Glycogen storage disease type IV
Encyclopedia
Synonyms
It is also known as:-- Glycogenosis type IV,
- Glycogen Branching Enzyme Deficiency (GBED),
- polyglucosan body disease.
- Amylopectinosis
Human pathology
It is a result of the absence of the glycogen branching enzymeGlycogen branching enzyme
A glycogen branching enzyme is an enzyme that takes part in converting glucose to glycogen. It adds branches to the growing glycogen molecule. Glycogen is a branching polymer of large numbers of glucose units linked together. The structure is based on chains of glucose units with linkages between...
amylo-1,4-1,6 transglucosidase, which is critical in the production of glycogen
Glycogen
Glycogen is a molecule that serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue...
. This leads to very long unbranched glucose chains being stored in glycogen. The long unbranched molecules have a low solubility which leads to glycogen precipitation in the liver. These deposits subsequently build up in the body tissue, especially the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
and liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
. The probable end result is cirrhosis and death within 5 years. In adult polyglucosan body disease the activity of the enzyme is higher and symptoms do not appear until later in life.