Acid maltase deficiency (AMD), also known as Pompe disease, is a genetically inherited disease that affects muscle function. Inherited diseases are passed on from parents to a child. Patients with AMD have a defect, or mutation, in a gene that functions in muscles, called the acid alpha-glucosidase (GAA) gene. This genetic mutation causes a substance called glycogen to build up in the muscles of patients with AMD. Glycogen is a form of starch that is used to store short-term energy.
Glycogen buildup in the muscles of patients with AMD causes damage to the muscles, which leads to a progressive weakening of the muscles. This glycogen buildup may weaken the muscles of the heart and respiratory system. Cardiac or respiratory failure is the most common cause of death in patients with AMD.
AMD is estimated to affect about one in 40,000 to 100,000 births. The time of onset of AMD can vary among patients and can occur in infants, children, or adults. The infant onset form is considered to be the most severe, and usually results in death within one year.
In general, the later the onset of AMD, the more slowly it will progress, and the less severe the symptoms. Children and adults diagnosed with AMD usually have a life expectancy from 10 to 20 years after symptoms begin to appear.
Currently there is no known way to prevent AMD. However, a treatment called Myozyme®, which restores functional alpha-glucosidase enzyme to a patient, has been shown to be effective in treating the disease.
Acid maltase deficiency should not be confused with age-related macular degeneration, a different disease that is also abbreviated as AMD.
Acid alpha-glucosidase, acid maltase enzyme, AMD, GAA, glycogen, glycogen storage disease type II, glycogenosis type II, lysosomal storage disease, muscle disorder, muscles, Pompe disease.