IKBKB and infection: Curiously, however, the consequences of a lack of IKKβ in humans are strikingly different; homozygous deletion of the IKBKB gene is not embryonic lethal—at least in patients examined to date—but leads to a lack of regulatory (Treg) and γδ T cells, defects in T- and B-cell activation and to SCID associated with early infections with various pathogens [141,142,143,144].