Glycogen Storage Disease

What is a Glycogen Storage Disease?

Glycogen storage diseases are genetic deficiencies that result in the storage of abnormal amounts of glycogen in the body. About 1 out of 100 000 babies are born with glycogen storage diseases each year in Canada. There are 5 different types of these diseases depending on the enzyme missing.

All people who are born with GSD have one thing in common. They are unable to properly metabolize or break down glycogen, the storage form of sugar in the body. The food we eat is usually used for growth, tissue repair and energy. The body stores what it does not use. Excess sugar, or glucose, is stored as glycogen in the liver and muscle tissue. Between meals and during sleep (i.e. periods of fasting), or during exercise, the body breaks down glycogen and uses the stored sugar for energy. Due to an enzyme deficiency, people with GSD have the ability to store sugar as glycogen but are unable to use these stores to provide the body with energy during fasting or exercise.

Think of a pantry where extra food is stored. In times of need, the pantry door can be opened and food can be accessed. In glycogen storage disease, food can be placed in the pantry for storage, but can’t be accessed in times of need. The pantry door is locked. Food can be pushed through a slot in the door but the door cannot be opened to get the food out.
How do people get glycogen storage disease?
Glycogen storage diseases are inborn errors of metabolism. They are genetic. This means that the person has the disorder from the time they are conceived. At conception, the baby receives two sets of genetic material, one from the mother, and one from the father. This genetic material, called DNA, acts as a recipe for the baby’s development.

DNA includes information about the baby’s eye and hair colour, sex and even whether the baby will be right or left-handed. DNA comes in units called genes. Each pair of genes gives directions to a certain part of the body.

Glycogen storage diseases are caused by getting two copies of the faulty gene, one from the mother, and one from the father. If the child inherits only one copy of the gene, they are a carrier for the disorder but are not affected. There is a 1 in 4, or 25% chance that 2 carriers of the gene will have a baby with glycogen storage disease. Boys and girls are equally affected.
Related Organizations
The Adult Metabolic Diseases Clinic
Vancouver General Hospital
Diamond Health Care Centre
4th Floor, 2775 Laurel Street
Vancouver, BC
V5Z 1M9
(604) 875-5965
National Organization for Rare Disorders, Inc.
P.O. Box 8933
New Fairfield, CT 06812-8923
Phone: 1-800-999-6673
Web site: www.rarediseases.org