Chromosome pattern of leukemias induced in mice with normal karyotype and with T/1:17/190Ca chromosome translocation.

The chromosome pattern of leukemias induced by gamma-irradiation in the translocation T190/tf and in the genetically related tf/tf strain was analyzed. The degree of variation in chromosome numbers was similar in both experimental groups. Karyotypically, the tumors of both strains showed slight and less frequent higher degree of variability. The most consistent karyotypic change was trisomy of chromosome 15, whose frequency was similar in both strains. In one of the leukemias a marker chromosome derived by translocation involving chromosome 15 was identified. Comparison of the breakpoint in this translocation with literature data on other translocations of chromosome 15 found in leukemias enabled narrowing the region on chromosome 15 containing the postulated genes essential for murine leukemogenesis. The incidence of leukemias was lower in the T190/tf translocation strain than in the tf/tf strain with normal karyotype.