IL23A and juvenile idiopathic arthritis: IL-12p40 is encoded on Chromosome 5q31–33 [5], produced mainly by macrophages, neutrophils, microglia and dendritic cells [6] and promotes in cooperation with IL-12p35 (as IL-12p70) the induction and activation of Th1-cells while it promotes in cooperation with IL-23p19 (as IL-23) the induction and activation of Th17-cells, both key elements in the pathophysiology of JIA.