 The Philadelphia translocation, t(9;22)(q34;q11), is the microscopically visible product of recombination between two genes, ABL1 on chromosome 9 and BCR on chromosome 22, and gives rise to a functional hybrid BCR-ABL1 gene with demonstrated leukemogenic properties.     ///    "For the present study, we carried out a detailed analysis of genomic BCR and ABL1 sequences to identify, classify, and locate interspersed repeat sequences and to relate their distribution to precisely mapped BCR-ABL1 recombination sites. "    ///    These findings counter the suggestion that occurrence of Alu at BCR-ABL1 recombination sites is likely by chance because of the high density of Alu in these two genes. 