The loss of chromosome 7 material (monosomy 7, -7 or deletion of its long arm [del(7q)]) is among the most frequent cytogenetic abnormalities in myeloid malignancies, affecting up to 10-20% of cases. It has been found to be associated with the occurrence of myeloid leukemia, myelodysplastic syndromes and relapsed acute myeloid leukemia in both adults and children.
In recent years, the role of recessive tumor suppressor genes in -7/del(7q) tumorigenesis has been studied using microarray comparative genomic hybridization and high-throughput sequencing. These approaches have led to a better understanding of the role of TSGs in disease development and pathogenesis.
A number of gene alterations were identified in patients with -7 and del(7q) and the most common ones were loss of TET2, loss of MLL3, and loss of EZH2. These alterations were not present in normal cells and may have been induced by mutations in additional genes involved in myeloid leukemia or myelodysplastic syndrome progression.
To further characterize these alterations, interphase FISH was performed on BM and PB leukemic cells. DNA LSI D7S 486/7q31 spectrum orange/CEP 7 spectrum green control (Vysis, USA) were used as probes. Hybridization was performed according to the manufacturer’s instructions. Slides were counterstained and viewed by a fluorescent microscope with DAPI, orange and green filters to visualize the fluorescence signals.
The results suggest that patients with -7 and del(7q) have a lower overall survival (OS) than patients with normal chromosome 7. This may be because these patients are more likely to experience relapse or resistance to therapy.