First, the initial intra-clonal heterogeneity of the CML clone and the existence of a specific profile of the immature CD34+ subpopulation [34,77] indicate that although BCR-ABL is expressed in all the cells of the clone, the DNA methylation alteration profile is different between immature and mature cells. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.