Introduction and history: The glycogen storage disorders may show two different presentations. One group present with permanent and progressive weakness (such as GSD II, GSD III and GSD IV). Another group have intermittent episodes of weakness, muscle pain and/or myoglobinuria (such as Mc Ardle disease). Glycogen storage disease type 2 is caused by acid maltase deficiency. GSD IIis an autosomal recessive disorder that was first described by Dutch pathologist Joannes C. Pompe in 1932. And can be categorized into two types, based on the age of onset of disease and degree of organ involvement: infantile (the most severe presentation), and late type (childhood and adult). Pompe diseaseis caused by deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA) or acid maltase. and is the only membersof glycogen storage diseases that is classified also as a lysosomal storage disorder.