Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) familial isolated hyperparathyroidism ?
    ### Response:
    Familial isolated hyperparathyroidism is an inherited condition characterized by overactivity of the parathyroid glands (hyperparathyroidism). The four parathyroid glands are located in the neck, and they release a hormone called parathyroid hormone that regulates the amount of calcium in the blood.
    