The mucopolysaccharidoses (mew-ko-pol-ee-sak-ah-ride-oh-sees), or MPS disorders, are a family of diseases which are defined by the body’s inability to break down and recycle certain long sugar molecules called mucopolysaccharides (mew-ko-pol-eesak-ah-rides), more commonly known as glycosaminoglycans (gli-ko-sah-mee-nogli-cans) or GAGs. This is due to a deficiency or absence of an enzyme that is able to break down these GAGs.
The specific enzyme involved in this process determines which type of MPS a person has. In all types of MPS disorder, this enzyme deficiency means that the GAGs build up in cellular compartments called lysosomes throughout the body. Because of this, the MPS disorders also come under the umbrella of lysosomal storage disorders (LSDs), which are a group of disorders that are caused by the storage of toxic materials in lysosomes.
There are seven types of MPS disorder, all of which are categorized as rare genetic disorders as they affect less than 200,000 people in the U.S.