IFNG and systemic-onset juvenile idiopathic arthritis: The pathogenesis of SJIA is complex, with an autoinflammatory presentation involving proinflammatory cytokines such as interleukin (IL)-1 and Il-6, a risk of life-threatening macrophage activation syndrome (MAS) in some patients also involving other cytokines, such as interferon gamma and IL-18 [3,4,5,6,7,8,9,10].