DETECTION OF THE AML1 ETO FUSION TRANSCRIPT IN THE T(8-21) MASKED TRANSLOCATION IN ACUTE MYELOGENOUS LEUKEMIA/

The fusion transcript AML1/ETO was detected in the bone marrow of two t(8;21)-negative acute myelogenous leukemia (AML) patients by means of reverse transcription-polymerase chain reaction. This fusion transcri pt is identical to the one transcribed from the t(8;21) translocation base, as deduced from (a) the size and restriction pattern of the ampl ified DNA fragment and (b) the DNA sequence analysis of the fusion jun ction. We also showed that the ETO gene is highly expressed in these p atients, much as it is in the t(8;21)-positive AML. Southern blot anal ysis showed rearrangement of the AML1 gene in one of the patients. Tog ether, our results demonstrate that there is a masked t(8;21) transloc ation in AML that is not detectable by cytogenetic analysis but is abl e to transcribe an AML1/ETO fusion transcript similar to that transcri bed in t(8;21)-positive AML-M2 patients.