Translocation (8;21) and its variants in acute nonlymphocytic leukemia. The relative importance of chromosomes 8 and 21 to the genesis of the disease.

Chromosome analysis was performed in 25 patients with acute nonlymphocytic leukemia (ANLL), mostly of the M2 type. Eighteen had the standard translocation, t(8;21)(q22;q22), four had complex translocations involving 1p36, 11p13, 17p11, and 17p23, respectively, with chromosomes 8 and 21, and the remaining three patients had simple translocations, one with t(3;21)(p14;q22) and two with t(16;21)(p11;q22), without involving chromosome 8. Chromosome abnormalities additional to t(8;21) and its variants that were most frequently observed were -X, -Y, and del(9). Complex translocations are thought to be derived from the standard translocation and to be essentially similar in nature. The finding that chromosome 21 was involved in all of the standard, simple, and complex translocations, and that chromosome 8 was not involved in simple variants suggest a greater weight of chromosome 21 in the relative importance of the two chromosomes to the genesis of ANLL.