Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Mitochondrial complex IV deficiency ?
    ### Response:
    Cytochrome C oxidase deficiency (COX deficiency) is a condition that can affect several parts of the body including the skeletal muscles, heart, brain and liver. The range and severity of signs and symptoms can vary widely among affected individuals (even within the same family) and depend on the form of the condition present.
    