Diseases with predominant heparan sulfate (HS) storage tend to show CNS involvement (MPSI, MPSII, MPSIIIA-D and MPSVII) whereas dermatan sulfate (DS) and keratan sulfate (KS) accumulation leads to more skeletal disease (MPSIVA-B and MPSVI) (Wraith, 2002). This evidence concerns the gene IDUA and mucopolysaccharidosis type 6.