PML and acute myeloid leukemia: By comparing AML samples with a known initiating event (PML-RARA) with normal karyotype AML samples and nonleukaemic blood stem/progenitor cells, this study suggests that most mutations in AML genomes are random events that occurred prior to the initiating leukaemogenic mutation, and that in many cases, only one or two additional, cooperating mutations are needed to generate the malignant founding clone.