Question

A child with exercise fatigue presented to OPD. The features were suggestive of McArdle disease. Which of the following enzymes will be deficient in this?

• A. Myo-Phosphorylase
• B. Glucose 6 Phosphatase
• C. Lysosomal Glucosidase
• D. Phosphofructokinase

Hint:

McArdle disease results in muscle fatigue and exercise intolerance due to the inability to break down glycogen in muscle cells.

Answer 1

The Correct Option is A

McArdle disease, also known as glycogen storage disease type V, is caused by a deficiency in the enzyme myophosphorylase. Myophosphorylase is responsible for breaking down glycogen, a stored form of glucose, into glucose-1-phosphate, which can be used as a source of energy. In individuals with McArdle disease, the deficiency of this enzyme leads to the accumulation of glycogen in muscle cells, causing exercise intolerance and fatigue.