Mucopolysaccharidosis I (MPS I; Hurler, Hurler-Scheie, Scheie syndrome) and MPS II (Hunter syndrome) are diseases characterized by deficiencies in the enzymes α-iduronidase (IDUA; EC 3.2.1.76) and iduronate-2-sulfatase (IDS), respectively. This evidence concerns the gene IDS and mucopolysaccharidosis type 2.