The infectious phenotype of autosomal recessive MYD88 deficiency (OMIM 612260) is dominated by invasive pyogenic infections and the main bacteria isolated in cases of invasive infection are Staphylococcus pneumoniae, S. aureus, and Pseudomonas aeruginosa. Also fungal infections, for example caused by the yeast C. albicans, are described in patients with MYD88 deficiency [18]. The gene discussed is MYD88; the disease is hyperinsulinemic hypoglycemia, familial, 4.