MSACL 2024 Abstract

Background: Mucopolysaccharidosis (MPS) and glycoproteinosis are two groups of heterogenous lysosomal storage disorders (LSDs) caused by defective degradation of glycosaminoglycans (GAGs) and glycoprotein, respectively. Oligosaccharides and glycoamino acids have been recognized as biomarkers for MPS and glycoproteinosis. Given both groups of diseases have overlapping clinical features, a multiplexed assay capable of unambiguous subtyping is desired for accurate diagnosis, and potentially for severity stratification and treatment monitoring.

Methods: Urinary oligosaccharides were derivatized with 3-methyl-1-phenyl-2-pyrazoline-5-one (PMP) and analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) together with the underivatized glycoamino acids. Novel biomarkers were identified with a semi-targeted approach with precursor mass, the fragmentation pattern (if applicable), and the biochemical basis of the condition.

Results: A UPLC-MS/MS analysis with improved chromatographic separation was developed. Novel biomarkers for MPS-IIIA, IIIB, IIIC, and VII were identified and validated. A total of 28 oligosaccharides, 2 glycoamino acids, and 2 ratios were selected as key diagnostic biomarkers. Validation studies including linearity, LLOQ and precision were carried out with the assay performance meeting the criteria. Age-specific reference ranges were collected. In the 76 untreated patients, unambiguous diagnosis was achieved with 100% sensitivity and specificity. Additionally, the levels of disease-specific biomarkers were substantially reduced in the treated patients.

Conclusions: A multiplexed UPLC-MS/MS assay for urinary oligosaccharides and glycoamino acids measurement was developed and validated. The assay is suitable for the accurate diagnosis and subtyping MPS and glycoproteinosis and potentially for severity stratification and monitoring response to treatment.