Pompe disease is a rare, autosomal recessive, inherited disorder in which toxic levels of the complex sugar glycogen accumulates in cells. Pompe disease is estimated to affect less than one in 50,000 individuals worldwide. There are two forms of the disease:
- Early-onset (or infantile onset): Pompe disease has an onset age <12 months and affects the heart muscle (cardiomyopathy); muscle weakness, enlarged liver and heart, difficulty breathing and feeding occur
- Late-onset: Pompe disease has an onset age >12 months or onset age <12 months without cardiomyopathy; progressive muscle weakness, difficulty breathing, chronic pain, enlarged organs, and other symptoms occur
Pompe is also known as acid maltase deficiency (AMD), glycogen storage disease (GSD) type II, acid alpha-glucosidase deficiency, or GAA deficiency.
Pompe disease is caused by low levels or absence of acid alpha-glucosidase (GAA), an enzyme that normally breaks down glycogen in the lysosome, due to mutations in the GAA gene encoding GAA. GAA deficiency results in glycogen accumulating in lysosomes in multiple tissues, particularly cardiac and skeletal muscles.