This raises the possibility that heterogeneity in expression levels or activity of TDP2 could be an important etiological factor both in the toxicity that accompanies chemotherapy involving TOP2 poisons [45] and on the incidence of treatment-related hematological malignancy, typically acute leukemia occurring in a relatively high proportion of patients [4], [7], [8]. The gene discussed is TDP2; the disease is acute leukemia.