing patient care based on aggregate data; to characterize the clinical response to long-term Naglazyme® (galsulfase) treatment; to further characterize the long-term safety of Naglazyme® treatment.