TP53 and B-cell chronic lymphocytic leukemia: The most deleterious alterations are ones that directly ablate the p53 pathway (for example, 17p deletions or somatic mutations in the TP53 gene).5 Although deletion of the 17p locus is routinely analyzed at diagnosis using FISH, identification of CLL patients harboring more subtle but equally debilitating p53 pathway alterations (for example, inactivating p53 mutations) remains challenging due to a lack of rapid and cost-effective diagnostic tools.