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Glycogen storage disease type 0
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Glycogen storage disease type 0

Glycogen storage disease type 0 is a rare genetic condition characterized by an inability to produce glycogen, resulting in muscle weakness and cardiac risks in the muscle type, or fasting hypoglycemia in the liver type.

Overview

Glycogen storage disease type 0 (also known as GSD 0) is a condition caused by the body's inability to form a complex sugar called glycogen, which is a major source of stored energy in the body. GSD 0 has two types: in muscle GSD 0, glycogen formation in the muscles is impaired, and in liver GSD 0, glycogen formation in liver cells is impaired.

Symptoms & Types

Muscle GSD 0

The signs and symptoms of muscle GSD 0 typically begin in early childhood. Key features include:

  • Muscle pain and weakness following moderate physical activity, such as walking up stairs.
  • Episodes of fainting (syncope) after physical activity, with the loss of consciousness typically lasting up to several hours.
  • A disruption of the heart rhythm (arrhythmia) known as long QT syndrome in some individuals.
  • Impaired heart function and an increased risk of cardiac arrest and sudden death, which can occur in childhood or adolescence, particularly after physical activity.

Liver GSD 0

Individuals with liver GSD 0 usually show signs and symptoms in infancy. Key features include:

  • Low blood sugar (hypoglycemia) after going long periods of time without food (fasting). This often

Frequently Asked Questions

Muscle GSD 0 impairs the ability of muscles to store glycogen, leading to exercise intolerance, muscle pain, and cramping after moderate physical activity. A significant risk is the development of long QT syndrome, a heart rhythm disorder that can lead to fainting (syncope) and potentially fatal cardiac arrest, particularly during or after exercise. Patients are advised to avoid strenuous or competitive sports and to engage in low-impact activities that do not trigger muscle pain or cardiac events. Regular cardiac monitoring, including ECGs, is essential to manage the risk of arrhythmias and to guide safe levels of physical activity.
Management of liver GSD 0 primarily focuses on dietary modifications to prevent fasting hypoglycemia. This includes frequent small meals and snacks, particularly those high in complex carbohydrates, and the use of uncooked cornstarch preparations before bedtime to provide a slow release of glucose overnight. While diet is the cornerstone of treatment, some patients may require medication to manage specific complications, such as anticonvulsants if seizures occur due to severe hypoglycemia. Regular monitoring of blood glucose levels and liver function is necessary to adjust the dietary plan and ensure adequate growth and development.
Individuals with liver GSD 0 experience fasting hypoglycemia, which can manifest as shakiness, sweating, confusion, irritability, or in severe cases, seizures and loss of consciousness. Because the liver cannot store glycogen, blood sugar levels drop rapidly during periods without food. Caregivers must be vigilant for these neuroglycopenic symptoms, especially in infants who may show lethargy, poor feeding, or pallor. Immediate treatment involves administering fast-acting carbohydrates, such as glucose gel or juice, to raise blood sugar levels. If the patient is unconscious or unable to swallow, emergency medical assistance is required for intravenous glucose administration.
Currently, there is no cure for GSD 0, and treatment is supportive, focusing on managing symptoms and preventing complications. With proper dietary management and medical supervision, individuals with liver GSD 0 can lead normal lives, though they must remain vigilant about fasting risks. The prognosis for muscle GSD 0 is more variable due to the risk of cardiac complications; however, many patients can live into adulthood with careful monitoring and avoidance of triggering activities. Genetic counseling is recommended for families, as the condition is inherited in an autosomal recessive pattern, and carrier testing can be offered to at-risk relatives.
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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