Rapid ultraperformance liquid chromatography-tandem mass spectrometry assay for a characteristic glycogen-derived tetrasaccharide in Pompe disease and other glycogen storage diseases.

Background: Urinary excretion of the tetrasaccharide 6-α-D-glucopyranosyl-maltotriose (Glc₄) is increased in various clinical conditions associated with increased turnover or storage of glycogen, making Glc₄ a potential biomarker for glycogen storage diseases (GSD). We developed an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay to detect Glc₄ in urine without interference of the Glc₄ isomer maltotetraose (M₄).

Methods: Urine samples, diluted in 0.