Chronic myeloid leukemia (CML) is a malignant hematopoietic stem cell disease characterized by the presence of Philadelphia chromosome, t(9:22)(q34:q11), resulting in the BCR-ABL fusion gene which encodes for a constitutively activated tyrosine kinase [1]. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.