IDS and mucopolysaccharidosis type 2: Mucopolysaccharidosis type II (MPS II, OMIM 607014; also known as Hunter syndrome) is a rare X-linked recessive disorder caused by a deficiency of the lysosomal enzyme Iduronate-2-Sulfatase (IDS), leading to the progressive accumulation of Glycosaminoglycans (GAGs) in several organs.