Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Autoimmune autonomic ganglionopathy ?
    ### Response:
    Autoimmune autonomic ganglionopathy (AAG) is rare autoimmune disorder in which the body's immune system mistakenly attacks and damages certain parts of the autonomic nervous system. Signs and symptoms of the condition vary but may include severe orthostatic hypotension (low blood pressure upon standing); fainting; constipation; fixed and dilated pupils; urinary retention; and/or dry mouth and eyes.
    