A rapid LC-MS/MS method to measure simultaneously IDUA, IDS, NAGLU, GALNS and ASRB enzymes activities in dried blood spots

Mucopolysaccharidoses (MPSs) is a group in lysosomal storage disorders (LSDs) caused by a deficiency of lysosomal hydrolases responsible for the catabolism of glycosaminoglycans (GAGs). Some techniques such as fluorometric and mass spectrometric assays have been developed to measure these enzyme activities for the purpose of newborn screening. The use of mass spectrometric techniques has exhibited advantages over the other techniques in the ability to multiplex several enzymes in one assay. In this study, we will present a novel method using tandem mass spectrometry that is capable to measure simultaneously the activities of the five MPS enzymes IDUA (MPS I), IDS (MPS II), NAGLU (MPS IIIB), GALNS (MPS IVA) and ARSB (MPS VI) in a short time scale. In the presentation, this developed method is detailed.