Karyotype conversion in two patients with chronic myeloid leukaemia after busulphan-induced marrow hypoplasia

We report two patients with chronic myeloid leukaemia (CML) developing hypoplasia and karyotype conversion after conventional busulphan therapy. Initially, the percentage of Ph-positive metaphases in marrow for both patients was 100%, which steadily diminished up to a complete disappearance in case 1 and decreased dramatically in case 2 following hypoplasia. Thereafter Southern blot and RT-PCR assays revealed no abnormalities. Both patients have survived 9 years and remained in good clinical and haematological remission without any treatment until recently. We believe that the high sensitivity to busulphan therapy result in hypoplasia and karyotype conversion, which contributed to prolonged survival.