MPS I disease is a rare inherited disease caused by a deficiency in an enzyme called alpha-L-iduronidase. Globally, MPS I occurs in about 1 in every 100,000 births.

About MPS I

MPS I (Mucopolysaccharidosis Type I) is a progressive, debilitating and often life-threatening disease. It is an inherited disorder caused by a deficiency of an enzyme called alpha-L-iduronidase (pronounced al-fa el eye-dur-on-I-dase). This enzyme is required for the breakdown of certain substances in the body commonly referred to as GAGs (glycosaminoglycans). As more and more GAGs build up in a person's body, almost all organs can be irreversibly damaged. Therefore, early diagnosis and treatment of MPS I is important.

MPS I is a broad spectrum disease and has also been called Hurler, Hurler-Scheie, and Scheie Syndromes. The incidence of MPS I is estimated to 1:111,000.1

Signs and Symptoms

Even though many people with MPS I have the same enzyme deficiency, they may experience a wide range of symptoms and many people have different degrees of disease severity.

Possible signs and symptoms include coarse facial features, enlarged tongue, vision impairment, hearing loss, gastro-intestinal upsets, hydrocephalus, skeletal deformities (joint stiffness, carpel tunnel syndrome, short stature), obstructive airway disease and cardiovascular disease.

People with the most severe form of MPS I (Hurler) typically have central nervous system involvement that worsens over time. Their lifespan is approximately eight to ten years. Individuals at the opposite end of the spectrum (Hurler-Scheie and Scheie) have symptoms that progress over time, with patients showing normal intelligence. These patients may also have a normal lifespan.

Ben, USA, MPSI patient

Additional Information

To learn more about MPS I contact your doctor or other healthcare professionals, or the following patient associations:

Mucopolysaccharide and Related Diseases Society Aust. Ltd
PO Box 623, Hornsby NSW 1630
T: 02 9476-8411
F: 02 9476-8422


  1. Meikle PJ, Hopwood JJ, Claque WF. Prevalence of lysosomal storage disorders. JAMA. Jan 20;281(3):249-54.
Last Updated: 12/12/2014
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