Below is an instruction from Human. Write a response.
    ### Instruction:
    How many people are affected by primary macronodular adrenal hyperplasia ?
    ### Response:
    PMAH is a rare disorder. It is present in less than 1 percent of cases of endogenous Cushing syndrome, which describes forms of Cushing syndrome caused by factors internal to the body rather than by external factors such as long-term use of certain medicines called corticosteroids.
    