t(1;3)(p36;p21) is a recurring therapy-related translocation.

Chromosome bands 1p36 and 3p21 are known to be recurring breakpoints in therapy-related (t-) leukemia. We identified a recurring translocation, t(1;3)(p36;p21), in eight patients with various hematologic malignancies: three patients with ALL, one with chronic myelogenous leukemia (CML) in accelerated phase (AP), two with MDS, and two with AML(M3). Five of the eight patients had a history of chemotherapy, including alkylating agents in three, before the translocation was detected. In two of these five patients, the t(1;3)(p36;p21) emerged only at relapse or in the accelerated phase of CML. The karyotypes of the patients were complex, including -7 and structural abnormalities of 5q, 6q, 7q, 9p, and 11q23. Survival time varied among patients (25 days to more than 16 years). Using FISH with 13 1p35-36 cosmid probes (tel-FB12-CA5-G7-FD2-CB1-ED8-FD9-G32-AE3-G50-AD8-GG4-G43-cen), we delineated the 1p36 breakpoint in two patients with MDS and ALL as lying between FB12 and FD2 (between BAC47P3 and PAC963K15), with a small deletion near the breakpoint in both cases. In the patient with MDS, there was also a deletion at 3p21.3, as detected with the cosmid probe cosNRL9. The results of the present study suggest that t(1;3)(p36;p21) in hematologic diseases is associated with prior exposure to mutagens, including alkylating agents.