MPS (Unknown Type)

What else is it called?

  • Mucopolysaccharidoses  
  • MPS disorder 

Subdivisions of Mucopolysaccharidoses (MPS) 

  • MPS 1 H/S (Hurler/Scheie syndrome) 
  • MPS I H (Hurler disease) 
  • MPS II (Hunter syndrome) 
  • MPS III A, B, C, and D (Sanfillipo syndrome) 
  • MPS I S (Scheie syndrome) 
  • MPS IV A and B (Morquio syndrome) 
  • MPS IX (hyaluronidase deficiency) 
  • MPS VII (Sly syndrome) 
  • MPS VI (Maroteaux-Lamy syndrome) 

Get in touch

Contact our caring team on 08452 412 173 for help and support. Our phone lines open 10am-4pm, Monday to Friday.

Prefer to email? Our email address is contact@metabolicsupportuk.org.

What causes it?

All MPS disorders are caused by a lack or malfunction (problem) of a specific lysosomal enzyme which is needed to break down dermatan sulfate, heparan sulfate or keratan sulfate. When these mucopolysaccharides cannot be broken down, there will be a build-up in the cells, tissues and organs throughout the body. This leads to the various symptoms associated with MPS disorders.  

How common is it?

The estimated prevalence of all forms of MPS is 1 in 25,000 births. However, the milder forms of this condition often go unrecognized, leading to underdiagnosis or misdiagnosis. This makes it difficult to know the exact prevalence of MPS in the general population. 

 

What are the signs and symptoms?

There are several symptoms that are common amongst many MPS disorders including:  

  • Problems with multiple organs 
  • Distinctive “coarse” facial features  
  • Joint problems  
  • Short stature (height significantly shorter than average) 
  • Heart abnormalities  
  • Irregular breathing  
  • Enlarged liver and spleen (hepatosplenomegaly) 

The severity of the symptoms of the different MPS disorders can vary greatly amongst patients, even among those with the same type of MPS disorder or patients within the same family. 

Individuals with MPS usually appear normal at birth and symptoms start around the age of one or two years. In the exception of MPS VII, where approximately 40% of pregnancies with an affected baby result in complications by a condition called non-immune hydrops fetalis. For more information on this, refer to the summary for MPS VII.  

For more information about symptoms specific to one type of MPS, refer to these summaries. 

How is it diagnosed?

A diagnosis of MPS is made through clinical evaluation, identification of characteristic symptoms and a variety of specialized tests including urine tests to detect excess levels of mucopolysaccharides and enzyme assays to detect deficient levels of lysosomal enzymes in the cells of the body.  

Newborn screening for MPS I has recently been approved in some states in the US. MPS I (or any other MPS disorders) are currently not included in the newborn screening in the UK. 

Can it be treated?

Treatment for most forms of MPS is aimed at specific symptoms present in each individual.  

A number of special drugs have been approved for the treatment of MPS VI, MPS I, MPSII, MPS VI and MPS IVA. For more information on this, please refer to the individual summaries specific to these conditions.  

Surgery may be necessary in some cases to treat a number of symptoms associated with MPS such as carpal tunnel syndrome (a common condition that causes pain, numbness, and tingling in the hand and arm), skeletal abnormalities and hernias.  

Physical therapy and exercise may also help improve joint stiffness.  

Do my family need to be tested?

All MPS disorders are inherited in an autosomal recessive pattern, except for Hunter syndrome (MPS II), which is inherited in an X-linked recessive pattern. 

*Please look at the summary for Hunter syndrome/ MPS II for more information regarding this inheritance pattern.  

For all other MPS conditions: 

MPS is an inherited condition. Humans have chromosomes made up of DNA. Genes are pieces of DNA that carry the genetic information. Each chromosome may have several thousand genes. We inherit chromosomes from the egg of the mother and sperm of the father. The genes on those chromosomes carry the instructions that determine a person’s characteristics, which are a combination of the parents. 

The pattern of inheritance of MPS is autosomal recessive. This means that carriers of the condition do not have the disorder because the other gene of this pair is working normally. Parents of children with MPS are carriers.  

When both parents are carriers, the risk to the baby in each pregnancy is 

  • 25% chance (1 in 4) of developing the condition 
  • 50% chance (1 in 2) for the baby to be a carrier of the condition 
  • 25% chance (1 in 4) for the baby to have two working genes and neither have the condition nor be a carrier 

Genetic counselling can be requested to get a full explanation.  

Relevant Organisations

References

References are available on request. Please contact Helen Morris by phoning 0845 241 2173 or emailing helen@metabolicsupportuk.org [Resource Library No: AAP002]. 

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