Interleukin (IL)-1 receptor-associated kinase 4 (IRAK4) plays an important role in the intracellular signal transduction from IL-1, IL-18, and Toll-like receptors (TLRs) other than TLR3.1 IRAK4 deficiency is an autosomal recessive primary immunodeficiency of the innate immune system.2 IRAK4-deficient patients suffer from severe invasive bacterial infections in early childhood.3,4Streptococcus pneumoniae, Staphylococcus aureus, and Pseudomonas aeruginosa are, by far, the most commonly isolated pathogens. This evidence concerns the gene IRAK4 and inborn error of immunity.