Hyper-IgM syndrome is an X-linked genetic disorder more commonly affecting males than females. It is caused by the lack of heavy chain class-switching from IgM to other isotypes. Patients with hyper-IgM syndrome are susceptible to a variety of infections as demonstrated in this medical case study. Students are presented patient information, symptoms and a diagnosis that must be interpreted. The case was written for use with the team-based learning (TBL) format involving groups of 4-5 students per group, but it could also be completed as an individual project. The case is targeted to premedical/allied health advanced students and is appropriate for any immunology course at the undergraduate or graduate level in a biomedical science program, or health-related professional courses such as advanced physiology, pathophysiology, microbiology, or histology and cytology.