Reverse transcriptase polymerase chain reaction (RT-PCR) for quantitative detection of t(15;17) PML-RARA, a recurrent genetic abnormality found in acute promyelocytic leukemia (APL). This RNA-based test detects all three gene fusion patterns: type A (short, S-form, bcr-3), type B (long, L-form, bcr-1), and type B variant (variable, V-form, bcr-2).