It has been underlined that patients suffering from CRMO show a decreased production of anti-inflammatory cytokines (interleukins 9, 10, and 18; IL-9, IL-10, IL-18) and increased production of proinflammatory cytokines (IL-1b, IL-6, tumor necrosis factor-α, TNF-a) (4, 16–22). This evidence concerns the gene IL9 and chronic recurrent multifocal osteomyelitis.