A primary immunodeficiency with characteristics of increased susceptibility to pyogenic bacterial infections, including invasive pneumococcal, invasive staphylococcal and pseudomonas disease. Only 24 cases have been reported. The disease presents in childhood with recurrent, life-threatening, pyogenic bacterial infections. This predisposition to life-threatening infections seems transient and lasts during the first 10 years of life in the cases reported so far. Myeloid differentiation primary response 88 (MyD88) deficiency results from mutations in the MYD88 gene (3p22-3p21.3) which generally abolishes the cytokine responses of the blood cells. Transmission is autosomal recessive.