The value of fluorescence in situ hybridization for the detection of 11q in multiple myeloma.

Objective: A large number of chromosomal abnormalities have been detected in multiple myeloma (MM). The most frequent are chromosome 13q deletions and translocations affecting the immunoglobulin heavy chain gene (IGH). Recent studies using comparative genomic hybridization (CGH) have shown that gains of 11q represent one of the most frequent genomic changes in MM. However CGH is not generally used in routine clinical laboratories.

Methods: In the present study, efficiency of fluorescent in situ analysis (FIS)H analysis in the detection of 11q abnormalities in MM patients was investigated. Cytogenetic and FISH studies with three different specific probes for the regions containing the genes BCL1 (11q13), ATM (11q22) and MLL (11q23) were simultaneously performed in 52 patients: 9 cases with 11q abnormalities detected by conventional cytogenetics and 43 cases without 11q abnormalities. FISH analysis identified 11q aberrations that were undetected by cytogenetics in 16 out the 43 cases (37%).

Results: Gains on 11q were present in 13 cases (30%) while rearrangements on 11q were observed in the remaining 3 cases. No losses were found. All 11q gains involved the three regions analyzed (BCL1, ATM and MLL genes) while only rearrangements of BCL1 were observed. In all control cases the 11q alterations were confirmed by FISH. A good overall correlation between CGH and FISH was observed. Nevertheless gains on BCL1, ATM and MLL genes were observed in 3 cases displaying a normal CGH.

Conclusions: In summary, chromosomal abnormalities on 11q are frequent in MM. FISH studies demonstrate a high sensitivity at detecting this abnormality and should be used in the routine evaluation of MM.