Mucopolysaccharidoses (MPS) are a group of inherited diseases caused by mutations in genes encoding several lysosomal enzymes (including ARSB, GALNS, GLB1, GNS, GUSB, HGSNAT, HYAL1, IDS, IDUA, NAGLU, and SGSH), which are involved in the degradation of glycosaminoglycans (GAGs). The gene discussed is SGSH; the disease is mucopolysaccharidosis.