Breakpoint cluster region (BCR) gene rearrangement studies in chronic myeloid and acute lymphoblastic leukemias

Deoxyribonucleic acid (DNA) of twenty chronic myeloid leukemia (CML) and thirty acute lymphoblastic leukemia (ALL) patients were analysed by Southern hybridization. The DNA was digested with BglII and hybridized with a 4.5-kilobase (kb) ph1/bcr-3 DNA probe. All the 20 CML patients showed gene rearrangement within a 5.8-kb segment (the major breakpoint cluster region, M-bcr) of the breakpoint cluster region (bcr) gene of chromosome 22, indicating the presence of the Philadelphia chromosome. M-bcr rearrangement at the bcr gene of chromosome twenty-two was not detected in all the thirty ALL patients (nine adults and twenty-one children) and two normal controls.