Mutations that affect the NF-kappa-B inhibitor alpha (NFκBIA or IKBA) or the kinases responsible for its inactivation (IKK-β or IKK-γ/NF-κB essential modifier) are known causes of combined immunodeficiency with increased susceptibility to mycobacteria (11, 127, 128). This evidence concerns the gene NFKBIA and severe combined immunodeficiency.