ACUTE-LEUKEMIA WITH STRUCTURAL REARRANGEMENTS OF CHROMOSOME-3

Cytogenetic investigations have distinguished at least 3 distinct clin ical-cytogenetic syndromes of hematopoietic malignancy with structural rearrangement of 3q. The majority of cases have breakpoints at both 3 q21 and 3q26, frequently associated with monosomy 7, abnormal thrombop oiesis, and adverse outcome. Cases with only one of these breakpoints may have milder features of the syndrome. A subgroup with t(3q;5q) occ urs in younger patients, occasionally with megakaryocytic dysplasia bu t rarely having thrombocytosis. The t(3;21) is encountered in secondar y leukemias or after chemotherapy of myeloproliferative disorders. The genetic deregulations associated with each of these syndromes involve distinct genes on 3q. The majority of cases of acute leukemias with 3 q rearrangements have a poor prognosis and do not respond to current m odes of therapy.