The disease of MPS caused by the deficiency of one of the lysosomal enzymes involved in the glycosaminoglycan (GAG) breakdown pathway.
This metabolic block leads to the accumulation of GAG. Fragments of partially degraded GAGs accumulate in the lysosomes of the various organs and tissues of the affected patients, resulting in cellular dysfunction and clinical abnormalities.
Glycosaminoglycans (GAGs) are large, complex polymers of linear, repeating sulfated acidic and amino sugar disaccharide units attached to a protein core. They are widely distributed in many tissues, where they play important roles. These cells help build bone, cartilage, tendons, corneas, skin, and connective tissue. Glycosaminoglycans (formerly known as mucopolysaccharides) are also found in the fluid lubricating our joints.
MPS occur worldwide in various forms though have relative a low incidence. The prevalent type of MPS varies among different continents, indicating that it may be associated with region and ethnic background.
It is estimated that one in 25,000 newborn children has some type of mucopolysaccharidosis (an incidence of 1:25,000).
Undegraded glycosaminoglycans (GAGs) induced by deficiency of enzymes are the primary cause of MPS. Clinical features differ depending on the specific enzyme deficiency including coarse facial features, cognitive retardation, hepatosplenomegaly, hernias, kyphoscoliosis, corneal clouding, etc.
To date, eleven enzyme defects that cause seven different types of MPS have been identified.
*MPS type I. Hurler syndrome. Hurler-Scheie syndrome. Scheie syndrome.
*MPS type II (Hunter syndrome)
*MPS type III (Sanfilippo syndrome)
*MPS type IV (Morquio syndrome)
*MPS type VI (Maroteaux-Lamy syndrome)
*MPS type VII (Sly syndrome)
*MPS type IX (Hyaluronidase deficiency)
MPS I is the most common. People with MPS I do not make an enzyme called lysosomal alpha-L-iduronidase. This enzyme helps break down long chains of sugar molecules called glycosaminoglycans. These molecules are found throughout the body, often in mucus and in fluid around the joints.
Disease of mucopolysaccharidosis
