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GAA gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GAA gene

The GAA gene provides instructions for producing the enzyme acid alpha-glucosidase, which is essential for breaking down glycogen into glucose within cells.

Normal Function

The GAA gene provides instructions for producing an enzyme called acid alpha-glucosidase (also known as acid maltase). This enzyme is active in lysosomes, which are structures that serve as recycling centers within cells. Lysosomes use digestive enzymes to break down complex molecules into simpler ones that can be used by cells.

Acid alpha-glucosidase normally breaks down a complex sugar called glycogen into a simpler sugar called glucose. Glucose is the main energy source for most cells.

Health Conditions Related to Genetic Changes

Pompe disease

More than 200 mutations in the GAA gene have been identified in people with Pompe disease. Many of these mutations change one of the protein building blocks (amino acids) used to make acid alpha-glucosidase. Other mutations insert or delete genetic material in the GAA gene.

Mutations in this gene significantly reduce the activity of acid alpha-glucosidase, preventing the enzyme from breaking down glycogen effectively. As a result, this complex sugar can build up to toxic levels in lysosomes. The abnormal buildup of glycogen damages organs and tissues throughout the body, particularly the muscles, leading to progressive muscle weakness, heart problems, and the other features of Pompe disease.

Other Names for This Gene

  • acid alpha-glucosidase
  • acid alpha-glucosidase preproprotein
  • acid maltase
  • Aglucosidase alfa
  • Alpha-1,4-glucosidase
  • Amyloglucosidase
  • Glucoamylase
  • glucosidase, alpha; acid
  • glucosidase, alpha; acid (Pompe disease, glycogen storage disease type II)
  • LYAG
  • LYAG_HUMAN
  • lysosomal alpha-glucosidase

Frequently Asked Questions

Pompe disease is inherited in an autosomal‑recessive pattern. A carrier (one mutated GAA allele) is asymptomatic. If both parents are carriers, each pregnancy has a 25 % chance of producing an affected child, a 50 % chance of a carrier child, and a 25 % chance of an unaffected, non‑carrier child. Carrier testing and genetic counseling are recommended for family planning.
Regular, low‑impact aerobic exercise (e.g., swimming, stationary cycling) under physiotherapist guidance can preserve muscle strength and endurance. Maintaining adequate caloric intake, especially protein, supports muscle repair. Monitoring cardiac function with routine echocardiograms and avoiding extreme fatigue or heat exposure are also important.
The mainstay is enzyme replacement therapy (ERT) with alglucosidase alfa, which is given intravenously every two weeks and can improve muscle and cardiac function, especially when started early. Emerging options include gene therapy trials that aim to deliver a functional GAA copy to liver or muscle cells, and supportive measures such as respiratory physiotherapy, cardiac medications, and physical therapy.
Diagnosis usually starts with measuring acid alpha‑glucosidase activity in a blood spot, fibroblasts, or muscle tissue. If enzyme activity is low, targeted genetic testing of the GAA gene is performed to identify pathogenic variants. Some centers also use newborn screening panels that include GAA activity.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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