The appearance of the BTK inhibitors has dramatically improved the treatment of several B-cell malignancies, such as marginal zone lymphoma, Waldenström macroglobulinemia, chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and mantle cell lymphoma (MCL) [2,3,4]. The gene discussed is BTK; the disease is B-cell chronic lymphocytic leukemia.