Bruton’s tyrosine kinase (BTK) inhibitors such as zanubrutinib and acalabrutinib are increasingly replacing chemotherapy-based regimens, especially for patients with mantle cell lymphoma (MCL), chronic lymphocytic leukemia (CLL) (Burger, 2019) and small lymphocytic lymphoma (SLL) (Abbas and Wierda, 2021; Tam et al., 2021). The gene discussed is BTK; the disease is B-cell chronic lymphocytic leukemia.