Glycogen storage diseases

[Marquetta]

Glycogen storage diseases are carbohydrate metabolism disorders that occur when there is a defect in the enzymes that are involved in the metabolism of glycogen, often resulting in growth abnormalities, weakness, a large liver, low blood sugar, and confusion. Glycogen storage diseases occur when parents pass the defective genes that cause these diseases on to their children.

Glycogen storage diseases are caused by the lack of an enzyme needed to change glucose into glycogen and break down glycogen into glucose.
Typical symptoms include weakness, sweating, confusion, kidney stones, a large liver, low blood sugar, and stunted growth.
The diagnosis is made by doing blood tests, by examining a piece of tissue under a microscope (biopsy), and by doing magnetic resonance imaging.
Treatment depends on the type of glycogen storage disease and usually involves regulating the intake of carbohydrates.

There are different types of inherited disorders. In many hereditary metabolic disorders, both parents of the affected child carry a copy of the abnormal gene. Because usually two copies of the abnormal gene are necessary for the disorder to occur, usually neither parent has the disorder. (See also Overview of Hereditary Metabolic Disorders.)
Glycogen (a carbohydrate) is made of many glucose molecules linked together. The sugar glucose is the body’s main source of energy for the muscles (including the heart) and brain. Any glucose that is not used immediately for energy is held in reserve in the liver, muscles, and kidneys in the form of glycogen and is released when needed by the body.
Children who have a glycogen storage disease are missing one of the enzymes that is essential to the process of forming glucose into glycogen or breaking down (metabolizing) glycogen into glucose. About 1 in 25,000 infants has some form of glycogen storage disease.
There are many different glycogen storage diseases (also called glycogenoses). Each is identified by a Roman numeral.