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 strongly associated with acute promyelocytic leukemia (APL). Since treatment response to a/Z-trans retinoic acid correlates directly with PML/RARalpha, 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/ RARalpha. 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/RARalpha was complete in 22 minutes, and the entire test required 41/2hours. This method permits exceptional turnaround time and is an alternative to cytogenetics and slower PCR assays.