Mucopolysaccharidoses consist of a group of inherited metabolic disorders caused by a deficiency of the specific lysosomal enzymes needed to break down mucopolysaccharides. Mucopolysaccharides are long chains of sugar molecules used to build connective tissues and organs in the body. When mutations occur in the genes for the enzymes involved in the normal turnover of mucopolysaccharides, excess amounts of them are stored in the body, causing progressive damage and, in most cases, eventual death. Because some of the excess mucopolysaccharides are excreted through the urine, diagnosis often can be made through clinical examination and urine tests.
Prenatal diagnosis is also available.
Eight clinical types and numerous subtypes of mucopolysaccharidoses have been identified. Death usually occurs before age 10. MPS II, also called Hunter syndrome, affects juveniles and includes a mild and a severe form. Signs of the severe form are joint stiffness, mental deterioration, dwarfing, and progressive deafness. Death usually occurs by age 15.