source: National Institute of Neurological Disorders and Stroke
The mucopolysaccharidoses are a group of inherited metabolic diseases caused by the absence or malfunctioning of certain enzymes the body needs to break down molecules called glycosaminoglycans—long chains of sugars (carbohydrates) in each of our cells. These cells help build bone, cartilage, tendons, corneas, skin, and connective tissue. Glycosaminoglycans (formerly called mucopolysaccharides) are also found in the fluid that lubricates our joints.
People with a mucopolysaccharidosis disorder either do not produce enough of one of the 11 enzymes required to break down these sugar chains into proteins and simpler molecules or they produce enzymes that do not work properly. Over time, these glycosaminoglycans collect in the cells, blood, brain and spinal cord, and connective tissues. The result is permanent, progressive cellular damage that affects the individual’s appearance, physical abilities, organ and system functioning, and, in most cases, mental development. Symptoms may be similar or vary among the different types of the disorder.
The mucopolysaccharidoses are classified within a larger group of disorders called lysosomal storage diseases. These are conditions in which large numbers of molecules that normally break down or degrade into smaller pieces in intracellular compartments called lysosomes accumulate in harmful amounts in the body’s cells and tissues, particularly in the lysosomes. The main function of lysosomes is to digest nonfunctional cell and other materials (including bacteria and cellular debris).