5th February 2024

Glycogen metabolism

As a revision to the previous section, glycogen is converted to glucose-6-phosphate under the regulation of debranching enzyme, hepatic glycogen phosphorylase and phosphorylase kinase. Glucose-6-phosphatase is responsible for converting glucose-6-phosphate to glucose.

Glycogen storage disorders are inherited disorders characterised by enzyme deficiencies which impair glycogen synthesis, glycogen degradation or glycolysis, leading to the deposition of an abnormal quantity or form of glycogen in the tissues. The liver and the skeletal muscles are the most commonly affected. The following are the diseases in this category that are favourites in the MRCP Part 1 exam:

• Maturity onset diabetes of the young type 2 (MODY type 2)
• Glucose-6-phosphatase deficiency (GSD type I, von Gierke’s disease) vs. G6PD deficiency
• McArdle disease