Four Mendelian primary immunodeficiencies associated with impaired signalling of the TLR pathway have been reported with mutations in MyD88, interleukin-1 receptor-associated kinase-4 (IRAK4), nuclear factor-kappa B essential modulator (NEMO) and IκBα (nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha) [26]. This evidence concerns the gene IRAK4 and inborn error of immunity.