Relevance of trisomy 15 and other chromosome abnormalities in spontaneous AKR leukemia of mice with and without Robertsonian rearrangement.

The types and frequencies of chromosomal abnormalities in spontaneous AKR leukemia are presented: 45% to 58% of leukemic animals exhibit chromosome abnormalities; trisomy of chromosome 15 (Ts 15) occurs as the predominant chromosome abnormality not only in AKR/J but also in two AKR sublines characterized by the presence of two or one Robertsonian biarmed translocation Rb (6.15) of the chromosomes 6 and 15. Most often a triplication of the whole Rb (6.15) is found in Rb (6.15) homozygotes corresponding to combined Ts 6 + Ts 15. In the Rb (6.15) heterozygotes both trisomy of the biarmed (6.15) and of the acrocentric 15 is observed. Centric fission of the (6.15) chromosome is also possible in Rb (6.15) homozygotes resulting in Ts 15 without simultaneous Ts 6. Trisomies of other chromosomes are found either in addition to Ts 15 or as the only abnormality. If the data of Dofuku et al. (1975) are considered, abnormal karyotypes in AKR leukemia show Ts 15 in 90%, Ts 12 and Ts 17 in 18%-20%, and Ts 3, Ts 10 and Ts 14 in 8%-10% of the cases.