Multiple recent publications tried to establish the role of pro-inflammatory cytokines, such as interleukin-18 (IL-18), interferon-γ (IFN-γ), and IL-1β on MAS pathogenesis and proposed the detection of these cytokines as biomarkers to classify MAS as well as cytokine antagonists to treat the disease (8–11). The gene discussed is IFNG; the disease is macrophage activation syndrome.