title: tdic(9;12): a nonrandom chromosome abnormality in childhood B-cell precursor acute lymphoblastic leukemia: a Pediatric Oncology Group Study.
abstract: In a review of 432 children with newly diagnosed acute lymphoblastic leukemia (ALL), we identified a new nonrandom translocation, tdic(9;12)(p1?1;p1?2), in the leukemic marrow cells of eight patients. Seven had hypodiploid karyotypes that lacked chromosomes 9 and 12 and contained a der(12), tdic(9;12); the eighth had a pseudodiploid karyotype with two normal 9 chromosomes, one normal 12 and the der(12), tdic(9;12). Abnormalities involving chromosomes other than 9 and 12 were noted in four of the eight patients. All cells with the tdic(9;12) expressed both the common ALL antigen and HLA-DR. Cytoplasmic immunoglobulin, a marker of pre-B ALL, was detected in one case with the tdic(9;12) but was absent in the other seven. Our results suggest that the tdic(9;12)(p1?1;p1?2) rearrangement is specifically associated with leukemic B cell precursors.
mesh_terms: D001402:B-Lymphocytes; D002648:Child; D002869:Chromosome Aberrations / Q000235:genetics*; D002871:Chromosome Banding; D025063:Chromosome Disorders; D002881:Chromosomes, Human, Pair 12; D002899:Chromosomes, Human, Pair 9; D006801:Humans; D007945:Leukemia, Lymphoid / Q000235:genetics*; D014178:Translocation, Genetic