In diffuse large B cell lymphoma (DLBCL), a common, genetically diverse, and still often fatal B cell malignancy, the mutations that disarm the immune system range from highly predictable suspects, including genes encoding products directly involved in antigen processing/presentation (e.g., B2M, CIITA, and HLA-A/B/C) (4–6), to less immediately obvious candidates, such as chromatin modifiers (e.g., CREBBP and EZH2) (7–9). Here, B2M is linked to diffuse large B-cell lymphoma.