Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Porphyria ?
    ### Response:
    Heme is a red pigment composed of iron linked to a chemical called protoporphyrin. Heme has important functions in the body. The largest amounts of heme are in the form of hemoglobin, found in red blood cells and bone marrow. Hemoglobin carries oxygen from the lungs to all parts of the body.
    