Chronic myeloid leukemia is a myeloproliferative disease that originates from pluripotent stem cells carrying a characteristic reciprocal translocation between an Abelson leukemia virus (ABL) oncogene from the long arm of chromosome 9 and the breakpoint cluster region (BCR) from the long arm of chromosome 22. The gene discussed is BCR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.