Snapshot A 1-year-old boy is brought to the emergency room for bloody diarrhea. He has a history of recurrent ear infections, diarrhea, and atopic dermatitis. He had an older sibling who died of a pulmonary infection at a young age. On physical exam, there is dried blood in his nares bilaterally and bleeding at intravenous puncture sites. Additionally, purpura is noted on his arms. Laboratory results show marked thrombocytopenia requiring platelet transfusions. Immunoglobulin levels show decreased IgG and IgM but increased IgE and IgA. Introduction Clinical definition login to view 7 more bullets etiology Pathogenesis login to view 1 more bullet Genetics login to view 4 more bullets Presentation Symptoms/physical exam login to view 19 more bullets Studies Diagnostic testing login to view 5 more bullets Differential Severe combined immunodeficiency login to view 3 more bullets Transient hypogammaglobulinemia of infancy login to view 2 more bullets DIAGNOSIS Diagnostic criteria login to view 1 more bullet Treatment Management approach login to view 2 more bullets First-line login to view 9 more bullets Complications Increased risk of login to view 3 more bullets Chronic eczema login to view 1 more bullet Prognosis Reduced life expectancy Bleeding is the main cause of death