A case of acute lymphoblastic leukemia with severe hypodiploidy.

A case of acute lymphoblastic leukemia with a severe hypodiploid chromosome constitution is reported. The modal chromosome number was 36, and the karyotype of these cells was 36,X, -X, -2, -3, -5, -7, -9, -12, -13, -15, -16, -17, -20, +21, +mar,del(1) (p13.1p22.3),inv(3)(q13.3q29). In addition to a haploid set, extra copies of chromosomes #6, #10, #14, #18, and #21 were found, as in most cases with severe hypodiploid karyotypes. A second, near-triploid cell line was also observed. An examination of chromosomal heteromorphisms suggested that the severe hypodiploid clone originated either from a near-triploid cell or from a common precursor cell.