High resolution chromosomes of the t(9;22) positive leukemias

A combined bromodeoxyuridine (BrdU) and actinomycin D (AMD) treatment of methotrexate (MTX) synchronized bone marrow cells from four patients with chronic myelogenous leukemia (CML), and two each with acute lymphocytic (ALL) and acute nonlymphocytic (ANLL) leukemia were used to define the breakpoints involved in the t(9;22) found in subgroups of these three disorders. An additional 20 patients with CML were studied with the MTX technique alone. All cases showed the same breakpoints at subbands 9q34.1 and 22q11.2. In CML, it was possible to further define the breakpoint of chromosome 22 to subband q11.21.