The Second International Workshop Criteria (2° IWWM) formulated the following requirements for WM diagnosis: (a) the presence of IgM monoclonal gammopathy of any size, (b) a BM trephine biopsy with lymphoplasmacytic infiltration and (c) an immunophenotype that excludes the possibility of other lymphoproliferative disorders [9] (Figure 1). The gene discussed is CD40LG; the disease is monoclonal gammopathy.