Methylation topology of the ABL1 promoter region. The region amplified corresponds to coordinates −473 to +46 with respect to the start of exon 1a or coordinates 37352 to 37871 of GenBank sequence U07563.42 The relative position of dots on the diagram corresponds to the relative position of CpG dinucleotides along the island. Yellow dots indicate methylated CpG dinucleotides; blue dots indicate unmethylated CpG dinucleotides. Amplification products obtained from total peripheral blood and/or bone marrow mononuclear cells were cloned and individual clones were sequenced on a fluorescent sequencer. The designation “CML blast crisis cell lines” refers to cell lines EM2, BV173, and KBM5. Patients 469 and 1457 were in accelerated-phase CML when samples were collected and patient 424 was in blast crisis. For each patient, several clones of methylated DNA are depicted alongside a representative clone of unmethylated DNA.