Three years experience with dried blood spot α-glucosidase screening for Pompe disease in British Columbia, Canada

Introduction Pompe disease (OMIM #232300) or glycogen storage disease type II is an autosomal recessive lysosomal storage disease caused by mutations in the glucosidase alpha acid (GAA) gene. The acid alpha-glucosidase enzyme is required for the degradation of cellular glycogen, and its reduced activity results in accumulation of glycogen in muscle and cardiac tissues with variable clinical presentation. Demonstration of deficient acid alpha-glucosidase (GAA) enzyme activity is diagnostic, and molecular testing is available for confirmation or clarification. As Pompe disease is in the differential diagnosis of a wide variety of myopathies, simple first-line tests are needed. Use of dried blood spots (DBS) has logistical advantages over the traditional approach of enzyme assay in isolated lymphocytes, and enzyme stability permits DBS shipment to a central laboratory.