Immune system dysregulation in patients who develop HLH involves numerous cytokines such as IL-1, IL-2, IL-6, IL-10, and interferon-gamma which are signaled through the Janus kinase (JAK) and signal transducers and activators of transcription pathways.17,18 Given the lack of success with etoposide-based therapies in adults, inhibition or interruption of key cytokine pathways associated with the clinical manifestations of HLH has been a clinical area of interest. The gene discussed is IL2; the disease is hemophagocytic syndrome.