As additional disease controls, we also tested patients with clinically (fever of unknown origin, FUO, n = 8) or genetically defined autoinflammatory syndromes (familial Mediterranean fever, FMF, n = 3; cryopyrin-associated periodic syndrome, CAPS, n = 2), which are in part primarily driven by excessive IL-1b expression and signaling and thus present with an immunopathology similar to that of Still’s disease. Here, IL1B is linked to systemic-onset juvenile idiopathic arthritis.