MPS IV Morquio

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 IV are either type A or B. Each type is missing or low in in a specific enzyme

• MPS IVA is missing or low in N-acetyl-galactosamine 6-sulfatase

• MPS IVB is missing or low in beta-galactosidase

These enzymes are essential in breaking down mucopolysaccharides keratan sulphate and chondroitin sulphate in type A and keratan sulphate in type B. When these mucopolysaccharides are not completely broken down they remain stored in the body. The symptoms of MPS IV are a result of the build-up of keratan sulphate and chondroitin sulphate in the body. Babies may show little sign of the disease but as more and more cells build up with partially broken down keratan sulphate and chondroitin sulphate symptoms start to appear.