Maroteaux Lamy Disease

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

Maroteaux-Lamy Disease (MPS VI)

Maroteaux-Lamy disease, also known as MPS VI, is one of the rarer mucopolysaccharide diseases. It takes its name from two French doctors, Dr Maroteaux and Dr Lamy, who first described the condition in 1963.

The disease varies enormously in the severity of the problems it causes. It is important to remember this variation if you are a parent of a newly diagnosed child. There are a range of possible symptoms but this does not mean your child will experience them all, or that he or she will be severely affected by them. In fact some patients have very few physical problems and are able to lead a relatively normal life.

What causes Maroteaux-Lamy disease?
There is a continuous process in the body of replacing used materials and breaking them down for disposal. Children with Maroteaux-Lamy disease are missing an enzyme which is essential in cutting up the mucopolysaccharide called dermatan sulphate. The incompletely broken down mucopolysaccharides cannot be used in the proper development of bones and cartilage and 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 Maroteaux-Lamy disease?
The MPS Society has data which show that over a ten-year period 5 babies with Maroteaux-Lamy disease were born in Britain. A particularly severe form of the disease has been reported among Australian aborigines. It also occurs in Siamese cats.

How is the disease inherited?
We all have genes inherited from our parents which control whether we are tall, short, fair etc. Some genes we inherit are 'recessive', that is to say we carry the gene but it does not have any effect on our development. Maroteaux-Lamy disease is caused by a recessive gene. If an adult carrying the abnormal gene has a partner who is another carrier there will be a one in four chance with every pregnancy that the child will inherit the defective gene from each parent and will suffer from the disease. There is a two in three chance that unaffected brothers and sisters of children with Maroteaux-Lamy disease will be carriers. They can be reassured however that, as the disease is so rare, the chance of having a partner who is another carrier is very slight as long as their partner is not a cousin or other blood relative.

All families of affected children should seek further information from their doctor or genetic counsellor before planning to have more children. There is a more detailed explanation of this complex subject in the booklet on the pattern of inheritance available from the MPS Society.

At the time of writing there are no tests which can predict whether a child will be mildly or severely affected.

Is there a cure?
Bone marrow transplants have been used to treat patients with Maroteaux-Lamy disease and, although not a cure, have helped to relieve some of the symptoms of the disease. There are considerable risks involved in bone marrow transplantation and it is important to take time to weigh up these risks and the possible advantages. If you wish, the Society can put you in touch with parents whose children have already had this treatment so that you can be better informed before taking a decision.

It is possible that one day a laboratory may be able to produce the missing enzyme which could then be given to patients to replace what they are lacking (enzyme replacement therapy). Progress is being made but it is important to recognise that research programmes take many years and are often affected by unexpected delays. At the time of writing no one can say when or if such a treatment will be available.

Prenatal diagnosis
If you already have a child with Maroteaux-Lamy 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.

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