Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Mitochondrial complex II deficiency ?
    ### Response:
    Complex II deficiency is a mitochondrial disease. Mitochondria are specialized compartments in cells that create more than 90% of the energy needed by the body. In mitochondrial diseases, the mitochondria don't work correctly resulting in less energy in the cell, cell injury and cell death.
    