PML and acute promyelocytic leukemia: APL has been shown to require only the PML–RARα fusion protein, however Shen et al. (2015) in their study of 535 APL patients in two cohorts (training; n = 266 and testing; n = 269) showed by systematic analysis of genetic markers the presence of a range of additional mutations typically associated with normal karyotype AML patients in patients with APL.