Enzyme deficiency in McArdle syndrome: (A) Muscle phosphorylase, (B) Liver phosphorylase, (C) Liver debranching enzyme, (D) Glycogen synthase
Answer is A. Glycogen storage disorderTypeNameEnzyme DeficiencyClinical FeaturesType VMyophosphorylase deficiency,McArdle syndromeMuscle phosphorylasePoor exercise tolerance; muscle glycogen abnormally high(2.5%-4%); blood lactate very low after exerciseRef: Harper&;s Biochemistry; 30th edition; Table 18-2; Chapter 18; Metabolism of Glycogen