A myeloproliferative tumor known as chronic myelogenous leukemia (CML) is characterized by unchecked proliferation of bone marrow myeloid progenitor cells resulted from the translocation of t (9:22) producing the hallmark BCR-ABL1, a constitutively active tyrosine kinase (12). The gene discussed is BCR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.