Double 20q- anomaly in myelodysplastic syndrome.

Two patients with myelodysplastic syndrome (MDS) whose bone marrow (BM) cells contained duplicate 20q- chromosomes are reported. No particular differences between the hematologic findings of four patients with single 20q- and the two patients with double 20q- chromosomes were noted. No differences in breakpoints on the 20q- chromosome were noted in these six patients, and the breakpoint was identified as 20q11. The presence of double 20q- chromosomes in MDS patients suggests, however, that the deleted chromosome has oncogenic activity.