Ph1-positive acute leukemia with a 17q;21q translocation.

Chromosome studies on the neoplastic cells of an adult patient with poorly differentiated acute leukemia revealed two Ph1-positive subpopulations, with and without a 17q;21q (q22;q22) translocation. The breakpoints appeared to be the same as in the 8;21 and 15;17 translocations of acute mytelogenous leukemia (AML) and acute promyelocytic leukemia (APL), emphasizing the significance of rearrangements involving these sites in the pathogenesis of acute leukemia. Terminally, there was clonal evolution, with the new predominant subline having an additional translocation, 1q;19q, resulting in trisomy for most of 1q and, apparently, additional selective advantage.