Glycogen Storage Disease
What is Glycogen Storage Disease?
Glycogen storage disease (GSD, also glycogenosis and dextrinosis) is the result of defects in the processing of glycogen synthesis or breakdown within muscles, liver, and other cell types.
In normal physiology, when a person eats, blood sugar levels rise and glucose is used for immediate energy. The glucose that is not used is stored as glycogen in the liver. The body detects when blood sugar is dropping, when you need energy, and signals glycogen to be released from the liver. People affected by GSD lack the enzymes required to store or release stored glycogen. People with GSD must maintain the blood sugar from outside the body. With various missing enzymes, depending on the type of GSD one has, the body tries to use alternative pathways to supply the body with energy. These alternative pathways create serious health risks such as elevated triglycerides, cholesterol, uric acid, ketones, lactates, etc.
GSD has two classes of cause: genetic and acquired. Genetic GSD is caused by any inborn error of metabolism (genetically defective enzymes) involved in these processes. In livestock, acquired GSD is caused by intoxication with the alkaloid castanospermine.
Overall, according to a study in British Columbia, approximately 2.3 children per 100 000 births (1 in 43,000) have some form of glycogen storage disease. In the United States, they are estimated to occur in 1 per 20,000-25,000 births. A Dutch study estimated it to be 1 in 40,000.
Micrograph of glycogen storage disease with histologic features consistent with Cori disease. There are eleven (11) distinct diseases that are commonly considered to be glycogen storage diseases (some previously thought to be distinct have been reclassified). (Although glycogen synthase deficiency does not result in storage of extra glycogen in the liver, it is often classified with the GSDs as type 0 because it is another defect of glycogen storage and can cause similar problems.)