Given the well-documented hypogammaglobulinemia in CLL patients and prior studies demonstrating hypogammaglobulinemia with persistently stable antibody levels against latent viruses like CMV and EBV [23], we investigated the levels of CMV-specific soluble IgM and IgG antibodies, which were found to be similar between CLL patients with increasing vs. stable clones (Table S6). The gene discussed is CD40LG; the disease is B-cell chronic lymphocytic leukemia.