sJIA has many characteristics of an autoinflammatory pathology, associated with an increased synthesis of pro-inflammatory interleukins such as IL-1, IL-6, and IL-18, as well as S100 proteins; at the same time, in its evolution, sJIA can be complicated by macrophage activation syndrome (MAS). The gene discussed is IL1A; the disease is systemic-onset juvenile idiopathic arthritis.