Gia, a six-year-old with celiac disease, presents with gastrointestinal issues despite avoiding gluten. Stool tests reveal a Giardia infection, and immunoglobulin tests show low IgA and high IgE levels, pointing to selective IgA deficiency. Meanwhile, Joe, a 10-year-old with a fractured arm, has increased IgE levels, normal IgA, and recurrent skin abscesses, suggesting hyper-IgE syndrome (Job syndrome). This educational video explores the diagnostic process for immune deficiencies, including selective IgA deficiency and hyper-IgE syndrome, while highlighting the importance of clinical history, lab results, and genetic testing in managing such cases effectively.