IL6ST is the interleukin 6 (IL-6) signal transducer and is the drug target of satralizumab, a biological drug that is currently in Phase III of a clinical trial for neuromyelitis optica, a rare autoimmune disease of the nervous system.31 Considering that other biological drugs targeting the IL-6 pathway, such as tocilizumab, are currently in use for the treatment of JIA, our findings provide genetic support for the study of satralizumab as a new therapeutic target for JIA. This evidence concerns the gene IL6ST and neuromyelitis optica.