Molecular diagnosis of Pompe disease using MALDI TOF/TOF and 1 H NMR

Pompe disease, glycosomal storage disorder type II, is caused by a deficiency of lysosomal exo-α-1,4-glucosidase, which participates in glycogen degradation. Due to the wide variety of its clinical symptoms, this lysosomal storage disorder is difficult to diagnose. The “gold standard” diagnosis of Pompe disease is based on an enzyme activity analysis in leucocytes, dried blood spots or tissues, followed by confirmation through mutational analysis. Screening of many inborn metabolic diseases normally requires also the detection of a specific metabolite. In Pompe disease, high levels of a specific glucose tetrasaccharide, αGlc(1→6)αGlc(1→4)αGlc(1→4)Glc, accumulate in patients’ urine. Some medical laboratories continue to favour traditional 1-dimensional TLC for the analysis of urine oligosaccharides, however, this method has some limitations in its analytical specificity and sensitivity. More modern and robust spectral techniques, including mass spectrometry and NMR spectroscopy, possess many advantages and are increasingly used. Here, the different analytical methods applied in Pompe disease diagnosis are experimentally compared.