Ibrutinib: Ibrutinib is an irreversible Bruton’s tyrosine kinase (BTK) inhibitor that impedes B-cell proliferation and survival, and is commonly used in the treatment of various malignancies, including mantle cell lymphoma, chronic lymphocytic leukemia, and Waldenstrom’s macroglobulinemia. The gene discussed is BTK; the disease is B-cell chronic lymphocytic leukemia.