Chromosomes and causation of human cancer and leukemia. XXIII. Near-haploidy in acute leukemia.

A case of acute lymphoblastic leukemia (ALL) with a near-haploid (27 chromosomes) leukemic cell population in the marrow has been described and the findings compared to those of the only other such case in the literature. In both cases the cells with 27 chromosomes, except for one chromosomal group, had karyotypic findings which were identical. Cells with 54 chromosomes, karyotypically exact duplicates of the cells with 27 chromosomes, were also encountered; on morphological basis it appeared that the marrow contained large and small lymphoblasts, possibly matching the metaphases with 54 and 27 chromosomes, respectively. The genesis of the cells with 27 chromosomes was uncertain and several postulates are discussed, as well as the relation of the findings to the cytogenetic observations encountered in ALL and their possible role in human leukemogenesis.