A type of lysosomal storage disease due to the absence or the inadequacy of certain groups of lysosomal enzymes resulting in the accumulation of mucopolysaccharides, as evidenced by the excretion of various mucopolysaccharides in urine and infiltration of these substances into connective tissue, with resulting various defects of bone, cartilage, and connective tissue
Lysosomal storage disease is a collective term for the various metabolic disorders due to defects in lysosomal function resulting in an abnormal accumulation of toxic materials in the cell. One of them is mucopolysaccharidosis. This metabolic disorder is characterized by an accumulation of mucopolysaccharides (now, glycosaminoglycans) in the body due to the absence or insufficiency of certain lysosomal enzymes.
There are many types of mucopolysaccharidosis (MPS):
- MPS I Hurler syndrome, Scheie syndrome (formerly, MPS V), and Hurler-Scheie syndrome
- MPS II (Hunter syndrome) – characterized by a deficiency of iduronate-2-sulfatase resulting in the accumulation of heparan sulfate and dermatan sulfate. It is an X-linked disorder and associated with a defective IDS gene.
- MPS III (Sanfilippo syndrome) – characterized by a deficiency of heparan N-sulfatase due to a defect in the SGSH gene (MPS-IIIA), of N-acetyl-alpha-D-glucosaminidase due to a defect in NAGLU gene (MPS-IIIB), and of acetyl-CoA:alpha-glucosaminide N-acetyltransferase due to a defective HGSNAT gene (MPS-IIIC). It is inherited in an autosomal recessive pattern.
- MPS IV (Morquio) – N-acetyl-galactosamine-6-sulfatase is the lysosomal enzyme that is deficient in MPS IVA whereas beta-galactosidase in MPS IVB. It is inherited in an autosomal recessive pattern.
- MPS VI (Maroteaux-Lamy syndrome) – caused by inadequate levels of arylsulfatase B (N -acetylgalactosamine-4-sulfatase). It is inherited in an autosomal recessive pattern. It is associated with a defective ARSB gene.
- MPS VII (Sly syndrome) – caused by inadequate levels of β-glucuronidase, due to pathological mutation in the GUSB gene. It is inherited in an autosomal recessive pattern.
- MPS IX (hyaluronidase deficiency) – caused by a pathological mutation in HYAL1 gene thereby affecting the production of enzyme hyaluronidase. It is inherited in autosomal recessive manner.