IDS and mucopolysaccharidosis type 2: As mentioned above, in contrast to several other lysosomal enzymes, an iduronate-2-sulfatase enzyme assay cannot simply be added to the FIA-MS/MS method currently used by most programs already screening for Pompe disease and MPS I. That means that more effort, more equipment and a dedicated DBS punch are required to screen for MPS-II using either LC-MS/MS or fluorometry.