Of the more than ten globally-approved JAK inhibitors66, we chose to employ in our clinical trial the JAK1/3 inhibitor tofacitinib, which is used to treat diverse autoimmune/inflammatory conditions and which was approved in 2020 for treatment of polyarticular course juvenile idiopathic arthritis (pcJIA) in children 2 years and older66,67. This evidence concerns the gene JAK1 and juvenile idiopathic arthritis.