Rapid diagnosis of late-onset Pompe disease by fluorometric assay of alpha-glucosidase activities in dried blood spots.

The enzymatic defect in Pompe disease is insufficient lysosomal acid alpha-glucosidase (GAA) activity which leads to lysosomal glycogen accumulation. We recently introduced a simple and reliable method to measure GAA activity in dried blood spots using Acarbose, a highly selective alpha-glucosidase inhibitor, to eliminate isoenzyme interference. Here we demonstrate that this method efficiently detects late-onset Pompe patients who are frequently misdiagnosed by conventional methods due to residual GAA activity in other tissue types.