MONDO_0019437 (enthesitis-related juvenile idiopathic arthritis) is a subtype of juvenile idiopathic arthritis that is characterized by both arthritis and inflammation of an enthesitis site (the point at which a ligament, tendon, or joint capsule attaches to the bone). Signs and symptoms generally develop in late childhood or early adolescence and include pain, tenderness, and swelling in joints and at the enthesis. The knee and the back of the ankle (at the Achilles tendon) are the most commonly affected parts of the body. The underlying cause of enthesitis-related juvenile idiopathic arthritis is currently unknown (idiopathic). It is very rare for more than one member of a family to have juvenile arthritis; however, research suggests that having a family member with juvenile arthritis or any autoimmune disease may increase the risk of having juvenile arthritis, in general. Treatment usually involves different types of medications to help manage symptoms and/or physical therapy. Also known as: ERA, enthesitis-related JIA, era.