Translocation between chromosomes 1 and 9 in childhood acute lymphoblastic leukemia.

A case of a non-T, non-B acute lymphoblastic leukemia with a translocation between chromosomes #1 and #9 is described. The breakpoints in these chromosomes were determined to be at bands 1q23 and 9p22, respectively. The breakpoint in chromosome #1 was at the same site as that in a subgroup of acute lymphoblastic leukemia with t(1;19), and the breakpoint in #9 was the same as that in t(9;11)(p22;q23) in acute monoblastic leukemia. We discuss the possible association between these chromosome bands (1q23, 9p22, 11q23, and 19p13) and the morphologic features of the leukemic cells. The breakpoint in chromosome band 1q23 may be specifically associated with acute lymphoblastic leukemia.