Multiplex-polymerase chain reaction assay for the detection of prognostically significant translocations in acute lymphoblastic leukemia

Background and Objectives. The presence of specific chromosomal translocati ons in acute lymphoblastic leukemias (ALL) plays an important role in deter mining the prognosis of the patients. Our aim is to develop a highly sensit ive and specific method to screen simultaneously for the four most frequent translocations in ALL: t(9;22), t(1;19), t(4;11), t(12;21). Design and Methods. Our approach uses a multiplex-polymerase chain reaction (PCR) method, which involves two rounds of PCR using fluorescence-labeled nested primers. The chimeric transcripts resulting from these translocation s can be identified by agarose gel electrophoresis or by fluorescence analy sis. To validate this method we carried out the analysis in 42 pediatric AL L samples previously studied by cytogenetic and fluorescent in situ hybridi zation (FISH) techniques. Results. In all samples with a known translocation detected by cytogenetic or FISH techniques, the same translocation was identified by the multiplex- PCR assay. Moreover, with this method we detected rearrangements in five pa tients in clinical remission and in two patients at diagnosis for whom kary otypes were normal and rearrangements had not been detected. The applicatio n of this multiplex-PCR assay was also useful in cases without cytogenetic results. Interpretation and Conclusions. These results show that the multiplex-PCR m ethod allows reliable, sensitive and rapid detection of the prognostically significant translocations in ALL. We believe that this assay combined with cytogenetic analysis should be the strategy of choice for the initial diag nostic phase of acute lymphoblastic leukemia, and that it could be used not only at diagnosis but also to follow-up these alterations in remission sam ples without previous controls. (C) 2001, Ferrata Storti Foundation.