ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Chronic myeloid leukemia (CML) is caused by a chromosomal translocation between the Abelson (Abl) gene on chromosome 9 and the breakpoint cluster region (BCR) on chromosome 22, resulting in the constitutively active BCR-ABL tyrosine kinase that promotes myeloid proliferation (Jain, Kantarjian, & Cortes, 2013).