Human Biochemistry, Volume 1 - Murray R. 1993

Bioenergetics and Carbohydrate and Lipid Metabolism
Glycogen Metabolism
Glycogen Storage Diseases (Glycogenoses)

The term "glycogenosis" is a general designation for a group of inherited disorders characterized by the accumulation in Tissues of either abnormally large amounts of Glycogen or atypical forms of it.

In type I glycogen storage disease (Von Gierke disease), the Cells of The Liver and convoluted renal tubules are engorged with glycogen; however, these reserves remain unavailable, as evidenced by hypoglycemia and the failure of Blood glucose levels to rise in response to epinephrine and Glucagon. Affected patients typically develop Ketosis and hyperlipemia, which are generally characteristic of carbohydrate deprivation. The activity of glucose-6-phosphatase in the liver, Kidneys, and intestinal tissues is either extremely low or entirely absent.

Type II glycogen storage disease (Pompe disease) has fatal consequences and is characterized by a deficiency of lysosomal $\alpha$-(1$\rightarrow$4)- and (1$\rightarrow$6)-glucosidase (acid maltase), whose function is to degrade glycogen and prevent its excessive accumulation.

Type III glycogen storage disease (limit dextrinosis; Forbes disease or Cori disease) is characterized by a deficiency of the debranching enzyme, resulting in the accumulation of a characteristically branched polysaccharide (limit dextrin).

Type IV glycogen storage disease (amylopectinosis; Andersen disease) is characterized by a deficiency of the branching enzyme, which leads to the accumulation of a polysaccharide with a minimal number of branch points. A fatal outcome typically occurs due to cardiac or hepatic failure within the first year of life.

A deficiency of Muscle phosphorylase (myophosphorylase) is the cause of type V glycogen storage disease (myophosphorylase deficiency; McArdle syndrome). Patients exhibit reduced tolerance to physical exertion. Although their skeletal Muscles contain an abnormally high glycogen content (2.5–4.1%), little to no lactate is detected in the blood following physical work.

Other glycogenoses have been described, including those associated with hepatic phosphorylase deficiency (type VI glycogen storage disease), deficiency of Phosphofructokinase in muscles and erythrocytes (type VII glycogenosis; Tarui disease), as well as a glycogenosis caused by phosphorylase kinase deficiency. Cases of adenylate kinase and cAMP-dependent protein kinase deficiencies have also been reported.

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