Glycogen storage disease (GSD) is a rare, inherited condition in which the body improperly uses and stores glycogen, one of its main sources of energy.
When a child has glycogen storage disease (GSD), it means they have a genetic disorder that changes the way their body uses and stores glycogen.
Normally, glycogen is stored in the liver, where enzymes can break it down into glucose when the body needs more energy. When glycogen is not stored or used properly, or when the enzyme needed to break it down into glucose is missing, the glycogen builds up in the child’s tissues and can cause problems in the liver, muscles and organs.
There are eight types of glycogen storage disease, depending on the specific enzyme that is affected or missing. The three most common types of the disease are:
Also called Von Gierke disease, this is the most common type of glycogen storage disease. In type I, the enzyme in the liver that is needed to turn glycogen into glucose is missing.
Also called Cori disease or Forbes disease, type III occurs when a child doesn’t have enough of the debranching enzyme, which helps break down glycogen.
Also called Andersen disease, type IV causes abnormal formation of glycogen which triggers the body’s immune system to attack the liver and other organs.
The symptoms of glycogen storage disease are similar for the most common types of the disease. Symptoms include:
Glycogen storage disease is caused by a genetic defect. In order to have glycogen storage disease, a child must inherit the defective gene from both parents.