A classic example of this is the formation of the Philadelphia chromosome in chronic myelogenous leukemia (CML) arising from a translocation between chromosomes 9 and 22, creating a fusion gene known as BCR-ABL1 that results in upregulated tyrosine kinase activity [12,17,24]. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.