Pompe Disease

About Pompe Disease

Pompe disease is a rare multisystem inherited disorder caused by mutations in the gene that makes an enzyme called acid alpha-glucosidase (GAA). The body uses GAA to break down glycogen (a complex sugar), without the proper function of this enzyme, the glycogen cannot be degraded to a simple sugar like glucose. In Pompe disease, mutations in the GAA gene reduce or completely eliminate this essential enzyme. Excessive amounts of lysosomal glycogen accumulate everywhere in the body, but causes the most damage to tissue structure and functioning in skeletal muscle, smooth muscle and cardiac muscle. Researchers have identified up to 300 different mutations in the GAA gene that cause the symptoms of Pompe disease, the severity of the disease and the age of onset are related to the degree of enzyme deficiency. Pompe disease may also be classified as a glycogen storage disease, a group of metabolic disorders characterized by abnormalities involving the use and/or storage of glycogen.

Researchers have described three types of Pompe disease, which differ in severity and the age at which they appear. The classic form or infantile-onset Pompe disease usually presents during early infancy (4-8 months of age); The non-classic form or infantile-onset Pompe disease usually appears by age 1 or 2; The late/later-onset type of Pompe disease may not become apparent until after age 2, adolescence, or adulthood. In general, the later the age of onset, the slower the progression of the disease. It is estimated that Pompe disease occurs in 1 in every 40,000 births. Other names for this condition: acid maltase deficiency (AMD), alpha-1,4-glucosidase deficiency, acid alpha-glucosidase (GAA) deficiency, glycogen storage disease type II (Type II GSD), glycogenosis Type II, GSD II, and GSD2.