Among the14 studies in the review, Weiss et al. reported that a total IL-18 (i.e., IL-18 bound to IL-18 binding protein [BP]) cut-off value at >11,600 pg/mL distinguished sJIA (or AOSD) or MAS complicating sJIA (or AOSD) from familial or infection-associated HLH, with 88% sensitivity and 93% specificity (35). This evidence concerns the gene IL18 and adult-onset Still disease.