The Mucopolysaccharidosis I (MPS I) Registry is an ongoing, observational database that tracks the outcomes of patients with MPS I. The data collected by the MPS I Registry will provide information to better characterize the natural history and progression of MPS I as well as the clinical responses of patients receiving enzyme replacement therapy, such as Aldurazyme (Recombinant Human Alpha-L-Iduronidase), or other treatment modalities.

The objectives of the Registry are:

• To evaluate the long-term effectiveness and safety of Aldurazyme® (laronidase)
• To characterize and describe the MPS I population as a whole, including the variability, progression, and natural history of MPS I
• To help the MPS I medical community with the development of recommendations for monitoring patients and reports on patient outcomes to optimize patient care

The MPS I Registry is an international program; in addition to the central contact information provided under the "Location" heading, patients may contact:

• In Asia-Pacific - Vivian Liu, +65-6431-2548, Vivian.liu@genzyme.com
• In Europe - +31-35-699-1232, europe@mpsiregistry.com
• In Latin America - +617-591-5500, help@mpsiregistry.com
• In North America - +617-591-5500, help@mpsiregistry.com

Inclusion Criteria:

• All patients with a confirmed diagnosis of MPS I are eligible for inclusion. Confirmed diagnosis is defined as: A. documented biochemical evidence of a deficiency in alpha (a)-L-iduronidase enzyme activity and/or B. mutation(s) in the gene coding for a-L-iduronidase, or measurable clinical signs and symptoms of MPS I
• For all patients there should be a completed patient authorization form

Exclusion Criteria:

• No exclusion criteria for participation in the MPS I Registry. NOTE: Registry participation does not exclude participation in other clinical studies.

All Patients with MPS I