<prompt> A 24-year-old woman who had previously been uneventfully transfused,receives a blood transfusion during surgery and sholy thereafter develops itching, generalized uicaria, laryngeal edema, and dyspnea with wheezing respiration. She has a past history of recurrent upper respiratory tract infections and frequent episodes of diarrhea. Laboratory studies are most likely to reveal decreased concentrations of which of the following immunoglobulins?IgAIgDIgEIgG  <response>: Isolated IgA deficiency It is most often asymptomatic but can be characterized by anaphylactic reactions to transfused blood. It is critical to notify the transfusion service about a patient with possible IgA deficiency prior to giving blood products so that products can be washed to remove any immunoglobulins prior to administration. Associated with:- Frequent episodes of diarrhea and recurrent infections. This inherited B-cell defect is due to inability of B cells to mature into IgA-producing plasma cells Patients lacking IgA can develop IgE antibodies against the IgA antibodies present in transfused blood. As the body dont recognise it as a self antigen. This sensitization can result in susceptibility to anaphylaxis on subsequent transfusion. 