This case study follows the process of diagnosing a patient, 67-year-old “Chester Fitzgerald,” who has suffered an ischemic stroke. An ECG is performed, but is not conclusive. During a physical exam, his doctor discovers a splenomegaly and orders a CBC to determine the cause. The results, combined with the other symptoms that Chester reports, lead the doctor to suspect an underlying disease rather than just an age-related stroke. This suspicion is confirmed by genetic testing, and the case closes with a brief description of a suitable treatment plan for the patient. The case walks students through multiple tests in the diagnosing process and aspects of healthcare to help them understand how these tests fit in the context of a real-life situation. The case study is divided into three parts that correlate with the three phases of this patient’s diagnosis. Each part ends with a series of questions designed to help students apply previous knowledge. The case study is appropriate for use in undergraduate anatomy and physiology courses.