Long chains of sugar molecules that are found throughout the body, often in mucus and in fluid around the joints.

They are more commonly called glycosaminoglycans.

When the body cannot break down mucopolysaccharides, a condition called mucopolysaccharidoses (MPS) occurs.

Mucopolysaccharidoses refers to a group of inherited disorders of metabolism. People with MPS do not have any, or enough, of a substance (enzyme) needed to break down the sugar molecule chains.