Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Sjgren syndrome ?
    ### Response:
    Sjgren syndrome is a disorder whose main features are dry eyes and a dry mouth. The condition typically develops gradually beginning in middle adulthood, but can occur at any age.  Sjgren syndrome is classified as an autoimmune disorder, one of a large group of conditions that occur when the immune system attacks the body's own tissues and organs.
    