Quantification of keratan sulfate in biofluids by validated HPCE-LIF: application to Morquio syndrome

Background: Keratan sulfate (KS) is altered in several pathological conditions. We report the capillary electrophoresis-laser induced fluorescence separation and validation of KS-derived disaccharides Gal(3 (1-4)GlcNAc(6S) and Gal(6S)(3(1-4)GlcNAc(6S) in human urine and plasma after keratanase II treatment and AMAC fluorotagging.Results: The calibration curves of the two disaccharides from 50 to 1000 ng showed an average correlation coefficient greater than 0.9970 and the calculated LOD and LOQ were 3 and 10 ng, respectively. The inter-day precision was similar to 13% and the inter-day accuracy was similar to 10% for both disaccharides. The % recovery ranged between 88% and 106% for 200, 500, and 800 ng of each disaccharide added to biofluids. Urine and plasma of Morquio A and B subjects and of patients submitted to ERT treatment were tested. Urinary KS was similar to 13-16-fold more abundant in MPSIVA and plasmatic KS was significantly similar to 2-3-fold more than controls. No differences were observed for the disaccharides ratio between Patients and not-affected Subjects.Conclusion: The capillary electrophoresis separation of the two main KS disaccharides in human biofluids was found specific, sensitive, and accurate and suitable for application to Morquio syndrome early detection and progression as well as for other conditions in which KS is altered in content and structure.