IFNG and Crouzon syndrome-acanthosis nigricans syndrome: reported responders to canakinumab had higher serum IL-18 and IFN-γ levels and lower CXCL9 levels at baseline; that is, higher IL-18:CXCL9 and IFN-γ:CXCL9 ratios at baseline were associated with a better clinical response to CAN treatment in s-JIA (21).