IL2RA and Autoimmunity: Interestingly, the lack of surface CD25 led to IPEX-like syndrome, which is characterized by early immune dysfunction and systemic autoimmunity, in both patients, similar to other reported cases with mutations within the IL-2Rα gene that completely impaired CD25 expression.53,54 It remains unclear why humans but not Cd25Y129H mice develop spontaneous autoimmunity, even though surface levels of CD25 are reduced to a similar degree.