Increase in BAFF levels occurs during HIV infection [32,33,34], as well as in B-cell lymphoproliferative disorders [35,36], such as B chronic lymphocytic leukemia [37], non-Hodgkin lymphoma [38], multiple myeloma [39] and Waldenström macroglobulinemia [40]. The gene discussed is TNFSF13B; the disease is plasma cell myeloma.