Identification of two atypical PML-RARα transcripts in two patients with acute promyelocytic leukemia

We identified two patients with atypical PML-RARalpha rearrangements, 53 and 13 base pairs longer than the typical bcrl transcript. Sequence analysis revealed a new PML breakpoint at the end of exon 7a in patient 1, and a PML exon 6 breakpoint in patient 2, with an insertion of 35 nucleotides of RARalpha intron 2. Patient I did not express RARalpha,-PML and patient 2 showed the RARalpha-PML transcript, which corresponded to the typical bcrl. These results emphasize on the relevance of the correct identification of atypical PML-RARalpha rearrangements because of the potential implications in leukemogenesis, in the response to treatment, and for the correct monitoring of minimal residual disease. (C) 2002 Elsevier Science Ltd. All rights reserved.