Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) phosphoglycerate mutase deficiency ?
    ### Response:
    Phosphoglycerate mutase deficiency is a disorder that primarily affects muscles used for movement (skeletal muscles). Beginning in childhood or adolescence, affected individuals experience muscle aches or cramping following strenuous physical activity. Some people with this condition also have recurrent episodes of myoglobinuria.
    