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

Abstract

We identified two patients with atypical PML–RARα rearrangements, 53 and 13 base pairs longer than the typical bcr1 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 RARα intron 2. Patient 1 did not express RARα–PML and patient 2 showed the RARα–PML transcript, which corresponded to the typical bcr1. These results emphasize on the relevance of the correct identification of atypical PML–RARα rearrangements because of the potential implications in leukemogenesis, in the response to treatment, and for the correct monitoring of minimal residual disease.