In AML samples with higher IgA2, besides having a lower level of IgG (Additional file 2: Figure S9) which is known to promote T cell-mediated antitumor immunity [48], the CSR events of IgM B cells are almost restricted to IgA1 and IgA2 (Fig. 5b). The gene discussed is CD40LG; the disease is acute myeloid leukemia.