Surgery McArdle’s disease causes muscle cramps and muscle fatigue with increased muscle glycogen. Which of the following enzymes is deficient? A Hepatic hexokinase B Muscle glycogen synthetase C Muscle phosphorylase D Muscle hexokinase 💡 Explanation McArdle's disease causes muscle cramps and muscle fatigue with increased muscle glycogen. Which of the following enzymes is deficient? ✓ Correct Answer: C. Muscle phosphorylase