OBJECTIVETo evaluate the possibility of applying oligonucleotide microarrays for detection of the fusion genes in childhood acute lymphoblastic leukemia (ALL).

METHODSTo detect five types of fusion genes emerging frequently in childhood ALL including TEL/AML1, E2A/PBX1, BCR/ABLp190, BCR/ABLp210, MLL/AF4, probes were designed, synthesized and spotted on the chemical-material-coated-glass plates in array. The total RNAs were extracted from patients' bone marrow or peripheral blood cells at the beginning of diagnosis, analyzed by multiplex nested reverse-transcription-polymerase chain reaction (RT-PCR), and labeled by fluorescein. The products of RT-PCR were hybridized with microarray in order to detect specific types of fusion genes in leukemia cells.

RESULTSDistinctive hybridization signals were obtained for internal positive control and specific types of fusion genes. TEL/AML1 gene was found positive in 2 of the 36 cases, E2A/PBX1 gene in 3, BCR/ABLp190 gene in 2, BCR/ ABLp210 gene in one, and MLL/ AF4 gene in one. The results of the microarray and RT-PCR were consistent.

CONCLUSIONThe microarray-based assay could screen 5 types of chromosome structural aberrations and the splice variants at the same time. It can provide reliable and helpful information for patient stratification, evaluation of therapeutic effects and prediction of prognosis in childhood ALL, although there are both advantages and disadvantages in applying this new method.