alpha-L-Iduronidase, encoded by the IDUA gene, is an important enzyme required for the lysosomal degradation of glycosaminoglycans (GAGs). It hydrolyzes the non-reducing terminal a-L-iduronic acid residues in GAGs, including dermatan sulfate and heparan sulfate. Mutations in IDUA that result in enzymatic deficiency lead to the autosomal recessive disease mucopolysaccharidosis type I (MPS I). MPS I causes progressive cellular, tissue, and organ damage.