Lysosomal sulfatases involved in mucopolysaccharidoses: iduronate 2-sulfatase, herapan N-sulfatase, N-Acetylglucosamine  6-sulfatase, galactose 6-sulfatase and N-Acetylgalactosamine have been widely analysis on genes coding for these enzymes showed 375 molecular alterations, highlighting  the existence of heterogenous mutations as well as of  prevalent  mutations  in some populations and the functional importance of several residues within each protein, Site-directed mutagenesis reproducing identified mutations followed by in vitro expression of mutant enzymes was reported only on approximately 50 defects, resulting often in increased degradation of the mutant protein. Mutation identification and characterization are potentially valuable also for the choice of the patients amenable to therapies (BMT, enzyme replacement therapy, gene therapy)at least for those defects showing a good genotype/phenotype relationship.