Juvenile idiopathic arthritis (JIA), is the most common, chronic rheumatic disease of childhood, affecting approximately one per 1,000 children. Juvenile, in this context, refers to disease onset before age 16 years, 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. [Source: Wikipedia 
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