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NORD is very grateful to Paul Plotz, MD, Senior Clinician, National Institutes of Health, for reviewing this report.
Synonyms of Pompe Disease
- acid alpha glucosidase (GAA) deficiency
- acid maltase deficiency (AMD)
- glycogen storage disease type II
- infantile onset Pompe disease
- late onset Pompe disease
Pompe disease is a rare multisystem genetic disorder that is characterized by absence or deficiency of the lysosomal enzyme alpha-glucosidase (GAA). This enzyme is required to breakdown (metabolize) the complex carbohydrate glycogen and convert it into the simple sugar glucose. Glycogen is a thick, sticky substance and failure to properly break it down results in massive accumulation of lysosomal glycogen in cells, particularly in cardiac, smooth, and skeletal muscle cells. Pompe disease is a single disease continuum with variable rates of disease progression and different ages of onset. The infantile form is characterized by severe muscle weakness and abnormally diminished muscle tone (hypotonia) without muscle wasting, and usually manifests within the first few months of life. Additional abnormalities may include enlargement of the heart (cardiomegaly), the liver (hepatomegaly), and/or the tongue (macroglossia). Without treatment, progressive cardiac failure usually causes life-threatening complications by the age of 12 to 18 months. Pompe disease can also present in childhood, adolescence or adulthood, collectively known as late-onset Pompe disease. The extent of organ involvement may vary among affected individuals; however, skeletal muscle weakness is usually present with minimal cardiac involvement. Initial symptoms of late-onset Pompe disease may be subtle and may go unrecognized for years. Pompe disease is caused by mutations of the GAA gene and is inherited as an autosomal recessive trait.
Pompe disease belongs to a group of diseases known as the lysosomal storage disorders. Lysosomes are particles bound in membranes within cells that function as the primary digestive units of cells. Enzymes within the lysosomes break down or digest particular nutrients, such as complex molecules composed of a sugar attached to a protein (glycoproteins). There are more than 40 different lysosomal enzymes. Low levels or inactivity of the GAA lysosomal enzyme leads to the accumulation of glycogen in the lysosomes of various cells within the body with unwanted consequences. 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.
Organizations related to Pompe Disease
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