Although previous in vitro studies using murine erythroid cells demonstrated that IL-15 enhances the erythropoiesis-stunting effect of IFN-γ [54], elevation of both IL-15 and IFN-γ in the G[−] group, in the absence of decreased erythropoietic indices, suggests that their elevation does not necessarily promote worsening anemia. The gene discussed is IFNG; the disease is anemia (phenotype).