A near haploid clone: 24,XY, t (9; 22) (q34; q11) from a patient in blast crisis of chronic myeloid leukaemia.

Chromosome studies on bone marrow in a patient with chronic myeloid leukaemia (CML) revealed a mosaic picture with a dominant clone of 24, XY, t (9; 22) (q34; q11). This corresponded to a preponderance of minute blasts in smears of bone marrow aspirate. It is suggested that a haploidy event rather than progressive hypodiploid loss, is responsible for the genesis of the miniature blast cells.