Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Autoimmune atrophic gastritis ?
    ### Response:
    Autoimmune atrophic gastritis is an autoimmune disorder in which the immune system mistakenly attacks the healthy cells of the stomach lining. Overtime, this can wear away the stomach's protective barrier and interfere with the absorption of several key vitamins (i.
    