Mucopolysaccharidosis (MPS) are inherited metabolic disorders caused by a deficiency of lysosomal enzymes required for the degradation of mucopolysaccharides or glycosaminoglycans (GAGs). Depending on the deficient enzyme, MPSs can be classified to many types. MPS IV or Morquio syndrome, occurs due to the deficiency of the enzymes N-acetyl-galactosamine-6-sulfatase and beta-galactosidase that are required for the degeneration of keratan sulfate (KS). Morquio syndrome is classified into two forms: MPS4A and MPS4B.
Like all MPS, except MPS II, MPS IV (Morquio syndrome) is an autosomal recessive disorder. Morquio syndrome A is caused by mutations in the GALNS gene which an enzyme (N-acetyl-galactosamine-6-sulfatase) that is necessary for efficient catabolism of KS.