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GYS2 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GYS2 gene

The GYS2 gene provides instructions for making liver glycogen synthase, an enzyme that helps store energy in the liver to maintain blood glucose levels.

Normal Function

The GYS2 gene provides instructions for making an enzyme called liver glycogen synthase. Produced solely in liver cells, this enzyme helps form the complex sugar glycogen by linking together molecules of glucose. Glycogen stored in the liver can be broken down rapidly when glucose is needed to maintain normal blood glucose levels between meals.

Health Conditions Related to Genetic Changes

Glycogen storage disease type 0

Approximately 20 mutations in the GYS2 gene have been found to cause a form of glycogen storage disease type 0 (GSD 0) that affects the liver. These mutations typically lead to a lack of functional glycogen synthase, resulting in a complete absence of glycogen in liver cells.

In people with this condition, the body cannot form glycogen from leftover glucose. Consequently, affected individuals have no stored energy during long periods without food (fasting), which can lead to:

  • Low blood glucose (hypoglycemia)
  • Nausea
  • Other signs and symptoms of GSD 0

Other Names for This Gene

  • glycogen [starch] synthase, liver
  • glycogen synthase 2 (liver)
  • GYS2_HUMAN
  • liver glycogen synthase
  • liver glycogen synthase 2

Genomic Location

The GYS2 gene is found on chromosome 12.

Frequently Asked Questions

Management of GYS2-related liver GSD 0 primarily involves dietary strategies to prevent hypoglycemia. This often includes frequent, small meals throughout the day, avoiding long periods of fasting, and a diet rich in complex carbohydrates. In some cases, uncooked cornstarch may be used to provide a slow-release glucose source, especially overnight, to maintain stable blood sugar levels.
If someone with GYS2-related GSD 0 experiences severe hypoglycemia symptoms (e.g., confusion, unresponsiveness, seizures), immediately administer a fast-acting source of glucose, such as glucose tablets, gel, or a sugary drink (juice, regular soda). If the person is unconscious or unable to swallow, emergency medical attention should be sought, and glucagon may be administered by injection if prescribed and available.
GYS2-related glycogen storage disease type 0 is inherited in an autosomal recessive pattern. This means that for a child to develop the condition, they must inherit two copies of the altered GYS2 gene, one from each parent. If you are a carrier (have one altered copy) and your partner is also a carrier, each child has a 25% chance of inheriting GSD 0, a 50% chance of being a carrier, and a 25% chance of inheriting two normal copies.
The most important symptoms of GYS2-related liver GSD 0, particularly in children, are signs of low blood glucose (hypoglycemia) after periods without food (fasting). These can include extreme tiredness, irritability, sweating, shakiness, confusion, and in severe cases, seizures or loss of consciousness. Nausea is also a common symptom.
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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