IDS and mucopolysaccharidosis type 2: Mucopolysaccharidosis type II (MPS II, Hunter syndrome) is a rare metabolic genetic disorder due to the deficit of the lysosomal enzyme iduronate 2-sulfatase (I2S or IDS) (EC 3.1.6.13), which normally hydrolyzes the 2-sulfate groups of the L-iduronate 2-sulfate units of the glycosaminoglycans (GAGs) heparan-sulfate (HS), dermatan-sulfate (DS), and heparin [1].