IDUA and mucopolysaccharidosis type 1: Mucopolysaccharidosis type 1 (MPS I, also referred to as Hurler syndrome; OMIM #607014) is caused by deficiency of the lysosomal hydrolase alpha-l-iduronidase (IDUA, EC3.2.1.76), which leads to the accumulation of dermatan sulfate and heparan sulfate.