Mucopolysaccharidoses are a group of metabolic lysosomal storage diseases caused by the absence or impaired function of lysosomal enzymes required for glycosaminoglycan metabolism. As a result, glycosaminoglycans accumulate in the cells, causing cellular damage which affects the function of multiple organs and, in most cases, leads to mental retardation.
Mucopolysaccharidosis I (MPS I) arises from impaired or absent alpha-L-iduronidase (IDUA) enzyme function and is categorized into three subtypes (Hurler syndrome, Hurler–Scheie syndrome and Scheie syndrome) based on severity of symptoms.