Aims: Heparan sulfate (HS) accumulates in the central nervous system in mucopolysaccharidosis III type A (MPS IIIA). A validated LC-MS/MS assay was developed to measure HS in human cerebrospinal fluid (CSF).
Methods & results: HS was extracted and digested and the resultant disaccharides were derivatized with a novel label, 4-butylaniline, enabling isoform separation and isotope-tagged analog introduction as an internal standard for LC-MS/MS. The assay has a LLOQ for disaccharides of 0.1 μM, ±20% accuracy and ≤20% precision. CSF samples from patients with MPS IIIA showed elevated HS levels (mean 4.9 μM) compared with negative controls (0.37 μM).
Conclusion: This assay detected elevated HS levels in the CSF of patients with MPS IIIA and provides a method to assess experimental therapies.
Keywords: fit-for-purpose validation; reductive amination; reversed-phase chromatography; stable-isotope labeling; surrogate disaccharides.