IL-2Rα expression increases the affinity ofIL-2 binding ~100 times, facilitating IL-2 responses at low physiologicalconcentrations of IL-2 [9–11].Compromised expression of IL-2 or IL-2Rα leads to the development of autoimmunediseases and immunodeficiency [12–14]. The gene discussed is IL2RA; the disease is immunodeficiency disease.