Chronic myelogenous leukemia (CML) is a clonal disorder of the multiple pluripotent hematopoietic stem cells characterized by Philadelphia (Ph′) chromosome, which results from a reciprocal chromosomal translocation [t(9;22)(q34;q11)], in which the bcr gene on chromosome 22 is fused to the c-abl gene on chromosome 9, thereby creating a bcr-abl fusion gene [1, 2]. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.