Finally, although the absence of AIRE is a feature of APECED disease, significantly decreased levels of AIRE have also been observed in patients suffering from Omenn syndrome or Down syndrome, two disorders characterized by severe immunodeficiency and T-cell-mediated autoimmunity (Cavadini et al., 2005; Giménez-Barcons et al., 2014). This evidence concerns the gene AIRE and Omenn syndrome.