Cytogenetic mapping of the trisomic segment of chromosome 15 in murine T-cell leukaemia.

A NONRANDOM cytogenetic change in the form of trisomy of chromosome 15 is associated with mouse T-cell leukaemia induced by various agents, such as Gross, Rad and Moloney leukaemia viruses, X rays and a chemical carcinogen, 7,12-dimethylbenz(a)anthracene (DMBA)1–4. The uniformity of the chromosomal change and its apparent independence of the inducing agent suggest that it plays an important and perhaps decisive part in the neoplastic transformation of the mouse T lymphocyte. During our studies of the role of chromosome 15 and related factors in lymphoma development, we have investigated whether any particular region of the chromosome needs to be duplicated. Using DMBA to induce T-cell leukaemias in mice carrying chromosome 15 translocations, we have found, and now report that the duplicated chromosome segment is located distal to the T6 breakpoint of chromosome 15.