Ibrutinib (IMBRUVICA®) is an irreversible Bruton tyrosine kinase (BTK) inhibitor indicated as a single-agent or in combination regimens for the treatment of chronic lymphocytic leukemia (CLL) [7], mantle cell lymphoma (MCL) [8] and Waldenström’s macroglobulinaemia (WM) [9]. The gene discussed is BTK; the disease is mantle cell lymphoma.