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What Is Glycogen Storage Disease?

Medically Reviewed by Poonam Sachdev on October 07, 2022

What is glycogen storage disease?

Glycogen storage disease (GSD) occurs when your body has trouble metabolizing sugar for energy and distribution throughout the body. It’s a rare condition that is inherited. It affects only one in every 20,000 to 25,000 babies.

There are different types of GSD, and each can affect you in several ways. 

How Glycogen Storage Disease Can Affect Health 

Your body needs a regular supply of sugar to fuel its daily operation. Normally, a substance called glycogen is sent to your liver to be converted to glucose in a process called glycogen metabolism. Glucose is then distributed throughout your body to be used as fuel. 

When glycogen is sent to the liver, certain bodily proteins, or enzymes have the job of breaking it down into glucose. Some people are born without those enzymes, though, and it can affect their health in different ways. Since your liver isn’t able to store or metabolize glycogen properly, serious health issues can result. 

Because GSD is hereditary, it’s congenital (present from birth) and often first noticed in babies and children. It can continue to affect your health over the course of your life, though. 

Some ways GSD can influence your health include: 

  • Abnormally slow growth
  • Low amounts of muscle tone
  • Low energy levels or constant fatigue

Types of Glycogen Storage Disease

If you have GSD, that means you lack certain enzymes needed to break down glycogen in the liver. The type of enzymes you are lacking will dictate the type of GSD that you encounter. 

There are quite a few types of GSD, some more common than others. Each type affects a certain part of the body and has its own characteristics: 

  • Type 0 (known as Lewis' disease) affects the liver
  • Type I (known as von Gierke’s disease) 
    • Type Ia (affects the kidneys, intestines, and liver)
    • Type Ib (affects the kidneys, intestines, blood cells, and liver) 
  • Type II (known as Pompe’s disease) and affects the heart, muscles, nervous system, blood vessels, and liver
  • Type III (known as Forbes-Cori disease) affects the muscles, blood cells, heart, and liver
  • Type IV (known as Andersen’s disease) affects the heart, muscles, skin, nervous system, brain, and liver 
  • Type V (known as McArdle’s disease) affects the muscles
  • Type VI (known as Hers’ disease) affects the blood cells and liver
  • Type VII (known as Tarui’s disease) affects the blood cells and muscles 
  • Type IX (affects the liver) 
  • Type XI (known as Fanconi-Bickel syndrome and affects the intestines, kidneys, and liver) 

Types I, II, III, and IV are the most common. They make up almost 90% of diagnosed cases of glycogen storage disease. 

Each type of GSD is treated slightly differently by doctors. 

Glycogen Storage Disease Causes

GSD is an inherited disease. Both parents must have a certain mutated gene present in their DNA in order for their child to have GSD. 

Parents don’t have to have GSD themselves in order to pass on the disease. It is also possible for cases to go undiagnosed. 

Glycogen Storage Disease Symptoms

Each type of GSD can have different symptoms. There are several general symptoms to be on the lookout for, though, if you or your doctor suspects glycogen storage disease. 

An enlarged liver is linked to many types of GSD. You may be able to see it physically protruding through the abdominal area. Some other symptoms include: 

  • Muscle cramping or pain during periods of exertion
  • Low blood sugar (hypoglycemia)
  • Feeling constantly tired
  • Abnormal blood test results
  • Rapid weight changes 
  • Low immunity levels
  • Issues with blood clotting (i.e., blood won’t clot)
  • Gout

Complications of Glycogen Storage Disease 

If left untreated, complications of some types of GSD can include scarring of the liver (cirrhosis) or the appearance of benign tumors on the organ. 

How Is Glycogen Storage Disease Diagnosed?

If your doctor suspects that you or a loved one has glycogen storage disease, several tests can help with diagnosis. Blood tests, imaging tests, and biopsies might all be recommended. Since GSD is a genetic disease, doctor might request genetic testing of both parents in order to pinpoint the issue.

Physical checks. Sometimes, a doctor may examine the abdominal area, checking for enlarged areas that could indicate a swollen liver. If a child is growing at a slow pace, they might also check the size and strength of the abdominal muscles. 

Blood tests. These are usually done to examine the amount of glucose (sugar) in your blood. These tests can also examine other properties. GSD is usually diagnosed in the case of babies via blood tests. These tests look for high levels of acidity and cholesterol in the blood. They can also be performed in utero before the baby is born. 

Image tests. Ultrasounds can help confirm a suspected enlarged liver and can be used to examine other affected internal organs or bones. 

Biopsy. A biopsy involves taking a small sample of tissue to be examined in a laboratory. A biopsy of the muscles or liver can be requested by your doctor to help diagnose GSD. 

Glycogen Storage Disease Treatment and Prevention

Once you or your child has been diagnosed with GSD, there are several ways to make living with the disease more manageable. There is no known cure for GSD, but generally, if the disease is caught early, better outcomes become more likely. 

Daily management of GSD can include:

  • Taking vitamin supplements and improving nutrition
  • Limiting sugary foods
  • Taking medicine geared toward specific symptoms
  • Feeding consistently through gastronomy tubes (infants)

Cornstarch therapy has also proved an effective management tool. Cornstarch is a complex carbohydrate, and eating it in raw form can help regulate blood glucose levels. 

All of these methods are tools to treat someone who suffers from GSD, but your doctor or healthcare provider will determine the best course of treatment for you.

Glycogen Storage Disease Prevention

Genetic testing of both parents before conceiving a baby can help determine a child’s chances of having GSD. 

Show Sources

SOURCES: 
Children’s Hospital of Philadelphia: “Glycogen Storage Disease (GSD).”
Cleveland Clinic: “Glycogen Storage Disease (GSD).”
Johns Hopkins: “Glycogen Storage Disease.”

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