Juvenile idiopathic arthritis (JIA), formerly known as juvenile rheumatoid arthritis (JRA), is the most common chronic rheumatic disease of childhood, affecting approximately 3.8 to 400 out of 100,000 children. Juvenile, in this context, refers to disease onset before 16 years of age, while idiopathic refers to a condition with no defined cause, and arthritis is inflammation within the joint. JIA is an autoimmune, noninfective, inflammatory joint disease, the cause of which remains poorly understood...