Chronic myeloid leukemia (CML) is a myeloproliferative disorder created by reciprocal translocation of the Abelson (ABL) 1 oncogene on chromosome 9 and the breakpoint cluster region (BCR) on chromosome 22; referred to as t(9;22) thus known as the Philadelphia (Ph) chromosome. Here, BCR is linked to chronic myelogenous leukemia, BCR-ABL1 positive.