TRANSLOCATIONS BETWEEN THE LONG ARMS OF CHROMOSOME-1 AND CHROMOSOME-5IN HEMATOLOGIC MALIGNANCIES ARE STRONGLY ASSOCIATED WITH NEOPLASMS OFTHE MYELOID LINEAGES

The clinical, morphologic, and cytogenetic features of two hematologic malignancies-one acute myeloid leukemia with minimal differentiation (ARIL-MO) and one therapy-related myelodysplastic syndrome (MDS)-with unbalanced translocations between Iq and 5q are reported. The transloc ations resulted in loss of 5q material in both cases and gain of Iq in the MDS. A compilation of previously published hematologic malignanci es with translocations involving the long arms of chromosomes 1 and 5 revealed a fetal of 23 cases-11 with unbalanced and 12 with balanced t (1;5)-with the following morphologies: II AML, three MDS, two Philadel phia-positive chronic myeloid leukemias, three chronic myeloproliferat ive disorders, three acute lymphoblastic leukemias, and one chronic ly mphocytic leukemia. Four patients had received chemotherapy including alkylating agents for a previous malignancy and one had been exposed t o thorotrast. Among the 14 patients for whom survival data exist, all except three have died. The t(1;5) was found as the sole abnormality i n six cases, whereas it was apparently secondary-occurring in a subclo ne or together with the well-known primary abnormalities t(8;21), t(9; 22), and t(15;17)-in nine cases. The breakpoints in Iq varied from 1q1 1 to 1q43, with a clustering to 1q21-23, and the 5q breaks occurred in 5q11 to 5q35, mainly in the distal 5q3 region. The unbalanced 1;5 tra nslocations resulted in gain of Iq material in eight of the 11 cases, 1q21-1qter being duplicated in four of them, and in loss of 5q, most o ften the 5q3 region, in 10 of the neoplasms. We conclude that transloc ations between Iq and 5q, although cytogenetically heterogeneous, are associated with hematologic malignancies of the myeloid lineages and w ith previous mutagenic exposure, and that t(1;5) seems to confer a poo r prognosis. (C) Elsevier Science Inc., 1997.