MPS III Sanfilippo

Mucopolysaccharides are long chains of sugar molecules used in the building of bones, cartilage, skin, tendons and many other tissues in the body. “Muco” refers to the thick jelly-like consistency of the sugar molecules, “poly” means many, and “saccharide” is a general term for the sugar part of the molecule. In the course of normal life there is a continuous recycling process of building new mucopolysaccharides and breaking down old ones. The breakdown and recycling process requires a series of special biochemical tools called enzymes.

People with MPS III are either type A, B, C or D. Each type is missing or low in a specific enzyme

• MPS III A is caused by missing or altered heparan N sulphatase

• MPS III B is caused by missing or low in alpha-Nacetylglucosaminidase

• MPS III C is caused by missing or altered acetyl-CoAlpha-glucosaminide acetyltransferase

• MPS III D is caused by missing or low in N-acetylglucosamine-6-sulphatase

These enzymes are essential in breaking down mucopolysaccharides heparan sulphate. When heparan sulphate is not completely broken down it remains stored in the body. The symptoms of MPS III are a result of the build-up of heparan sulphate in the body. Babies may show little sign of the condition but as more and more cells build up with partially broken down heparan sulphate symptoms start to appear.