High-level amplification of the 11q23-24 region containing the MLL gene locus in patient 15.

(A) Results of a multiplex PCR for repeats D4S43 and MXI1 used as an internal control and microsatellite D11S1356 located in the MLL gene region. The individual amplificates show decreasing signal with increasing product size in reaction 15 M (tumor) as compared with 15 N (control); however, the 208 bp allele of the D11S1356 does not follow this pattern and its signal is actually increased. Comparison of the D11S1356 208/198 bp allele ratios in the normal and tumor tissues, 0.7 and 3.09, respectively, shows an increase of the 208 bp allele signal by 341% in the tumor. (B) CGH results for chromosome 11 performed with the same tumor DNA showing high-level amplification of the 11q23-24 region. The cut-off values for losses (0.80) and gains (1.25) are depicted as red and green lines, respectively. (C) Interphase FISH assay performed with the YAC clone 785c6 (green) localized to the MLL gene locus and the control YAC 878c12 (red) assigned to 11q21, showing multiple copies of the MLL gene region. The patient was tetraploid, the fourth signal associated with the control YAC is out of focus.