Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to porphyria ?
    ### Response:
    Each form of porphyria results from mutations in one of these genes: ALAD, ALAS2, CPOX, FECH, HMBS, PPOX, UROD, or UROS.  The genes related to porphyria provide instructions for making the enzymes needed to produce heme. Mutations in most of these genes reduce enzyme activity, which limits the amount of heme the body can produce.
    