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• 2: MPS Diseases
  • 2.1: Overview of symptoms
  • 2.2: Overview of treatment
  • 2.3: Which are the MPS Diseases
    • 2.3.1: MPS I
    • 2.3.2: MPS II
    • 2.3.3: MPS III
    • 2.3.4: MPS IVA
      • 2.3.4.1: Aisha's Story
    • 2.3.5: MPS VI
    • 2.3.6: MPS VII
    • 2.3.7: ML I
    • 2.3.8: ML II and III
    • 2.3.9: ML IV
    • 2.3.10: Fucosidosis
    • 2.3.11: Mannosidosis
    • 2.3.12: Sialic Acid Storage Disease
    • 2.3.13: MSD
    • 2.3.14: AGU
    • 2.3.15: Winchester
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MPS IVA Morquio Disease

Morquio disease is one of the mucopolysaccharide diseases also known as MPS IVA. It takes its name from Dr Morquio, a paediatrician in Uruguay, who in 1929 described a family of four children affected by the condition.

It is important to remember that Morquio disease varies widely in its severity; even individuals from the same family may be affected differently. A range of possible problems is described, but this does not mean that an individual will experience all of them. Some complications arise early in childhood, while others arise much later or may never occur.

What causes MPS IVA?

There is a continuous process in the body of replacing used materials and breaking them down for disposal. Individuals with Morquio disease are missing an enzyme which is essential in cutting up the mucopolysaccharide called keratan 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.

The usual form of Morquio disease is known as MPS IVA to distinguish it from the much rarer B form which is caused by the lack of a different enzyme. Sufferers with the B form have similar problems, but tend to be less severely affected.

How is MPS IVA 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. Morquio disease is caused by a recessive gene. If an adult carrying the abnormal gene marries 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 the disease. There is a two in three chance that unaffected brothers and sisters of Morquio sufferers 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 provided their partner is not a cousin or other close family member.

All families of affected children should seek further information from their doctor or from a genetic counsellor before planning to have more children. There is a more detailed explanation of this complex subject in a booklet available from the MPS Society on the Pattern of Inheritance in MPS diseases. Please visit our Information Resource section.

Prenatal diagnosis

If you already have a child with Morquio disease, it is possible to have tests during a subsequent pregnancy and to be told whether the baby you are carrying is affected. It is important to consult your doctor as soon as you suspect you might be pregnant if you wish tests to be arranged.

Further information

There is a detailed booklet on MPS IVA produced by the MPS Society in collaboration with parents and doctors drawing on their experience and with reference to medical literature. The booklet includes detailed information on the presentation and clinical management of the disease and treatment options available. Please visit our Information Resource section.

Personal story