IRAK-4 deficiency

IRAK-4 deficiency is an inherited disorder of the immune system (primary immunodeficiency). This immunodeficiency leads to recurrent infections by a subset of bacteria known as pyogenic bacteria but not by other infectious agents. (Infection with pyogenic bacteria causes the production of pus.) The most common infections in IRAK-4 deficiency are caused by the Streptococcus pneumoniae, Staphylococcus aureus, and Pseudomonas aeruginosa bacteria. Most people with this condition have their first bacterial infection before age 2, and the infections can be life-threatening in infancy and childhood. Infections become less frequent with age.

Most people with IRAK-4 deficiency have invasive bacterial infections, which can involve the blood (septicemia), the membrane covering the brain and spinal cord (meningitis), or the joints (leading to inflammation and arthritis). Invasive infections can also cause areas of tissue breakdown and pus production (abscesses) on internal organs. In addition, affected individuals can have localized infections of the upper respiratory tract, skin, or eyes. Although fever is a common reaction to bacterial infections, many people with IRAK-4 deficiency do not at first develop a high fever in response to these infections, even if the infection is severe.