While the current CML prevalence of 24,000 affected patients in the United States (http://www.leukemia-lymphoma.org) is relatively low, it is expected to increase significantly over the next 20 years as a result of widespread use of BCR-ABL tyrosine kinase inhibitor (TKI) therapy. This evidence concerns the gene BCR and chronic myelogenous leukemia, BCR-ABL1 positive.