(A) Pa methylation analysis in different phases of CML: 201 samples of 99 CML patients and 12 samples of non-CML patients underwent molecular analysis. The bars represent the ratio of samples characterized by patterns A, B, or C in each phase of the disease. The numbers (N) above the bars indicate the number of samples of a given pattern. (B) PCR analysis of Pa methylation of an individual patient in different phases of the disease: genomic DNA was cut with BamHI (1), Msp I (2), Bgl II (3), Sac II (4), and Hpa II (5). After digestion, samples were amplified by PCR and analyzed on ethidium-bromide agarose gel. On diagnosis, the patient displayed pattern A. Nineteen months later, the patient was still in the chronic phase, but the Sac II site was already methylated (pattern B). After an additional 5 months, the patient was in blastic crisis with evidence of methylation at both the Sac II and the Hpa II sites (pattern C).