IRAK4 and immune system disorder: Moreover, the genetic variability in TLR signaling pathway molecules (i.e., interleukin-1 receptor-associated kinase 4 [IRAK4], an inhibitor of nuclear factor κB kinase γ [IKKγ], and an inhibitor of nuclear factor κB α [IκBα]) causes rare inherited immunodeficiencies that can also influence the susceptibility to human diseases [37,38].