CML is a myeloproliferative disorder and it was first described (Nowell and Hungerford, 1960) as a shortened chromosome 22 (within the Bcr locus) and a reciprocal translocation that transfers the c-abl proto-oncogene from the chromosome 9–22 (Lugo et al, 1990; McWhirter and Wang, 1991). Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.