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.

Comparison of maltose and acarbose as inhibitors of maltase-glucoamylase activity in assaying acid alpha-glucosidase activity in dried blood spots for the diagnosis of infantile Pompe disease.

Purpose: The study's purpose was to compare acarbose and maltose as inhibitors of maltase-glucoamylase activity for determining acid alpha-glucosidase activity in dried blood spot specimens for early identification of patients with infantile Pompe disease, a severe form of acid alpha-glucosidase deficiency.

Methods: Acid alpha-glucosidase activities in dried blood spot extracts were determined fluorometrically using the artificial substrate 4-methylumbelliferyl-alpha-D-pyranoside. Acarbose or maltose was used to inhibit maltase-glucoamylase, an enzyme present in polymorphonuclear neutrophils that contributes to the total alpha-glucosidase activity at acidic pH.