Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) prekallikrein deficiency ?
    ### Response:
    Prekallikrein deficiency is a blood condition that usually causes no health problems. In people with this condition, blood tests show a prolonged activated partial thromboplastin time (PTT), a result that is typically associated with bleeding problems; however, bleeding problems generally do not occur in prekallikrein deficiency.
    