- What is the definition of Mucopolysaccharide?
- What are Mucopolysaccharide diseases?
- What is the cause of these diseases?
- How are they inherited?
- What are the effects?
- Is there a cure?
- Which diseases are classified as Mucopolysaccharide Diseases?
Mucopolysaccharides are long molecular chains of sugar. They are used by the body in the building of connective tissues. The word “Mucopolysaccharide” can be broken down as follows:
- “muco” refers to the thick jelly-like consistency of the molecules
- “poly” means many
- “saccharide” is a general term for a sugar molecule
These rare metabolic diseases are refered to as MPS I-VII or more commonly by the name of the doctor who first described the condition. These commonly include
- Maroteaux Lamy
Also included are the Mucolipidoses, other ‘storage diseases’ and the following conditions which are similar to Mucopolysaccharide:-
- MLI Neuramidase Deficiency
- MLII I-Cell Disease
- MLIII Pseudo Hurler Polydystrophy
- MLIV / Sialidosis / Fucosidosis
- Mannosidosis / Sialic Acid Storage Disease
- Multiple Sulphatase Deficiency
- Winchester Syndrome
There is a continuous process in the body of replacing used materials and breaking them down for disposal. Children born with a Mucopolysaccharide or related disease are unable to produce one of the enzymes essential for this process. If even one enzyme is missing, the cycle is interrupted. Used materials cannot be broken down and remain stored in the cells of the body.
Babies may show no sign of the disease, but as more and more cells become damaged by the storage of used material, symptoms begin to appear. Sadly these are progressive diseases which lead to an increase in problems as the years go by.
We all have genes inherited from our parents, which control our height, eye colour, hair colour etc. Some genes we inherit are recessive, that is to say, we carry the gene but it does not have any effect on our characteristics or development. The Mucopolysaccharide diseases are caused by such recessive genes. In all MPS and related disorders except Hunter Disease, both men and women can be carriers.
The effects vary from one disease to another. Some sufferers may be mildly affected, but for many the diseases cause severe disabilities. In most cases growth is restricted. Some diseases cause progressive mental as well as physical handicap. Those diseases causing severe mental handicap may also lead to death in childhood.
At present there is no cure. Research funded by the MPS Society on Gene Therapy for Hurler Disease was carried out on three patients in 1998. More recently the development of ‘Enzyme Replacement Therapy’ (ERT) for Fabry and MPS I has been approved as a treatment and ERT for MPS II and MPS VI has reached the clinical trial stage for MPS Type I. This is being developed jointly by Biomarin and Genzyme pharmaceutical companies. Early indications from the clinical trials are promising, but there are still serious obstacles to overcome if there is to be enzyme replacement therapy for all types of Mucopolysaccharide and related diseases.