In the current clinical practice generalized to date, a certain number of specific biomarkers for JIA have already been adopted by expert guidelines and are currently applied, such as ESR, CRP, serum ferritin, RF, HLA-B27 molecule, ANA, etc., which can help clinicians to better discriminate between the different subtypes and anticipate the response to the applied therapy, as well as relapses, which ideally should indicate the most appropriate medication for that patient and the point at which the therapy can be safely stopped after remission [225]. The gene discussed is ESR1; the disease is juvenile idiopathic arthritis.