Snapshot A 7-year-old patient presents to the emergency room after a motor vehicle accident, in which she loses a lot of blood. She is immediately transfused with blood. However, she develops difficulty breathing and oral-facial swelling. Physical exam reveals expiratory wheezes. She is immediately given epinephrine. On further questioning, physical exam reveals atopic dermatitis and recurrent ear and lung infections. Introduction Primary immunodeficiency with decreased levels of IgA Epidemiology most common primary immunodeficiency Pathogenesis B-cells fail to differentiate into IgA-producing plasma cells unknown cause impairs mucosal immunity, leading to sinopulmonary infections Associated conditions increased incidence of autoimmune diseases celiac disease atopy allergies atopic dermatitis asthma Presentation Symptoms most = asymptomatic sinus and lung infections GI infections anaphylaxis with exposure to blood products with IgA Evaluation Diagnosis based on clinical history Serology ↓ IgA (< 7 mg/dL) normal IgG, IgM, and IgE false positive β-HCG Differential Common variable immunodeficiency IgG deficiency Ataxia-telangiectasia (↓ IgA, IgG, and IgE) Hyper-IgM syndrome (↓ IgA, IgG, IgE, and ↑ IgM) Treatment Usually no specific treatment Antibiotics as needed for infections Immunizations Blood transfusions obtain blood from IgA-deficient donor Prognosis, Prevention, and Complications Prognosis typically very good some patients spontaneously develop normal IgA levels Prevention avoid blood transfusions unless from IgA-deficient individual Complications recurrent sinopulmonary infections diarrhea from giardiasis fatal anaphylaxis