Chromosome 11 participation in acute lymphoblastic leukaemia in Sprague-Dawley rats.

: Five cases of spontaneous acute lymphoblastic leukaemias (ALL) of Sprague-Dawley (SD) inbred rats have been studied cytogenetically. Chromosome studies were performed on direct preparations of the lymphomas using common cytogenetic methods. For detailed karyology, G-banded preparations were used. The chromosome numbers of metaphase cells in all leukaemias were near diploidy, the majority of metaphases being pseudodiploid with 1-2 stable marker chromosomes. The most frequent change involved chromosome 11, where the translocation form of trisomy 11 or 11q+ aberration was observed. Chromosome 11 abnormalities were found in all five leukaemias studied, suggesting to be a nonrandom change. 11 q11-q12 is supposed to be the critical region involved in the genesis or progression of SD ALL. These results are in agreement with our previous observations in nine cases of SD ALL (Sladka et al., 1988).