Secondary chromosome aberrations in the acute leukemias

Information was retrieved from a computer-based data bank about additional chromosome aberrations in patients with acute lymphatic or nonlymphatic leukemia (ALL or ANLL) and one of the following primary rearrangements: In ALL t(9;22), t(11;14), t(1;19), t(4;11), t(8;14), and del(6q); in ANLL t(9;22), t(6;9), t(8;21), t(15;17), t(9;11), inv(16), and del(20q). The distribution of secondary changes was nonrandom. Chromosomes #1, #7, #8, and #9 were frequently involved in both disease groups, albeit with some pointed differences regarding the types of rearrangements making up the majority of aberrations. Chromosome #6 was clearly more affected in ALL, whereas, loss of a sex chromosome was largely restricted to ANLL patients. Differences between specific subtypes were detectable in both ALL and ANLL. Sex chromosome loss occurred almost exclusively in patients with t(8;21), who also tended to have del(9q) and/or trisomy 8. On the other hand, patients with t(15;17) often had del(7q) or monosomy 7, trisomy 8, and del (9q) as part of their karyotypes. None of the patients with inv(16) had del(9q). Instead, structural aberrations of chromosomes #7, #16, and #19 were fairly numerous in this subgroup, as was trisomy 8. Structural changes of #1, particularly translocations and duplications, were especially frequent in ALL patients with primary rearrangements t(8;14) or del(6q). In both ALL and ANLL, patients with t(9;22) had similar additional changes, often +8, -7, and/or +Ph. The findings indicate that the initial cytogenetic change is an important factor in determining the nature of subsequent chromosomal abnormalities developing in the malignant clone.