Detection and clinical significance of rearrangements of MLL gene and its fusion gene in leukemia

Objective:To study the detection and clinical significance of the rearrangements of MLL gene and its fusion gene in leukemia.Method:Rearrangements of MLL gene of 70 leukemia patients were detected by fluorescence in situ hybridization(FISH) and 6 common MLL fusion genes were detected by nested RT-PCR.Result:9 of 70 leukemic patients were found with rearrangements of MLL gene,the incidence of which was 12.86%.5 of 9 patients were diagnosed as B-ALL.3 patients were diagnosed as AML-M5,1 patient was diagnosed as JMML.Among 5 B-ALL patients,2 patients were confirmed to express MLL/ENL fusion gene,1 patient was confirmed to express MLL/AF4 fusion gene,the other 2 patients did not express the fusion genes.Among 3 AML-M5 patients,2 patients were confirmed to express MLL/MF9 fusion gene,the other 1 patient did not express the fusion gene.The fusion gene of 1 JMML patient with rearrangements of MLL gene was MLL/ENL.Conclusion:Nested RT-PCR is a convenient and effective method to detect the fusion genes resulting from rearrangements of MLL gene.The rearrangements of MLL gene were found in B-ALL,AML-M5 and JMML.It indicates a poor prognosis.