Systemic symptoms, i.e., fever, increased erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), polyarticular or hip involvement, radiological damage, need for glucocorticoids, increased immunoglobulin A (IgA), thrombocytopenia, and elevated serum ferritin levels (very important if glycosylated ferritin < 20% according to Fautrel) have all been described as poor prognostic signs, and major complications include amyloidosis and macrophage activation syndrome (MAS) [8, 15–17]. The gene discussed is CD79A; the disease is macrophage activation syndrome.