Mc Ardle's disease is due to deficiency of?
High-Yield Explanation
Glycogen storage disease (GSD; type V)(McArdle disease): Deficiency of myophosphorylase (muscle glycogen phosphorylase) enzyme that catalyzes the removal of glucose residues from glycogen to form glucose-1-phosphate that ultimately enters glycolysis to provide muscle energy. Also Know: In McArdle disease only the skeletal muscle isoform is defective. Muscular weakness and fatigue are observed with attempted exercise; tiredness and cramping affects normal activity. Vigorous exercise may cause muscle breakdown (rhabdomyolysis), leading to myoglobin in the urine (myoglobinuria). Ref: Kishnani P.S., Chen Y. (2012). Chapter 362. Glycogen Storage Diseases and Other Inherited Disorders of Carbohydrate Metabolism. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.