In the course of normal life there is a continuous recycling process of building new materials and breaking down old ones ready for disposal. This activity takes place in a special part of the body’s cells called the lysosome. This process requires a series of biochemical tools called enzymes.
Normally, sulphatases a group of lysosomal enzymes, are responsible for breaking down and recycling complex sulphate containing molecules from both fats (lipids) and sugars (mucopolysaccharides). The sulphatase enzymes are switched on (activated) by an enzyme called Formylglycine Generating Enzyme (FGE). The activated sulphatases aid in breaking down substances that contain chemical groups known as sulphates. These substances include a variety of sugars, fats, and hormones.
In people with MSD FGE is not produced or does not function normally which results in the diminished functioning of all the different sulphatase enzymes. Sulphate-containing molecules that are not broken down build up in cells, often resulting in cell death. The death of cells in particular parts of the body, specifically the brain, skeleton, and skin, cause many of the signs and symptoms of MSD.
MSD has been classified into three types based on severity of symptoms. Symptoms can vary greatly but all forms share features of brain related impairment:
neonatal is the most severe
late-infantile type is the most common
juvenile type is the rarest.
