The Association for Glycogen Storage Disease defines GSD as such: "Glycogen Storage Diseases are considered inherited metabolic disorders. A metabolic disorder is a disease that disrupts metabolism. Metabolism is the process by which our body breaks down the food we eat and converts it to energy. Therefore, a person who has a metabolic disorder has a difficult time breaking down certain foods and creating energy. A metabolic disease is most frequently caused by an absence or deficiency in an enzyme (or protein). An enzyme can act to help the body break down food into energy. There are many enzymes in the body and each act like a machine on an assembly line. When one of the enzymes is not working properly, the process of breaking down of specific foods can go more slowly or shut down completely.
The underlying problem in all of the glycogen storage diseases is the use and storage of glycogen. Glycogen is the storage form of glucose (sugar). To briefly review metabolism, a simple form of sugar (glucose) is our bodies’ main source of energy. After we eat, we have too much glucose in our blood, so our bodies store the extra glucose in the form of glycogen (much like we deposit our extra money in a bank). When our bodies need more energy, certain enzymes convert the glycogen back to glucose and withdraw it from the liver and the muscles (just like we withdraw spending money from the bank). Glycogen is a complex material made of individual glucoses linked together in long chains with many branches off the chains (just like a tree). Sometimes GSDs are also referred to as glycogenoses because they are caused by difficulty in glycogen metabolism."
..."There are about eleven known types of GSD, which are classified by a number, by the name of the defective enzyme, or by the name of the doctor who first described the condition. For example, Glycogen Storage Disease type Ia, caused by a defect in the enzyme glucose-6-phosphatase, was originally known as “von Gierke's Disease” but is also referred to as “Glucose-6-Phosphatase Deficiency Glycogen Storage Disease”."
Our SweetiePie has Type Ia. He lacks an enzyme that allows the body to release sugars that are stored as glycogen in his liver. To learn more about this type specifically click HERE
