AMP Deaminase Deficiency
Consider what happens in an individual who has a genetic deficiency in the production of AMP deaminase (also called myoadenylate deaminase). Increase in muscle activity requires energy, and this is generated by activation of the citric acid cycle resulting in the release of free energy. The citric acid cycle is activated by an increase in its intermediates, but the only intermediate that muscle tissue can generate is fumarate. Without sufficient AMP deaminase activity, sufficient fumarate is not generated and muscles fatigue easily and cramp following exercise.