Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder (LSD) caused by mutations in the IDUA gene coding for the enzyme α-l-Iduronidase (IDUA) involved in the degradation of glycosaminoglycans (GAGs), such as heparan sulfate (HS) and dermatan sulfate (DS) in lysosome. The gene discussed is IDUA; the disease is lysosomal storage disease.