RAPID COMMUNICATION The t(15;17) Breakpoint in Acute Promyelocytic Leukemia Cluster Within Two Different Sites of the myl Gene: Targets for the Detection of Minimal Residual Disease by the Polymerase Chain Reaction

The retinoic acid receptor a (RARa) and the my1 gene are involved in the translocation breakpoint t(15;17)(q22;q21) in acute promyelocytic leukemia (APL). The majority of the breakpoint sites have been mapped within the second intron of the RARa gene; however, the breakpoint sites on the my1 gene are variable. Using primer sets derived from exon 2 or exon 3 of the RARa gene and a primer derived from the my1 cDNA, we were able to amplify the breakpoint sites of the fusion transcripts of all six APL RNA samples by the reverse transcriptase-polymerase chain reaction (RT-PCR). A DNA fragment of 290 bp (breakpoint A) was amplified using RNA samples from three patients, whereas two DNA fragments of 630 and 774 bp (breakpoint B) were amplified using RNA