CML is the most common form of chronic myeloproliferative diseases and is characterized by a balanced genetic translocation, t(9;22), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.