Mucopolysaccharidosis (MPS)

One of a series of inherited metabolic disorders affecting a type of complex carbohydrate called a mucopolysaccharide that is deposited in body tissues because the person lacks the specific enzyme needed to metabolize it. The deposition of mucopolysaccharide in tissues damages and distorts them, stunts the child's growth and development, limits their joint movement and in some (but not all) types of MPS causes mental retardation. The condition usually becomes evident in early childhood. That something is wrong may be noticed by parents or doctors. The diagnosis may be suspected by the clinical features. Confirmation of the diagnosis, however, requires biochemical tests of blood, urine, or tissues. Prenatal diagnosis is feasible in all types of MPS. The prognosis (long-term outlook) depends upon the particular type of MPS. There are a number of different types of MPS that are designated somewhat confusingly by number (and letter), by syndrome name, and by precising what enzyme is lacking. The classification (as of 2001) is as follows: {{}}MPS type I — Hurler syndrome, Scheie syndrome, and Hurler-Scheie syndrome — due to varying degrees of deficiency of the enzyme alpha-L-iduronidase MPS type II — Hunter syndrome — due to deficiency of the enzyme iduronate sulfatase MPS type IIIA — Sanfilippo syndrome — due to deficiency of the enzyme heparan N-sulfatase MPS type IIIB — Sanfilippo syndrome — due to deficiency of the enzyme alpha-N-acetylglucosaminidase MPS type IIIC — Sanfilippo syndrome — due to deficiency of the enzyme acetyl CoA:alpha-glucosaminide acetyltransferase MPS type IIID — Sanfilippo syndrome — due to deficiency of the enzyme N-acetylglucosamine 6-sulfatase MPS type IVA — Morquio syndrome — due to deficiency of the enzyme N-acetylgalactosamine-6-sulfate sulfatase MPS type IVB — Morquio syndrome — due to deficiency of the enzyme beta-galactosidase MPS type VI — Maroteaux-Lamy syndrome — due to deficiency of the enzyme N-acetylgalactosamine-4-sulfatase MPS type VII — Sly syndrome — due to deficiency of the enzyme beta-glucuronidase MPS type VIII — DiFerrante syndrome — due to deficiency of the enzyme glucosamine-6-sulfate