Juvenile Rheumatoid Arthritis (JRA) is arthritis that causes joint inflammation and stiffness for more than 6 weeks in a child of 16 years of age or less.

Inflammation causes redness, swelling, warmth, and soreness in the joints, although many children with JRA do not complain of joint pain. Any joint can be affected and inflammation may limit the mobility of affected joints. The temporomandibular joint is one of the joints commonly affected. One form of JRA can also affect the internal organs.

Doctors classify JRA into three types by the number of joints involved, the symptoms, and the presence or absence of certain antibodies found by a blood test. (Antibodies are special proteins made by the immune system.) These classifications help the doctor determine how the disease will progress and whether the internal organs or skin is affected.

Source: National Institutes of Health