Below is an instruction from Human. Write a response.
    ### Instruction:
    How many people are affected by familial isolated pituitary adenoma ?
    ### Response:
    Pituitary adenomas, including sporadic tumors, are relatively common; they are identified in an estimated 1 in 1,000 people. FIPA, though, is quite rare, accounting for approximately 2 percent of pituitary adenomas. More than 200 families with FIPA have been described in the medical literature.
    