What is it?

Glycogen storage disease type III (GSDIII) is a rare genetic disorder that causes glycogen (a type of sugar that the body uses for energy) to build up in the liver and muscles, preventing them from working properly.

What causes it?

GSDIII is caused by mutations in the AGL gene. The AGL gene provides the instructions for an enzyme that helps break down glycogen. When glycogen is not broken down completely, it can cause damage to the liver, muscles, and other organs and tissues in the body.1

What are some of the common symptoms?

  • Chronic liver disease
  • Decreased muscle tone
  • High concentration of fats in the blood
  • Larger liver than normal
  • Low blood sugar
  • Muscle weakness
  • Poor growth (failure to thrive)
  • Heart complications

How many people have it?

About 10,000 people worldwide have GSDIII.

Common names for GSDIII

  • Cori disease
  • Forbes disease
  • AGL deficiency
  • Glycogen storage disease type 3 (GSD3)

1Glycogen storage disease type III. National Institutes of Health: Genetics Home Reference website. https://ghr.nlm.nih.gov/condition/glycogen-storage-disease-type-iii#genes. Published May 28, 2019. Accessed June 5, 2019.

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