ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Most CML patients present a BCR-ABL1 fusion downstream of the exons 13 and 14 of the BCR gene (Figure 1), originating mRNA transcripts with an e14 and/or an e13 junction, resulting in a 210 kDa chimeric protein-p210 BCR-ABL1 (M-BCR) [9].