Splenic marginal zone lymphoma (SMZL) appears to be a particular concern and sometimes a challenge for diagnosticians, yet mantle cell lymphoma (MCL), rare cases of IgM-producing multiple myeloma (IgM-MM), and B cell chronic lymphocytic leukemia (B-CLL) must also be considered when a patient presents with symptoms suggestive of WM. The gene discussed is CD40LG; the disease is B-cell chronic lymphocytic leukemia.