MPS II (Hunter Syndrome)

MPS II is one of the mucopolysaccharide diseases and is also known as Hunter syndrome. It takes its name from Charles Hunter, the professor of medicine in Manitoba, Canada, who first described two brothers with the disease in 1917. MPS II has a wide range of symptoms that vary in severity.

There is no cure for MPS diseases, but there are ways of managing and treating the problems they cause, including enzyme replacement therapies.

What causes the disease?

Mucopolysaccharides are long chains of sugar molecule used in the building of connective tissues in the body.

  • “saccharide” is a general term for a sugar molecule (think of saccharin)
  • “poly” means many
  • “muco” refers to the thick jelly-like consistency of the molecules

There is a continuous process in the body of replacing used materials and breaking them down for disposal. Children with MPS II are missing an enzyme called iduronate sulfatase, which is essential in cutting up the mucopolysaccharides called dermatan and heparan sulphate. The incomplete broken down mucopolysaccharides remain stored in cells in the body causing progressive damage. Babies may show little sign of the disease, but as more and more cells become damaged, symptoms start to appear.

How common is Hunter Syndrome?

This is a rare condition affecting 1 in 100,000 to 1 in 150,000 males. There is an estimate in the United States that 1 in 25,000 births will result in some form of MPS.

How is the disease inherited?

MPS II occurs in boys, and girls may be carriers of the gene for MPS II. Although rare, MPS II has been diagnosed in girls.

All families of children with MPS II should seek further information from their doctor or genetic counselor before planning to have more children.

If the mother is a carrier, there is a 50% risk that any boy born will have the disease.

The sisters and maternal aunts of a person with MPS II may be carriers of the disease and would also have a 50% chance of passing the syndrome to a son. There are tests available for carriers, so it is important for all female relatives on the mother’s side to seek advice from their doctor.

Is there a Cure for MPS II?

There is no cure but treatments such as enzyme replacement therapies can help make the disease more manageable.

For more information on the treatment, visit

All families of affected children should seek further information from their doctor or from a Genetic Counselor.

For more information, please contact us at or by calling 1-800-667-1846.