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About MPS I

MPS I (also known as Hurler, Hurler-Scheie, and Scheie Syndromes) is an inherited lysosomal storage disorder caused by the deficiency of an enzyme called alpha-L-iduronidase.

This enzyme is required for the breakdown of certain substances in the body known as glycosaminoglycans (commonly referred to as GAGs). Glycosaminoglycans are complex substances produced by the body that are found in all types of connective tissue. Connective tissue provides structural support to organs and tissues and makes up the cartilage of growing bones, joints, and heart valves. Without sufficient quantities of this enzyme, GAGs accumulate in virtually all organs of the body causing progressive disease.

The incidence of MPS I is estimated at about 1 in 100,000 births.

Even though many patients with this disease may have the same enzyme deficiency, patients with this disease can have a wide range of symptoms and experience variable degrees of disease severity.

Signs and Symptoms

Common symptoms of MPS I: 

  • Frequent ear and lung infections
  • Slow growth
  • Upper airway obstruction and reduced pulmonary function
  • Enlarged liver and spleen
  • Joint deformities and reduced range of motion
  • Sleep apnoea (temporary cessation of breathing during sleep)
  • Malaise and reduced endurance
  • Delay and regression of mental development
  • Impaired vision and hearing
  • Impaired cardiovascular and heart function


Before a diagnosis is made, patients may see several specialists since some of the early signs and symptoms of MPS I are commonly seen in many children. As MPS I is a rare disease, physicians may not consider MPS I as a diagnosis.

There are two methods your physician can use to diagnose MPS I. One of the first steps is to look for abnormally high levels of glycosaminoglycans (GAGs) in a urine sample. A definitive diagnosis of MPS I is established by testing the level of enzyme activity in a blood or skin sample.

Family Screening

MPS I is an inherited disorder, and therefore family screening is extremely important. One diagnosis of MPS I may uncover other affected siblings within a family. With early diagnosis, the disease may be better managed.

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Tel: +01440 703522
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