Muscle glycogen storage disease

Glycogen storage diseases (GSD) are inherited metabolic disorders of glycogen metabolism. They are divided into types 0 to XV, according to enzyme or transporter deficiency and organ distribution. Disorders of glycogen degradation may affect primarily the liver, the muscle, or both. GSD has been known to mainly be a liver disease with the exception of Pompe (GSD II), McArdle (GSD V), or Tarui (GSD VII) diseases. Recently, however, various muscular disorders involving different types of muscles have been described to be caused by defective glycogen metabolism. In the Muscle GSDs, the consequence of a block in skeletal muscle glycogenolysis, or in the glycolysis, is an impairment of muscular performance, owing to an increase in glycogen storage that disrupts contractile function and/or a reduced substrate turnover, which inhibits skeletal muscle ATP production.