Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Imerslund-Grsbeck syndrome ?
    ### Response:
    Imerslund-Grsbeck syndrome is a condition caused by low levels of vitamin B12 (also known as cobalamin). The primary feature of this condition is a blood disorder called megaloblastic anemia. In this form of anemia, which is a disorder characterized by the shortage of red blood cells, the red cells that are present are abnormally large.
    