IDS and mucopolysaccharidosis type 2: Mucopolysaccharidosis type II (MPS II, or Hunter Syndrome, MIM #309900) is a rare X-linked lysosomal storage disorder caused by the deficit of the iduronate 2-sulfatase (IDS, EC3.1.6.13) enzyme, leading to storage of the glycosaminoglycans (GAGs), heparan- and dermatan-sulfate in all organs and tissues.