This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Muscle phosphorylase deficiency leads to which glycogen storage disorder? 
Select and explain. 
A. Her's disease, B. McArdle's disease, C. Cori's disease, D. Andersen disease
B: McArdle's disease
Answer: B: McArdle's disease 
Explanation: Muscle phosphorylase deficiency leads to Mc Ardle's disease.  which is characterised by poor exercise tolerance, muscle glycogen being abnormally high and blood lactate level very low after exercise.
Mnemonic

Her's disease - Hepatic phorphorylase
Andersen disease - Branching enzyme
Cori's disease - Debranching enzyme.

Mnemonic A for B, C for D