IDUA and mucopolysaccharidosis: In addition to peripheral disease such as organomegaly, cardiac and respiratory insufficiency, there are MPS sub-types that store dermatan sulphate and chondroitin sulphate and exhibit bone and joint disease (eg MPSI, II, IV, VI and VII), whereas those that store heparan sulphate (HS; eg MPSI, II, III and VII) show severe progressive neurodegeneration [1], [2].