Assessing chromosomal abnormalities in leukemias by imaging flow cytometry

Chromosome analysis assists in the diagnostic classification and prognostication of leukemias. It is typically performed by karyotyping or fluorescent in situ hybridization (FISH) on glass slides. Flow cytometry offers an alternative high throughput automated methodology to analyze chromosomal content. With the advent of imaging flow cytometers, specific chromosomes and regions of interest can be identified and enumerated within specific cell types. The inclusion of immunophenotyping increases the specificity of this technique to ensure only the leukemic cell is analyzed. With many thousands of cells acquired, and neoplastic cells of interest identified by antigen expression, this technology has expanded the role of flow cytometry for cytogenomics in oncology. Applications to date have focused on hematological malignancies to detect aneuploidy (chromosome gains and losses) and structural defects (e.g., deletions; translocations) of diagnostic or prognostic significance at the time of diagnosis. With limits of detection of 1 cytogenetically abnormal cell in 100,000, also makes this new flow cytometry protocol eminently suitable for monitoring low level disease, detecting clonal evolution after therapy and identifying circulating tumor cells. The technique is equally applicable to solid tumors, many of which have chromosomal aberrations, with selection of appropriate immunophenotypic markers and FISH probes.