cytogenetic abnormalities can be detected in multiple myeloma by imaging flow cytometry.

Aims: Cytogenetic abnormalities involving the gene are seen in up to 55% of patients with multiple myeloma. Current testing is performed manually by fluorescence hybridisation (FISH) on purified plasma cells. We aimed to assess whether an automated imaging flow cytometric method that uses immunophenotypic cell identification, and does not require cell isolation, can identify abnormalities.

Methods: Aspirated bone marrow from 10 patients with multiple myeloma were studied. Plasma cells were identified by CD38 and CD138 coexpression and assessed with FISH probes for numerical or structural abnormalities of . Thousands of cells were acquired on an imaging flow cytometer and numerical data and digital images were analysed.

Results: Up to 30 000 cells were acquired and chromosomal abnormalities were detected in 5 of the 10 marrow samples. FISH signal patterns seen included fused signals for and , indicating t(4;14) and t(11;14), respectively. In addition, three signals were identified, indicating trisomy 14 or translocation with an alternate chromosome. The lowest limit of detection of an abnormality was in 0.05% of all cells.

Conclusions: This automated high-throughput immuno-flowFISH method was able to identify translocations and trisomy involving the gene in plasma cells in multiple myeloma. Thousands of cells were analysed and without prior cell isolation. The inclusion of positive plasma cell identification based on immunophenotype led to a lowest detection level of 0.05% marrow cells. This imaging flow cytometric FISH method offers the prospect of increased precision of detection of critical genetic lesions involving and other chromosomal defects in multiple myeloma.