These included a tMDS that developed 8 months after AML and both were found to harbor a NUP98-NSD1 fusion (Fig. 4b) with multiple discrete WT1mut subclones, and 2 cases where the initial lymphoid malignancy (ALL or NHL) and tMN developed from a common clone that subsequently underwent a lineage switch (Fig. 4c–f). The gene discussed is NSD1; the disease is acute myeloid leukemia.