Mucopolysaccharidosis type I is a rare condition in which the body lacks or does not have enough of an enzyme required to break down long chains of sugar molecules. These molecular chains are known as glycosaminoglycans (formerly called mucopolysaccharides). Consequently, the molecules accumulate in various body places, causing multiple health issues.

People with Mucopolysaccharidosis type I do not produce the enzyme lysosomal alpha-L-iduronidase. This enzyme aids in the breakdown of glycosaminoglycans, which are long chains of sugar molecules. These molecules are present throughout the body, most notably in mucus and fluid surrounding the joints.

Without the enzyme, glycosaminoglycans accumulate and harm organs such as the heart. The severity of the symptoms might vary from minor to severe. Moreover, the moderate variant attenuates MPS I, whereas the intense version is severe Mucopolysaccharidosis type I.


There are various kinds of MPSs, such as:

  • MPS I
  • MPS II (Hunter syndrome)
  • MPS III (Sanfilippo syndrome)
  • MPS IV (Morquio syndrome)


Mucopolysaccharidosis type I usually emerge between the ages of 3 and 8. Children with severe MPS I have symptoms sooner than those with a less extreme variety.

Some of the symptoms are as follows:

  • Spine bones that are not typical
  • Inability to open the fingers completely (claw hand)
  • Corneal cloudiness
  • Deafness
  • Halted growth
  • Heart valve issues
  • Joint inflammation, including stiffness
  • Intellectual impairment that worsens over time (commonly on severe cases of MPS I) 
  • Face characteristics that are thick and coarse, with a low nasal bridge


If MPS I symptoms continue to persist and hinder your daily routines, visit your health care provider at once.


As a part of the overall newborn screening process in some jurisdictions, infants are checked for Mucopolysaccharidosis type I.

The following are some examples of additional tests that they might perform based on the symptoms:

  • ECG
  • Identification of alterations in the alpha-L-iduronidase (IDUA) gene using genetic testing
  • Extra mucopolysaccharide urine tests
  • A spine X-ray


Treatment will be determined by which organs were affected by MPS I. For instance, there is a possibility that enzyme replacement treatment may be advised for Mucopolysaccharidosis type I. The medication known as laronidase (Aldurazyme) may also be administered intravenously (IV, intravenously). It acts as a substitute for the enzyme that was lost. For more information, you should consult your child’s provider.

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