Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm defined by the presence of the Philadelphia chromosome (Ph), which is a result of reciprocal translocation of the Abelson (ABL) gene on chromosome 9 and the breakpoint cluster region (BCR) gene on chromosome 22. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.