Chromosome analysis in two unusual malignant blood disorders presumably induced by benzene.

Two patients with presumably benzene-induced malignant blood disorders with preleukemic phases were cytogenetically monitored through the courses of their diseases. Patient 1, in addition to a familial chromosome translocation [t(3;16)], developed karyotypic abnormalities in 100% of the marrow cells, including two translocation: t(9;16)] and t(4;15). Monosomy of chromosome 7 characterized the cells of patient 2. Cytogenetic monitoring of the patients at various phases of their diseases served as an important indicator of the transformation or progression of the preleukemia into frank leukemia and of the unusual behavior of such leukemic cells.