Hunter

Society for Mucopolysaccharide Diseases
MPS House, Repton Place, White Lion Road, Amersham, Buckinghamshire, HP7 9LP, UK
Tel: 0845 389 9901 Fax: 0845 389 9902
National Registered Charity No. 287034

Hunter Disease (MPS II)

Introduction
Hunter disease is one of the mucopolysaccharide diseases and is also known as MPS Type II. Hunter disease takes its name from Charles Hunter, the professor of Medicine in Manitoba, Canada, who first described two brothers with the disorder in 1917.

It is devastating news for parents to learn that their child has Hunter disease and some time may pass before it is clear how severely affected the child will be. It is important to remember that the disease is very varied in its effects and that your child will not necessarily have all the symptoms described.

The MPS Society has produced a booklet which shows that, while no magic cure exists, there are many ways of helping children and adults to enjoy their lives and to manage the problems they may have. The booklet has been developed in collaboration with parents and doctors, drawing on their experiences and with reference to medical literature.

What causes Hunter disease?
Mucopolysaccharides are long chains of sugar molecules 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 and '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 sulphate sulphatase which is essential in cutting up the mucopolysaccharides called dermatan and heparan sulphate. The incompletely 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 disease?
The MPS Society which co-ordinates the Registry for Mucopolysaccharide and Related Diseases has shown that this is a rare condition affecting one in 150,000 live births. Over a ten year period 39 babies with Hunter Disease were born in the United Kingdom.

How is it inherited?
Hunter disease has a different form of inheritance from all the other MPS diseases as it is 'sex linked' like haemophilia. Girls may be carriers of the disease but, except in very rare cases, only boys will be sufferers. The few girls who have been found to have the disease have an associated chromosomal abnormality.

All families of children with Hunter disease should seek further information from their doctor or from a genetic counsellor before planning to have more children. If the mother is a carrier there is a 1 in 2 risk that any boy born to her will have the disease and that any girl will be a carrier.

The sisters and maternal aunts of an individual with MPS II may be carriers of the disease who would also have a 1 in 2 chance of passing the disease to a son.

In many families it is possible to detect female carriers by direct analysis of the genetic material. The doctor may wish to take a sample of blood from your affected child so that the exact genetic abnormality can be detected.

There is a more detailed explanation of this complex subject in a booklet on the pattern of inheritance available from the MPS Society.

Is there a cure?
At present there is treatment for symptoms as they arise, but no cure for the disease. Research continues to try to find a way of replacing the missing enzyme.

Prenatal diagnosis
If you already have a child with Hunter disease, if you know you are a carrier, or if you have not been carrier tested but are related on the mother's side to a boy with Hunter's Disease, it will be possible to have tests during a subsequent pregnancy to find out whether the baby you are carrying is affected. It is important to contact your doctor as soon as you suspect that you may be pregnant if you wish tests to be arranged. If you have any difficulty please contact the Society without delay.