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Genetic and Rare Diseases Information Center (GARD)

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Mucopolysaccharidosis type II

Other Names for this Disease
  • Attenuated MPS (subtype; formerly known as mild MPS II)
  • Hunter syndrome
  • I2S deficiency
  • Iduronate 2-sulfatase deficiency
  • MPS 2
More Names
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What is mucopolysaccharidosis II (MPS II)?

How is mucopolysaccharidosis II (MPS II) inherited?

Is carrier testing for mucopolysaccharidosis II (MPS II) available?

What is mucopolysaccharidosis II (MPS II)?

Mucopolysaccharidosis II (MPS II), also commonly known as Hunter syndrome, is a condition that occurs almost exclusively in males. Affected individuals typically have distinctive facial features, a large head, hydrocephalus, an enlarged liver and spleen, umbilical or inguinal hernia, and hearing loss. Individuals with this condition may have joint deformities and heart valve problems. MPS II is caused by mutations in the IDS gene.[1]

There are two types of MPS II, called the severe and attenuated types. While both types affect many different parts of the body, people with the severe type also experience a decline in intellectual function and a more rapid disease progression. The life expectancy for people with the severe type is 10 to 20 years. Individuals with the attenuated type typically live into adulthood and their intelligence is not affected. Heart disease and airway obstruction are major causes of death in people with both types of MPS II.[1]
Last updated: 12/29/2008

How is mucopolysaccharidosis II (MPS II) inherited?

MPS II is inherited in an X-linked recessive pattern, which means that this conditions occurs almost exclusively in males. Females are generally unaffected carriers of this condition. In a family with more than one affected individual, the mother of the affected males must be a carrier. When a carrier female has a child, there is a 25% (1 in 4) chance that she will have a affected son.[1]
Last updated: 9/20/2013

Is carrier testing for mucopolysaccharidosis II (MPS II) available?

Yes, carrier testing for MPS II is available. Testing usually begins with an affected male relative, if one is available for testing, to determine the disease-causing mutation. If there is not living affected male relative, testing possible female carriers involves a type of genetic testing called sequence analysis. This test requires a small blood sample and reads through the genetic code of the IDS gene looking for errors. If a mutation is not found using sequence analysis, then two other tests can be performed to look for mutations that cause MPS II. Genetic testing detects most of the mutations that cause MPS II, but may not detect all mutations that cause this condition  Therefore, testing cannot definitively determine that a person is not a carrier for MPS II.[1]

The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. Click here to link directly to a list of labs conducting carrier screening for MPS II. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.


Last updated: 9/20/2013

  1. Martin RA. Mucopolysaccharidosis Type II. Gene Reviews. November 6, 2007; Accessed 12/29/2008.