Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Erythromelalgia ?
    ### Response:
    What causes erythromelalgia? About 15% of cases of erythromelalgia are caused by mutations in the SCN9A gene. The SCN9A gene gives instructions for making part of a sodium channel which carries sodium into cells and helps them make and transmit electrical signals.
    