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Glycogen Storage Diseases

  • Michelle Badash, MS
Publication Type:


Glycogen Storage Diseases

(Glycogenoses; GSD)


Glycogen storage diseases (GSDs) are a group genetic disorders passed from parents to children. They cause glycogen to be improperly formed or released in the body. This results in a buildup of abnormal amounts or types of glycogen in tissues. Glycogen is the storage form of glucose in a person's body. Glucose is a simple sugar that is the main source of energy for people.

The main types of GSDs include:

  • Type 0—Liver glycogen synthase deficiency
  • Type 1—Von Gierke disease, the most common type of GSD
  • Type 2—Pompes disease, acid maltase deficiency
  • Type 3—Coris disease, debrancher enzyme deficiency
  • Type 4—Andersens disease, brancher enzyme deficiency
  • Type 5—McArdles disease, muscle phosphorylase deficiency
  • Type 6—Hers disease, liver phosphorylase deficiency
  • Type 7— Tarui disease, muscle phosphofructokinase deficiency
  • Type 9—phosphorylase kinase deficiency

Glycogen is mainly stored in the liver or muscle tissue. GSDs usually affect how the liver, muscles or both work.


GSDs are caused by a genetic enzyme problem. It is passed on from one or both parents.

Enzymes help convert glucose into glycogen for storage. Other enzymes convert the glycogen back to glucose when energy is needed. This happens during activity like exercise. With GSD, some of these enzymes do not work, do not work well enough, or are absent.

The abnormal glycogen builds up in the liver and/or muscle tissues.

Risk Factors

People who have family members with GSDs are at a higher risk of having this. The risk varies with the type of GSD.


Each type of GSD has its own symptoms.


The doctor will ask about the child's symptoms and health history. A physical exam will be done. GSDs are often diagnosed in infancy or childhood. It is often done by the symptoms listed above. Tests that may also be done include:

  • Biopsy of the affected organs
  • Blood tests
  • Urine tests
  • Genetic testing

An MRI scan may be done to check the liver and other organs.

This test may be used for an early diagnosis of some types of GSD. It is often done when there is a family history.

Eggs and sperm are harvested from a couple who have a known risk. The egg is fertilized in the lab. The GSD free embryo is then implanted in the uterus. This allows parents to have more children who do not have a GSD. This process may pose ethical or religious concerns for some couples.


Treatment depends on the type of GSD and the symptoms.


There is no way to prevent GSDs. Early treatment can help control the disease and prevent other problems. A genetic counselor can help people with GSD or a family history learn what the risk is of passing it to their children.

Type 0

Type 0 symptoms often appear in late infancy when night feedings stop. In the early morning the child may have low blood sugar which could cause:

  • Paleness
  • Vomiting
  • Extreme fatigue
  • Convulsions

The children may also have a mild growth delay. They also may have not be able to be very active.

Type 1

Type 1 may appear as early as 3 months old. Common symptoms include:

  • Bulging belly from an enlarged liver
  • Seizures from low blood sugar
  • Signs of low blood sugar including
    • Paleness
    • Irritability
    • Fatigue
  • Growth delay
Enlarged Liver.

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Type 2

Type 2 is grouped by the time when symptoms start. Infants often show symptoms at 4 to 8 months of age. Type 2 can also form when a person is a child or even later in life.

Infant-onset Type 2 GSD symptoms include:

  • Muscle weakness and floppiness
  • Delayed motor skills
  • Weak breathing
  • Heart muscles that keep getting bigger—this can cause the heart to pump less and lead to fatal heart failure within first year of life

Late-onset Type 2 GSD symptoms include:

  • Muscle weakness that gets worse and spreads from the legs into the arms
  • Breathing problems

Type 3

Type 3 may appear in childhood. Common symptoms include:

  • Muscle weakness
  • Growth delay
  • Swollen belly due to an enlarged liver
  • Signs of low blood sugar such as
    • Paleness
    • Irritability
    • Fatigue

Type 4

Type 4 appears during infancy. Common symptoms include:

  • Physical and mental growth stops at a certain point and does not continue as normal
  • Muscle weakness that gets worse
  • Poor muscle development
  • Cirrhosis of the liver that gets worse and may lead to liver failure

Type 5

Common symptoms of Type 5 include:

  • Muscle cramps while working out
  • Muscles get very tired while working out
  • Fainting or seizure after working out
  • Red or brown-colored urine after working out

Type 6 and 9

People with Types 6 or 9 may not have symptoms. When they do happen, they include:

  • Enlarged liver in infancy
  • Mild growth delay
  • Anxiety, sweating, confusion, or seizures linked to low blood sugar

Type 7

Common symptoms of Type 7 include:

  • Muscle cramps and tenderness with working out
  • Muscles get really tired when working out
  • Red or brown-colored urine after working out




  • Glycogen storage disease type I (von Gierke disease). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/glycogen-storage-disease-type-i-von-gierke-disease.
  • Glycogen storage disease type II (Pompe disease). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/glycogen-storage-disease-type-ii-pompe-disease.
  • Glycogen storage disease type III (Cori disease). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/glycogen-storage-disease-type-iii-cori-disease.
  • Glycogen storage disease type IV (Andersen disease). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/glycogen-storage-disease-type-iv-Andersen-disease.
  • Glycogen storage disease type V (McArdle syndrome). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/glycogen-storage-disease-type-v-mcardle-syndrome.
  • Glycogen storage disease type VI (Hers disease). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/glycogen-storage-disease-type-vi-hers-disease.
  • Low blood glucose (hypoglycemia). National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia.


  • Chelsea Skucek, MSN, BS, RNC-NIC
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.