MGAM and Glycogen storage disease due to acid maltase deficiency: Glycogen storage disease II (GSDII, OMIM 232300), or Pompe disease, is a rare autosomal recessive disorder caused by the enzymatic deficiency of the alpha-1,4-glucosidase (GAA or acid maltase) which is deputed to the glycogen degradation within lysosomes (Stevens et al., 2022).