Mucopolysaccharidosis Type 1 (MPSI)

What is Mucopolysaccharidosis type 1 disease (MPSI)?

The mucopolysaccharidoses are a group of lysosomal storage disorders that share similar features. Your body is made up of trillions of individual cells and each cell contains a small part called the lysosome. This is primarily responsible for breaking down and recycling worn out cell components. Inside the lysosome are enzymes which perform this very important housekeeping role. In the mucopolysaccharidoses the necessary enzymes are not working effectively allowing these products to build up and become stored in very specific areas of your body. There are many different enzymes in your lysosomes, and deficiencies of each enzyme will cause a different disease. All of these different diseases together are called lysosomal storage disorders.

There are three forms of MPSI according to the severity of your symptoms and these are sometimes referred to as Hurler, Hurler-Scheie and Scheie.

How will this affect me?

In MPSI the cells most commonly affected are in the connective tissue found throughout your body and also sometimes the brain.

This means you may experience or be at risk of the following:

• Corneal clouding
• Stiff and painful joints
• Abnormal bone development
• Carpal tunnel syndrome
• Recurrent respiratory infections
• Obstructiv sleep apnoea
• Enlarged liver/spleen
• Hernia
• Hearing loss
• Poor teeth
• Fluid on the brain
• Cognitive difficulties

Not all people affected by MPSI will experience all of the symptoms described above and the progress of the disease in adults is extremely variable.

If you have any questions about the effects and progression of the disease please do ask your doctor or specialist nurse.

Is there any treatment?

For the severe form of MPSI bone marrow transplantation is usually carried out in childhood.

Treatment is currently available for some types of MPSI in the form of enzyme replacement therapy (ERT). All medication is supplied to you directly at home using a medical homecare delivery company.

Enzyme replacement therapy

This is an intravenous infusion usually administered every week. It provides you with extra enzyme that will supplement your own and help to reduce the amount of stored material in your cells. This is initially administered in hospital but after that you receive this treatment at home with a homecare nurse who will teach you how to manage your infusions for yourself when you are ready.

You can only receive this treatment for your MPSI if you attend one of the UK national referral centres at least once per year for regular assessment and review.

How did I get MPSI?

Your disease is a genetic condition which means that you inherited it from your parents. There are instructions in your genes for making lysosomal enzymes and a small change in the DNA can be enough to stop the enzyme from working properly. You have two copies of every gene, having received one from each parent.

To be affected by MPSI you need to have two copies of the gene with the DNA change on it – one from each parent. Only receiving one affected copy means you are a carrier and will not be affected. Please do talk to your doctor or specialist nurse who can explain this in more detail.

What do I need to do next?

Do ask your doctor or nurse for more information.

Do attend your regular appointments with the lysosomal disorders team so that we can ensure you receive the most appropriate care for your current difficulties and can keep you informed of any new developments.

You may find it helpful to contact your patient support group.

MPS society

Tel: 0345 3899901

Email MPS Society

Please visit the MPS Society (opens in a new tab)y

Contact us

LDU Box 135, Addenbrooke’s Hospital, Hills Road, Cambridge. CB2 0QQ

Tel: 01223 274634

Email LDU Cambridge

Please visit our Lysosomal disorders webpage

Please note the department is open Monday to Friday 08:30-17:00.

If you are unwell outside of these hours you should seek medical advice from your local healthcare team.

If your emergency doctor needs specific advice they should call the hospital switchboard on 01223 245151 and ask for the metabolic consultant on call.