The MPS disorders are all inherited defects of lysozyme exoenzymes that normally help degrade GAGs such as keratin sulfate and heparin sulfate. Excessive quantities of these incompletely metabolized mucopolysaccharides get stuck in the lysozymes and eventually cause problems. Examples include:
MPS 1h: Hurlers syndrome
MPS 1s: Scheie syndrome
MPS 2: Hunters
MPS 3: Sanfilippo (also associated with a pigmentary retinopathy)
