What is Glycogen Storage Disease (GSD) ?
Glycogen Storage Disease (GSD) encompasses various metabolic disorders that affect glycogen metabolism. Patients affected with GSD lack or are deficient in enzymes responsible for the conversion of glycogen into glucose. Glucose serves as the primary energy source in the body. It is stored as glycogen, a complex chain of molecules. Glycogen is stored mainly in the liver and muscle cells and is converted into glucose through a series of enzymatic reactions as needed by the body. Various types of GSD are differentiated by the enzyme involved. They are either classified by number, defective enzyme or the individual who first described the condition. There are currently eleven known types of GSD.


Symptoms present in GSD include an enlarged liver, low blood sugar, growth retardation, and an abnormal blood chemistry. Each type of GSD also has its own specific symptoms. Definitive diagnosis can only be made through a biopsy of the affected organ. A primary treatment for individuals with GSD is a well-controlled diet that ensures consistent levels of blood glucose. Symptoms, if properly treated, may subside by the time the patient reaches adulthood. In severe cases, an organ transplant may be the only option for the patient.

Because GSD is an inherited condition, it is not preventable. If both parents carry the defective gene, there is a one-in-four chance that their offspring will inherit the disorder. Other children may be carriers or they may miss inheriting the gene altogether.

what symptoms present?

The symptoms of a glycogen storage disease depend on its type. The following is a list of common glycogen storage disease symptoms:
Low blood sugar
Enlarged liver
Slow growth
Muscle cramps

Glycogen Storage Disease Diagnosis
Glycogen storage disease is usually diagnosed in infancy or childhood as a result of the above symptoms. If your child's doctor suspects a glycogen storage diseases, he or she will ask about your child's symptoms and medical history, then perform a physical exam. The doctor will perform tests to rule out or confirm the diagnosis. These tests may include:
Biopsy of the affected organs
Blood and urine samples
MRI scan – a test that uses magnetic waves to make pictures of the inside of the body

Glycogen Storage Disease Treatment
Treatment will depend on the type of glycogen storage disease and the symptoms. The following general treatment guidelines apply to people who have glycogen storage diseases that affect the liver, or types I, III, IV, and VI. Your child's doctor will develop a treatment regimen based on your child's specific symptoms.

The goal of treatment is to maintain normal blood glucose levels. This may be done with:
A nasogastric infusion of glucose in infants and children under age two
Dietary changes, including:
In children over age two, frequent small carbohydrate feedings are given throughout the day. This may include uncooked cornstarch. (Uncooked cornstarch provides a steady slow-release form of glucose.)
Elimination of foods that are high in fructose or lactose (type I only)
Allopurinol (Aloprim, Zyloprim) may be prescribed to reduce uric acid levels in the blood. This is done to prevent gout and kidney stones.
Type IV is sometimes treated with liver transplantation.
This next group of treatment guidelines applies to people who have glycogen storage diseases that affect the muscles, or types V and VII. Your child's doctor will develop a treatment regimen based on your child's specific symptoms.

The goal of treatment is to avoid muscle fatigue and/or cramps induced by exercise. This is done by:
1)Regulating or limiting strenuous exercise to avoid fatigue symptoms
Improving exercise tolerance by oral intake of glucose or fructose (fructose must be avoided in people with type I), or an injection of glucagon
2)Eating a high protein diet
3)There is no way to prevent glycogen storage diseases. However, early treatment can help control the disease once a person has it. If you have a glycogen storage disease or a family history of the disorder, you can talk to a genetic counselor when deciding to have children.

  Patients affected with GSD lack or are deficient in enzymes

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