OBJECTIVETo investigate the efficiency of direct fluorescence in situ hybridization (D-FISH) versus FISH on CD138 immunomagnetic sorting myeloma cells (MACS-FISH) to detect the cytogenetic abnormalities of multiple myeloma.

METHODSThirty-one patients with multiple myeloma (MM) were detected by D-FISH and MACS-FISH, using 5 probes, including 1q21, D13S319, RB1, IgH, P53. The IgH rearrangement positive patients were further examined by 3 IgH rearrangement subtype FISH probes including IgH/FGFR3, IgH/MAF and IgH/CCND1.

RESULTSMetaphase karyotyping revealed cytogenetic abnormalities in 5 cases (16.1%), clonal aberrations were detected in 13 cases(41.9%) by D-FISH, while 25 case(80.6%) with clonal aberrations by MACS-FISH. The results between these 2 FISH methods were significantly different (P=0.042). The detection frequency of clonal aberration by each probes of D-FISH was 22.6%,25.8%,29%,38.7% and 9.7% respectively for 1q21 amplification, D13S319 deletion,RB1 deletion, IgH rearrangement and P53 deletion, compared with 48.4%,45.2%,48.4%,67.7% and 16.1% respectively by MACS-FISH. The 2 FISH methods were well consistent when the percentage of plasma cells was ≥20% in bone marrow smears. When the percentage of plasma cells was<20% in bone marrow smears, the difference between these 2 methods was very statistically significant (P=0.00).

CONCLUSIONMACS-FISH can obviously improve the detection efficiency of cytogenetic abnormalities in patients with MM. Conventional cytogenetics combined with MACS-FISH is an ideal efficient method to detect the cytogenetic abnormalities in MM patients, and should be applied widely, especially for those patients with the plasma cells <20% in bone marrow smears.