Detection of BCR rearrangement in negative and high ABL1 methylation groups. Shown are representative (composite) Southern blots of DNA restricted with EcoRI and probed with a BCR cDNA probe. The N lane contains DNA from normal colon, whereas lanes 1 through 10 contain DNA from cases of CML-ECP with either negative or high levels of ABL1 methylation (as indicated on the top of each group). The arrow points to the normal (nonrearranged band). All CML cases except those in lanes 4 and 8 contain additional bands, reflecting the presence of a BCR rearrangement. Quantitation of the rearranged band relative to the normal band showed no differences between the high versus negative methylation groups. Slight variations in the apparent size of the normal band are due to the fact that it runs at greater than 20 kb, an area that is difficult to resolve by Southern analysis.