Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) juvenile idiopathic arthritis ?
    ### Response:
    Juvenile idiopathic arthritis refers to a group of conditions involving joint inflammation (arthritis) that first appears before the age of 16. This condition is an autoimmune disorder, which means that the immune system malfunctions and attacks the body's organs and tissues, in this case the joints.
    