Glycogen Storage Disease type II (GSDII) or Pompe disease (OMIM 232300) is a lysosomal storage disorder caused by mutations in the acid alpha-glucosidase (GAA) gene whose frequency is about 1 in 40000–50000 in European and US Populations and apparently much lower in Australia or Portugal [1]. The gene discussed is GAA; the disease is lysosomal storage disease.