In normal B-cell development, immunoglobulin genes undergo V(D)J recombination in the bone marrow and somatic hypermutation and class switch recombination in the lymph nodes. All of the IgM MM cases analyzed by Bazarbachi et al harbor a t(11;14) translocation; 60% of them have evidence of the event occurring at the pro–B-cell stage during V(D)J recombination. In non-IgM MM, most translocations occur in the germinal center; only 25% of t(11;14) has evidence of earlier onset in the bone marrow. WM is further distinguished from IgM MM because of the lack of t(11;14) and the presence of the MYD88 L265P mutation in the majority of cases. Bazarbachi et al also identify upregulated markers in IgM MM, such as BTK, BCL2/BLC2L1, and CD20, suggesting potential therapeutic options specific for this disease. germ, germinal center; recomb, recombination.