OBJECTIVETo explore the clonal evolution of monosomy 7 in patients with aplastic anemia (AA).

METHODSMonosomy 7 (-7) in 81 AA patients with normal karyotype at diagnosis and 46 AA treated with immunosuppressive therapy (IST) and more than 6 months of recombinant human granulocyte colony-stimulating factor (rhuG-CSF) were detected by interphase- fluorescence in situ hybridization (FISH) retrospectively.

RESULTSThere were 5.4% - 7.6% of -7 cells in 11 (13.6%) of 81 patients at diagnosis, the survival and response rate to IST in -7 positive patients did not differ significantly from that in -7 negative patients (P = 0.481, 0.865); -7 cells disappeared after IST in all of the 11 patients including 5 received long-term rhuG-CSF therapy, and none of them evolved to myelodysplastic syndromes/acute myeloid leukemia (MDS/AML) at a median follow-up of 44 months. Serial assessments of -7 clones were performed in 46 patients, none of whom detected -7 clones 3-6 months after IST, but -7 recurrence in 5 patients 12 - 15 months after IST. At a median follow-up of 48 months, FISH identified 6 patients with -7 clones while the conventional cytogenetic analysis (CCA) recognized in 5. Moreover, the first demonstration of -7 by FISH was 3 - 18 months earlier than that by CCA. All of the 6 patients with FISH detected -7 evolved to MDS/AML with -7 and four of them were retrospectively analysed for in samples at -7 diagnosis of AA, but none of them was positive.

CONCLUSIONSMonosomy 7 exists in a part of AA patients, but the preexisting -7 cells seems neither associated with fatality nor evolvation to MDS/AML. rhuG-CSF might facilitate the expansion of -7 clones; It is necessary to monitor -7 in AA, especially when received long-term rhuG-CSF therapy.