A hypodiploid clone and its duplicate in acute lymphoblastic leukemia.

Examination of the bone marrow of a 63-year-old man who had acute lymphoblastic leukemia revealed a population of cells with 32 chromosomes and another population with 64 chromosomes, the karyotypical exact duplicate of the first clone. The karyotypic evolution was studied and the findings compared with those described in two similar cases previously reported. It is postulated that severe hypodiploidy is associated with reduced capability of cellular survival, promoting a strong tendency for duplication.