A rapid practical RT-PCR-based approach for the detection of the PML/RAR alpha fusion transcript in acute promyelocytic leukemia

The t(15;17) and its molecular equivalent, PML/RAR alpha gene fusion, is strongly associated with acute promyelocytic leukemia (APL). Since treatment response to all-trans retinoic acid correlates directly with PML/RAR alpha, expeditious documentation is critical to patient care. We have designed an extremely rapid, practical, polymerase chain reaction (PCR)-based method using a rapid air thermal cycler to detect type A, B, and B-variant fusion patterns of PML/RAR alpha. We examined 15 cases of APL and 13 cases of leukemias other than APL with a nested reverse-transcription PCR assay. Three APL samples were type A, 11 were type B, and 1 was a B variant based on gel band patterns. PCR products exhibited positive probe hybridization signals and had sequences containing type A, B, or B-variant fusion patterns. PCR amplification of PML/RAR alpha was complete in 22 minutes, and the entire test required 4 1/2 hours. This method permits exceptional turnaround time and is an alternative to cytogenetics and slower PCR assays.