The molecular hallmark of CML is the Philadelphia chromosome, which involves the fusion of the v-abl Abelson murine leukemia viral oncogene homologue 1 (ABL1) gene on chromosome 9 with the breakpoint cluster region (BCR) gene on chromosome 22 [1]. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.