Comparative Analysis of 3q26 (EVI1 MDS1) Breakpoints in CML-BP and AML by Interphase FISH Using Bacterial Artificial Chromosome Probes
KJ Jabbar, P Lennon, LJ Medeiros, J Abraham, P Hu, P Lin. MD Anderson Cancer Center, Houston, TX
Background: Chromosome rearrangements involving 3q26 occurs in acute myeloid leukemia (AML), myelodysplastic syndrome (MDS) and chronic myelogenous leukemia in blast phase (CML-BP) resulting in EVI1/MDS1 gene disruption. The 3q26 rearrangements are heterogeneous with variable breakpoints in different diseases making FISH analysis challenging. One study, however, found in 3 of 4 CML-BP carrying the inv(3)(q21q26) that the breakpoint is located within the EVI1 gene detectable by BAC clone RP11-82c9 (BJH 2007;136:806-813). Based on this report, we performed a larger scale study comparing CML-BP and AML with inv(3)(q21q26) using the same clone.
Design: Cases of AML, CML-BP with inv(3)(q21q26) from 1999-2007 were searched from our database and those with adequate materials were analyzed. A dual-color interphase fluorescence in situ-hybridization assay using RP11-82c9 (labeled green) and centromere 3 (labeled red) were performed. Presence of split green signals indicates EVI1 gene rearrangement.
Results: We analyzed 18 cases with inv(3)(q21q26), 11 CML-BP and 7 AML. The RP11-82c9 clone identified EVI1 rearrangement in 13/18 (72%) cases, including 10 (91%) CML-BP compared with 3/7 (43%) of AML cases. The positive signals ranged from 6.5% to greater than 32 % in the CML-BP cases and 6% to greater than 32% in the AML cases. One case of CML-BP had 3.5% signals and was considered indeterminate.
Conclusions: The RP11-82c9 clone is preferentially involved in CML-BP and a subset of AML with inv(3)(q21q26). This clone is useful for detection of residual disease.
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 182, Wednesday Afternoon