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Scientific literature and patient education texts

A Guide to Understanding MPS III (Sanfilippo Syndrome)

key information

source: National MPS Society

year: 2021


MPS III belongs to a group of inherited metabolic diseases called mucopolysaccharidoses (MPSs), a subgroup of lysosomal storage disorders (LSDs). MPS is a degenerative disease in which at least one long chain sugar carbohydrate called glycosaminoglycan accumulates in the lysosome, an organelle within cells. There are seven distinct clinical types of MPS, some of which have several subtypes. Each form of MPS is caused by deficiency of a specific enzyme, which is involved in the breakdown of one or more GAGs.

What Causes MPS III?

In healthy individuals, GAGs are used in the building of bones, cartilage, skin, tendons, and many other tissues in the body. For instance, the slippery synovial fluid that lubricates your joints contains GAG as does the rubbery cartilage in your joints. All tissues have some of this substance as a normal part of their structure. As more GAGs are produced, older GAGs are broken down; this is the normal cycle of events that maintains a healthy balance in the body. However, when this cycle does not function properly and GAGs are not broken down, they accumulate within the cells. This malfunction results in progressive, often permanent, cellular damage that affects the individual’s appearance, physical abilities, proper functioning of organs and systems, and, in most cases, mental development.


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