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Mucopolysaccharidosis type II

(myoo-koh-PAH-lee-SAK-uh-rie-DOH-sis • type • 2)

General Condition Information

Other Names

  • Hunter
  • Hunter's Syndrome
  • MPS II (Hunter's Syndrome)

Condition Type

Birth Prevalence

  • It is estimated that fewer than 40 babies are born with this rare condition each year in the United States.
  • Visit GeneReviews to learn more about how often this condition occurs.

Screening Finding

Decreased iduronate-2-sulfatase (I2S) enzyme activity +/- increased GAG levels

What is mucopolysaccharidosis type ii

Mucopolysaccharidosis type II (MPS II) is one of a group of inherited (genetic) conditions that prevents the body from processing sugars properly. Mucopolysaccharidosis Type I is another condition in this group.

Your body uses complicated sugars called glycosaminoglycans (GAGs) in several important processes. An enzyme called iduronate-2-sulfatase (I2S) breaks down GAGs for your body to use. This process occurs in special compartments inside your cells called lysosomes.

MPS II results when I2S is absent or present at low levels. The lysosomes then have trouble breaking down GAGs. This causes a buildup of GAGs in the tissues that can result in problems throughout the body. GAGs used to be called mucopolysaccharides, which is how the condition got its name.

There are two main types of MPS II – the severe type and the attenuated type – that differ in signs, symptoms, and age of onset. The severity of the condition depends on how much I2S activity is present in the body. The amount of I2S activity depends on the type of genetic change that causes the disorder.

High levels of GAGs can damage many parts of the body. This damage leads to the signs and symptoms of the condition.

Newborn Screening and Follow-Up

Condition Details

Treatment and Management

It is important to talk to your health care provider about what type of evaluations may be useful to look for problems, and which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.

Testing may include:

  • X-rays
  • Ultrasound picture of the heart (echocardiogram)
  • Hearing tests

Treatments may include the following:

Health outcomes for MPS II vary based on a child’s form of the condition. For children with the attenuated form, early and ongoing treatment can lead to healthy growth and development. For children with the severe form, early treatment can prevent or delay some serious symptoms of the condition.

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