BCR and acute promyelocytic leukemia: The reciprocal t(15;17) translocation is present in 90–95% of APL cases, and, depending on the location of the PML breakpoint, three PML::RARA fusion transcript isoforms can be produced: long (bcr1; intron 6), variant (bcr2; exon 6), and short (bcr3; intron 3), with the bcr1 and bcr3 isoforms being the most common [2,7,8].