For example, chronic myeloid leukemia (CML) and asubset of acute lymphocytic leukemia (ALL) are causally linked tothe expression of BCR-ABL, a gene fusion product that arises on thePhiladelphia chromosome, a translocation between human chromosomes22 and 9.2 Different versions of the fusionprotein are associated with the different forms of leukemia. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.