After the diagnosis of ANA-positive polyarticular JIA, a 3-year-old female started to be treated with non-steroidal anti-inflammatory drugs (NSAIDS, ibuprofen 10 mg/kg/dose 3 times a day), methotrexate (15 mg/m2/subcutaneously once a week) and later with etanercept (anti-TNF soluble receptor antagonist; dosage: 0.8 mg/kg subcutaneously once a week) with good clinical control of arthritis. The gene discussed is BTG3; the disease is juvenile idiopathic arthritis.