A novel method for the detection, quantitation, and breakpoint cluster region determination of t(15;17) fusion transcripts using a one-step real-time multiplex RT-PCR.

Individuals with acute promyelocytic leukemia (APL) usually express 1 of 3 primary hybrid transcripts associated with a t(15;17). The 3 fusion transcripts are the result of heterogeneous breakpoint cluster regions (bcr) within the promyelocytic leukemia (PML) gene and are denoted bcr1 (long), bcr2 (variant), and bcr3 (short) forms. Many researchers have shown that real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) of the involved transcript is a valuable tool for monitoring APL and its treatment. In addition, some research suggests that identification of a specific breakpoint region may be used to predict an individual's likelihood of relapse and possibly their response to all-trans retinoic acid treatment. We describe the first reported 1-step multiplex RT-PCR assay capable of t(15;17) fusion transcript real-time relative quantitation and simultaneous transcript form identification in 2 reactions. This assay uses a novel dual-probe technique to achieve what has required a laborious procedure of 2 or more reactions followed by postamplification analysis. We found a correlation of 100% in detection and breakpoint determination of the long, short, and variant forms with a breakpoint 5' to nucleotide 1709 compared with results from traditional methods.