The causes of juvenile idiopathic arthritis are not yet clear. In the vast majority of those affected, certain genetic traits can be identified. Girls are more often affected by the disease than boys.
The symptoms tend to be swelling, redness, hyperthermia, limited mobility or pain in the affected joints. In some cases there is a so-called joint effusion, an accumulation of fluid in the joint. Furthermore, affected children and adolescents tend to suffer from joint stiffness in the mornings, which means they are less mobile in the morning or after a longer period of rest. They often adopt a protective posture so as to move their joints as little as possible. For example, children refuse to walk if their leg joints are affected and painful. Depending on the subform of the disease, the inflammation can spread to other parts of the body, e.g. the tendons and skin. Another concomitant disease is uveitis, in which the vascular membrane of the eye can become inflamed.