In this episode of The Differential, Dr. Assem Al Refaei breaks down a structured approach to diagnosing immunodeficiencies. Focusing on high-yield Step 2 CK concepts and practical clinical insights, we explore the identification of immunodeficiency causes using clinical patterns, lab findings, and essential physical exam clues. Key topics include CVID, X-linked agammaglobulinemia, SCID, Job syndrome, Wiskott-Aldrich syndrome, and other critical conditions.