IDUA and Scheie syndrome: Mucopolysaccharidosis type I (MPS I) is a severe, genetic, multisystem disorder caused by a deficiency of the lysosomal enzyme α-L-iduronidase (IDUA), which is responsible for the hydrolysis of glycosidic bonds in terminal α-L-iduronic acid residues of the complex glycosaminoglycans dermatan sulfate and heparan sulfate.