Snapshot A 3-year-old boy is brought to the pediatrician’s office for an ear infection. He has had multiple upper respiratory, ear, and skin infections since 6 months of age. He has required inpatient admissions to the pediatric ward twice for intravenous antibiotics. On physical exam, he has no tonsils and has no history of tonsillectomy. Levels of IgG, IgM, and IgA are decreased. Genetic testing is sent to confirm the diagnosis. Introduction Clinical definition primary humoral immunodeficiency characterized by decreased immunoglobulins Epidemiology Demographics boys etiology Pathogenesis defective maturation of B-cells login to view 3 more bullets impaired antibody immune response Genetics X-linked recessive defect in Bruton tyrosine kinase (BTK) Presentation Symptoms recurrent infections login to view 3 more bullets increased susceptibility to encapsulated bacteria and blood-borne viruses login to view 1 more bullet Physical exam absent/scant lymphoid tissues login to view 1 more bullet Studies Diagnostic testing studies login to view 3 more bullets Differential Severe combined immunodeficiency distinguishing factor login to view 2 more bullets Transient hypogammaglobulinemia of infancy distinguishing factor login to view 1 more bullet DIAGNOSIS Diagnostic criteria confirmed with DNA, mRNA, or protein analysis showing mutation in BTK Treatment Management approach mainstay of treatment is to treat each infection with antibiotics First-line intravenous immunoglobulin Complications Small risk of malignancy Prognosis Normal prognosis with regular intravenous immunoglobulin (IVIG) therapy and early detection