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

The t(15;17) and its molecular equivalent PML/RARalpha gene fusion, is stro ngly associated with acute promyelocytic leukemia (APL). Since treatment re sponse to all-trans retinoic acid correlates directly with PML/RARalpha, ex peditious documentation is critical to patient care. We have designed an ex tremely rapid, practical, polymerase chain reaction (PCR)based method using a rapid air thermal cycler to detect type A, B, and B-variant fusion patte rns of PML/ RARalpha. We examined 15 cases of APL and 13 cases of leukemias other than APL with a nested reverse-transcription PCR assay. Three APL sa mples were type A, II were type B, and 1 was a B variant based on gel band patterns. PCR products exhibited positive probe hybridization signals and h ad sequences containing type A, B, or B-variant fusion patterns. PCR amplif ication of PML/RARalpha was complete in 22 minutes, and the entire test req uired 41/2 hours. This method permits exceptional turnaround time and is an alternative to cytogenetics and slower PCR assays.