Juvenile arthritis (JA), also known as pediatric rheumatic disease, isn’t a specific disease. It’s an umbrella term to describe the inflammatory and rheumatic diseases that develop in children under the age of 16. These conditions affect nearly 300,000 kids and teens in the United States. Most kinds of JA are autoimmune or autoinflammatory diseases. That means the immune system, which is supposed to fight against foreign invaders like viruses and germs, gets confused and releases inflammatory chemicals that attack healthy cells and tissue. In most JA cases this causes joint inflammation, swelling, pain and tenderness, but some types of JA have few or no joint symptoms or only affect the skin and internal organs. The exact causes of JA are unknown, but researchers believe that certain genes may cause JA when activated by a virus, bacteria or other external factors. There is no evidence that foods, toxins, allergies or lack of vitamins cause the disease. Juvenile idiopathic arthritis is the most common form of juvenile arthritis and includes six types: oligoarthritis, polyarthritis, systemic, enthesitis-related, juvenile psoriatic arthritis and undifferentiated.