Mucopolysaccharidosis Type 4 (MPSIV)

What is Mucopolysaccharidosis type 4 disease (MPSIV)?

The mucopolysaccharisodes 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.

MPSVI is also referred to as Morquio syndrome.

How will this affect me?

In MPSIV the cells most commonly affected are in the connective tissue found throughout your body and in particular in your skeleton.

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

• Corneal clouding and sight impairment
• Hearing loss
• Significant skeletal abnormalities including extreme short stature, excessive rounding of the back, joint pains and knock knees
• Unstable neck
• Heart valve abnormalities
• Breathing difficulties - airway obstruction, sleep apnoea and restrictive lung disease
• Poor teeth
• Slightly enlarged liver
• Hypermobile joints

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?

MPSIV specific treatment (an enzyme replacement therapy) is available.

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.

How did I get MPSIV?

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 MPSIV 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.