Myeloid Cell Maturation Is Disrupted By Monosomy 7 or By Gain of Additional Genetic Aberrations during Clonal Evolution in Myelodysplastic Syndromes

• Published in: Blood 2014-12, Vol.124 (21), p.3244-3244
• Main Authors: Zehentner, Barbara Katharina, Cutler, Jevon, Hartmann, Luise, Johnson, Krystal, Bennington, Richard, Fritschle, Wayne, Ghirardelli, Keely, Broderson, Lisa, Chapman, Doug, Stephenson, Christine F, de Baca, Monica E, Singleton, Timothy, Wells, Denise A., Loken, Michael R.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V124.21.3244.3244

Background: Myelodysplastic syndromes (MDS) are associated with cytogenetic clones. To follow the maturation sequence of original clones and evolved subclones with additional cytogenetic abnormalities, progenitor cells, immature and mature myeloid cells were sorted by flow cytometry and analyzed separately by fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). Methods: Flow cytometry sorted cell fractions from bone marrows for sixteen patients with MDS-associated cytogenetic abnormalities were evaluated by FISH. Flow cytometric cell sorting was based on CD34+/low side scatter (SS) for progenitors, CD13+/CD16-/high SS for immature myeloid cells, and CD13+/CD16+/high SS for mature myeloid cells. Customized color labeling (spectrum orange, green and aqua) of FISH probe combinations were designed to detect and to analyze clonal evolution for each patient based on their known cytogenetic abnormalities and clonal evolution patterns. Three marrow aspirates were sorted for analysis by SNP/CGH microarray. Results: The 16 bone marrow specimens evaluated by FISH were categorized into three groups: (1) eight patients with a single, good-to-intermediate cytogenetic abnormality; (2) four patients with monosomy 7; and (3) four patients with more than one chromosome abnormality with evidence of clonal evolution by conventional cytogenetic analysis, excluding monosomy 7. The Group-1 abnormalities included deletion 20q (n=4), trisomy 8 (n=2), deletion 5q (n=1), and trisomy 11 (n=1). All specimens from this group showed FISH abnormalities in equal proportions in myeloid progenitors, immature and mature myeloid cells. Group-2 had four patients with monosomy 7. All four had monosomy 7 concentrated in the progenitor cells (45-79%) compared to immature and mature myeloid compartments (less than 9-36%). For Group-3, known original clones with single cytogenetic abnormalities (deletion 20q, monosomy 3, deletion 7q or 5q) were monitored by FISH analysis. Using customized FISH panels, the presence of subclones with additional cytogenetic aberrations (trisomy 8 in three patients and gain of a marker chromosome characterized by the centromere of chromosome 4 in a fourth patient) was assessed using single-cell resolution. The progenitor and immature myeloid compartments had the original founding clones containing a single cytogenetic abnormality at 15-34% and the subclones with the additional aberrations at 23-76%. In contrast, the mature myeloid cell